1 /** 2 * @license 3 * Copyright 2011 Dan Vanderkam (danvdk@gmail.com) 4 * MIT-licenced: https://opensource.org/licenses/MIT 5 */ 6 7 /** 8 * @fileoverview Description of this file. 9 * @author danvk@google.com (Dan Vanderkam) 10 */ 11 12 /* 13 * A ticker is a function with the following interface: 14 * 15 * function(a, b, pixels, options_view, dygraph, forced_values); 16 * -> [ { v: tick1_v, label: tick1_label[, label_v: label_v1] }, 17 * { v: tick2_v, label: tick2_label[, label_v: label_v2] }, 18 * ... 19 * ] 20 * 21 * The returned value is called a "tick list". 22 * 23 * Arguments 24 * --------- 25 * 26 * [a, b] is the range of the axis for which ticks are being generated. For a 27 * numeric axis, these will simply be numbers. For a date axis, these will be 28 * millis since epoch (convertable to Date objects using "new Date(a)" and "new 29 * Date(b)"). 30 * 31 * opts provides access to chart- and axis-specific options. It can be used to 32 * access number/date formatting code/options, check for a log scale, etc. 33 * 34 * pixels is the length of the axis in pixels. opts('pixelsPerLabel') is the 35 * minimum amount of space to be allotted to each label. For instance, if 36 * pixels=400 and opts('pixelsPerLabel')=40 then the ticker should return 37 * between zero and ten (400/40) ticks. 38 * 39 * dygraph is the Dygraph object for which an axis is being constructed. 40 * 41 * forced_values is used for secondary y-axes. The tick positions are typically 42 * set by the primary y-axis, so the secondary y-axis has no choice in where to 43 * put these. It simply has to generate labels for these data values. 44 * 45 * Tick lists 46 * ---------- 47 * Typically a tick will have both a grid/tick line and a label at one end of 48 * that line (at the bottom for an x-axis, at left or right for the y-axis). 49 * 50 * A tick may be missing one of these two components: 51 * - If "label_v" is specified instead of "v", then there will be no tick or 52 * gridline, just a label. 53 * - Similarly, if "label" is not specified, then there will be a gridline 54 * without a label. 55 * 56 * This flexibility is useful in a few situations: 57 * - For log scales, some of the tick lines may be too close to all have labels. 58 * - For date scales where years are being displayed, it is desirable to display 59 * tick marks at the beginnings of years but labels (e.g. "2006") in the 60 * middle of the years. 61 */ 62 63 /*jshint sub:true */ 64 /*global Dygraph:false */ 65 "use strict"; 66 67 import * as utils from './dygraph-utils'; 68 69 /** @typedef {Array.<{v:number, label:string, label_v:(string|undefined)}>} */ 70 var TickList = undefined; // the ' = undefined' keeps jshint happy. 71 72 /** @typedef {function( 73 * number, 74 * number, 75 * number, 76 * function(string):*, 77 * Dygraph=, 78 * Array.<number>= 79 * ): TickList} 80 */ 81 var Ticker = undefined; // the ' = undefined' keeps jshint happy. 82 83 /** @type {Ticker} */ 84 export var numericLinearTicks = function(a, b, pixels, opts, dygraph, vals) { 85 var nonLogscaleOpts = function(opt) { 86 if (opt === 'logscale') return false; 87 return opts(opt); 88 }; 89 return numericTicks(a, b, pixels, nonLogscaleOpts, dygraph, vals); 90 }; 91 92 /** @type {Ticker} */ 93 export var numericTicks = function(a, b, pixels, opts, dygraph, vals) { 94 var pixels_per_tick = /** @type{number} */(opts('pixelsPerLabel')); 95 var ticks = []; 96 var i, j, tickV, nTicks; 97 if (vals) { 98 for (i = 0; i < vals.length; i++) { 99 ticks.push({v: vals[i]}); 100 } 101 } else { 102 // TODO(danvk): factor this log-scale block out into a separate function. 103 if (opts("logscale")) { 104 nTicks = Math.floor(pixels / pixels_per_tick); 105 var minIdx = utils.binarySearch(a, PREFERRED_LOG_TICK_VALUES, 1); 106 var maxIdx = utils.binarySearch(b, PREFERRED_LOG_TICK_VALUES, -1); 107 if (minIdx == -1) { 108 minIdx = 0; 109 } 110 if (maxIdx == -1) { 111 maxIdx = PREFERRED_LOG_TICK_VALUES.length - 1; 112 } 113 // Count the number of tick values would appear, if we can get at least 114 // nTicks / 4 accept them. 115 var lastDisplayed = null; 116 if (maxIdx - minIdx >= nTicks / 4) { 117 for (var idx = maxIdx; idx >= minIdx; idx--) { 118 var tickValue = PREFERRED_LOG_TICK_VALUES[idx]; 119 var pixel_coord = Math.log(tickValue / a) / Math.log(b / a) * pixels; 120 var tick = { v: tickValue }; 121 if (lastDisplayed === null) { 122 lastDisplayed = { 123 tickValue : tickValue, 124 pixel_coord : pixel_coord 125 }; 126 } else { 127 if (Math.abs(pixel_coord - lastDisplayed.pixel_coord) >= pixels_per_tick) { 128 lastDisplayed = { 129 tickValue : tickValue, 130 pixel_coord : pixel_coord 131 }; 132 } else { 133 tick.label = ""; 134 } 135 } 136 ticks.push(tick); 137 } 138 // Since we went in backwards order. 139 ticks.reverse(); 140 } 141 } 142 143 // ticks.length won't be 0 if the log scale function finds values to insert. 144 if (ticks.length === 0) { 145 // Basic idea: 146 // Try labels every 1, 2, 5, 10, 20, 50, 100, etc. 147 // Calculate the resulting tick spacing (i.e. this.height_ / nTicks). 148 // The first spacing greater than pixelsPerYLabel is what we use. 149 // TODO(danvk): version that works on a log scale. 150 var kmg2 = opts("labelsKMG2"); 151 var mults, base; 152 if (kmg2) { 153 mults = [1, 2, 4, 8, 16, 32, 64, 128, 256]; 154 base = 16; 155 } else { 156 mults = [1, 2, 5, 10, 20, 50, 100]; 157 base = 10; 158 } 159 160 // Get the maximum number of permitted ticks based on the 161 // graph's pixel size and pixels_per_tick setting. 162 var max_ticks = Math.ceil(pixels / pixels_per_tick); 163 164 // Now calculate the data unit equivalent of this tick spacing. 165 // Use abs() since graphs may have a reversed Y axis. 166 var units_per_tick = Math.abs(b - a) / max_ticks; 167 168 // Based on this, get a starting scale which is the largest 169 // integer power of the chosen base (10 or 16) that still remains 170 // below the requested pixels_per_tick spacing. 171 var base_power = Math.floor(Math.log(units_per_tick) / Math.log(base)); 172 var base_scale = Math.pow(base, base_power); 173 174 // Now try multiples of the starting scale until we find one 175 // that results in tick marks spaced sufficiently far apart. 176 // The "mults" array should cover the range 1 .. base^2 to 177 // adjust for rounding and edge effects. 178 var scale, low_val, high_val, spacing; 179 for (j = 0; j < mults.length; j++) { 180 scale = base_scale * mults[j]; 181 low_val = Math.floor(a / scale) * scale; 182 high_val = Math.ceil(b / scale) * scale; 183 nTicks = Math.abs(high_val - low_val) / scale; 184 spacing = pixels / nTicks; 185 if (spacing > pixels_per_tick) break; 186 } 187 188 // Construct the set of ticks. 189 // Allow reverse y-axis if it's explicitly requested. 190 if (low_val > high_val) scale *= -1; 191 for (i = 0; i <= nTicks; i++) { 192 tickV = low_val + i * scale; 193 ticks.push( {v: tickV} ); 194 } 195 } 196 } 197 198 var formatter = /**@type{AxisLabelFormatter}*/(opts('axisLabelFormatter')); 199 200 // Add labels to the ticks. 201 for (i = 0; i < ticks.length; i++) { 202 if (ticks[i].label !== undefined) continue; // Use current label. 203 // TODO(danvk): set granularity to something appropriate here. 204 ticks[i].label = formatter.call(dygraph, ticks[i].v, 0, opts, dygraph); 205 } 206 207 return ticks; 208 }; 209 210 /** @type {Ticker} */ 211 export var dateTicker = function(a, b, pixels, opts, dygraph, vals) { 212 var chosen = pickDateTickGranularity(a, b, pixels, opts); 213 214 if (chosen >= 0) { 215 return getDateAxis(a, b, chosen, opts, dygraph); 216 } else { 217 // this can happen if self.width_ is zero. 218 return []; 219 } 220 }; 221 222 // Time granularity enumeration 223 export var Granularity = { 224 MILLISECONDLY: 0, 225 TWO_MILLISECONDLY: 1, 226 FIVE_MILLISECONDLY: 2, 227 TEN_MILLISECONDLY: 3, 228 FIFTY_MILLISECONDLY: 4, 229 HUNDRED_MILLISECONDLY: 5, 230 FIVE_HUNDRED_MILLISECONDLY: 6, 231 SECONDLY: 7, 232 TWO_SECONDLY: 8, 233 FIVE_SECONDLY: 9, 234 TEN_SECONDLY: 10, 235 THIRTY_SECONDLY: 11, 236 MINUTELY: 12, 237 TWO_MINUTELY: 13, 238 FIVE_MINUTELY: 14, 239 TEN_MINUTELY: 15, 240 THIRTY_MINUTELY: 16, 241 HOURLY: 17, 242 TWO_HOURLY: 18, 243 SIX_HOURLY: 19, 244 DAILY: 20, 245 TWO_DAILY: 21, 246 WEEKLY: 22, 247 MONTHLY: 23, 248 QUARTERLY: 24, 249 BIANNUAL: 25, 250 ANNUAL: 26, 251 DECADAL: 27, 252 CENTENNIAL: 28, 253 NUM_GRANULARITIES: 29 254 } 255 256 // Date components enumeration (in the order of the arguments in Date) 257 // TODO: make this an @enum 258 var DateField = { 259 DATEFIELD_Y: 0, 260 DATEFIELD_M: 1, 261 DATEFIELD_D: 2, 262 DATEFIELD_HH: 3, 263 DATEFIELD_MM: 4, 264 DATEFIELD_SS: 5, 265 DATEFIELD_MS: 6, 266 NUM_DATEFIELDS: 7 267 }; 268 269 /** 270 * The value of datefield will start at an even multiple of "step", i.e. 271 * if datefield=SS and step=5 then the first tick will be on a multiple of 5s. 272 * 273 * For granularities <= HOURLY, ticks are generated every `spacing` ms. 274 * 275 * At coarser granularities, ticks are generated by incrementing `datefield` by 276 * `step`. In this case, the `spacing` value is only used to estimate the 277 * number of ticks. It should roughly correspond to the spacing between 278 * adjacent ticks. 279 * 280 * @type {Array.<{datefield:number, step:number, spacing:number}>} 281 */ 282 var TICK_PLACEMENT = []; 283 TICK_PLACEMENT[Granularity.MILLISECONDLY] = {datefield: DateField.DATEFIELD_MS, step: 1, spacing: 1}; 284 TICK_PLACEMENT[Granularity.TWO_MILLISECONDLY] = {datefield: DateField.DATEFIELD_MS, step: 2, spacing: 2}; 285 TICK_PLACEMENT[Granularity.FIVE_MILLISECONDLY] = {datefield: DateField.DATEFIELD_MS, step: 5, spacing: 5}; 286 TICK_PLACEMENT[Granularity.TEN_MILLISECONDLY] = {datefield: DateField.DATEFIELD_MS, step: 10, spacing: 10}; 287 TICK_PLACEMENT[Granularity.FIFTY_MILLISECONDLY] = {datefield: DateField.DATEFIELD_MS, step: 50, spacing: 50}; 288 TICK_PLACEMENT[Granularity.HUNDRED_MILLISECONDLY] = {datefield: DateField.DATEFIELD_MS, step: 100, spacing: 100}; 289 TICK_PLACEMENT[Granularity.FIVE_HUNDRED_MILLISECONDLY] = {datefield: DateField.DATEFIELD_MS, step: 500, spacing: 500}; 290 TICK_PLACEMENT[Granularity.SECONDLY] = {datefield: DateField.DATEFIELD_SS, step: 1, spacing: 1000 * 1}; 291 TICK_PLACEMENT[Granularity.TWO_SECONDLY] = {datefield: DateField.DATEFIELD_SS, step: 2, spacing: 1000 * 2}; 292 TICK_PLACEMENT[Granularity.FIVE_SECONDLY] = {datefield: DateField.DATEFIELD_SS, step: 5, spacing: 1000 * 5}; 293 TICK_PLACEMENT[Granularity.TEN_SECONDLY] = {datefield: DateField.DATEFIELD_SS, step: 10, spacing: 1000 * 10}; 294 TICK_PLACEMENT[Granularity.THIRTY_SECONDLY] = {datefield: DateField.DATEFIELD_SS, step: 30, spacing: 1000 * 30}; 295 TICK_PLACEMENT[Granularity.MINUTELY] = {datefield: DateField.DATEFIELD_MM, step: 1, spacing: 1000 * 60}; 296 TICK_PLACEMENT[Granularity.TWO_MINUTELY] = {datefield: DateField.DATEFIELD_MM, step: 2, spacing: 1000 * 60 * 2}; 297 TICK_PLACEMENT[Granularity.FIVE_MINUTELY] = {datefield: DateField.DATEFIELD_MM, step: 5, spacing: 1000 * 60 * 5}; 298 TICK_PLACEMENT[Granularity.TEN_MINUTELY] = {datefield: DateField.DATEFIELD_MM, step: 10, spacing: 1000 * 60 * 10}; 299 TICK_PLACEMENT[Granularity.THIRTY_MINUTELY] = {datefield: DateField.DATEFIELD_MM, step: 30, spacing: 1000 * 60 * 30}; 300 TICK_PLACEMENT[Granularity.HOURLY] = {datefield: DateField.DATEFIELD_HH, step: 1, spacing: 1000 * 3600}; 301 TICK_PLACEMENT[Granularity.TWO_HOURLY] = {datefield: DateField.DATEFIELD_HH, step: 2, spacing: 1000 * 3600 * 2}; 302 TICK_PLACEMENT[Granularity.SIX_HOURLY] = {datefield: DateField.DATEFIELD_HH, step: 6, spacing: 1000 * 3600 * 6}; 303 TICK_PLACEMENT[Granularity.DAILY] = {datefield: DateField.DATEFIELD_D, step: 1, spacing: 1000 * 86400}; 304 TICK_PLACEMENT[Granularity.TWO_DAILY] = {datefield: DateField.DATEFIELD_D, step: 2, spacing: 1000 * 86400 * 2}; 305 TICK_PLACEMENT[Granularity.WEEKLY] = {datefield: DateField.DATEFIELD_D, step: 7, spacing: 1000 * 604800}; 306 TICK_PLACEMENT[Granularity.MONTHLY] = {datefield: DateField.DATEFIELD_M, step: 1, spacing: 1000 * 7200 * 365.2425}; // 1e3 * 60 * 60 * 24 * 365.2425 / 12 307 TICK_PLACEMENT[Granularity.QUARTERLY] = {datefield: DateField.DATEFIELD_M, step: 3, spacing: 1000 * 21600 * 365.2425}; // 1e3 * 60 * 60 * 24 * 365.2425 / 4 308 TICK_PLACEMENT[Granularity.BIANNUAL] = {datefield: DateField.DATEFIELD_M, step: 6, spacing: 1000 * 43200 * 365.2425}; // 1e3 * 60 * 60 * 24 * 365.2425 / 2 309 TICK_PLACEMENT[Granularity.ANNUAL] = {datefield: DateField.DATEFIELD_Y, step: 1, spacing: 1000 * 86400 * 365.2425}; // 1e3 * 60 * 60 * 24 * 365.2425 * 1 310 TICK_PLACEMENT[Granularity.DECADAL] = {datefield: DateField.DATEFIELD_Y, step: 10, spacing: 1000 * 864000 * 365.2425}; // 1e3 * 60 * 60 * 24 * 365.2425 * 10 311 TICK_PLACEMENT[Granularity.CENTENNIAL] = {datefield: DateField.DATEFIELD_Y, step: 100, spacing: 1000 * 8640000 * 365.2425}; // 1e3 * 60 * 60 * 24 * 365.2425 * 100 312 313 /** 314 * This is a list of human-friendly values at which to show tick marks on a log 315 * scale. It is k * 10^n, where k=1..9 and n=-39..+39, so: 316 * ..., 1, 2, 3, 4, 5, ..., 9, 10, 20, 30, ..., 90, 100, 200, 300, ... 317 * NOTE: this assumes that utils.LOG_SCALE = 10. 318 * @type {Array.<number>} 319 */ 320 var PREFERRED_LOG_TICK_VALUES = (function() { 321 var vals = []; 322 for (var power = -39; power <= 39; power++) { 323 var range = Math.pow(10, power); 324 for (var mult = 1; mult <= 9; mult++) { 325 var val = range * mult; 326 vals.push(val); 327 } 328 } 329 return vals; 330 })(); 331 332 /** 333 * Determine the correct granularity of ticks on a date axis. 334 * 335 * @param {number} a Left edge of the chart (ms) 336 * @param {number} b Right edge of the chart (ms) 337 * @param {number} pixels Size of the chart in the relevant dimension (width). 338 * @param {function(string):*} opts Function mapping from option name -> value. 339 * @return {number} The appropriate axis granularity for this chart. See the 340 * enumeration of possible values in dygraph-tickers.js. 341 */ 342 var pickDateTickGranularity = function(a, b, pixels, opts) { 343 var pixels_per_tick = /** @type{number} */(opts('pixelsPerLabel')); 344 for (var i = 0; i < Granularity.NUM_GRANULARITIES; i++) { 345 var num_ticks = numDateTicks(a, b, i); 346 if (pixels / num_ticks >= pixels_per_tick) { 347 return i; 348 } 349 } 350 return -1; 351 }; 352 353 /** 354 * Compute the number of ticks on a date axis for a given granularity. 355 * @param {number} start_time 356 * @param {number} end_time 357 * @param {number} granularity (one of the granularities enumerated above) 358 * @return {number} (Approximate) number of ticks that would result. 359 */ 360 var numDateTicks = function(start_time, end_time, granularity) { 361 var spacing = TICK_PLACEMENT[granularity].spacing; 362 return Math.round(1.0 * (end_time - start_time) / spacing); 363 }; 364 365 /** 366 * Compute the positions and labels of ticks on a date axis for a given granularity. 367 * @param {number} start_time 368 * @param {number} end_time 369 * @param {number} granularity (one of the granularities enumerated above) 370 * @param {function(string):*} opts Function mapping from option name -> value. 371 * @param {Dygraph=} dg 372 * @return {!TickList} 373 */ 374 export var getDateAxis = function(start_time, end_time, granularity, opts, dg) { 375 var formatter = /** @type{AxisLabelFormatter} */( 376 opts("axisLabelFormatter")); 377 var utc = opts("labelsUTC"); 378 var accessors = utc ? utils.DateAccessorsUTC : utils.DateAccessorsLocal; 379 380 var datefield = TICK_PLACEMENT[granularity].datefield; 381 var step = TICK_PLACEMENT[granularity].step; 382 var spacing = TICK_PLACEMENT[granularity].spacing; 383 384 // Choose a nice tick position before the initial instant. 385 // Currently, this code deals properly with the existent daily granularities: 386 // DAILY (with step of 1) and WEEKLY (with step of 7 but specially handled). 387 // Other daily granularities (say TWO_DAILY) should also be handled specially 388 // by setting the start_date_offset to 0. 389 var start_date = new Date(start_time); 390 var date_array = []; 391 date_array[DateField.DATEFIELD_Y] = accessors.getFullYear(start_date); 392 date_array[DateField.DATEFIELD_M] = accessors.getMonth(start_date); 393 date_array[DateField.DATEFIELD_D] = accessors.getDate(start_date); 394 date_array[DateField.DATEFIELD_HH] = accessors.getHours(start_date); 395 date_array[DateField.DATEFIELD_MM] = accessors.getMinutes(start_date); 396 date_array[DateField.DATEFIELD_SS] = accessors.getSeconds(start_date); 397 date_array[DateField.DATEFIELD_MS] = accessors.getMilliseconds(start_date); 398 399 var start_date_offset = date_array[datefield] % step; 400 if (granularity == Granularity.WEEKLY) { 401 // This will put the ticks on Sundays. 402 start_date_offset = accessors.getDay(start_date); 403 } 404 405 date_array[datefield] -= start_date_offset; 406 for (var df = datefield + 1; df < DateField.NUM_DATEFIELDS; df++) { 407 // The minimum value is 1 for the day of month, and 0 for all other fields. 408 date_array[df] = (df === DateField.DATEFIELD_D) ? 1 : 0; 409 } 410 411 // Generate the ticks. 412 // For granularities not coarser than HOURLY we use the fact that: 413 // the number of milliseconds between ticks is constant 414 // and equal to the defined spacing. 415 // Otherwise we rely on the 'roll over' property of the Date functions: 416 // when some date field is set to a value outside of its logical range, 417 // the excess 'rolls over' the next (more significant) field. 418 // However, when using local time with DST transitions, 419 // there are dates that do not represent any time value at all 420 // (those in the hour skipped at the 'spring forward'), 421 // and the JavaScript engines usually return an equivalent value. 422 // Hence we have to check that the date is properly increased at each step, 423 // returning a date at a nice tick position. 424 var ticks = []; 425 var tick_date = accessors.makeDate.apply(null, date_array); 426 var tick_time = tick_date.getTime(); 427 if (granularity <= Granularity.HOURLY) { 428 if (tick_time < start_time) { 429 tick_time += spacing; 430 tick_date = new Date(tick_time); 431 } 432 while (tick_time <= end_time) { 433 ticks.push({ v: tick_time, 434 label: formatter.call(dg, tick_date, granularity, opts, dg) 435 }); 436 tick_time += spacing; 437 tick_date = new Date(tick_time); 438 } 439 } else { 440 if (tick_time < start_time) { 441 date_array[datefield] += step; 442 tick_date = accessors.makeDate.apply(null, date_array); 443 tick_time = tick_date.getTime(); 444 } 445 while (tick_time <= end_time) { 446 if (granularity >= Granularity.DAILY || 447 accessors.getHours(tick_date) % step === 0) { 448 ticks.push({ v: tick_time, 449 label: formatter.call(dg, tick_date, granularity, opts, dg) 450 }); 451 } 452 date_array[datefield] += step; 453 tick_date = accessors.makeDate.apply(null, date_array); 454 tick_time = tick_date.getTime(); 455 } 456 } 457 return ticks; 458 }; 459