1 /**
  2  * @license
  3  * Copyright 2006 Dan Vanderkam (danvdk@gmail.com)
  4  * MIT-licensed (http://opensource.org/licenses/MIT)
  5  */
  6 
  7 /**
  8  * @fileoverview Creates an interactive, zoomable graph based on a CSV file or
  9  * string. Dygraph can handle multiple series with or without error bars. The
 10  * date/value ranges will be automatically set. Dygraph uses the
 11  * <canvas> tag, so it only works in FF1.5+.
 12  * @author danvdk@gmail.com (Dan Vanderkam)
 13 
 14   Usage:
 15    <div id="graphdiv" style="width:800px; height:500px;"></div>
 16    <script type="text/javascript">
 17      new Dygraph(document.getElementById("graphdiv"),
 18                  "datafile.csv",  // CSV file with headers
 19                  { }); // options
 20    </script>
 21 
 22  The CSV file is of the form
 23 
 24    Date,SeriesA,SeriesB,SeriesC
 25    YYYYMMDD,A1,B1,C1
 26    YYYYMMDD,A2,B2,C2
 27 
 28  If the 'errorBars' option is set in the constructor, the input should be of
 29  the form
 30    Date,SeriesA,SeriesB,...
 31    YYYYMMDD,A1,sigmaA1,B1,sigmaB1,...
 32    YYYYMMDD,A2,sigmaA2,B2,sigmaB2,...
 33 
 34  If the 'fractions' option is set, the input should be of the form:
 35 
 36    Date,SeriesA,SeriesB,...
 37    YYYYMMDD,A1/B1,A2/B2,...
 38    YYYYMMDD,A1/B1,A2/B2,...
 39 
 40  And error bars will be calculated automatically using a binomial distribution.
 41 
 42  For further documentation and examples, see http://dygraphs.com/
 43 
 44  */
 45 
 46 /*jshint globalstrict: true */
 47 /*global DygraphLayout:false, DygraphCanvasRenderer:false, DygraphOptions:false, G_vmlCanvasManager:false */
 48 "use strict";
 49 
 50 /**
 51  * Creates an interactive, zoomable chart.
 52  *
 53  * @constructor
 54  * @param {div | String} div A div or the id of a div into which to construct
 55  * the chart.
 56  * @param {String | Function} file A file containing CSV data or a function
 57  * that returns this data. The most basic expected format for each line is
 58  * "YYYY/MM/DD,val1,val2,...". For more information, see
 59  * http://dygraphs.com/data.html.
 60  * @param {Object} attrs Various other attributes, e.g. errorBars determines
 61  * whether the input data contains error ranges. For a complete list of
 62  * options, see http://dygraphs.com/options.html.
 63  */
 64 var Dygraph = function(div, data, opts, opt_fourth_param) {
 65   if (opt_fourth_param !== undefined) {
 66     // Old versions of dygraphs took in the series labels as a constructor
 67     // parameter. This doesn't make sense anymore, but it's easy to continue
 68     // to support this usage.
 69     this.warn("Using deprecated four-argument dygraph constructor");
 70     this.__old_init__(div, data, opts, opt_fourth_param);
 71   } else {
 72     this.__init__(div, data, opts);
 73   }
 74 };
 75 
 76 Dygraph.NAME = "Dygraph";
 77 Dygraph.VERSION = "1.2";
 78 Dygraph.__repr__ = function() {
 79   return "[" + this.NAME + " " + this.VERSION + "]";
 80 };
 81 
 82 /**
 83  * Returns information about the Dygraph class.
 84  */
 85 Dygraph.toString = function() {
 86   return this.__repr__();
 87 };
 88 
 89 // Various default values
 90 Dygraph.DEFAULT_ROLL_PERIOD = 1;
 91 Dygraph.DEFAULT_WIDTH = 480;
 92 Dygraph.DEFAULT_HEIGHT = 320;
 93 
 94 // For max 60 Hz. animation:
 95 Dygraph.ANIMATION_STEPS = 12;
 96 Dygraph.ANIMATION_DURATION = 200;
 97 
 98 // Label constants for the labelsKMB and labelsKMG2 options.
 99 // (i.e. '100000' -> '100K')
100 Dygraph.KMB_LABELS = [ 'K', 'M', 'B', 'T', 'Q' ];
101 Dygraph.KMG2_BIG_LABELS = [ 'k', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y' ];
102 Dygraph.KMG2_SMALL_LABELS = [ 'm', 'u', 'n', 'p', 'f', 'a', 'z', 'y' ];
103 
104 // These are defined before DEFAULT_ATTRS so that it can refer to them.
105 /**
106  * @private
107  * Return a string version of a number. This respects the digitsAfterDecimal
108  * and maxNumberWidth options.
109  * @param {Number} x The number to be formatted
110  * @param {Dygraph} opts An options view
111  * @param {String} name The name of the point's data series
112  * @param {Dygraph} g The dygraph object
113  */
114 Dygraph.numberValueFormatter = function(x, opts, pt, g) {
115   var sigFigs = opts('sigFigs');
116 
117   if (sigFigs !== null) {
118     // User has opted for a fixed number of significant figures.
119     return Dygraph.floatFormat(x, sigFigs);
120   }
121 
122   var digits = opts('digitsAfterDecimal');
123   var maxNumberWidth = opts('maxNumberWidth');
124 
125   var kmb = opts('labelsKMB');
126   var kmg2 = opts('labelsKMG2');
127 
128   var label;
129 
130   // switch to scientific notation if we underflow or overflow fixed display.
131   if (x !== 0.0 &&
132       (Math.abs(x) >= Math.pow(10, maxNumberWidth) ||
133        Math.abs(x) < Math.pow(10, -digits))) {
134     label = x.toExponential(digits);
135   } else {
136     label = '' + Dygraph.round_(x, digits);
137   }
138 
139   if (kmb || kmg2) {
140     var k;
141     var k_labels = [];
142     var m_labels = [];
143     if (kmb) {
144       k = 1000;
145       k_labels = Dygraph.KMB_LABELS;
146     }
147     if (kmg2) {
148       if (kmb) Dygraph.warn("Setting both labelsKMB and labelsKMG2. Pick one!");
149       k = 1024;
150       k_labels = Dygraph.KMG2_BIG_LABELS;
151       m_labels = Dygraph.KMG2_SMALL_LABELS;
152     }
153 
154     var absx = Math.abs(x);
155     var n = Dygraph.pow(k, k_labels.length);
156     for (var j = k_labels.length - 1; j >= 0; j--, n /= k) {
157       if (absx >= n) {
158         label = Dygraph.round_(x / n, digits) + k_labels[j];
159         break;
160       }
161     }
162     if (kmg2) {
163       // TODO(danvk): clean up this logic. Why so different than kmb?
164       var x_parts = String(x.toExponential()).split('e-');
165       if (x_parts.length === 2 && x_parts[1] >= 3 && x_parts[1] <= 24) {
166         if (x_parts[1] % 3 > 0) {
167           label = Dygraph.round_(x_parts[0] /
168               Dygraph.pow(10, (x_parts[1] % 3)),
169               digits);
170         } else {
171           label = Number(x_parts[0]).toFixed(2);
172         }
173         label += m_labels[Math.floor(x_parts[1] / 3) - 1];
174       }
175     }
176   }
177 
178   return label;
179 };
180 
181 /**
182  * variant for use as an axisLabelFormatter.
183  * @private
184  */
185 Dygraph.numberAxisLabelFormatter = function(x, granularity, opts, g) {
186   return Dygraph.numberValueFormatter(x, opts, g);
187 };
188 
189 /**
190  * Convert a JS date (millis since epoch) to YYYY/MM/DD
191  * @param {Number} date The JavaScript date (ms since epoch)
192  * @return {String} A date of the form "YYYY/MM/DD"
193  * @private
194  */
195 Dygraph.dateString_ = function(date) {
196   var zeropad = Dygraph.zeropad;
197   var d = new Date(date);
198 
199   // Get the year:
200   var year = "" + d.getFullYear();
201   // Get a 0 padded month string
202   var month = zeropad(d.getMonth() + 1);  //months are 0-offset, sigh
203   // Get a 0 padded day string
204   var day = zeropad(d.getDate());
205 
206   var ret = "";
207   var frac = d.getHours() * 3600 + d.getMinutes() * 60 + d.getSeconds();
208   if (frac) ret = " " + Dygraph.hmsString_(date);
209 
210   return year + "/" + month + "/" + day + ret;
211 };
212 
213 /**
214  * Convert a JS date to a string appropriate to display on an axis that
215  * is displaying values at the stated granularity.
216  * @param {Date} date The date to format
217  * @param {Number} granularity One of the Dygraph granularity constants
218  * @return {String} The formatted date
219  * @private
220  */
221 Dygraph.dateAxisFormatter = function(date, granularity) {
222   if (granularity >= Dygraph.DECADAL) {
223     return date.strftime('%Y');
224   } else if (granularity >= Dygraph.MONTHLY) {
225     return date.strftime('%b %y');
226   } else {
227     var frac = date.getHours() * 3600 + date.getMinutes() * 60 + date.getSeconds() + date.getMilliseconds();
228     if (frac === 0 || granularity >= Dygraph.DAILY) {
229       return new Date(date.getTime() + 3600*1000).strftime('%d%b');
230     } else {
231       return Dygraph.hmsString_(date.getTime());
232     }
233   }
234 };
235 
236 /**
237  * Standard plotters. These may be used by clients.
238  * Available plotters are:
239  * - Dygraph.Plotters.linePlotter: draws central lines (most common)
240  * - Dygraph.Plotters.errorPlotter: draws error bars
241  * - Dygraph.Plotters.fillPlotter: draws fills under lines (used with fillGraph)
242  *
243  * By default, the plotter is [fillPlotter, errorPlotter, linePlotter].
244  * This causes all the lines to be drawn over all the fills/error bars.
245  */
246 Dygraph.Plotters = DygraphCanvasRenderer._Plotters;
247 
248 
249 // Default attribute values.
250 Dygraph.DEFAULT_ATTRS = {
251   highlightCircleSize: 3,
252   highlightSeriesOpts: null,
253   highlightSeriesBackgroundAlpha: 0.5,
254 
255   labelsDivWidth: 250,
256   labelsDivStyles: {
257     // TODO(danvk): move defaults from createStatusMessage_ here.
258   },
259   labelsSeparateLines: false,
260   labelsShowZeroValues: true,
261   labelsKMB: false,
262   labelsKMG2: false,
263   showLabelsOnHighlight: true,
264 
265   digitsAfterDecimal: 2,
266   maxNumberWidth: 6,
267   sigFigs: null,
268 
269   strokeWidth: 1.0,
270   strokeBorderWidth: 0,
271   strokeBorderColor: "white",
272 
273   axisTickSize: 3,
274   axisLabelFontSize: 14,
275   xAxisLabelWidth: 50,
276   yAxisLabelWidth: 50,
277   rightGap: 5,
278 
279   showRoller: false,
280   xValueParser: Dygraph.dateParser,
281 
282   delimiter: ',',
283 
284   sigma: 2.0,
285   errorBars: false,
286   fractions: false,
287   wilsonInterval: true,  // only relevant if fractions is true
288   customBars: false,
289   fillGraph: false,
290   fillAlpha: 0.15,
291   connectSeparatedPoints: false,
292 
293   stackedGraph: false,
294   stackedGraphNaNFill: 'all',
295   hideOverlayOnMouseOut: true,
296 
297   // TODO(danvk): support 'onmouseover' and 'never', and remove synonyms.
298   legend: 'onmouseover',  // the only relevant value at the moment is 'always'.
299 
300   stepPlot: false,
301   avoidMinZero: false,
302   xRangePad: 0,
303   yRangePad: null,
304   drawAxesAtZero: false,
305 
306   // Sizes of the various chart labels.
307   titleHeight: 28,
308   xLabelHeight: 18,
309   yLabelWidth: 18,
310 
311   drawXAxis: true,
312   drawYAxis: true,
313   axisLineColor: "black",
314   axisLineWidth: 0.3,
315   gridLineWidth: 0.3,
316   axisLabelColor: "black",
317   axisLabelFont: "Arial",  // TODO(danvk): is this implemented?
318   axisLabelWidth: 50,
319   drawYGrid: true,
320   drawXGrid: true,
321   gridLineColor: "rgb(128,128,128)",
322 
323   interactionModel: null,  // will be set to Dygraph.Interaction.defaultModel
324   animatedZooms: false,  // (for now)
325 
326   // Range selector options
327   showRangeSelector: false,
328   rangeSelectorHeight: 40,
329   rangeSelectorPlotStrokeColor: "#808FAB",
330   rangeSelectorPlotFillColor: "#A7B1C4",
331 
332   // The ordering here ensures that central lines always appear above any
333   // fill bars/error bars.
334   plotter: [
335     Dygraph.Plotters.fillPlotter,
336     Dygraph.Plotters.errorPlotter,
337     Dygraph.Plotters.linePlotter
338   ],
339 
340   plugins: [ ],
341 
342   // per-axis options
343   axes: {
344     x: {
345       pixelsPerLabel: 60,
346       axisLabelFormatter: Dygraph.dateAxisFormatter,
347       valueFormatter: Dygraph.dateString_,
348       drawGrid: true,
349       independentTicks: true,
350       ticker: null  // will be set in dygraph-tickers.js
351     },
352     y: {
353       pixelsPerLabel: 30,
354       valueFormatter: Dygraph.numberValueFormatter,
355       axisLabelFormatter: Dygraph.numberAxisLabelFormatter,
356       drawGrid: true,
357       independentTicks: true,
358       ticker: null  // will be set in dygraph-tickers.js
359     },
360     y2: {
361       pixelsPerLabel: 30,
362       valueFormatter: Dygraph.numberValueFormatter,
363       axisLabelFormatter: Dygraph.numberAxisLabelFormatter,
364       drawGrid: false,
365       independentTicks: false,
366       ticker: null  // will be set in dygraph-tickers.js
367     }
368   }
369 };
370 
371 // Directions for panning and zooming. Use bit operations when combined
372 // values are possible.
373 Dygraph.HORIZONTAL = 1;
374 Dygraph.VERTICAL = 2;
375 
376 // Installed plugins, in order of precedence (most-general to most-specific).
377 // Plugins are installed after they are defined, in plugins/install.js.
378 Dygraph.PLUGINS = [
379 ];
380 
381 // Used for initializing annotation CSS rules only once.
382 Dygraph.addedAnnotationCSS = false;
383 
384 Dygraph.prototype.__old_init__ = function(div, file, labels, attrs) {
385   // Labels is no longer a constructor parameter, since it's typically set
386   // directly from the data source. It also conains a name for the x-axis,
387   // which the previous constructor form did not.
388   if (labels !== null) {
389     var new_labels = ["Date"];
390     for (var i = 0; i < labels.length; i++) new_labels.push(labels[i]);
391     Dygraph.update(attrs, { 'labels': new_labels });
392   }
393   this.__init__(div, file, attrs);
394 };
395 
396 /**
397  * Initializes the Dygraph. This creates a new DIV and constructs the PlotKit
398  * and context <canvas> inside of it. See the constructor for details.
399  * on the parameters.
400  * @param {Element} div the Element to render the graph into.
401  * @param {String | Function} file Source data
402  * @param {Object} attrs Miscellaneous other options
403  * @private
404  */
405 Dygraph.prototype.__init__ = function(div, file, attrs) {
406   // Hack for IE: if we're using excanvas and the document hasn't finished
407   // loading yet (and hence may not have initialized whatever it needs to
408   // initialize), then keep calling this routine periodically until it has.
409   if (/MSIE/.test(navigator.userAgent) && !window.opera &&
410       typeof(G_vmlCanvasManager) != 'undefined' &&
411       document.readyState != 'complete') {
412     var self = this;
413     setTimeout(function() { self.__init__(div, file, attrs); }, 100);
414     return;
415   }
416 
417   // Support two-argument constructor
418   if (attrs === null || attrs === undefined) { attrs = {}; }
419 
420   attrs = Dygraph.mapLegacyOptions_(attrs);
421 
422   if (typeof(div) == 'string') {
423     div = document.getElementById(div);
424   }
425 
426   if (!div) {
427     Dygraph.error("Constructing dygraph with a non-existent div!");
428     return;
429   }
430 
431   this.isUsingExcanvas_ = typeof(G_vmlCanvasManager) != 'undefined';
432 
433   // Copy the important bits into the object
434   // TODO(danvk): most of these should just stay in the attrs_ dictionary.
435   this.maindiv_ = div;
436   this.file_ = file;
437   this.rollPeriod_ = attrs.rollPeriod || Dygraph.DEFAULT_ROLL_PERIOD;
438   this.previousVerticalX_ = -1;
439   this.fractions_ = attrs.fractions || false;
440   this.dateWindow_ = attrs.dateWindow || null;
441 
442   this.is_initial_draw_ = true;
443   this.annotations_ = [];
444 
445   // Zoomed indicators - These indicate when the graph has been zoomed and on what axis.
446   this.zoomed_x_ = false;
447   this.zoomed_y_ = false;
448 
449   // Clear the div. This ensure that, if multiple dygraphs are passed the same
450   // div, then only one will be drawn.
451   div.innerHTML = "";
452 
453   // For historical reasons, the 'width' and 'height' options trump all CSS
454   // rules _except_ for an explicit 'width' or 'height' on the div.
455   // As an added convenience, if the div has zero height (like <div></div> does
456   // without any styles), then we use a default height/width.
457   if (div.style.width === '' && attrs.width) {
458     div.style.width = attrs.width + "px";
459   }
460   if (div.style.height === '' && attrs.height) {
461     div.style.height = attrs.height + "px";
462   }
463   if (div.style.height === '' && div.clientHeight === 0) {
464     div.style.height = Dygraph.DEFAULT_HEIGHT + "px";
465     if (div.style.width === '') {
466       div.style.width = Dygraph.DEFAULT_WIDTH + "px";
467     }
468   }
469   // These will be zero if the dygraph's div is hidden. In that case,
470   // use the user-specified attributes if present. If not, use zero
471   // and assume the user will call resize to fix things later.
472   this.width_ = div.clientWidth || attrs.width || 0;
473   this.height_ = div.clientHeight || attrs.height || 0;
474 
475   // TODO(danvk): set fillGraph to be part of attrs_ here, not user_attrs_.
476   if (attrs.stackedGraph) {
477     attrs.fillGraph = true;
478     // TODO(nikhilk): Add any other stackedGraph checks here.
479   }
480 
481   // DEPRECATION WARNING: All option processing should be moved from
482   // attrs_ and user_attrs_ to options_, which holds all this information.
483   //
484   // Dygraphs has many options, some of which interact with one another.
485   // To keep track of everything, we maintain two sets of options:
486   //
487   //  this.user_attrs_   only options explicitly set by the user.
488   //  this.attrs_        defaults, options derived from user_attrs_, data.
489   //
490   // Options are then accessed this.attr_('attr'), which first looks at
491   // user_attrs_ and then computed attrs_. This way Dygraphs can set intelligent
492   // defaults without overriding behavior that the user specifically asks for.
493   this.user_attrs_ = {};
494   Dygraph.update(this.user_attrs_, attrs);
495 
496   // This sequence ensures that Dygraph.DEFAULT_ATTRS is never modified.
497   this.attrs_ = {};
498   Dygraph.updateDeep(this.attrs_, Dygraph.DEFAULT_ATTRS);
499 
500   this.boundaryIds_ = [];
501   this.setIndexByName_ = {};
502   this.datasetIndex_ = [];
503 
504   this.registeredEvents_ = [];
505   this.eventListeners_ = {};
506 
507   this.attributes_ = new DygraphOptions(this);
508 
509   // Create the containing DIV and other interactive elements
510   this.createInterface_();
511 
512   // Activate plugins.
513   this.plugins_ = [];
514   var plugins = Dygraph.PLUGINS.concat(this.getOption('plugins'));
515   for (var i = 0; i < plugins.length; i++) {
516     var Plugin = plugins[i];
517     var pluginInstance = new Plugin();
518     var pluginDict = {
519       plugin: pluginInstance,
520       events: {},
521       options: {},
522       pluginOptions: {}
523     };
524 
525     var handlers = pluginInstance.activate(this);
526     for (var eventName in handlers) {
527       // TODO(danvk): validate eventName.
528       pluginDict.events[eventName] = handlers[eventName];
529     }
530 
531     this.plugins_.push(pluginDict);
532   }
533 
534   // At this point, plugins can no longer register event handlers.
535   // Construct a map from event -> ordered list of [callback, plugin].
536   for (var i = 0; i < this.plugins_.length; i++) {
537     var plugin_dict = this.plugins_[i];
538     for (var eventName in plugin_dict.events) {
539       if (!plugin_dict.events.hasOwnProperty(eventName)) continue;
540       var callback = plugin_dict.events[eventName];
541 
542       var pair = [plugin_dict.plugin, callback];
543       if (!(eventName in this.eventListeners_)) {
544         this.eventListeners_[eventName] = [pair];
545       } else {
546         this.eventListeners_[eventName].push(pair);
547       }
548     }
549   }
550 
551   this.createDragInterface_();
552 
553   this.start_();
554 };
555 
556 /**
557  * Triggers a cascade of events to the various plugins which are interested in them.
558  * Returns true if the "default behavior" should be performed, i.e. if none of
559  * the event listeners called event.preventDefault().
560  * @private
561  */
562 Dygraph.prototype.cascadeEvents_ = function(name, extra_props) {
563   if (!(name in this.eventListeners_)) return true;
564 
565   // QUESTION: can we use objects & prototypes to speed this up?
566   var e = {
567     dygraph: this,
568     cancelable: false,
569     defaultPrevented: false,
570     preventDefault: function() {
571       if (!e.cancelable) throw "Cannot call preventDefault on non-cancelable event.";
572       e.defaultPrevented = true;
573     },
574     propagationStopped: false,
575     stopPropagation: function() {
576       e.propagationStopped = true;
577     }
578   };
579   Dygraph.update(e, extra_props);
580 
581   var callback_plugin_pairs = this.eventListeners_[name];
582   if (callback_plugin_pairs) {
583     for (var i = callback_plugin_pairs.length - 1; i >= 0; i--) {
584       var plugin = callback_plugin_pairs[i][0];
585       var callback = callback_plugin_pairs[i][1];
586       callback.call(plugin, e);
587       if (e.propagationStopped) break;
588     }
589   }
590   return e.defaultPrevented;
591 };
592 
593 /**
594  * Returns the zoomed status of the chart for one or both axes.
595  *
596  * Axis is an optional parameter. Can be set to 'x' or 'y'.
597  *
598  * The zoomed status for an axis is set whenever a user zooms using the mouse
599  * or when the dateWindow or valueRange are updated (unless the
600  * isZoomedIgnoreProgrammaticZoom option is also specified).
601  */
602 Dygraph.prototype.isZoomed = function(axis) {
603   if (axis === null || axis === undefined) {
604     return this.zoomed_x_ || this.zoomed_y_;
605   }
606   if (axis === 'x') return this.zoomed_x_;
607   if (axis === 'y') return this.zoomed_y_;
608   throw "axis parameter is [" + axis + "] must be null, 'x' or 'y'.";
609 };
610 
611 /**
612  * Returns information about the Dygraph object, including its containing ID.
613  */
614 Dygraph.prototype.toString = function() {
615   var maindiv = this.maindiv_;
616   var id = (maindiv && maindiv.id) ? maindiv.id : maindiv;
617   return "[Dygraph " + id + "]";
618 };
619 
620 /**
621  * @private
622  * Returns the value of an option. This may be set by the user (either in the
623  * constructor or by calling updateOptions) or by dygraphs, and may be set to a
624  * per-series value.
625  * @param { String } name The name of the option, e.g. 'rollPeriod'.
626  * @param { String } [seriesName] The name of the series to which the option
627  * will be applied. If no per-series value of this option is available, then
628  * the global value is returned. This is optional.
629  * @return { ... } The value of the option.
630  */
631 Dygraph.prototype.attr_ = function(name, seriesName) {
632 // <REMOVE_FOR_COMBINED>
633   if (typeof(Dygraph.OPTIONS_REFERENCE) === 'undefined') {
634     this.error('Must include options reference JS for testing');
635   } else if (!Dygraph.OPTIONS_REFERENCE.hasOwnProperty(name)) {
636     this.error('Dygraphs is using property ' + name + ', which has no entry ' +
637                'in the Dygraphs.OPTIONS_REFERENCE listing.');
638     // Only log this error once.
639     Dygraph.OPTIONS_REFERENCE[name] = true;
640   }
641 // </REMOVE_FOR_COMBINED>
642   return seriesName ? this.attributes_.getForSeries(name, seriesName) : this.attributes_.get(name);
643 };
644 
645 /**
646  * Returns the current value for an option, as set in the constructor or via
647  * updateOptions. You may pass in an (optional) series name to get per-series
648  * values for the option.
649  *
650  * All values returned by this method should be considered immutable. If you
651  * modify them, there is no guarantee that the changes will be honored or that
652  * dygraphs will remain in a consistent state. If you want to modify an option,
653  * use updateOptions() instead.
654  *
655  * @param { String } name The name of the option (e.g. 'strokeWidth')
656  * @param { String } [opt_seriesName] Series name to get per-series values.
657  * @return { ... } The value of the option.
658  */
659 Dygraph.prototype.getOption = function(name, opt_seriesName) {
660   return this.attr_(name, opt_seriesName);
661 };
662 
663 Dygraph.prototype.getOptionForAxis = function(name, axis) {
664   return this.attributes_.getForAxis(name, axis);
665 };
666 
667 /**
668  * @private
669  * @param  String} axis The name of the axis (i.e. 'x', 'y' or 'y2')
670  * @return { ... } A function mapping string -> option value
671  */
672 Dygraph.prototype.optionsViewForAxis_ = function(axis) {
673   var self = this;
674   return function(opt) {
675     var axis_opts = self.user_attrs_.axes;
676     if (axis_opts && axis_opts[axis] && axis_opts[axis].hasOwnProperty(opt)) {
677       return axis_opts[axis][opt];
678     }
679     // user-specified attributes always trump defaults, even if they're less
680     // specific.
681     if (typeof(self.user_attrs_[opt]) != 'undefined') {
682       return self.user_attrs_[opt];
683     }
684 
685     axis_opts = self.attrs_.axes;
686     if (axis_opts && axis_opts[axis] && axis_opts[axis].hasOwnProperty(opt)) {
687       return axis_opts[axis][opt];
688     }
689     // check old-style axis options
690     // TODO(danvk): add a deprecation warning if either of these match.
691     if (axis == 'y' && self.axes_[0].hasOwnProperty(opt)) {
692       return self.axes_[0][opt];
693     } else if (axis == 'y2' && self.axes_[1].hasOwnProperty(opt)) {
694       return self.axes_[1][opt];
695     }
696     return self.attr_(opt);
697   };
698 };
699 
700 /**
701  * Returns the current rolling period, as set by the user or an option.
702  * @return {Number} The number of points in the rolling window
703  */
704 Dygraph.prototype.rollPeriod = function() {
705   return this.rollPeriod_;
706 };
707 
708 /**
709  * Returns the currently-visible x-range. This can be affected by zooming,
710  * panning or a call to updateOptions.
711  * Returns a two-element array: [left, right].
712  * If the Dygraph has dates on the x-axis, these will be millis since epoch.
713  */
714 Dygraph.prototype.xAxisRange = function() {
715   return this.dateWindow_ ? this.dateWindow_ : this.xAxisExtremes();
716 };
717 
718 /**
719  * Returns the lower- and upper-bound x-axis values of the
720  * data set.
721  */
722 Dygraph.prototype.xAxisExtremes = function() {
723   var pad = this.attr_('xRangePad') / this.plotter_.area.w;
724   if (this.numRows() === 0) {
725     return [0 - pad, 1 + pad];
726   }
727   var left = this.rawData_[0][0];
728   var right = this.rawData_[this.rawData_.length - 1][0];
729   if (pad) {
730     // Must keep this in sync with dygraph-layout _evaluateLimits()
731     var range = right - left;
732     left -= range * pad;
733     right += range * pad;
734   }
735   return [left, right];
736 };
737 
738 /**
739  * Returns the currently-visible y-range for an axis. This can be affected by
740  * zooming, panning or a call to updateOptions. Axis indices are zero-based. If
741  * called with no arguments, returns the range of the first axis.
742  * Returns a two-element array: [bottom, top].
743  */
744 Dygraph.prototype.yAxisRange = function(idx) {
745   if (typeof(idx) == "undefined") idx = 0;
746   if (idx < 0 || idx >= this.axes_.length) {
747     return null;
748   }
749   var axis = this.axes_[idx];
750   return [ axis.computedValueRange[0], axis.computedValueRange[1] ];
751 };
752 
753 /**
754  * Returns the currently-visible y-ranges for each axis. This can be affected by
755  * zooming, panning, calls to updateOptions, etc.
756  * Returns an array of [bottom, top] pairs, one for each y-axis.
757  */
758 Dygraph.prototype.yAxisRanges = function() {
759   var ret = [];
760   for (var i = 0; i < this.axes_.length; i++) {
761     ret.push(this.yAxisRange(i));
762   }
763   return ret;
764 };
765 
766 // TODO(danvk): use these functions throughout dygraphs.
767 /**
768  * Convert from data coordinates to canvas/div X/Y coordinates.
769  * If specified, do this conversion for the coordinate system of a particular
770  * axis. Uses the first axis by default.
771  * Returns a two-element array: [X, Y]
772  *
773  * Note: use toDomXCoord instead of toDomCoords(x, null) and use toDomYCoord
774  * instead of toDomCoords(null, y, axis).
775  */
776 Dygraph.prototype.toDomCoords = function(x, y, axis) {
777   return [ this.toDomXCoord(x), this.toDomYCoord(y, axis) ];
778 };
779 
780 /**
781  * Convert from data x coordinates to canvas/div X coordinate.
782  * If specified, do this conversion for the coordinate system of a particular
783  * axis.
784  * Returns a single value or null if x is null.
785  */
786 Dygraph.prototype.toDomXCoord = function(x) {
787   if (x === null) {
788     return null;
789   }
790 
791   var area = this.plotter_.area;
792   var xRange = this.xAxisRange();
793   return area.x + (x - xRange[0]) / (xRange[1] - xRange[0]) * area.w;
794 };
795 
796 /**
797  * Convert from data x coordinates to canvas/div Y coordinate and optional
798  * axis. Uses the first axis by default.
799  *
800  * returns a single value or null if y is null.
801  */
802 Dygraph.prototype.toDomYCoord = function(y, axis) {
803   var pct = this.toPercentYCoord(y, axis);
804 
805   if (pct === null) {
806     return null;
807   }
808   var area = this.plotter_.area;
809   return area.y + pct * area.h;
810 };
811 
812 /**
813  * Convert from canvas/div coords to data coordinates.
814  * If specified, do this conversion for the coordinate system of a particular
815  * axis. Uses the first axis by default.
816  * Returns a two-element array: [X, Y].
817  *
818  * Note: use toDataXCoord instead of toDataCoords(x, null) and use toDataYCoord
819  * instead of toDataCoords(null, y, axis).
820  */
821 Dygraph.prototype.toDataCoords = function(x, y, axis) {
822   return [ this.toDataXCoord(x), this.toDataYCoord(y, axis) ];
823 };
824 
825 /**
826  * Convert from canvas/div x coordinate to data coordinate.
827  *
828  * If x is null, this returns null.
829  */
830 Dygraph.prototype.toDataXCoord = function(x) {
831   if (x === null) {
832     return null;
833   }
834 
835   var area = this.plotter_.area;
836   var xRange = this.xAxisRange();
837   return xRange[0] + (x - area.x) / area.w * (xRange[1] - xRange[0]);
838 };
839 
840 /**
841  * Convert from canvas/div y coord to value.
842  *
843  * If y is null, this returns null.
844  * if axis is null, this uses the first axis.
845  */
846 Dygraph.prototype.toDataYCoord = function(y, axis) {
847   if (y === null) {
848     return null;
849   }
850 
851   var area = this.plotter_.area;
852   var yRange = this.yAxisRange(axis);
853 
854   if (typeof(axis) == "undefined") axis = 0;
855   if (!this.axes_[axis].logscale) {
856     return yRange[0] + (area.y + area.h - y) / area.h * (yRange[1] - yRange[0]);
857   } else {
858     // Computing the inverse of toDomCoord.
859     var pct = (y - area.y) / area.h;
860 
861     // Computing the inverse of toPercentYCoord. The function was arrived at with
862     // the following steps:
863     //
864     // Original calcuation:
865     // pct = (logr1 - Dygraph.log10(y)) / (logr1 - Dygraph.log10(yRange[0]));
866     //
867     // Move denominator to both sides:
868     // pct * (logr1 - Dygraph.log10(yRange[0])) = logr1 - Dygraph.log10(y);
869     //
870     // subtract logr1, and take the negative value.
871     // logr1 - (pct * (logr1 - Dygraph.log10(yRange[0]))) = Dygraph.log10(y);
872     //
873     // Swap both sides of the equation, and we can compute the log of the
874     // return value. Which means we just need to use that as the exponent in
875     // e^exponent.
876     // Dygraph.log10(y) = logr1 - (pct * (logr1 - Dygraph.log10(yRange[0])));
877 
878     var logr1 = Dygraph.log10(yRange[1]);
879     var exponent = logr1 - (pct * (logr1 - Dygraph.log10(yRange[0])));
880     var value = Math.pow(Dygraph.LOG_SCALE, exponent);
881     return value;
882   }
883 };
884 
885 /**
886  * Converts a y for an axis to a percentage from the top to the
887  * bottom of the drawing area.
888  *
889  * If the coordinate represents a value visible on the canvas, then
890  * the value will be between 0 and 1, where 0 is the top of the canvas.
891  * However, this method will return values outside the range, as
892  * values can fall outside the canvas.
893  *
894  * If y is null, this returns null.
895  * if axis is null, this uses the first axis.
896  *
897  * @param { Number } y The data y-coordinate.
898  * @param { Number } [axis] The axis number on which the data coordinate lives.
899  * @return { Number } A fraction in [0, 1] where 0 = the top edge.
900  */
901 Dygraph.prototype.toPercentYCoord = function(y, axis) {
902   if (y === null) {
903     return null;
904   }
905   if (typeof(axis) == "undefined") axis = 0;
906 
907   var yRange = this.yAxisRange(axis);
908 
909   var pct;
910   var logscale = this.attributes_.getForAxis("logscale", axis);
911   if (!logscale) {
912     // yRange[1] - y is unit distance from the bottom.
913     // yRange[1] - yRange[0] is the scale of the range.
914     // (yRange[1] - y) / (yRange[1] - yRange[0]) is the % from the bottom.
915     pct = (yRange[1] - y) / (yRange[1] - yRange[0]);
916   } else {
917     var logr1 = Dygraph.log10(yRange[1]);
918     pct = (logr1 - Dygraph.log10(y)) / (logr1 - Dygraph.log10(yRange[0]));
919   }
920   return pct;
921 };
922 
923 /**
924  * Converts an x value to a percentage from the left to the right of
925  * the drawing area.
926  *
927  * If the coordinate represents a value visible on the canvas, then
928  * the value will be between 0 and 1, where 0 is the left of the canvas.
929  * However, this method will return values outside the range, as
930  * values can fall outside the canvas.
931  *
932  * If x is null, this returns null.
933  * @param { Number } x The data x-coordinate.
934  * @return { Number } A fraction in [0, 1] where 0 = the left edge.
935  */
936 Dygraph.prototype.toPercentXCoord = function(x) {
937   if (x === null) {
938     return null;
939   }
940 
941   var xRange = this.xAxisRange();
942   return (x - xRange[0]) / (xRange[1] - xRange[0]);
943 };
944 
945 /**
946  * Returns the number of columns (including the independent variable).
947  * @return { Integer } The number of columns.
948  */
949 Dygraph.prototype.numColumns = function() {
950   if (!this.rawData_) return 0;
951   return this.rawData_[0] ? this.rawData_[0].length : this.attr_("labels").length;
952 };
953 
954 /**
955  * Returns the number of rows (excluding any header/label row).
956  * @return { Integer } The number of rows, less any header.
957  */
958 Dygraph.prototype.numRows = function() {
959   if (!this.rawData_) return 0;
960   return this.rawData_.length;
961 };
962 
963 /**
964  * Returns the value in the given row and column. If the row and column exceed
965  * the bounds on the data, returns null. Also returns null if the value is
966  * missing.
967  * @param { Number} row The row number of the data (0-based). Row 0 is the
968  * first row of data, not a header row.
969  * @param { Number} col The column number of the data (0-based)
970  * @return { Number } The value in the specified cell or null if the row/col
971  * were out of range.
972  */
973 Dygraph.prototype.getValue = function(row, col) {
974   if (row < 0 || row > this.rawData_.length) return null;
975   if (col < 0 || col > this.rawData_[row].length) return null;
976 
977   return this.rawData_[row][col];
978 };
979 
980 /**
981  * Generates interface elements for the Dygraph: a containing div, a div to
982  * display the current point, and a textbox to adjust the rolling average
983  * period. Also creates the Renderer/Layout elements.
984  * @private
985  */
986 Dygraph.prototype.createInterface_ = function() {
987   // Create the all-enclosing graph div
988   var enclosing = this.maindiv_;
989 
990   this.graphDiv = document.createElement("div");
991 
992   // TODO(danvk): any other styles that are useful to set here?
993   this.graphDiv.style.textAlign = 'left';  // This is a CSS "reset"
994   enclosing.appendChild(this.graphDiv);
995 
996   // Create the canvas for interactive parts of the chart.
997   this.canvas_ = Dygraph.createCanvas();
998   this.canvas_.style.position = "absolute";
999 
1000   // ... and for static parts of the chart.
1001   this.hidden_ = this.createPlotKitCanvas_(this.canvas_);
1002 
1003   this.resizeElements_();
1004 
1005   this.canvas_ctx_ = Dygraph.getContext(this.canvas_);
1006   this.hidden_ctx_ = Dygraph.getContext(this.hidden_);
1007 
1008   // The interactive parts of the graph are drawn on top of the chart.
1009   this.graphDiv.appendChild(this.hidden_);
1010   this.graphDiv.appendChild(this.canvas_);
1011   this.mouseEventElement_ = this.createMouseEventElement_();
1012 
1013   // Create the grapher
1014   this.layout_ = new DygraphLayout(this);
1015 
1016   var dygraph = this;
1017 
1018   this.mouseMoveHandler_ = function(e) {
1019     dygraph.mouseMove_(e);
1020   };
1021 
1022   this.mouseOutHandler_ = function(e) {
1023     // The mouse has left the chart if:
1024     // 1. e.target is inside the chart
1025     // 2. e.relatedTarget is outside the chart
1026     var target = e.target || e.fromElement;
1027     var relatedTarget = e.relatedTarget || e.toElement;
1028     if (Dygraph.isNodeContainedBy(target, dygraph.graphDiv) &&
1029         !Dygraph.isNodeContainedBy(relatedTarget, dygraph.graphDiv)) {
1030       dygraph.mouseOut_(e);
1031     }
1032   };
1033 
1034   this.addAndTrackEvent(window, 'mouseout', this.mouseOutHandler_);
1035   this.addAndTrackEvent(this.mouseEventElement_, 'mousemove', this.mouseMoveHandler_);
1036 
1037   // Don't recreate and register the resize handler on subsequent calls.
1038   // This happens when the graph is resized.
1039   if (!this.resizeHandler_) {
1040     this.resizeHandler_ = function(e) {
1041       dygraph.resize();
1042     };
1043 
1044     // Update when the window is resized.
1045     // TODO(danvk): drop frames depending on complexity of the chart.
1046     this.addAndTrackEvent(window, 'resize', this.resizeHandler_);
1047   }
1048 };
1049 
1050 Dygraph.prototype.resizeElements_ = function() {
1051   this.graphDiv.style.width = this.width_ + "px";
1052   this.graphDiv.style.height = this.height_ + "px";
1053   this.canvas_.width = this.width_;
1054   this.canvas_.height = this.height_;
1055   this.canvas_.style.width = this.width_ + "px";    // for IE
1056   this.canvas_.style.height = this.height_ + "px";  // for IE
1057   this.hidden_.width = this.width_;
1058   this.hidden_.height = this.height_;
1059   this.hidden_.style.width = this.width_ + "px";    // for IE
1060   this.hidden_.style.height = this.height_ + "px";  // for IE
1061 };
1062 
1063 /**
1064  * Detach DOM elements in the dygraph and null out all data references.
1065  * Calling this when you're done with a dygraph can dramatically reduce memory
1066  * usage. See, e.g., the tests/perf.html example.
1067  */
1068 Dygraph.prototype.destroy = function() {
1069   this.canvas_ctx_.restore();
1070   this.hidden_ctx_.restore();
1071 
1072   var removeRecursive = function(node) {
1073     while (node.hasChildNodes()) {
1074       removeRecursive(node.firstChild);
1075       node.removeChild(node.firstChild);
1076     }
1077   };
1078 
1079   this.removeTrackedEvents_();
1080 
1081   // remove mouse event handlers (This may not be necessary anymore)
1082   Dygraph.removeEvent(window, 'mouseout', this.mouseOutHandler_);
1083   Dygraph.removeEvent(this.mouseEventElement_, 'mousemove', this.mouseMoveHandler_);
1084 
1085   // remove window handlers
1086   Dygraph.removeEvent(window,'resize',this.resizeHandler_);
1087   this.resizeHandler_ = null;
1088 
1089   removeRecursive(this.maindiv_);
1090 
1091   var nullOut = function(obj) {
1092     for (var n in obj) {
1093       if (typeof(obj[n]) === 'object') {
1094         obj[n] = null;
1095       }
1096     }
1097   };
1098   // These may not all be necessary, but it can't hurt...
1099   nullOut(this.layout_);
1100   nullOut(this.plotter_);
1101   nullOut(this);
1102 };
1103 
1104 /**
1105  * Creates the canvas on which the chart will be drawn. Only the Renderer ever
1106  * draws on this particular canvas. All Dygraph work (i.e. drawing hover dots
1107  * or the zoom rectangles) is done on this.canvas_.
1108  * @param {Object} canvas The Dygraph canvas over which to overlay the plot
1109  * @return {Object} The newly-created canvas
1110  * @private
1111  */
1112 Dygraph.prototype.createPlotKitCanvas_ = function(canvas) {
1113   var h = Dygraph.createCanvas();
1114   h.style.position = "absolute";
1115   // TODO(danvk): h should be offset from canvas. canvas needs to include
1116   // some extra area to make it easier to zoom in on the far left and far
1117   // right. h needs to be precisely the plot area, so that clipping occurs.
1118   h.style.top = canvas.style.top;
1119   h.style.left = canvas.style.left;
1120   h.width = this.width_;
1121   h.height = this.height_;
1122   h.style.width = this.width_ + "px";    // for IE
1123   h.style.height = this.height_ + "px";  // for IE
1124   return h;
1125 };
1126 
1127 /**
1128  * Creates an overlay element used to handle mouse events.
1129  * @return {Object} The mouse event element.
1130  * @private
1131  */
1132 Dygraph.prototype.createMouseEventElement_ = function() {
1133   if (this.isUsingExcanvas_) {
1134     var elem = document.createElement("div");
1135     elem.style.position = 'absolute';
1136     elem.style.backgroundColor = 'white';
1137     elem.style.filter = 'alpha(opacity=0)';
1138     elem.style.width = this.width_ + "px";
1139     elem.style.height = this.height_ + "px";
1140     this.graphDiv.appendChild(elem);
1141     return elem;
1142   } else {
1143     return this.canvas_;
1144   }
1145 };
1146 
1147 /**
1148  * Generate a set of distinct colors for the data series. This is done with a
1149  * color wheel. Saturation/Value are customizable, and the hue is
1150  * equally-spaced around the color wheel. If a custom set of colors is
1151  * specified, that is used instead.
1152  * @private
1153  */
1154 Dygraph.prototype.setColors_ = function() {
1155   var labels = this.getLabels();
1156   var num = labels.length - 1;
1157   this.colors_ = [];
1158   this.colorsMap_ = {};
1159   var colors = this.attr_('colors');
1160   var i;
1161   if (!colors) {
1162     var sat = this.attr_('colorSaturation') || 1.0;
1163     var val = this.attr_('colorValue') || 0.5;
1164     var half = Math.ceil(num / 2);
1165     for (i = 1; i <= num; i++) {
1166       if (!this.visibility()[i-1]) continue;
1167       // alternate colors for high contrast.
1168       var idx = i % 2 ? Math.ceil(i / 2) : (half + i / 2);
1169       var hue = (1.0 * idx/ (1 + num));
1170       var colorStr = Dygraph.hsvToRGB(hue, sat, val);
1171       this.colors_.push(colorStr);
1172       this.colorsMap_[labels[i]] = colorStr;
1173     }
1174   } else {
1175     for (i = 0; i < num; i++) {
1176       if (!this.visibility()[i]) continue;
1177       var colorStr = colors[i % colors.length];
1178       this.colors_.push(colorStr);
1179       this.colorsMap_[labels[1 + i]] = colorStr;
1180     }
1181   }
1182 };
1183 
1184 /**
1185  * Return the list of colors. This is either the list of colors passed in the
1186  * attributes or the autogenerated list of rgb(r,g,b) strings.
1187  * This does not return colors for invisible series.
1188  * @return {Array<string>} The list of colors.
1189  */
1190 Dygraph.prototype.getColors = function() {
1191   return this.colors_;
1192 };
1193 
1194 /**
1195  * Returns a few attributes of a series, i.e. its color, its visibility, which
1196  * axis it's assigned to, and its column in the original data.
1197  * Returns null if the series does not exist.
1198  * Otherwise, returns an object with column, visibility, color and axis properties.
1199  * The "axis" property will be set to 1 for y1 and 2 for y2.
1200  * The "column" property can be fed back into getValue(row, column) to get
1201  * values for this series.
1202  */
1203 Dygraph.prototype.getPropertiesForSeries = function(series_name) {
1204   var idx = -1;
1205   var labels = this.getLabels();
1206   for (var i = 1; i < labels.length; i++) {
1207     if (labels[i] == series_name) {
1208       idx = i;
1209       break;
1210     }
1211   }
1212   if (idx == -1) return null;
1213 
1214   return {
1215     name: series_name,
1216     column: idx,
1217     visible: this.visibility()[idx - 1],
1218     color: this.colorsMap_[series_name],
1219     axis: 1 + this.attributes_.axisForSeries(series_name)
1220   };
1221 };
1222 
1223 /**
1224  * Create the text box to adjust the averaging period
1225  * @private
1226  */
1227 Dygraph.prototype.createRollInterface_ = function() {
1228   // Create a roller if one doesn't exist already.
1229   if (!this.roller_) {
1230     this.roller_ = document.createElement("input");
1231     this.roller_.type = "text";
1232     this.roller_.style.display = "none";
1233     this.graphDiv.appendChild(this.roller_);
1234   }
1235 
1236   var display = this.attr_('showRoller') ? 'block' : 'none';
1237 
1238   var area = this.plotter_.area;
1239   var textAttr = { "position": "absolute",
1240                    "zIndex": 10,
1241                    "top": (area.y + area.h - 25) + "px",
1242                    "left": (area.x + 1) + "px",
1243                    "display": display
1244                   };
1245   this.roller_.size = "2";
1246   this.roller_.value = this.rollPeriod_;
1247   for (var name in textAttr) {
1248     if (textAttr.hasOwnProperty(name)) {
1249       this.roller_.style[name] = textAttr[name];
1250     }
1251   }
1252 
1253   var dygraph = this;
1254   this.roller_.onchange = function() { dygraph.adjustRoll(dygraph.roller_.value); };
1255 };
1256 
1257 /**
1258  * @private
1259  * Converts page the x-coordinate of the event to pixel x-coordinates on the
1260  * canvas (i.e. DOM Coords).
1261  */
1262 Dygraph.prototype.dragGetX_ = function(e, context) {
1263   return Dygraph.pageX(e) - context.px;
1264 };
1265 
1266 /**
1267  * @private
1268  * Converts page the y-coordinate of the event to pixel y-coordinates on the
1269  * canvas (i.e. DOM Coords).
1270  */
1271 Dygraph.prototype.dragGetY_ = function(e, context) {
1272   return Dygraph.pageY(e) - context.py;
1273 };
1274 
1275 /**
1276  * Set up all the mouse handlers needed to capture dragging behavior for zoom
1277  * events.
1278  * @private
1279  */
1280 Dygraph.prototype.createDragInterface_ = function() {
1281   var context = {
1282     // Tracks whether the mouse is down right now
1283     isZooming: false,
1284     isPanning: false,  // is this drag part of a pan?
1285     is2DPan: false,    // if so, is that pan 1- or 2-dimensional?
1286     dragStartX: null, // pixel coordinates
1287     dragStartY: null, // pixel coordinates
1288     dragEndX: null, // pixel coordinates
1289     dragEndY: null, // pixel coordinates
1290     dragDirection: null,
1291     prevEndX: null, // pixel coordinates
1292     prevEndY: null, // pixel coordinates
1293     prevDragDirection: null,
1294     cancelNextDblclick: false,  // see comment in dygraph-interaction-model.js
1295 
1296     // The value on the left side of the graph when a pan operation starts.
1297     initialLeftmostDate: null,
1298 
1299     // The number of units each pixel spans. (This won't be valid for log
1300     // scales)
1301     xUnitsPerPixel: null,
1302 
1303     // TODO(danvk): update this comment
1304     // The range in second/value units that the viewport encompasses during a
1305     // panning operation.
1306     dateRange: null,
1307 
1308     // Top-left corner of the canvas, in DOM coords
1309     // TODO(konigsberg): Rename topLeftCanvasX, topLeftCanvasY.
1310     px: 0,
1311     py: 0,
1312 
1313     // Values for use with panEdgeFraction, which limit how far outside the
1314     // graph's data boundaries it can be panned.
1315     boundedDates: null, // [minDate, maxDate]
1316     boundedValues: null, // [[minValue, maxValue] ...]
1317 
1318     // We cover iframes during mouse interactions. See comments in
1319     // dygraph-utils.js for more info on why this is a good idea.
1320     tarp: new Dygraph.IFrameTarp(),
1321 
1322     // contextB is the same thing as this context object but renamed.
1323     initializeMouseDown: function(event, g, contextB) {
1324       // prevents mouse drags from selecting page text.
1325       if (event.preventDefault) {
1326         event.preventDefault();  // Firefox, Chrome, etc.
1327       } else {
1328         event.returnValue = false;  // IE
1329         event.cancelBubble = true;
1330       }
1331 
1332       contextB.px = Dygraph.findPosX(g.canvas_);
1333       contextB.py = Dygraph.findPosY(g.canvas_);
1334       contextB.dragStartX = g.dragGetX_(event, contextB);
1335       contextB.dragStartY = g.dragGetY_(event, contextB);
1336       contextB.cancelNextDblclick = false;
1337       contextB.tarp.cover();
1338     }
1339   };
1340 
1341   var interactionModel = this.attr_("interactionModel");
1342 
1343   // Self is the graph.
1344   var self = this;
1345 
1346   // Function that binds the graph and context to the handler.
1347   var bindHandler = function(handler) {
1348     return function(event) {
1349       handler(event, self, context);
1350     };
1351   };
1352 
1353   for (var eventName in interactionModel) {
1354     if (!interactionModel.hasOwnProperty(eventName)) continue;
1355     this.addAndTrackEvent(this.mouseEventElement_, eventName,
1356         bindHandler(interactionModel[eventName]));
1357   }
1358 
1359   // If the user releases the mouse button during a drag, but not over the
1360   // canvas, then it doesn't count as a zooming action.
1361   var mouseUpHandler = function(event) {
1362     if (context.isZooming || context.isPanning) {
1363       context.isZooming = false;
1364       context.dragStartX = null;
1365       context.dragStartY = null;
1366     }
1367 
1368     if (context.isPanning) {
1369       context.isPanning = false;
1370       context.draggingDate = null;
1371       context.dateRange = null;
1372       for (var i = 0; i < self.axes_.length; i++) {
1373         delete self.axes_[i].draggingValue;
1374         delete self.axes_[i].dragValueRange;
1375       }
1376     }
1377 
1378     context.tarp.uncover();
1379   };
1380 
1381   this.addAndTrackEvent(document, 'mouseup', mouseUpHandler);
1382 };
1383 
1384 /**
1385  * Draw a gray zoom rectangle over the desired area of the canvas. Also clears
1386  * up any previous zoom rectangles that were drawn. This could be optimized to
1387  * avoid extra redrawing, but it's tricky to avoid interactions with the status
1388  * dots.
1389  *
1390  * @param {Number} direction the direction of the zoom rectangle. Acceptable
1391  * values are Dygraph.HORIZONTAL and Dygraph.VERTICAL.
1392  * @param {Number} startX The X position where the drag started, in canvas
1393  * coordinates.
1394  * @param {Number} endX The current X position of the drag, in canvas coords.
1395  * @param {Number} startY The Y position where the drag started, in canvas
1396  * coordinates.
1397  * @param {Number} endY The current Y position of the drag, in canvas coords.
1398  * @param {Number} prevDirection the value of direction on the previous call to
1399  * this function. Used to avoid excess redrawing
1400  * @param {Number} prevEndX The value of endX on the previous call to this
1401  * function. Used to avoid excess redrawing
1402  * @param {Number} prevEndY The value of endY on the previous call to this
1403  * function. Used to avoid excess redrawing
1404  * @private
1405  */
1406 Dygraph.prototype.drawZoomRect_ = function(direction, startX, endX, startY,
1407                                            endY, prevDirection, prevEndX,
1408                                            prevEndY) {
1409   var ctx = this.canvas_ctx_;
1410 
1411   // Clean up from the previous rect if necessary
1412   if (prevDirection == Dygraph.HORIZONTAL) {
1413     ctx.clearRect(Math.min(startX, prevEndX), this.layout_.getPlotArea().y,
1414                   Math.abs(startX - prevEndX), this.layout_.getPlotArea().h);
1415   } else if (prevDirection == Dygraph.VERTICAL) {
1416     ctx.clearRect(this.layout_.getPlotArea().x, Math.min(startY, prevEndY),
1417                   this.layout_.getPlotArea().w, Math.abs(startY - prevEndY));
1418   }
1419 
1420   // Draw a light-grey rectangle to show the new viewing area
1421   if (direction == Dygraph.HORIZONTAL) {
1422     if (endX && startX) {
1423       ctx.fillStyle = "rgba(128,128,128,0.33)";
1424       ctx.fillRect(Math.min(startX, endX), this.layout_.getPlotArea().y,
1425                    Math.abs(endX - startX), this.layout_.getPlotArea().h);
1426     }
1427   } else if (direction == Dygraph.VERTICAL) {
1428     if (endY && startY) {
1429       ctx.fillStyle = "rgba(128,128,128,0.33)";
1430       ctx.fillRect(this.layout_.getPlotArea().x, Math.min(startY, endY),
1431                    this.layout_.getPlotArea().w, Math.abs(endY - startY));
1432     }
1433   }
1434 
1435   if (this.isUsingExcanvas_) {
1436     this.currentZoomRectArgs_ = [direction, startX, endX, startY, endY, 0, 0, 0];
1437   }
1438 };
1439 
1440 /**
1441  * Clear the zoom rectangle (and perform no zoom).
1442  * @private
1443  */
1444 Dygraph.prototype.clearZoomRect_ = function() {
1445   this.currentZoomRectArgs_ = null;
1446   this.canvas_ctx_.clearRect(0, 0, this.canvas_.width, this.canvas_.height);
1447 };
1448 
1449 /**
1450  * Zoom to something containing [lowX, highX]. These are pixel coordinates in
1451  * the canvas. The exact zoom window may be slightly larger if there are no data
1452  * points near lowX or highX. Don't confuse this function with doZoomXDates,
1453  * which accepts dates that match the raw data. This function redraws the graph.
1454  *
1455  * @param {Number} lowX The leftmost pixel value that should be visible.
1456  * @param {Number} highX The rightmost pixel value that should be visible.
1457  * @private
1458  */
1459 Dygraph.prototype.doZoomX_ = function(lowX, highX) {
1460   this.currentZoomRectArgs_ = null;
1461   // Find the earliest and latest dates contained in this canvasx range.
1462   // Convert the call to date ranges of the raw data.
1463   var minDate = this.toDataXCoord(lowX);
1464   var maxDate = this.toDataXCoord(highX);
1465   this.doZoomXDates_(minDate, maxDate);
1466 };
1467 
1468 /**
1469  * Transition function to use in animations. Returns values between 0.0
1470  * (totally old values) and 1.0 (totally new values) for each frame.
1471  * @private
1472  */
1473 Dygraph.zoomAnimationFunction = function(frame, numFrames) {
1474   var k = 1.5;
1475   return (1.0 - Math.pow(k, -frame)) / (1.0 - Math.pow(k, -numFrames));
1476 };
1477 
1478 /**
1479  * Zoom to something containing [minDate, maxDate] values. Don't confuse this
1480  * method with doZoomX which accepts pixel coordinates. This function redraws
1481  * the graph.
1482  *
1483  * @param {Number} minDate The minimum date that should be visible.
1484  * @param {Number} maxDate The maximum date that should be visible.
1485  * @private
1486  */
1487 Dygraph.prototype.doZoomXDates_ = function(minDate, maxDate) {
1488   // TODO(danvk): when yAxisRange is null (i.e. "fit to data", the animation
1489   // can produce strange effects. Rather than the y-axis transitioning slowly
1490   // between values, it can jerk around.)
1491   var old_window = this.xAxisRange();
1492   var new_window = [minDate, maxDate];
1493   this.zoomed_x_ = true;
1494   var that = this;
1495   this.doAnimatedZoom(old_window, new_window, null, null, function() {
1496     if (that.attr_("zoomCallback")) {
1497       that.attr_("zoomCallback")(minDate, maxDate, that.yAxisRanges());
1498     }
1499   });
1500 };
1501 
1502 /**
1503  * Zoom to something containing [lowY, highY]. These are pixel coordinates in
1504  * the canvas. This function redraws the graph.
1505  *
1506  * @param {Number} lowY The topmost pixel value that should be visible.
1507  * @param {Number} highY The lowest pixel value that should be visible.
1508  * @private
1509  */
1510 Dygraph.prototype.doZoomY_ = function(lowY, highY) {
1511   this.currentZoomRectArgs_ = null;
1512   // Find the highest and lowest values in pixel range for each axis.
1513   // Note that lowY (in pixels) corresponds to the max Value (in data coords).
1514   // This is because pixels increase as you go down on the screen, whereas data
1515   // coordinates increase as you go up the screen.
1516   var oldValueRanges = this.yAxisRanges();
1517   var newValueRanges = [];
1518   for (var i = 0; i < this.axes_.length; i++) {
1519     var hi = this.toDataYCoord(lowY, i);
1520     var low = this.toDataYCoord(highY, i);
1521     newValueRanges.push([low, hi]);
1522   }
1523 
1524   this.zoomed_y_ = true;
1525   var that = this;
1526   this.doAnimatedZoom(null, null, oldValueRanges, newValueRanges, function() {
1527     if (that.attr_("zoomCallback")) {
1528       var xRange = that.xAxisRange();
1529       that.attr_("zoomCallback")(xRange[0], xRange[1], that.yAxisRanges());
1530     }
1531   });
1532 };
1533 
1534 /**
1535  * Reset the zoom to the original view coordinates. This is the same as
1536  * double-clicking on the graph.
1537  */
1538 Dygraph.prototype.resetZoom = function() {
1539   var dirty = false, dirtyX = false, dirtyY = false;
1540   if (this.dateWindow_ !== null) {
1541     dirty = true;
1542     dirtyX = true;
1543   }
1544 
1545   for (var i = 0; i < this.axes_.length; i++) {
1546     if (typeof(this.axes_[i].valueWindow) !== 'undefined' && this.axes_[i].valueWindow !== null) {
1547       dirty = true;
1548       dirtyY = true;
1549     }
1550   }
1551 
1552   // Clear any selection, since it's likely to be drawn in the wrong place.
1553   this.clearSelection();
1554 
1555   if (dirty) {
1556     this.zoomed_x_ = false;
1557     this.zoomed_y_ = false;
1558 
1559     var minDate = this.rawData_[0][0];
1560     var maxDate = this.rawData_[this.rawData_.length - 1][0];
1561 
1562     // With only one frame, don't bother calculating extreme ranges.
1563     // TODO(danvk): merge this block w/ the code below.
1564     if (!this.attr_("animatedZooms")) {
1565       this.dateWindow_ = null;
1566       for (i = 0; i < this.axes_.length; i++) {
1567         if (this.axes_[i].valueWindow !== null) {
1568           delete this.axes_[i].valueWindow;
1569         }
1570       }
1571       this.drawGraph_();
1572       if (this.attr_("zoomCallback")) {
1573         this.attr_("zoomCallback")(minDate, maxDate, this.yAxisRanges());
1574       }
1575       return;
1576     }
1577 
1578     var oldWindow=null, newWindow=null, oldValueRanges=null, newValueRanges=null;
1579     if (dirtyX) {
1580       oldWindow = this.xAxisRange();
1581       newWindow = [minDate, maxDate];
1582     }
1583 
1584     if (dirtyY) {
1585       oldValueRanges = this.yAxisRanges();
1586       // TODO(danvk): this is pretty inefficient
1587       var packed = this.gatherDatasets_(this.rolledSeries_, null);
1588       var extremes = packed.extremes;
1589 
1590       // this has the side-effect of modifying this.axes_.
1591       // this doesn't make much sense in this context, but it's convenient (we
1592       // need this.axes_[*].extremeValues) and not harmful since we'll be
1593       // calling drawGraph_ shortly, which clobbers these values.
1594       this.computeYAxisRanges_(extremes);
1595 
1596       newValueRanges = [];
1597       for (i = 0; i < this.axes_.length; i++) {
1598         var axis = this.axes_[i];
1599         newValueRanges.push((axis.valueRange !== null &&
1600                              axis.valueRange !== undefined) ?
1601                             axis.valueRange : axis.extremeRange);
1602       }
1603     }
1604 
1605     var that = this;
1606     this.doAnimatedZoom(oldWindow, newWindow, oldValueRanges, newValueRanges,
1607         function() {
1608           that.dateWindow_ = null;
1609           for (var i = 0; i < that.axes_.length; i++) {
1610             if (that.axes_[i].valueWindow !== null) {
1611               delete that.axes_[i].valueWindow;
1612             }
1613           }
1614           if (that.attr_("zoomCallback")) {
1615             that.attr_("zoomCallback")(minDate, maxDate, that.yAxisRanges());
1616           }
1617         });
1618   }
1619 };
1620 
1621 /**
1622  * Combined animation logic for all zoom functions.
1623  * either the x parameters or y parameters may be null.
1624  * @private
1625  */
1626 Dygraph.prototype.doAnimatedZoom = function(oldXRange, newXRange, oldYRanges, newYRanges, callback) {
1627   var steps = this.attr_("animatedZooms") ? Dygraph.ANIMATION_STEPS : 1;
1628 
1629   var windows = [];
1630   var valueRanges = [];
1631   var step, frac;
1632 
1633   if (oldXRange !== null && newXRange !== null) {
1634     for (step = 1; step <= steps; step++) {
1635       frac = Dygraph.zoomAnimationFunction(step, steps);
1636       windows[step-1] = [oldXRange[0]*(1-frac) + frac*newXRange[0],
1637                          oldXRange[1]*(1-frac) + frac*newXRange[1]];
1638     }
1639   }
1640 
1641   if (oldYRanges !== null && newYRanges !== null) {
1642     for (step = 1; step <= steps; step++) {
1643       frac = Dygraph.zoomAnimationFunction(step, steps);
1644       var thisRange = [];
1645       for (var j = 0; j < this.axes_.length; j++) {
1646         thisRange.push([oldYRanges[j][0]*(1-frac) + frac*newYRanges[j][0],
1647                         oldYRanges[j][1]*(1-frac) + frac*newYRanges[j][1]]);
1648       }
1649       valueRanges[step-1] = thisRange;
1650     }
1651   }
1652 
1653   var that = this;
1654   Dygraph.repeatAndCleanup(function(step) {
1655     if (valueRanges.length) {
1656       for (var i = 0; i < that.axes_.length; i++) {
1657         var w = valueRanges[step][i];
1658         that.axes_[i].valueWindow = [w[0], w[1]];
1659       }
1660     }
1661     if (windows.length) {
1662       that.dateWindow_ = windows[step];
1663     }
1664     that.drawGraph_();
1665   }, steps, Dygraph.ANIMATION_DURATION / steps, callback);
1666 };
1667 
1668 /**
1669  * Get the current graph's area object.
1670  *
1671  * Returns: {x, y, w, h}
1672  */
1673 Dygraph.prototype.getArea = function() {
1674   return this.plotter_.area;
1675 };
1676 
1677 /**
1678  * Convert a mouse event to DOM coordinates relative to the graph origin.
1679  *
1680  * Returns a two-element array: [X, Y].
1681  */
1682 Dygraph.prototype.eventToDomCoords = function(event) {
1683   if (event.offsetX && event.offsetY) {
1684     return [ event.offsetX, event.offsetY ];
1685   } else {
1686     var canvasx = Dygraph.pageX(event) - Dygraph.findPosX(this.mouseEventElement_);
1687     var canvasy = Dygraph.pageY(event) - Dygraph.findPosY(this.mouseEventElement_);
1688     return [canvasx, canvasy];
1689   }
1690 };
1691 
1692 /**
1693  * Given a canvas X coordinate, find the closest row.
1694  * @param {Number} domX graph-relative DOM X coordinate
1695  * Returns: row number, integer
1696  * @private
1697  */
1698 Dygraph.prototype.findClosestRow = function(domX) {
1699   var minDistX = Infinity;
1700   var closestRow = -1;
1701   var sets = this.layout_.points;
1702   for (var i = 0; i < sets.length; i++) {
1703     var points = sets[i];
1704     var len = points.length;
1705     for (var j = 0; j < len; j++) {
1706       var point = points[j];
1707       if (!Dygraph.isValidPoint(point, true)) continue;
1708       var dist = Math.abs(point.canvasx - domX);
1709       if (dist < minDistX) {
1710         minDistX = dist;
1711         closestRow = point.idx;
1712       }
1713     }
1714   }
1715 
1716   return closestRow;
1717 };
1718 
1719 /**
1720  * Given canvas X,Y coordinates, find the closest point.
1721  *
1722  * This finds the individual data point across all visible series
1723  * that's closest to the supplied DOM coordinates using the standard
1724  * Euclidean X,Y distance.
1725  *
1726  * @param {Number} domX graph-relative DOM X coordinate
1727  * @param {Number} domY graph-relative DOM Y coordinate
1728  * Returns: {row, seriesName, point}
1729  * @private
1730  */
1731 Dygraph.prototype.findClosestPoint = function(domX, domY) {
1732   var minDist = Infinity;
1733   var dist, dx, dy, point, closestPoint, closestSeries, closestRow;
1734   for ( var setIdx = this.layout_.points.length - 1 ; setIdx >= 0 ; --setIdx ) {
1735     var points = this.layout_.points[setIdx];
1736     for (var i = 0; i < points.length; ++i) {
1737       point = points[i];
1738       if (!Dygraph.isValidPoint(point)) continue;
1739       dx = point.canvasx - domX;
1740       dy = point.canvasy - domY;
1741       dist = dx * dx + dy * dy;
1742       if (dist < minDist) {
1743         minDist = dist;
1744         closestPoint = point;
1745         closestSeries = setIdx;
1746         closestRow = point.idx;
1747       }
1748     }
1749   }
1750   var name = this.layout_.setNames[closestSeries];
1751   return {
1752     row: closestRow,
1753     seriesName: name,
1754     point: closestPoint
1755   };
1756 };
1757 
1758 /**
1759  * Given canvas X,Y coordinates, find the touched area in a stacked graph.
1760  *
1761  * This first finds the X data point closest to the supplied DOM X coordinate,
1762  * then finds the series which puts the Y coordinate on top of its filled area,
1763  * using linear interpolation between adjacent point pairs.
1764  *
1765  * @param {Number} domX graph-relative DOM X coordinate
1766  * @param {Number} domY graph-relative DOM Y coordinate
1767  * Returns: {row, seriesName, point}
1768  * @private
1769  */
1770 Dygraph.prototype.findStackedPoint = function(domX, domY) {
1771   var row = this.findClosestRow(domX);
1772   var closestPoint, closestSeries;
1773   for (var setIdx = 0; setIdx < this.layout_.points.length; ++setIdx) {
1774     var boundary = this.getLeftBoundary_(setIdx);
1775     var rowIdx = row - boundary;
1776     var points = this.layout_.points[setIdx];
1777     if (rowIdx >= points.length) continue;
1778     var p1 = points[rowIdx];
1779     if (!Dygraph.isValidPoint(p1)) continue;
1780     var py = p1.canvasy;
1781     if (domX > p1.canvasx && rowIdx + 1 < points.length) {
1782       // interpolate series Y value using next point
1783       var p2 = points[rowIdx + 1];
1784       if (Dygraph.isValidPoint(p2)) {
1785         var dx = p2.canvasx - p1.canvasx;
1786         if (dx > 0) {
1787           var r = (domX - p1.canvasx) / dx;
1788           py += r * (p2.canvasy - p1.canvasy);
1789         }
1790       }
1791     } else if (domX < p1.canvasx && rowIdx > 0) {
1792       // interpolate series Y value using previous point
1793       var p0 = points[rowIdx - 1];
1794       if (Dygraph.isValidPoint(p0)) {
1795         var dx = p1.canvasx - p0.canvasx;
1796         if (dx > 0) {
1797           var r = (p1.canvasx - domX) / dx;
1798           py += r * (p0.canvasy - p1.canvasy);
1799         }
1800       }
1801     }
1802     // Stop if the point (domX, py) is above this series' upper edge
1803     if (setIdx === 0 || py < domY) {
1804       closestPoint = p1;
1805       closestSeries = setIdx;
1806     }
1807   }
1808   var name = this.layout_.setNames[closestSeries];
1809   return {
1810     row: row,
1811     seriesName: name,
1812     point: closestPoint
1813   };
1814 };
1815 
1816 /**
1817  * When the mouse moves in the canvas, display information about a nearby data
1818  * point and draw dots over those points in the data series. This function
1819  * takes care of cleanup of previously-drawn dots.
1820  * @param {Object} event The mousemove event from the browser.
1821  * @private
1822  */
1823 Dygraph.prototype.mouseMove_ = function(event) {
1824   // This prevents JS errors when mousing over the canvas before data loads.
1825   var points = this.layout_.points;
1826   if (points === undefined || points === null) return;
1827 
1828   var canvasCoords = this.eventToDomCoords(event);
1829   var canvasx = canvasCoords[0];
1830   var canvasy = canvasCoords[1];
1831 
1832   var highlightSeriesOpts = this.attr_("highlightSeriesOpts");
1833   var selectionChanged = false;
1834   if (highlightSeriesOpts && !this.isSeriesLocked()) {
1835     var closest;
1836     if (this.attr_("stackedGraph")) {
1837       closest = this.findStackedPoint(canvasx, canvasy);
1838     } else {
1839       closest = this.findClosestPoint(canvasx, canvasy);
1840     }
1841     selectionChanged = this.setSelection(closest.row, closest.seriesName);
1842   } else {
1843     var idx = this.findClosestRow(canvasx);
1844     selectionChanged = this.setSelection(idx);
1845   }
1846 
1847   var callback = this.attr_("highlightCallback");
1848   if (callback && selectionChanged) {
1849     callback(event,
1850         this.lastx_,
1851         this.selPoints_,
1852         this.lastRow_,
1853         this.highlightSet_);
1854   }
1855 };
1856 
1857 /**
1858  * Fetch left offset from the specified set index or if not passed, the 
1859  * first defined boundaryIds record (see bug #236).
1860  * @private
1861  */
1862 Dygraph.prototype.getLeftBoundary_ = function(setIdx) {
1863   if (this.boundaryIds_[setIdx]) {
1864       return this.boundaryIds_[setIdx][0];
1865   } else {
1866     for (var i = 0; i < this.boundaryIds_.length; i++) {
1867       if (this.boundaryIds_[i] !== undefined) {
1868         return this.boundaryIds_[i][0];
1869       }
1870     }
1871     return 0;
1872   }
1873 };
1874 
1875 Dygraph.prototype.animateSelection_ = function(direction) {
1876   var totalSteps = 10;
1877   var millis = 30;
1878   if (this.fadeLevel === undefined) this.fadeLevel = 0;
1879   if (this.animateId === undefined) this.animateId = 0;
1880   var start = this.fadeLevel;
1881   var steps = direction < 0 ? start : totalSteps - start;
1882   if (steps <= 0) {
1883     if (this.fadeLevel) {
1884       this.updateSelection_(1.0);
1885     }
1886     return;
1887   }
1888 
1889   var thisId = ++this.animateId;
1890   var that = this;
1891   Dygraph.repeatAndCleanup(
1892     function(n) {
1893       // ignore simultaneous animations
1894       if (that.animateId != thisId) return;
1895 
1896       that.fadeLevel += direction;
1897       if (that.fadeLevel === 0) {
1898         that.clearSelection();
1899       } else {
1900         that.updateSelection_(that.fadeLevel / totalSteps);
1901       }
1902     },
1903     steps, millis, function() {});
1904 };
1905 
1906 /**
1907  * Draw dots over the selectied points in the data series. This function
1908  * takes care of cleanup of previously-drawn dots.
1909  * @private
1910  */
1911 Dygraph.prototype.updateSelection_ = function(opt_animFraction) {
1912   /*var defaultPrevented = */
1913   this.cascadeEvents_('select', {
1914     selectedX: this.lastx_,
1915     selectedPoints: this.selPoints_
1916   });
1917   // TODO(danvk): use defaultPrevented here?
1918 
1919   // Clear the previously drawn vertical, if there is one
1920   var i;
1921   var ctx = this.canvas_ctx_;
1922   if (this.attr_('highlightSeriesOpts')) {
1923     ctx.clearRect(0, 0, this.width_, this.height_);
1924     var alpha = 1.0 - this.attr_('highlightSeriesBackgroundAlpha');
1925     if (alpha) {
1926       // Activating background fade includes an animation effect for a gradual
1927       // fade. TODO(klausw): make this independently configurable if it causes
1928       // issues? Use a shared preference to control animations?
1929       var animateBackgroundFade = true;
1930       if (animateBackgroundFade) {
1931         if (opt_animFraction === undefined) {
1932           // start a new animation
1933           this.animateSelection_(1);
1934           return;
1935         }
1936         alpha *= opt_animFraction;
1937       }
1938       ctx.fillStyle = 'rgba(255,255,255,' + alpha + ')';
1939       ctx.fillRect(0, 0, this.width_, this.height_);
1940     }
1941 
1942     // Redraw only the highlighted series in the interactive canvas (not the
1943     // static plot canvas, which is where series are usually drawn).
1944     this.plotter_._renderLineChart(this.highlightSet_, ctx);
1945   } else if (this.previousVerticalX_ >= 0) {
1946     // Determine the maximum highlight circle size.
1947     var maxCircleSize = 0;
1948     var labels = this.attr_('labels');
1949     for (i = 1; i < labels.length; i++) {
1950       var r = this.attr_('highlightCircleSize', labels[i]);
1951       if (r > maxCircleSize) maxCircleSize = r;
1952     }
1953     var px = this.previousVerticalX_;
1954     ctx.clearRect(px - maxCircleSize - 1, 0,
1955                   2 * maxCircleSize + 2, this.height_);
1956   }
1957 
1958   if (this.isUsingExcanvas_ && this.currentZoomRectArgs_) {
1959     Dygraph.prototype.drawZoomRect_.apply(this, this.currentZoomRectArgs_);
1960   }
1961 
1962   if (this.selPoints_.length > 0) {
1963     // Draw colored circles over the center of each selected point
1964     var canvasx = this.selPoints_[0].canvasx;
1965     ctx.save();
1966     for (i = 0; i < this.selPoints_.length; i++) {
1967       var pt = this.selPoints_[i];
1968       if (!Dygraph.isOK(pt.canvasy)) continue;
1969 
1970       var circleSize = this.attr_('highlightCircleSize', pt.name);
1971       var callback = this.attr_("drawHighlightPointCallback", pt.name);
1972       var color = this.plotter_.colors[pt.name];
1973       if (!callback) {
1974         callback = Dygraph.Circles.DEFAULT;
1975       }
1976       ctx.lineWidth = this.attr_('strokeWidth', pt.name);
1977       ctx.strokeStyle = color;
1978       ctx.fillStyle = color;
1979       callback(this.g, pt.name, ctx, canvasx, pt.canvasy,
1980           color, circleSize, pt.idx);
1981     }
1982     ctx.restore();
1983 
1984     this.previousVerticalX_ = canvasx;
1985   }
1986 };
1987 
1988 /**
1989  * Manually set the selected points and display information about them in the
1990  * legend. The selection can be cleared using clearSelection() and queried
1991  * using getSelection().
1992  * @param { Integer } row number that should be highlighted (i.e. appear with
1993  * hover dots on the chart). Set to false to clear any selection.
1994  * @param { seriesName } optional series name to highlight that series with the
1995  * the highlightSeriesOpts setting.
1996  * @param { locked } optional If true, keep seriesName selected when mousing
1997  * over the graph, disabling closest-series highlighting. Call clearSelection()
1998  * to unlock it.
1999  */
2000 Dygraph.prototype.setSelection = function(row, opt_seriesName, opt_locked) {
2001   // Extract the points we've selected
2002   this.selPoints_ = [];
2003 
2004   var changed = false;
2005   if (row !== false && row >= 0) {
2006     if (row != this.lastRow_) changed = true;
2007     this.lastRow_ = row;
2008     for (var setIdx = 0; setIdx < this.layout_.points.length; ++setIdx) {
2009       var points = this.layout_.points[setIdx];
2010       var setRow = row - this.getLeftBoundary_(setIdx);
2011       if (setRow < points.length) {
2012         var point = points[setRow];
2013         if (point.yval !== null) this.selPoints_.push(point);
2014       }
2015     }
2016   } else {
2017     if (this.lastRow_ >= 0) changed = true;
2018     this.lastRow_ = -1;
2019   }
2020 
2021   if (this.selPoints_.length) {
2022     this.lastx_ = this.selPoints_[0].xval;
2023   } else {
2024     this.lastx_ = -1;
2025   }
2026 
2027   if (opt_seriesName !== undefined) {
2028     if (this.highlightSet_ !== opt_seriesName) changed = true;
2029     this.highlightSet_ = opt_seriesName;
2030   }
2031 
2032   if (opt_locked !== undefined) {
2033     this.lockedSet_ = opt_locked;
2034   }
2035 
2036   if (changed) {
2037     this.updateSelection_(undefined);
2038   }
2039   return changed;
2040 };
2041 
2042 /**
2043  * The mouse has left the canvas. Clear out whatever artifacts remain
2044  * @param {Object} event the mouseout event from the browser.
2045  * @private
2046  */
2047 Dygraph.prototype.mouseOut_ = function(event) {
2048   if (this.attr_("unhighlightCallback")) {
2049     this.attr_("unhighlightCallback")(event);
2050   }
2051 
2052   if (this.attr_("hideOverlayOnMouseOut") && !this.lockedSet_) {
2053     this.clearSelection();
2054   }
2055 };
2056 
2057 /**
2058  * Clears the current selection (i.e. points that were highlighted by moving
2059  * the mouse over the chart).
2060  */
2061 Dygraph.prototype.clearSelection = function() {
2062   this.cascadeEvents_('deselect', {});
2063 
2064   this.lockedSet_ = false;
2065   // Get rid of the overlay data
2066   if (this.fadeLevel) {
2067     this.animateSelection_(-1);
2068     return;
2069   }
2070   this.canvas_ctx_.clearRect(0, 0, this.width_, this.height_);
2071   this.fadeLevel = 0;
2072   this.selPoints_ = [];
2073   this.lastx_ = -1;
2074   this.lastRow_ = -1;
2075   this.highlightSet_ = null;
2076 };
2077 
2078 /**
2079  * Returns the number of the currently selected row. To get data for this row,
2080  * you can use the getValue method.
2081  * @return { Integer } row number, or -1 if nothing is selected
2082  */
2083 Dygraph.prototype.getSelection = function() {
2084   if (!this.selPoints_ || this.selPoints_.length < 1) {
2085     return -1;
2086   }
2087 
2088   for (var setIdx = 0; setIdx < this.layout_.points.length; setIdx++) {
2089     var points = this.layout_.points[setIdx];
2090     for (var row = 0; row < points.length; row++) {
2091       if (points[row].x == this.selPoints_[0].x) {
2092         return points[row].idx;
2093       }
2094     }
2095   }
2096   return -1;
2097 };
2098 
2099 /**
2100  * Returns the name of the currently-highlighted series.
2101  * Only available when the highlightSeriesOpts option is in use.
2102  */
2103 Dygraph.prototype.getHighlightSeries = function() {
2104   return this.highlightSet_;
2105 };
2106 
2107 /**
2108  * Returns true if the currently-highlighted series was locked
2109  * via setSelection(..., seriesName, true).
2110  */
2111 Dygraph.prototype.isSeriesLocked = function() {
2112   return this.lockedSet_;
2113 };
2114 
2115 /**
2116  * Fires when there's data available to be graphed.
2117  * @param {String} data Raw CSV data to be plotted
2118  * @private
2119  */
2120 Dygraph.prototype.loadedEvent_ = function(data) {
2121   this.rawData_ = this.parseCSV_(data);
2122   this.predraw_();
2123 };
2124 
2125 /**
2126  * Add ticks on the x-axis representing years, months, quarters, weeks, or days
2127  * @private
2128  */
2129 Dygraph.prototype.addXTicks_ = function() {
2130   // Determine the correct ticks scale on the x-axis: quarterly, monthly, ...
2131   var range;
2132   if (this.dateWindow_) {
2133     range = [this.dateWindow_[0], this.dateWindow_[1]];
2134   } else {
2135     range = this.xAxisExtremes();
2136   }
2137 
2138   var xAxisOptionsView = this.optionsViewForAxis_('x');
2139   var xTicks = xAxisOptionsView('ticker')(
2140       range[0],
2141       range[1],
2142       this.width_,  // TODO(danvk): should be area.width
2143       xAxisOptionsView,
2144       this);
2145   // var msg = 'ticker(' + range[0] + ', ' + range[1] + ', ' + this.width_ + ', ' + this.attr_('pixelsPerXLabel') + ') -> ' + JSON.stringify(xTicks);
2146   // console.log(msg);
2147   this.layout_.setXTicks(xTicks);
2148 };
2149 
2150 /**
2151  * @private
2152  * Computes the range of the data series (including confidence intervals).
2153  * @param { [Array] } series either [ [x1, y1], [x2, y2], ... ] or
2154  * [ [x1, [y1, dev_low, dev_high]], [x2, [y2, dev_low, dev_high]], ...
2155  * @return [low, high]
2156  */
2157 Dygraph.prototype.extremeValues_ = function(series) {
2158   var minY = null, maxY = null, j, y;
2159 
2160   var bars = this.attr_("errorBars") || this.attr_("customBars");
2161   if (bars) {
2162     // With custom bars, maxY is the max of the high values.
2163     for (j = 0; j < series.length; j++) {
2164       y = series[j][1][0];
2165       if (y === null || isNaN(y)) continue;
2166       var low = y - series[j][1][1];
2167       var high = y + series[j][1][2];
2168       if (low > y) low = y;    // this can happen with custom bars,
2169       if (high < y) high = y;  // e.g. in tests/custom-bars.html
2170       if (maxY === null || high > maxY) {
2171         maxY = high;
2172       }
2173       if (minY === null || low < minY) {
2174         minY = low;
2175       }
2176     }
2177   } else {
2178     for (j = 0; j < series.length; j++) {
2179       y = series[j][1];
2180       if (y === null || isNaN(y)) continue;
2181       if (maxY === null || y > maxY) {
2182         maxY = y;
2183       }
2184       if (minY === null || y < minY) {
2185         minY = y;
2186       }
2187     }
2188   }
2189 
2190   return [minY, maxY];
2191 };
2192 
2193 /**
2194  * @private
2195  * This function is called once when the chart's data is changed or the options
2196  * dictionary is updated. It is _not_ called when the user pans or zooms. The
2197  * idea is that values derived from the chart's data can be computed here,
2198  * rather than every time the chart is drawn. This includes things like the
2199  * number of axes, rolling averages, etc.
2200  */
2201 Dygraph.prototype.predraw_ = function() {
2202   var start = new Date();
2203 
2204   this.layout_.computePlotArea();
2205 
2206   // TODO(danvk): move more computations out of drawGraph_ and into here.
2207   this.computeYAxes_();
2208 
2209   // Create a new plotter.
2210   if (this.plotter_) {
2211     this.cascadeEvents_('clearChart');
2212     this.plotter_.clear();
2213   }
2214 
2215   if (!this.is_initial_draw_) {
2216     this.canvas_ctx_.restore();
2217     this.hidden_ctx_.restore();
2218   }
2219 
2220   this.canvas_ctx_.save();
2221   this.hidden_ctx_.save();
2222 
2223   this.plotter_ = new DygraphCanvasRenderer(this,
2224                                             this.hidden_,
2225                                             this.hidden_ctx_,
2226                                             this.layout_);
2227 
2228   // The roller sits in the bottom left corner of the chart. We don't know where
2229   // this will be until the options are available, so it's positioned here.
2230   this.createRollInterface_();
2231 
2232   this.cascadeEvents_('predraw');
2233 
2234   // Convert the raw data (a 2D array) into the internal format and compute
2235   // rolling averages.
2236   this.rolledSeries_ = [null];  // x-axis is the first series and it's special
2237   for (var i = 1; i < this.numColumns(); i++) {
2238     // var logScale = this.attr_('logscale', i); // TODO(klausw): this looks wrong // konigsberg thinks so too.
2239     var logScale = this.attr_('logscale');
2240     var series = this.extractSeries_(this.rawData_, i, logScale);
2241     series = this.rollingAverage(series, this.rollPeriod_);
2242     this.rolledSeries_.push(series);
2243   }
2244 
2245   // If the data or options have changed, then we'd better redraw.
2246   this.drawGraph_();
2247 
2248   // This is used to determine whether to do various animations.
2249   var end = new Date();
2250   this.drawingTimeMs_ = (end - start);
2251 };
2252 
2253 /**
2254  * Point structure.
2255  *
2256  * xval_* and yval_* are the original unscaled data values,
2257  * while x_* and y_* are scaled to the range (0.0-1.0) for plotting.
2258  * yval_stacked is the cumulative Y value used for stacking graphs,
2259  * and bottom/top/minus/plus are used for error bar graphs.
2260  *
2261  * @typedef {{
2262  *     idx: number,
2263  *     name: string,
2264  *     x: ?number,
2265  *     xval: ?number,
2266  *     y_bottom: ?number,
2267  *     y: ?number,
2268  *     y_stacked: ?number,
2269  *     y_top: ?number,
2270  *     yval_minus: ?number,
2271  *     yval: ?number,
2272  *     yval_plus: ?number,
2273  *     yval_stacked
2274  * }}
2275  */
2276 Dygraph.PointType = undefined;
2277 
2278 // TODO(bhs): these loops are a hot-spot for high-point-count charts. In fact,
2279 // on chrome+linux, they are 6 times more expensive than iterating through the
2280 // points and drawing the lines. The brunt of the cost comes from allocating
2281 // the |point| structures.
2282 /**
2283  * Converts a series to a Point array.
2284  *
2285  * @private
2286  * @param {Array.<Array.<(?number|Array<?number>)>} series Array where
2287  *     series[row] = [x,y] or [x, [y, err]] or [x, [y, yplus, yminus]].
2288  * @param {boolean} bars True if error bars or custom bars are being drawn.
2289  * @param {string} setName Name of the series.
2290  * @param {number} boundaryIdStart Index offset of the first point, equal to
2291  *     the number of skipped points left of the date window minimum (if any).
2292  * @return {Array.<Dygraph.PointType>} List of points for this series.
2293  */
2294 Dygraph.seriesToPoints_ = function(series, bars, setName, boundaryIdStart) {
2295   var points = [];
2296   for (var i = 0; i < series.length; ++i) {
2297     var item = series[i];
2298     var yraw = bars ? item[1][0] : item[1];
2299     var yval = yraw === null ? null : DygraphLayout.parseFloat_(yraw);
2300     var point = {
2301       x: NaN,
2302       y: NaN,
2303       xval: DygraphLayout.parseFloat_(item[0]),
2304       yval: yval,
2305       name: setName,  // TODO(danvk): is this really necessary?
2306       idx: i + boundaryIdStart
2307     };
2308 
2309     if (bars) {
2310       point.y_top = NaN;
2311       point.y_bottom = NaN;
2312       point.yval_minus = DygraphLayout.parseFloat_(item[1][1]);
2313       point.yval_plus = DygraphLayout.parseFloat_(item[1][2]);
2314     }
2315     points.push(point);
2316   }
2317   return points;
2318 };
2319 
2320 
2321 /**
2322  * Calculates point stacking for stackedGraph=true.
2323  *
2324  * For stacking purposes, interpolate or extend neighboring data across
2325  * NaN values based on stackedGraphNaNFill settings. This is for display
2326  * only, the underlying data value as shown in the legend remains NaN.
2327  *
2328  * @param {Array.<Dygraph.PointType>} points Point array for a single series.
2329  *     Updates each Point's yval_stacked property.
2330  * @param {Array.<number>} cumulativeYval Accumulated top-of-graph stacked Y
2331  *     values for the series seen so far. Index is the row number. Updated
2332  *     based on the current series's values.
2333  * @param {Array.<number>} seriesExtremes Min and max values, updated
2334  *     to reflect the stacked values.
2335  * @param {string} fillMethod Interpolation method, one of 'all', 'inside', or
2336  *     'none'.
2337  * @private
2338  */
2339 Dygraph.stackPoints_ = function(
2340     points, cumulativeYval, seriesExtremes, fillMethod) {
2341   var lastXval = null;
2342   var prevPoint = null;
2343   var nextPoint = null;
2344   var nextPointIdx = -1;
2345 
2346   // Find the next stackable point starting from the given index.
2347   var updateNextPoint = function(idx) {
2348     // If we've previously found a non-NaN point and haven't gone past it yet,
2349     // just use that.
2350     if (nextPointIdx >= idx) return;
2351 
2352     // We haven't found a non-NaN point yet or have moved past it,
2353     // look towards the right to find a non-NaN point.
2354     for (var j = idx; j < points.length; ++j) {
2355       // Clear out a previously-found point (if any) since it's no longer
2356       // valid, we shouldn't use it for interpolation anymore.
2357       nextPoint = null;
2358       if (!isNaN(points[j].yval) && points[j].yval !== null) {
2359         nextPointIdx = j;
2360         nextPoint = points[j];
2361         break;
2362       }
2363     }
2364   };
2365 
2366   for (var i = 0; i < points.length; ++i) {
2367     var point = points[i];
2368     var xval = point.xval;
2369     if (cumulativeYval[xval] === undefined) {
2370       cumulativeYval[xval] = 0;
2371     }
2372 
2373     var actualYval = point.yval;
2374     if (isNaN(actualYval) || actualYval === null) {
2375       // Interpolate/extend for stacking purposes if possible.
2376       updateNextPoint(i);
2377       if (prevPoint && nextPoint && fillMethod != 'none') {
2378         // Use linear interpolation between prevPoint and nextPoint.
2379         actualYval = prevPoint.yval + (nextPoint.yval - prevPoint.yval) *
2380             ((xval - prevPoint.xval) / (nextPoint.xval - prevPoint.xval));
2381       } else if (prevPoint && fillMethod == 'all') {
2382         actualYval = prevPoint.yval;
2383       } else if (nextPoint && fillMethod == 'all') {
2384         actualYval = nextPoint.yval;
2385       } else {
2386         actualYval = 0;
2387       }
2388     } else {
2389       prevPoint = point;
2390     }
2391 
2392     var stackedYval = cumulativeYval[xval];
2393     if (lastXval != xval) {
2394       // If an x-value is repeated, we ignore the duplicates.
2395       stackedYval += actualYval;
2396       cumulativeYval[xval] = stackedYval;
2397     }
2398     lastXval = xval;
2399 
2400     point.yval_stacked = stackedYval;
2401 
2402     if (stackedYval > seriesExtremes[1]) {
2403       seriesExtremes[1] = stackedYval;
2404     }
2405     if (stackedYval < seriesExtremes[0]) {
2406       seriesExtremes[0] = stackedYval;
2407     }
2408   }
2409 };
2410 
2411 
2412 /**
2413  * Loop over all fields and create datasets, calculating extreme y-values for
2414  * each series and extreme x-indices as we go.
2415  *
2416  * dateWindow is passed in as an explicit parameter so that we can compute
2417  * extreme values "speculatively", i.e. without actually setting state on the
2418  * dygraph.
2419  *
2420  * @param {Array.<Array.<Array.<(number|Array<number>)>>} rolledSeries, where
2421  *     rolledSeries[seriesIndex][row] = raw point, where
2422  *     seriesIndex is the column number starting with 1, and
2423  *     rawPoint is [x,y] or [x, [y, err]] or [x, [y, yminus, yplus]].
2424  * @param {?Array.<number>} dateWindow [xmin, xmax] pair, or null.
2425  * @return {{
2426  *     points: Array.<Array.<Dygraph.PointType>>,
2427  *     seriesExtremes: Array.<Array.<number>>,
2428  *     boundaryIds: Array.<number>}}
2429  * @private
2430  */
2431 Dygraph.prototype.gatherDatasets_ = function(rolledSeries, dateWindow) {
2432   var boundaryIds = [];
2433   var points = [];
2434   var cumulativeYval = [];  // For stacked series.
2435   var extremes = {};  // series name -> [low, high]
2436   var i, k;
2437   var errorBars = this.attr_("errorBars");
2438   var customBars = this.attr_("customBars");
2439   var bars = errorBars || customBars;
2440   var isValueNull = function(sample) {
2441     if (!bars) {
2442       return sample[1] === null;
2443     } else {
2444       return customBars ? sample[1][1] === null : 
2445         errorBars ? sample[1][0] === null : false;
2446     }
2447   };
2448 
2449   // Loop over the fields (series).  Go from the last to the first,
2450   // because if they're stacked that's how we accumulate the values.
2451   var num_series = rolledSeries.length - 1;
2452   var series;
2453   for (i = num_series; i >= 1; i--) {
2454     if (!this.visibility()[i - 1]) continue;
2455 
2456     // Prune down to the desired range, if necessary (for zooming)
2457     // Because there can be lines going to points outside of the visible area,
2458     // we actually prune to visible points, plus one on either side.
2459     if (dateWindow) {
2460       series = rolledSeries[i];
2461       var low = dateWindow[0];
2462       var high = dateWindow[1];
2463 
2464       // TODO(danvk): do binary search instead of linear search.
2465       // TODO(danvk): pass firstIdx and lastIdx directly to the renderer.
2466       var firstIdx = null, lastIdx = null;
2467       for (k = 0; k < series.length; k++) {
2468         if (series[k][0] >= low && firstIdx === null) {
2469           firstIdx = k;
2470         }
2471         if (series[k][0] <= high) {
2472           lastIdx = k;
2473         }
2474       }
2475 
2476       if (firstIdx === null) firstIdx = 0;
2477       var correctedFirstIdx = firstIdx;
2478       var isInvalidValue = true;
2479       while (isInvalidValue && correctedFirstIdx > 0) {
2480         correctedFirstIdx--;
2481         isInvalidValue = isValueNull(series[correctedFirstIdx]);
2482       }
2483 
2484       if (lastIdx === null) lastIdx = series.length - 1;
2485       var correctedLastIdx = lastIdx;
2486       isInvalidValue = true;
2487       while (isInvalidValue && correctedLastIdx < series.length - 1) {
2488         correctedLastIdx++;
2489         isInvalidValue = isValueNull(series[correctedLastIdx]);
2490       }
2491 
2492 
2493       if (correctedFirstIdx!==firstIdx) {
2494         firstIdx = correctedFirstIdx;
2495       }
2496       if (correctedLastIdx !== lastIdx) {
2497         lastIdx = correctedLastIdx;
2498       }
2499       
2500       boundaryIds[i-1] = [firstIdx, lastIdx];
2501       
2502       // .slice's end is exclusive, we want to include lastIdx.
2503       series = series.slice(firstIdx, lastIdx + 1);
2504     } else {
2505       series = rolledSeries[i];
2506       boundaryIds[i-1] = [0, series.length-1];
2507     }
2508 
2509     var seriesName = this.attr_("labels")[i];
2510     var seriesExtremes = this.extremeValues_(series);
2511 
2512     var seriesPoints = Dygraph.seriesToPoints_(
2513         series, bars, seriesName, boundaryIds[i-1][0]);
2514 
2515     if (this.attr_("stackedGraph")) {
2516       Dygraph.stackPoints_(seriesPoints, cumulativeYval, seriesExtremes,
2517                            this.attr_("stackedGraphNaNFill"));
2518     }
2519 
2520     extremes[seriesName] = seriesExtremes;
2521     points[i] = seriesPoints;
2522   }
2523 
2524   return { points: points, extremes: extremes, boundaryIds: boundaryIds };
2525 };
2526 
2527 /**
2528  * Update the graph with new data. This method is called when the viewing area
2529  * has changed. If the underlying data or options have changed, predraw_ will
2530  * be called before drawGraph_ is called.
2531  *
2532  * @private
2533  */
2534 Dygraph.prototype.drawGraph_ = function() {
2535   var start = new Date();
2536 
2537   // This is used to set the second parameter to drawCallback, below.
2538   var is_initial_draw = this.is_initial_draw_;
2539   this.is_initial_draw_ = false;
2540 
2541   this.layout_.removeAllDatasets();
2542   this.setColors_();
2543   this.attrs_.pointSize = 0.5 * this.attr_('highlightCircleSize');
2544 
2545   var packed = this.gatherDatasets_(this.rolledSeries_, this.dateWindow_);
2546   var points = packed.points;
2547   var extremes = packed.extremes;
2548   this.boundaryIds_ = packed.boundaryIds;
2549 
2550   this.setIndexByName_ = {};
2551   var labels = this.attr_("labels");
2552   if (labels.length > 0) {
2553     this.setIndexByName_[labels[0]] = 0;
2554   }
2555   var dataIdx = 0;
2556   for (var i = 1; i < points.length; i++) {
2557     this.setIndexByName_[labels[i]] = i;
2558     if (!this.visibility()[i - 1]) continue;
2559     this.layout_.addDataset(labels[i], points[i]);
2560     this.datasetIndex_[i] = dataIdx++;
2561   }
2562 
2563   this.computeYAxisRanges_(extremes);
2564   this.layout_.setYAxes(this.axes_);
2565 
2566   this.addXTicks_();
2567 
2568   // Save the X axis zoomed status as the updateOptions call will tend to set it erroneously
2569   var tmp_zoomed_x = this.zoomed_x_;
2570   // Tell PlotKit to use this new data and render itself
2571   this.zoomed_x_ = tmp_zoomed_x;
2572   this.layout_.evaluate();
2573   this.renderGraph_(is_initial_draw);
2574 
2575   if (this.attr_("timingName")) {
2576     var end = new Date();
2577     Dygraph.info(this.attr_("timingName") + " - drawGraph: " + (end - start) + "ms");
2578   }
2579 };
2580 
2581 /**
2582  * This does the work of drawing the chart. It assumes that the layout and axis
2583  * scales have already been set (e.g. by predraw_).
2584  *
2585  * @private
2586  */
2587 Dygraph.prototype.renderGraph_ = function(is_initial_draw) {
2588   this.cascadeEvents_('clearChart');
2589   this.plotter_.clear();
2590 
2591   if (this.attr_('underlayCallback')) {
2592     // NOTE: we pass the dygraph object to this callback twice to avoid breaking
2593     // users who expect a deprecated form of this callback.
2594     this.attr_('underlayCallback')(
2595         this.hidden_ctx_, this.layout_.getPlotArea(), this, this);
2596   }
2597 
2598   var e = {
2599     canvas: this.hidden_,
2600     drawingContext: this.hidden_ctx_
2601   };
2602   this.cascadeEvents_('willDrawChart', e);
2603   this.plotter_.render();
2604   this.cascadeEvents_('didDrawChart', e);
2605   this.lastRow_ = -1;  // because plugins/legend.js clears the legend
2606 
2607   // TODO(danvk): is this a performance bottleneck when panning?
2608   // The interaction canvas should already be empty in that situation.
2609   this.canvas_.getContext('2d').clearRect(0, 0, this.canvas_.width,
2610                                           this.canvas_.height);
2611 
2612   if (this.attr_("drawCallback") !== null) {
2613     this.attr_("drawCallback")(this, is_initial_draw);
2614   }
2615 };
2616 
2617 /**
2618  * @private
2619  * Determine properties of the y-axes which are independent of the data
2620  * currently being displayed. This includes things like the number of axes and
2621  * the style of the axes. It does not include the range of each axis and its
2622  * tick marks.
2623  * This fills in this.axes_.
2624  * axes_ = [ { options } ]
2625  *   indices are into the axes_ array.
2626  */
2627 Dygraph.prototype.computeYAxes_ = function() {
2628   // Preserve valueWindow settings if they exist, and if the user hasn't
2629   // specified a new valueRange.
2630   var valueWindows, axis, index, opts, v;
2631   if (this.axes_ !== undefined && this.user_attrs_.hasOwnProperty("valueRange") === false) {
2632     valueWindows = [];
2633     for (index = 0; index < this.axes_.length; index++) {
2634       valueWindows.push(this.axes_[index].valueWindow);
2635     }
2636   }
2637 
2638   // this.axes_ doesn't match this.attributes_.axes_.options. It's used for
2639   // data computation as well as options storage.
2640   // Go through once and add all the axes.
2641   this.axes_ = [];
2642 
2643   for (axis = 0; axis < this.attributes_.numAxes(); axis++) {
2644     // Add a new axis, making a copy of its per-axis options.
2645     opts = { g : this };
2646     Dygraph.update(opts, this.attributes_.axisOptions(axis));
2647     this.axes_[axis] = opts;
2648   }
2649 
2650 
2651   // Copy global valueRange option over to the first axis.
2652   // NOTE(konigsberg): Are these two statements necessary?
2653   // I tried removing it. The automated tests pass, and manually
2654   // messing with tests/zoom.html showed no trouble.
2655   v = this.attr_('valueRange');
2656   if (v) this.axes_[0].valueRange = v;
2657 
2658   if (valueWindows !== undefined) {
2659     // Restore valueWindow settings.
2660 
2661     // When going from two axes back to one, we only restore
2662     // one axis.
2663     var idxCount = Math.min(valueWindows.length, this.axes_.length);
2664 
2665     for (index = 0; index < idxCount; index++) {
2666       this.axes_[index].valueWindow = valueWindows[index];
2667     }
2668   }
2669 
2670   for (axis = 0; axis < this.axes_.length; axis++) {
2671     if (axis === 0) {
2672       opts = this.optionsViewForAxis_('y' + (axis ? '2' : ''));
2673       v = opts("valueRange");
2674       if (v) this.axes_[axis].valueRange = v;
2675     } else {  // To keep old behavior
2676       var axes = this.user_attrs_.axes;
2677       if (axes && axes.y2) {
2678         v = axes.y2.valueRange;
2679         if (v) this.axes_[axis].valueRange = v;
2680       }
2681     }
2682   }
2683 };
2684 
2685 /**
2686  * Returns the number of y-axes on the chart.
2687  * @return {Number} the number of axes.
2688  */
2689 Dygraph.prototype.numAxes = function() {
2690   return this.attributes_.numAxes();
2691 };
2692 
2693 /**
2694  * @private
2695  * Returns axis properties for the given series.
2696  * @param { String } setName The name of the series for which to get axis
2697  * properties, e.g. 'Y1'.
2698  * @return { Object } The axis properties.
2699  */
2700 Dygraph.prototype.axisPropertiesForSeries = function(series) {
2701   // TODO(danvk): handle errors.
2702   return this.axes_[this.attributes_.axisForSeries(series)];
2703 };
2704 
2705 /**
2706  * @private
2707  * Determine the value range and tick marks for each axis.
2708  * @param {Object} extremes A mapping from seriesName -> [low, high]
2709  * This fills in the valueRange and ticks fields in each entry of this.axes_.
2710  */
2711 Dygraph.prototype.computeYAxisRanges_ = function(extremes) {
2712   var isNullUndefinedOrNaN = function(num) {
2713     return isNaN(parseFloat(num));
2714   };
2715   var numAxes = this.attributes_.numAxes();
2716   var ypadCompat, span, series, ypad;
2717   
2718   var p_axis;
2719 
2720   // Compute extreme values, a span and tick marks for each axis.
2721   for (var i = 0; i < numAxes; i++) {
2722     var axis = this.axes_[i];
2723     var logscale = this.attributes_.getForAxis("logscale", i);
2724     var includeZero = this.attributes_.getForAxis("includeZero", i);
2725     var independentTicks = this.attributes_.getForAxis("independentTicks", i);
2726     series = this.attributes_.seriesForAxis(i);
2727 
2728     // Add some padding. This supports two Y padding operation modes:
2729     //
2730     // - backwards compatible (yRangePad not set):
2731     //   10% padding for automatic Y ranges, but not for user-supplied
2732     //   ranges, and move a close-to-zero edge to zero except if
2733     //   avoidMinZero is set, since drawing at the edge results in
2734     //   invisible lines. Unfortunately lines drawn at the edge of a
2735     //   user-supplied range will still be invisible. If logscale is
2736     //   set, add a variable amount of padding at the top but
2737     //   none at the bottom.
2738     //
2739     // - new-style (yRangePad set by the user):
2740     //   always add the specified Y padding.
2741     //
2742     ypadCompat = true;
2743     ypad = 0.1; // add 10%
2744     if (this.attr_('yRangePad') !== null) {
2745       ypadCompat = false;
2746       // Convert pixel padding to ratio
2747       ypad = this.attr_('yRangePad') / this.plotter_.area.h;
2748     }
2749 
2750     if (series.length === 0) {
2751       // If no series are defined or visible then use a reasonable default
2752       axis.extremeRange = [0, 1];
2753     } else {
2754       // Calculate the extremes of extremes.
2755       var minY = Infinity;  // extremes[series[0]][0];
2756       var maxY = -Infinity;  // extremes[series[0]][1];
2757       var extremeMinY, extremeMaxY;
2758 
2759       for (var j = 0; j < series.length; j++) {
2760         // this skips invisible series
2761         if (!extremes.hasOwnProperty(series[j])) continue;
2762 
2763         // Only use valid extremes to stop null data series' from corrupting the scale.
2764         extremeMinY = extremes[series[j]][0];
2765         if (extremeMinY !== null) {
2766           minY = Math.min(extremeMinY, minY);
2767         }
2768         extremeMaxY = extremes[series[j]][1];
2769         if (extremeMaxY !== null) {
2770           maxY = Math.max(extremeMaxY, maxY);
2771         }
2772       }
2773 
2774       // Include zero if requested by the user.
2775       if (includeZero && !logscale) {
2776         if (minY > 0) minY = 0;
2777         if (maxY < 0) maxY = 0;
2778       }
2779 
2780       // Ensure we have a valid scale, otherwise default to [0, 1] for safety.
2781       if (minY == Infinity) minY = 0;
2782       if (maxY == -Infinity) maxY = 1;
2783 
2784       span = maxY - minY;
2785       // special case: if we have no sense of scale, center on the sole value.
2786       if (span === 0) {
2787         if (maxY !== 0) {
2788           span = Math.abs(maxY);
2789         } else {
2790           // ... and if the sole value is zero, use range 0-1.
2791           maxY = 1;
2792           span = 1;
2793         }
2794       }
2795 
2796       var maxAxisY, minAxisY;
2797       if (logscale) {
2798         if (ypadCompat) {
2799           maxAxisY = maxY + ypad * span;
2800           minAxisY = minY;
2801         } else {
2802           var logpad = Math.exp(Math.log(span) * ypad);
2803           maxAxisY = maxY * logpad;
2804           minAxisY = minY / logpad;
2805         }
2806       } else {
2807         maxAxisY = maxY + ypad * span;
2808         minAxisY = minY - ypad * span;
2809 
2810         // Backwards-compatible behavior: Move the span to start or end at zero if it's
2811         // close to zero, but not if avoidMinZero is set.
2812         if (ypadCompat && !this.attr_("avoidMinZero")) {
2813           if (minAxisY < 0 && minY >= 0) minAxisY = 0;
2814           if (maxAxisY > 0 && maxY <= 0) maxAxisY = 0;
2815         }
2816       }
2817       axis.extremeRange = [minAxisY, maxAxisY];
2818     }
2819     if (axis.valueWindow) {
2820       // This is only set if the user has zoomed on the y-axis. It is never set
2821       // by a user. It takes precedence over axis.valueRange because, if you set
2822       // valueRange, you'd still expect to be able to pan.
2823       axis.computedValueRange = [axis.valueWindow[0], axis.valueWindow[1]];
2824     } else if (axis.valueRange) {
2825       // This is a user-set value range for this axis.
2826       var y0 = isNullUndefinedOrNaN(axis.valueRange[0]) ? axis.extremeRange[0] : axis.valueRange[0];
2827       var y1 = isNullUndefinedOrNaN(axis.valueRange[1]) ? axis.extremeRange[1] : axis.valueRange[1];
2828       if (!ypadCompat) {
2829         if (axis.logscale) {
2830           var logpad = Math.exp(Math.log(span) * ypad);
2831           y0 *= logpad;
2832           y1 /= logpad;
2833         } else {
2834           span = y1 - y0;
2835           y0 -= span * ypad;
2836           y1 += span * ypad;
2837         }
2838       }
2839       axis.computedValueRange = [y0, y1];
2840     } else {
2841       axis.computedValueRange = axis.extremeRange;
2842     }
2843     
2844     
2845     if (independentTicks) {
2846       axis.independentTicks = independentTicks;
2847       var opts = this.optionsViewForAxis_('y' + (i ? '2' : ''));
2848       var ticker = opts('ticker');
2849       axis.ticks = ticker(axis.computedValueRange[0],
2850               axis.computedValueRange[1],
2851               this.height_,  // TODO(danvk): should be area.height
2852               opts,
2853               this);
2854       // Define the first independent axis as primary axis.
2855       if (!p_axis) p_axis = axis;
2856     }
2857   }
2858   if (p_axis === undefined) {
2859     throw ("Configuration Error: At least one axis has to have the \"independentTicks\" option activated.");
2860   }
2861   // Add ticks. By default, all axes inherit the tick positions of the
2862   // primary axis. However, if an axis is specifically marked as having
2863   // independent ticks, then that is permissible as well.
2864   for (var i = 0; i < numAxes; i++) {
2865     var axis = this.axes_[i];
2866     
2867     if (!axis.independentTicks) {
2868       var opts = this.optionsViewForAxis_('y' + (i ? '2' : ''));
2869       var ticker = opts('ticker');
2870       var p_ticks = p_axis.ticks;
2871       var p_scale = p_axis.computedValueRange[1] - p_axis.computedValueRange[0];
2872       var scale = axis.computedValueRange[1] - axis.computedValueRange[0];
2873       var tick_values = [];
2874       for (var k = 0; k < p_ticks.length; k++) {
2875         var y_frac = (p_ticks[k].v - p_axis.computedValueRange[0]) / p_scale;
2876         var y_val = axis.computedValueRange[0] + y_frac * scale;
2877         tick_values.push(y_val);
2878       }
2879 
2880       axis.ticks = ticker(axis.computedValueRange[0],
2881                           axis.computedValueRange[1],
2882                           this.height_,  // TODO(danvk): should be area.height
2883                           opts,
2884                           this,
2885                           tick_values);
2886     }
2887   }
2888 };
2889 
2890 /**
2891  * Extracts one series from the raw data (a 2D array) into an array of (date,
2892  * value) tuples.
2893  *
2894  * This is where undesirable points (i.e. negative values on log scales and
2895  * missing values through which we wish to connect lines) are dropped.
2896  * TODO(danvk): the "missing values" bit above doesn't seem right.
2897  *
2898  * @private
2899  * @param {Array.<Array.<(number|Array<Number>)>>} rawData Input data. Rectangular
2900  *     grid of points, where rawData[row][0] is the X value for the row,
2901  *     and rawData[row][i] is the Y data for series #i.
2902  * @param {number} i Series index, starting from 1.
2903  * @param {boolean} logScale True if using logarithmic Y scale.
2904  * @return {Array.<Array.<(?number|Array<?number>)>} Series array, where
2905  *     series[row] = [x,y] or [x, [y, err]] or [x, [y, yplus, yminus]].
2906  */
2907 Dygraph.prototype.extractSeries_ = function(rawData, i, logScale) {
2908   // TODO(danvk): pre-allocate series here.
2909   var series = [];
2910   var errorBars = this.attr_("errorBars");
2911   var customBars =  this.attr_("customBars");
2912   for (var j = 0; j < rawData.length; j++) {
2913     var x = rawData[j][0];
2914     var point = rawData[j][i];
2915     if (logScale) {
2916       // On the log scale, points less than zero do not exist.
2917       // This will create a gap in the chart.
2918       if (errorBars || customBars) {
2919         // point.length is either 2 (errorBars) or 3 (customBars)
2920         for (var k = 0; k < point.length; k++) {
2921           if (point[k] <= 0) {
2922             point = null;
2923             break;
2924           }
2925         }
2926       } else if (point <= 0) {
2927         point = null;
2928       }
2929     }
2930     // Fix null points to fit the display type standard.
2931     if (point !== null) {
2932       series.push([x, point]);
2933     } else {
2934       series.push([x, errorBars ? [null, null] : customBars ? [null, null, null] : point]);
2935     }
2936   }
2937   return series;
2938 };
2939 
2940 /**
2941  * @private
2942  * Calculates the rolling average of a data set.
2943  * If originalData is [label, val], rolls the average of those.
2944  * If originalData is [label, [, it's interpreted as [value, stddev]
2945  *   and the roll is returned in the same form, with appropriately reduced
2946  *   stddev for each value.
2947  * Note that this is where fractional input (i.e. '5/10') is converted into
2948  *   decimal values.
2949  * @param {Array} originalData The data in the appropriate format (see above)
2950  * @param {Number} rollPeriod The number of points over which to average the
2951  *                            data
2952  */
2953 Dygraph.prototype.rollingAverage = function(originalData, rollPeriod) {
2954   rollPeriod = Math.min(rollPeriod, originalData.length);
2955   var rollingData = [];
2956   var sigma = this.attr_("sigma");
2957 
2958   var low, high, i, j, y, sum, num_ok, stddev;
2959   if (this.fractions_) {
2960     var num = 0;
2961     var den = 0;  // numerator/denominator
2962     var mult = 100.0;
2963     for (i = 0; i < originalData.length; i++) {
2964       num += originalData[i][1][0];
2965       den += originalData[i][1][1];
2966       if (i - rollPeriod >= 0) {
2967         num -= originalData[i - rollPeriod][1][0];
2968         den -= originalData[i - rollPeriod][1][1];
2969       }
2970 
2971       var date = originalData[i][0];
2972       var value = den ? num / den : 0.0;
2973       if (this.attr_("errorBars")) {
2974         if (this.attr_("wilsonInterval")) {
2975           // For more details on this confidence interval, see:
2976           // http://en.wikipedia.org/wiki/Binomial_confidence_interval
2977           if (den) {
2978             var p = value < 0 ? 0 : value, n = den;
2979             var pm = sigma * Math.sqrt(p*(1-p)/n + sigma*sigma/(4*n*n));
2980             var denom = 1 + sigma * sigma / den;
2981             low  = (p + sigma * sigma / (2 * den) - pm) / denom;
2982             high = (p + sigma * sigma / (2 * den) + pm) / denom;
2983             rollingData[i] = [date,
2984                               [p * mult, (p - low) * mult, (high - p) * mult]];
2985           } else {
2986             rollingData[i] = [date, [0, 0, 0]];
2987           }
2988         } else {
2989           stddev = den ? sigma * Math.sqrt(value * (1 - value) / den) : 1.0;
2990           rollingData[i] = [date, [mult * value, mult * stddev, mult * stddev]];
2991         }
2992       } else {
2993         rollingData[i] = [date, mult * value];
2994       }
2995     }
2996   } else if (this.attr_("customBars")) {
2997     low = 0;
2998     var mid = 0;
2999     high = 0;
3000     var count = 0;
3001     for (i = 0; i < originalData.length; i++) {
3002       var data = originalData[i][1];
3003       y = data[1];
3004       rollingData[i] = [originalData[i][0], [y, y - data[0], data[2] - y]];
3005 
3006       if (y !== null && !isNaN(y)) {
3007         low += data[0];
3008         mid += y;
3009         high += data[2];
3010         count += 1;
3011       }
3012       if (i - rollPeriod >= 0) {
3013         var prev = originalData[i - rollPeriod];
3014         if (prev[1][1] !== null && !isNaN(prev[1][1])) {
3015           low -= prev[1][0];
3016           mid -= prev[1][1];
3017           high -= prev[1][2];
3018           count -= 1;
3019         }
3020       }
3021       if (count) {
3022         rollingData[i] = [originalData[i][0], [ 1.0 * mid / count,
3023                                                 1.0 * (mid - low) / count,
3024                                                 1.0 * (high - mid) / count ]];
3025       } else {
3026         rollingData[i] = [originalData[i][0], [null, null, null]];
3027       }
3028     }
3029   } else {
3030     // Calculate the rolling average for the first rollPeriod - 1 points where
3031     // there is not enough data to roll over the full number of points
3032     if (!this.attr_("errorBars")) {
3033       if (rollPeriod == 1) {
3034         return originalData;
3035       }
3036 
3037       for (i = 0; i < originalData.length; i++) {
3038         sum = 0;
3039         num_ok = 0;
3040         for (j = Math.max(0, i - rollPeriod + 1); j < i + 1; j++) {
3041           y = originalData[j][1];
3042           if (y === null || isNaN(y)) continue;
3043           num_ok++;
3044           sum += originalData[j][1];
3045         }
3046         if (num_ok) {
3047           rollingData[i] = [originalData[i][0], sum / num_ok];
3048         } else {
3049           rollingData[i] = [originalData[i][0], null];
3050         }
3051       }
3052 
3053     } else {
3054       for (i = 0; i < originalData.length; i++) {
3055         sum = 0;
3056         var variance = 0;
3057         num_ok = 0;
3058         for (j = Math.max(0, i - rollPeriod + 1); j < i + 1; j++) {
3059           y = originalData[j][1][0];
3060           if (y === null || isNaN(y)) continue;
3061           num_ok++;
3062           sum += originalData[j][1][0];
3063           variance += Math.pow(originalData[j][1][1], 2);
3064         }
3065         if (num_ok) {
3066           stddev = Math.sqrt(variance) / num_ok;
3067           rollingData[i] = [originalData[i][0],
3068                             [sum / num_ok, sigma * stddev, sigma * stddev]];
3069         } else {
3070           // This explicitly preserves NaNs to aid with "independent series".
3071           // See testRollingAveragePreservesNaNs.
3072           var v = (rollPeriod == 1) ? originalData[i][1][0] : null;
3073           rollingData[i] = [originalData[i][0], [v, v, v]];
3074         }
3075       }
3076     }
3077   }
3078 
3079   return rollingData;
3080 };
3081 
3082 /**
3083  * Detects the type of the str (date or numeric) and sets the various
3084  * formatting attributes in this.attrs_ based on this type.
3085  * @param {String} str An x value.
3086  * @private
3087  */
3088 Dygraph.prototype.detectTypeFromString_ = function(str) {
3089   var isDate = false;
3090   var dashPos = str.indexOf('-');  // could be 2006-01-01 _or_ 1.0e-2
3091   if ((dashPos > 0 && (str[dashPos-1] != 'e' && str[dashPos-1] != 'E')) ||
3092       str.indexOf('/') >= 0 ||
3093       isNaN(parseFloat(str))) {
3094     isDate = true;
3095   } else if (str.length == 8 && str > '19700101' && str < '20371231') {
3096     // TODO(danvk): remove support for this format.
3097     isDate = true;
3098   }
3099 
3100   this.setXAxisOptions_(isDate);
3101 };
3102 
3103 Dygraph.prototype.setXAxisOptions_ = function(isDate) {
3104   if (isDate) {
3105     this.attrs_.xValueParser = Dygraph.dateParser;
3106     this.attrs_.axes.x.valueFormatter = Dygraph.dateString_;
3107     this.attrs_.axes.x.ticker = Dygraph.dateTicker;
3108     this.attrs_.axes.x.axisLabelFormatter = Dygraph.dateAxisFormatter;
3109   } else {
3110     /** @private (shut up, jsdoc!) */
3111     this.attrs_.xValueParser = function(x) { return parseFloat(x); };
3112     // TODO(danvk): use Dygraph.numberValueFormatter here?
3113     /** @private (shut up, jsdoc!) */
3114     this.attrs_.axes.x.valueFormatter = function(x) { return x; };
3115     this.attrs_.axes.x.ticker = Dygraph.numericLinearTicks;
3116     this.attrs_.axes.x.axisLabelFormatter = this.attrs_.axes.x.valueFormatter;
3117   }
3118 };
3119 
3120 /**
3121  * Parses the value as a floating point number. This is like the parseFloat()
3122  * built-in, but with a few differences:
3123  * - the empty string is parsed as null, rather than NaN.
3124  * - if the string cannot be parsed at all, an error is logged.
3125  * If the string can't be parsed, this method returns null.
3126  * @param {String} x The string to be parsed
3127  * @param {Number} opt_line_no The line number from which the string comes.
3128  * @param {String} opt_line The text of the line from which the string comes.
3129  * @private
3130  */
3131 
3132 // Parse the x as a float or return null if it's not a number.
3133 Dygraph.prototype.parseFloat_ = function(x, opt_line_no, opt_line) {
3134   var val = parseFloat(x);
3135   if (!isNaN(val)) return val;
3136 
3137   // Try to figure out what happeend.
3138   // If the value is the empty string, parse it as null.
3139   if (/^ *$/.test(x)) return null;
3140 
3141   // If it was actually "NaN", return it as NaN.
3142   if (/^ *nan *$/i.test(x)) return NaN;
3143 
3144   // Looks like a parsing error.
3145   var msg = "Unable to parse '" + x + "' as a number";
3146   if (opt_line !== null && opt_line_no !== null) {
3147     msg += " on line " + (1+opt_line_no) + " ('" + opt_line + "') of CSV.";
3148   }
3149   this.error(msg);
3150 
3151   return null;
3152 };
3153 
3154 /**
3155  * @private
3156  * Parses a string in a special csv format.  We expect a csv file where each
3157  * line is a date point, and the first field in each line is the date string.
3158  * We also expect that all remaining fields represent series.
3159  * if the errorBars attribute is set, then interpret the fields as:
3160  * date, series1, stddev1, series2, stddev2, ...
3161  * @param {[Object]} data See above.
3162  *
3163  * @return [Object] An array with one entry for each row. These entries
3164  * are an array of cells in that row. The first entry is the parsed x-value for
3165  * the row. The second, third, etc. are the y-values. These can take on one of
3166  * three forms, depending on the CSV and constructor parameters:
3167  * 1. numeric value
3168  * 2. [ value, stddev ]
3169  * 3. [ low value, center value, high value ]
3170  */
3171 Dygraph.prototype.parseCSV_ = function(data) {
3172   var ret = [];
3173   var line_delimiter = Dygraph.detectLineDelimiter(data);
3174   var lines = data.split(line_delimiter || "\n");
3175   var vals, j;
3176 
3177   // Use the default delimiter or fall back to a tab if that makes sense.
3178   var delim = this.attr_('delimiter');
3179   if (lines[0].indexOf(delim) == -1 && lines[0].indexOf('\t') >= 0) {
3180     delim = '\t';
3181   }
3182 
3183   var start = 0;
3184   if (!('labels' in this.user_attrs_)) {
3185     // User hasn't explicitly set labels, so they're (presumably) in the CSV.
3186     start = 1;
3187     this.attrs_.labels = lines[0].split(delim);  // NOTE: _not_ user_attrs_.
3188     this.attributes_.reparseSeries();
3189   }
3190   var line_no = 0;
3191 
3192   var xParser;
3193   var defaultParserSet = false;  // attempt to auto-detect x value type
3194   var expectedCols = this.attr_("labels").length;
3195   var outOfOrder = false;
3196   for (var i = start; i < lines.length; i++) {
3197     var line = lines[i];
3198     line_no = i;
3199     if (line.length === 0) continue;  // skip blank lines
3200     if (line[0] == '#') continue;    // skip comment lines
3201     var inFields = line.split(delim);
3202     if (inFields.length < 2) continue;
3203 
3204     var fields = [];
3205     if (!defaultParserSet) {
3206       this.detectTypeFromString_(inFields[0]);
3207       xParser = this.attr_("xValueParser");
3208       defaultParserSet = true;
3209     }
3210     fields[0] = xParser(inFields[0], this);
3211 
3212     // If fractions are expected, parse the numbers as "A/B"
3213     if (this.fractions_) {
3214       for (j = 1; j < inFields.length; j++) {
3215         // TODO(danvk): figure out an appropriate way to flag parse errors.
3216         vals = inFields[j].split("/");
3217         if (vals.length != 2) {
3218           this.error('Expected fractional "num/den" values in CSV data ' +
3219                      "but found a value '" + inFields[j] + "' on line " +
3220                      (1 + i) + " ('" + line + "') which is not of this form.");
3221           fields[j] = [0, 0];
3222         } else {
3223           fields[j] = [this.parseFloat_(vals[0], i, line),
3224                        this.parseFloat_(vals[1], i, line)];
3225         }
3226       }
3227     } else if (this.attr_("errorBars")) {
3228       // If there are error bars, values are (value, stddev) pairs
3229       if (inFields.length % 2 != 1) {
3230         this.error('Expected alternating (value, stdev.) pairs in CSV data ' +
3231                    'but line ' + (1 + i) + ' has an odd number of values (' +
3232                    (inFields.length - 1) + "): '" + line + "'");
3233       }
3234       for (j = 1; j < inFields.length; j += 2) {
3235         fields[(j + 1) / 2] = [this.parseFloat_(inFields[j], i, line),
3236                                this.parseFloat_(inFields[j + 1], i, line)];
3237       }
3238     } else if (this.attr_("customBars")) {
3239       // Bars are a low;center;high tuple
3240       for (j = 1; j < inFields.length; j++) {
3241         var val = inFields[j];
3242         if (/^ *$/.test(val)) {
3243           fields[j] = [null, null, null];
3244         } else {
3245           vals = val.split(";");
3246           if (vals.length == 3) {
3247             fields[j] = [ this.parseFloat_(vals[0], i, line),
3248                           this.parseFloat_(vals[1], i, line),
3249                           this.parseFloat_(vals[2], i, line) ];
3250           } else {
3251             this.warn('When using customBars, values must be either blank ' +
3252                       'or "low;center;high" tuples (got "' + val +
3253                       '" on line ' + (1+i));
3254           }
3255         }
3256       }
3257     } else {
3258       // Values are just numbers
3259       for (j = 1; j < inFields.length; j++) {
3260         fields[j] = this.parseFloat_(inFields[j], i, line);
3261       }
3262     }
3263     if (ret.length > 0 && fields[0] < ret[ret.length - 1][0]) {
3264       outOfOrder = true;
3265     }
3266 
3267     if (fields.length != expectedCols) {
3268       this.error("Number of columns in line " + i + " (" + fields.length +
3269                  ") does not agree with number of labels (" + expectedCols +
3270                  ") " + line);
3271     }
3272 
3273     // If the user specified the 'labels' option and none of the cells of the
3274     // first row parsed correctly, then they probably double-specified the
3275     // labels. We go with the values set in the option, discard this row and
3276     // log a warning to the JS console.
3277     if (i === 0 && this.attr_('labels')) {
3278       var all_null = true;
3279       for (j = 0; all_null && j < fields.length; j++) {
3280         if (fields[j]) all_null = false;
3281       }
3282       if (all_null) {
3283         this.warn("The dygraphs 'labels' option is set, but the first row of " +
3284                   "CSV data ('" + line + "') appears to also contain labels. " +
3285                   "Will drop the CSV labels and use the option labels.");
3286         continue;
3287       }
3288     }
3289     ret.push(fields);
3290   }
3291 
3292   if (outOfOrder) {
3293     this.warn("CSV is out of order; order it correctly to speed loading.");
3294     ret.sort(function(a,b) { return a[0] - b[0]; });
3295   }
3296 
3297   return ret;
3298 };
3299 
3300 /**
3301  * @private
3302  * The user has provided their data as a pre-packaged JS array. If the x values
3303  * are numeric, this is the same as dygraphs' internal format. If the x values
3304  * are dates, we need to convert them from Date objects to ms since epoch.
3305  * @param {[Object]} data
3306  * @return {[Object]} data with numeric x values.
3307  */
3308 Dygraph.prototype.parseArray_ = function(data) {
3309   // Peek at the first x value to see if it's numeric.
3310   if (data.length === 0) {
3311     this.error("Can't plot empty data set");
3312     return null;
3313   }
3314   if (data[0].length === 0) {
3315     this.error("Data set cannot contain an empty row");
3316     return null;
3317   }
3318 
3319   var i;
3320   if (this.attr_("labels") === null) {
3321     this.warn("Using default labels. Set labels explicitly via 'labels' " +
3322               "in the options parameter");
3323     this.attrs_.labels = [ "X" ];
3324     for (i = 1; i < data[0].length; i++) {
3325       this.attrs_.labels.push("Y" + i); // Not user_attrs_.
3326     }
3327     this.attributes_.reparseSeries();
3328   } else {
3329     var num_labels = this.attr_("labels");
3330     if (num_labels.length != data[0].length) {
3331       this.error("Mismatch between number of labels (" + num_labels +
3332           ") and number of columns in array (" + data[0].length + ")");
3333       return null;
3334     }
3335   }
3336 
3337   if (Dygraph.isDateLike(data[0][0])) {
3338     // Some intelligent defaults for a date x-axis.
3339     this.attrs_.axes.x.valueFormatter = Dygraph.dateString_;
3340     this.attrs_.axes.x.ticker = Dygraph.dateTicker;
3341     this.attrs_.axes.x.axisLabelFormatter = Dygraph.dateAxisFormatter;
3342 
3343     // Assume they're all dates.
3344     var parsedData = Dygraph.clone(data);
3345     for (i = 0; i < data.length; i++) {
3346       if (parsedData[i].length === 0) {
3347         this.error("Row " + (1 + i) + " of data is empty");
3348         return null;
3349       }
3350       if (parsedData[i][0] === null ||
3351           typeof(parsedData[i][0].getTime) != 'function' ||
3352           isNaN(parsedData[i][0].getTime())) {
3353         this.error("x value in row " + (1 + i) + " is not a Date");
3354         return null;
3355       }
3356       parsedData[i][0] = parsedData[i][0].getTime();
3357     }
3358     return parsedData;
3359   } else {
3360     // Some intelligent defaults for a numeric x-axis.
3361     /** @private (shut up, jsdoc!) */
3362     this.attrs_.axes.x.valueFormatter = function(x) { return x; };
3363     this.attrs_.axes.x.ticker = Dygraph.numericLinearTicks;
3364     this.attrs_.axes.x.axisLabelFormatter = Dygraph.numberAxisLabelFormatter;
3365     return data;
3366   }
3367 };
3368 
3369 /**
3370  * Parses a DataTable object from gviz.
3371  * The data is expected to have a first column that is either a date or a
3372  * number. All subsequent columns must be numbers. If there is a clear mismatch
3373  * between this.xValueParser_ and the type of the first column, it will be
3374  * fixed. Fills out rawData_.
3375  * @param {[Object]} data See above.
3376  * @private
3377  */
3378 Dygraph.prototype.parseDataTable_ = function(data) {
3379   var shortTextForAnnotationNum = function(num) {
3380     // converts [0-9]+ [A-Z][a-z]*
3381     // example: 0=A, 1=B, 25=Z, 26=Aa, 27=Ab
3382     // and continues like.. Ba Bb .. Za .. Zz..Aaa...Zzz Aaaa Zzzz
3383     var shortText = String.fromCharCode(65 /* A */ + num % 26);
3384     num = Math.floor(num / 26);
3385     while ( num > 0 ) {
3386       shortText = String.fromCharCode(65 /* A */ + (num - 1) % 26 ) + shortText.toLowerCase();
3387       num = Math.floor((num - 1) / 26);
3388     }
3389     return shortText;
3390   };
3391 
3392   var cols = data.getNumberOfColumns();
3393   var rows = data.getNumberOfRows();
3394 
3395   var indepType = data.getColumnType(0);
3396   if (indepType == 'date' || indepType == 'datetime') {
3397     this.attrs_.xValueParser = Dygraph.dateParser;
3398     this.attrs_.axes.x.valueFormatter = Dygraph.dateString_;
3399     this.attrs_.axes.x.ticker = Dygraph.dateTicker;
3400     this.attrs_.axes.x.axisLabelFormatter = Dygraph.dateAxisFormatter;
3401   } else if (indepType == 'number') {
3402     this.attrs_.xValueParser = function(x) { return parseFloat(x); };
3403     this.attrs_.axes.x.valueFormatter = function(x) { return x; };
3404     this.attrs_.axes.x.ticker = Dygraph.numericLinearTicks;
3405     this.attrs_.axes.x.axisLabelFormatter = this.attrs_.axes.x.valueFormatter;
3406   } else {
3407     this.error("only 'date', 'datetime' and 'number' types are supported for " +
3408                "column 1 of DataTable input (Got '" + indepType + "')");
3409     return null;
3410   }
3411 
3412   // Array of the column indices which contain data (and not annotations).
3413   var colIdx = [];
3414   var annotationCols = {};  // data index -> [annotation cols]
3415   var hasAnnotations = false;
3416   var i, j;
3417   for (i = 1; i < cols; i++) {
3418     var type = data.getColumnType(i);
3419     if (type == 'number') {
3420       colIdx.push(i);
3421     } else if (type == 'string' && this.attr_('displayAnnotations')) {
3422       // This is OK -- it's an annotation column.
3423       var dataIdx = colIdx[colIdx.length - 1];
3424       if (!annotationCols.hasOwnProperty(dataIdx)) {
3425         annotationCols[dataIdx] = [i];
3426       } else {
3427         annotationCols[dataIdx].push(i);
3428       }
3429       hasAnnotations = true;
3430     } else {
3431       this.error("Only 'number' is supported as a dependent type with Gviz." +
3432                  " 'string' is only supported if displayAnnotations is true");
3433     }
3434   }
3435 
3436   // Read column labels
3437   // TODO(danvk): add support back for errorBars
3438   var labels = [data.getColumnLabel(0)];
3439   for (i = 0; i < colIdx.length; i++) {
3440     labels.push(data.getColumnLabel(colIdx[i]));
3441     if (this.attr_("errorBars")) i += 1;
3442   }
3443   this.attrs_.labels = labels;
3444   cols = labels.length;
3445 
3446   var ret = [];
3447   var outOfOrder = false;
3448   var annotations = [];
3449   for (i = 0; i < rows; i++) {
3450     var row = [];
3451     if (typeof(data.getValue(i, 0)) === 'undefined' ||
3452         data.getValue(i, 0) === null) {
3453       this.warn("Ignoring row " + i +
3454                 " of DataTable because of undefined or null first column.");
3455       continue;
3456     }
3457 
3458     if (indepType == 'date' || indepType == 'datetime') {
3459       row.push(data.getValue(i, 0).getTime());
3460     } else {
3461       row.push(data.getValue(i, 0));
3462     }
3463     if (!this.attr_("errorBars")) {
3464       for (j = 0; j < colIdx.length; j++) {
3465         var col = colIdx[j];
3466         row.push(data.getValue(i, col));
3467         if (hasAnnotations &&
3468             annotationCols.hasOwnProperty(col) &&
3469             data.getValue(i, annotationCols[col][0]) !== null) {
3470           var ann = {};
3471           ann.series = data.getColumnLabel(col);
3472           ann.xval = row[0];
3473           ann.shortText = shortTextForAnnotationNum(annotations.length);
3474           ann.text = '';
3475           for (var k = 0; k < annotationCols[col].length; k++) {
3476             if (k) ann.text += "\n";
3477             ann.text += data.getValue(i, annotationCols[col][k]);
3478           }
3479           annotations.push(ann);
3480         }
3481       }
3482 
3483       // Strip out infinities, which give dygraphs problems later on.
3484       for (j = 0; j < row.length; j++) {
3485         if (!isFinite(row[j])) row[j] = null;
3486       }
3487     } else {
3488       for (j = 0; j < cols - 1; j++) {
3489         row.push([ data.getValue(i, 1 + 2 * j), data.getValue(i, 2 + 2 * j) ]);
3490       }
3491     }
3492     if (ret.length > 0 && row[0] < ret[ret.length - 1][0]) {
3493       outOfOrder = true;
3494     }
3495     ret.push(row);
3496   }
3497 
3498   if (outOfOrder) {
3499     this.warn("DataTable is out of order; order it correctly to speed loading.");
3500     ret.sort(function(a,b) { return a[0] - b[0]; });
3501   }
3502   this.rawData_ = ret;
3503 
3504   if (annotations.length > 0) {
3505     this.setAnnotations(annotations, true);
3506   }
3507   this.attributes_.reparseSeries();
3508 };
3509 
3510 /**
3511  * Get the CSV data. If it's in a function, call that function. If it's in a
3512  * file, do an XMLHttpRequest to get it.
3513  * @private
3514  */
3515 Dygraph.prototype.start_ = function() {
3516   var data = this.file_;
3517 
3518   // Functions can return references of all other types.
3519   if (typeof data == 'function') {
3520     data = data();
3521   }
3522 
3523   if (Dygraph.isArrayLike(data)) {
3524     this.rawData_ = this.parseArray_(data);
3525     this.predraw_();
3526   } else if (typeof data == 'object' &&
3527              typeof data.getColumnRange == 'function') {
3528     // must be a DataTable from gviz.
3529     this.parseDataTable_(data);
3530     this.predraw_();
3531   } else if (typeof data == 'string') {
3532     // Heuristic: a newline means it's CSV data. Otherwise it's an URL.
3533     var line_delimiter = Dygraph.detectLineDelimiter(data);
3534     if (line_delimiter) {
3535       this.loadedEvent_(data);
3536     } else {
3537       var req = new XMLHttpRequest();
3538       var caller = this;
3539       req.onreadystatechange = function () {
3540         if (req.readyState == 4) {
3541           if (req.status === 200 ||  // Normal http
3542               req.status === 0) {    // Chrome w/ --allow-file-access-from-files
3543             caller.loadedEvent_(req.responseText);
3544           }
3545         }
3546       };
3547 
3548       req.open("GET", data, true);
3549       req.send(null);
3550     }
3551   } else {
3552     this.error("Unknown data format: " + (typeof data));
3553   }
3554 };
3555 
3556 /**
3557  * Changes various properties of the graph. These can include:
3558  * <ul>
3559  * <li>file: changes the source data for the graph</li>
3560  * <li>errorBars: changes whether the data contains stddev</li>
3561  * </ul>
3562  *
3563  * There's a huge variety of options that can be passed to this method. For a
3564  * full list, see http://dygraphs.com/options.html.
3565  *
3566  * @param {Object} attrs The new properties and values
3567  * @param {Boolean} [block_redraw] Usually the chart is redrawn after every
3568  * call to updateOptions(). If you know better, you can pass true to explicitly
3569  * block the redraw. This can be useful for chaining updateOptions() calls,
3570  * avoiding the occasional infinite loop and preventing redraws when it's not
3571  * necessary (e.g. when updating a callback).
3572  */
3573 Dygraph.prototype.updateOptions = function(input_attrs, block_redraw) {
3574   if (typeof(block_redraw) == 'undefined') block_redraw = false;
3575 
3576   // mapLegacyOptions_ drops the "file" parameter as a convenience to us.
3577   var file = input_attrs.file;
3578   var attrs = Dygraph.mapLegacyOptions_(input_attrs);
3579 
3580   // TODO(danvk): this is a mess. Move these options into attr_.
3581   if ('rollPeriod' in attrs) {
3582     this.rollPeriod_ = attrs.rollPeriod;
3583   }
3584   if ('dateWindow' in attrs) {
3585     this.dateWindow_ = attrs.dateWindow;
3586     if (!('isZoomedIgnoreProgrammaticZoom' in attrs)) {
3587       this.zoomed_x_ = (attrs.dateWindow !== null);
3588     }
3589   }
3590   if ('valueRange' in attrs && !('isZoomedIgnoreProgrammaticZoom' in attrs)) {
3591     this.zoomed_y_ = (attrs.valueRange !== null);
3592   }
3593 
3594   // TODO(danvk): validate per-series options.
3595   // Supported:
3596   // strokeWidth
3597   // pointSize
3598   // drawPoints
3599   // highlightCircleSize
3600 
3601   // Check if this set options will require new points.
3602   var requiresNewPoints = Dygraph.isPixelChangingOptionList(this.attr_("labels"), attrs);
3603 
3604   Dygraph.updateDeep(this.user_attrs_, attrs);
3605 
3606   this.attributes_.reparseSeries();
3607 
3608   if (file) {
3609     this.file_ = file;
3610     if (!block_redraw) this.start_();
3611   } else {
3612     if (!block_redraw) {
3613       if (requiresNewPoints) {
3614         this.predraw_();
3615       } else {
3616         this.renderGraph_(false);
3617       }
3618     }
3619   }
3620 };
3621 
3622 /**
3623  * Returns a copy of the options with deprecated names converted into current
3624  * names. Also drops the (potentially-large) 'file' attribute. If the caller is
3625  * interested in that, they should save a copy before calling this.
3626  * @private
3627  */
3628 Dygraph.mapLegacyOptions_ = function(attrs) {
3629   var my_attrs = {};
3630   for (var k in attrs) {
3631     if (k == 'file') continue;
3632     if (attrs.hasOwnProperty(k)) my_attrs[k] = attrs[k];
3633   }
3634 
3635   var set = function(axis, opt, value) {
3636     if (!my_attrs.axes) my_attrs.axes = {};
3637     if (!my_attrs.axes[axis]) my_attrs.axes[axis] = {};
3638     my_attrs.axes[axis][opt] = value;
3639   };
3640   var map = function(opt, axis, new_opt) {
3641     if (typeof(attrs[opt]) != 'undefined') {
3642       Dygraph.warn("Option " + opt + " is deprecated. Use the " +
3643           new_opt + " option for the " + axis + " axis instead. " +
3644           "(e.g. { axes : { " + axis + " : { " + new_opt + " : ... } } } " +
3645           "(see http://dygraphs.com/per-axis.html for more information.");
3646       set(axis, new_opt, attrs[opt]);
3647       delete my_attrs[opt];
3648     }
3649   };
3650 
3651   // This maps, e.g., xValueFormater -> axes: { x: { valueFormatter: ... } }
3652   map('xValueFormatter', 'x', 'valueFormatter');
3653   map('pixelsPerXLabel', 'x', 'pixelsPerLabel');
3654   map('xAxisLabelFormatter', 'x', 'axisLabelFormatter');
3655   map('xTicker', 'x', 'ticker');
3656   map('yValueFormatter', 'y', 'valueFormatter');
3657   map('pixelsPerYLabel', 'y', 'pixelsPerLabel');
3658   map('yAxisLabelFormatter', 'y', 'axisLabelFormatter');
3659   map('yTicker', 'y', 'ticker');
3660   return my_attrs;
3661 };
3662 
3663 /**
3664  * Resizes the dygraph. If no parameters are specified, resizes to fill the
3665  * containing div (which has presumably changed size since the dygraph was
3666  * instantiated. If the width/height are specified, the div will be resized.
3667  *
3668  * This is far more efficient than destroying and re-instantiating a
3669  * Dygraph, since it doesn't have to reparse the underlying data.
3670  *
3671  * @param {Number} [width] Width (in pixels)
3672  * @param {Number} [height] Height (in pixels)
3673  */
3674 Dygraph.prototype.resize = function(width, height) {
3675   if (this.resize_lock) {
3676     return;
3677   }
3678   this.resize_lock = true;
3679 
3680   if ((width === null) != (height === null)) {
3681     this.warn("Dygraph.resize() should be called with zero parameters or " +
3682               "two non-NULL parameters. Pretending it was zero.");
3683     width = height = null;
3684   }
3685 
3686   var old_width = this.width_;
3687   var old_height = this.height_;
3688 
3689   if (width) {
3690     this.maindiv_.style.width = width + "px";
3691     this.maindiv_.style.height = height + "px";
3692     this.width_ = width;
3693     this.height_ = height;
3694   } else {
3695     this.width_ = this.maindiv_.clientWidth;
3696     this.height_ = this.maindiv_.clientHeight;
3697   }
3698 
3699   if (old_width != this.width_ || old_height != this.height_) {
3700     // Resizing a canvas erases it, even when the size doesn't change, so
3701     // any resize needs to be followed by a redraw.
3702     this.resizeElements_();
3703     this.predraw_();
3704   }
3705 
3706   this.resize_lock = false;
3707 };
3708 
3709 /**
3710  * Adjusts the number of points in the rolling average. Updates the graph to
3711  * reflect the new averaging period.
3712  * @param {Number} length Number of points over which to average the data.
3713  */
3714 Dygraph.prototype.adjustRoll = function(length) {
3715   this.rollPeriod_ = length;
3716   this.predraw_();
3717 };
3718 
3719 /**
3720  * Returns a boolean array of visibility statuses.
3721  */
3722 Dygraph.prototype.visibility = function() {
3723   // Do lazy-initialization, so that this happens after we know the number of
3724   // data series.
3725   if (!this.attr_("visibility")) {
3726     this.attrs_.visibility = [];
3727   }
3728   // TODO(danvk): it looks like this could go into an infinite loop w/ user_attrs.
3729   while (this.attr_("visibility").length < this.numColumns() - 1) {
3730     this.attrs_.visibility.push(true);
3731   }
3732   return this.attr_("visibility");
3733 };
3734 
3735 /**
3736  * Changes the visiblity of a series.
3737  */
3738 Dygraph.prototype.setVisibility = function(num, value) {
3739   var x = this.visibility();
3740   if (num < 0 || num >= x.length) {
3741     this.warn("invalid series number in setVisibility: " + num);
3742   } else {
3743     x[num] = value;
3744     this.predraw_();
3745   }
3746 };
3747 
3748 /**
3749  * How large of an area will the dygraph render itself in?
3750  * This is used for testing.
3751  * @return A {width: w, height: h} object.
3752  * @private
3753  */
3754 Dygraph.prototype.size = function() {
3755   return { width: this.width_, height: this.height_ };
3756 };
3757 
3758 /**
3759  * Update the list of annotations and redraw the chart.
3760  * See dygraphs.com/annotations.html for more info on how to use annotations.
3761  * @param ann {Array} An array of annotation objects.
3762  * @param suppressDraw {Boolean} Set to "true" to block chart redraw (optional).
3763  */
3764 Dygraph.prototype.setAnnotations = function(ann, suppressDraw) {
3765   // Only add the annotation CSS rule once we know it will be used.
3766   Dygraph.addAnnotationRule();
3767   this.annotations_ = ann;
3768   if (!this.layout_) {
3769     this.warn("Tried to setAnnotations before dygraph was ready. " +
3770               "Try setting them in a drawCallback. See " +
3771               "dygraphs.com/tests/annotation.html");
3772     return;
3773   }
3774 
3775   this.layout_.setAnnotations(this.annotations_);
3776   if (!suppressDraw) {
3777     this.predraw_();
3778   }
3779 };
3780 
3781 /**
3782  * Return the list of annotations.
3783  */
3784 Dygraph.prototype.annotations = function() {
3785   return this.annotations_;
3786 };
3787 
3788 /**
3789  * Get the list of label names for this graph. The first column is the
3790  * x-axis, so the data series names start at index 1.
3791  *
3792  * Returns null when labels have not yet been defined.
3793  */
3794 Dygraph.prototype.getLabels = function() {
3795   var labels = this.attr_("labels");
3796   return labels ? labels.slice() : null;
3797 };
3798 
3799 /**
3800  * Get the index of a series (column) given its name. The first column is the
3801  * x-axis, so the data series start with index 1.
3802  */
3803 Dygraph.prototype.indexFromSetName = function(name) {
3804   return this.setIndexByName_[name];
3805 };
3806 
3807 /**
3808  * @private
3809  * Adds a default style for the annotation CSS classes to the document. This is
3810  * only executed when annotations are actually used. It is designed to only be
3811  * called once -- all calls after the first will return immediately.
3812  */
3813 Dygraph.addAnnotationRule = function() {
3814   // TODO(danvk): move this function into plugins/annotations.js?
3815   if (Dygraph.addedAnnotationCSS) return;
3816 
3817   var rule = "border: 1px solid black; " +
3818              "background-color: white; " +
3819              "text-align: center;";
3820 
3821   var styleSheetElement = document.createElement("style");
3822   styleSheetElement.type = "text/css";
3823   document.getElementsByTagName("head")[0].appendChild(styleSheetElement);
3824 
3825   // Find the first style sheet that we can access.
3826   // We may not add a rule to a style sheet from another domain for security
3827   // reasons. This sometimes comes up when using gviz, since the Google gviz JS
3828   // adds its own style sheets from google.com.
3829   for (var i = 0; i < document.styleSheets.length; i++) {
3830     if (document.styleSheets[i].disabled) continue;
3831     var mysheet = document.styleSheets[i];
3832     try {
3833       if (mysheet.insertRule) {  // Firefox
3834         var idx = mysheet.cssRules ? mysheet.cssRules.length : 0;
3835         mysheet.insertRule(".dygraphDefaultAnnotation { " + rule + " }", idx);
3836       } else if (mysheet.addRule) {  // IE
3837         mysheet.addRule(".dygraphDefaultAnnotation", rule);
3838       }
3839       Dygraph.addedAnnotationCSS = true;
3840       return;
3841     } catch(err) {
3842       // Was likely a security exception.
3843     }
3844   }
3845 
3846   this.warn("Unable to add default annotation CSS rule; display may be off.");
3847 };
3848 
3849 // Older pages may still use this name.
3850 var DateGraph = Dygraph;
3851