dygraph-layout.js

   1 /**
   2  * @license
   3  * Copyright 2011 Dan Vanderkam (danvdk@gmail.com)
   4  * MIT-licensed (http://opensource.org/licenses/MIT)
   5  */
   6
   7 /**
   8  * @fileoverview Based on PlotKitLayout, but modified to meet the needs of
   9  * dygraphs.
  10  */
  11
  12 /*jshint globalstrict: true */
  13 /*global Dygraph:false */
  14 "use strict";
  15
  16 /**
  17  * Creates a new DygraphLayout object.
  18  *
  19  * This class contains all the data to be charted.
  20  * It uses data coordinates, but also records the chart range (in data
  21  * coordinates) and hence is able to calculate percentage positions ('In this
  22  * view, Point A lies 25% down the x-axis.')
  23  *
  24  * Two things that it does not do are:
  25  * 1. Record pixel coordinates for anything.
  26  * 2. (oddly) determine anything about the layout of chart elements.
  27  *
  28  * The naming is a vestige of Dygraph's original PlotKit roots.
  29  *
  30  * @constructor
  31  */
  32 var DygraphLayout = function(dygraph) {
  33   this.dygraph_ = dygraph;
  34   this.datasets = [];
  35   this.setNames = [];
  36   this.annotations = [];
  37   this.yAxes_ = null;
  38
  39   // TODO(danvk): it's odd that xTicks_ and yTicks_ are inputs, but xticks and
  40   // yticks are outputs. Clean this up.
  41   this.xTicks_ = null;
  42   this.yTicks_ = null;
  43 };
  44
  45 DygraphLayout.prototype.attr_ = function(name) {
  46   return this.dygraph_.attr_(name);
  47 };
  48
  49 DygraphLayout.prototype.addDataset = function(setname, set_xy) {
  50   this.datasets.push(set_xy);
  51   this.setNames.push(setname);
  52 };
  53
  54 DygraphLayout.prototype.getPlotArea = function() {
  55   return this.computePlotArea_();
  56 };
  57
  58 // Compute the box which the chart should be drawn in. This is the canvas's
  59 // box, less space needed for axis and chart labels.
  60 DygraphLayout.prototype.computePlotArea_ = function() {
  61   var area = {
  62     // TODO(danvk): per-axis setting.
  63     x: 0,
  64     y: 0
  65   };
  66   if (this.attr_('drawYAxis')) {
  67    area.x = this.attr_('yAxisLabelWidth') + 2 * this.attr_('axisTickSize');
  68   }
  69
  70   area.w = this.dygraph_.width_ - area.x - this.attr_('rightGap');
  71   area.h = this.dygraph_.height_;
  72
  73   // Let plugins reserve space.
  74   var e = {
  75     chart_div: this.dygraph_.graphDiv,
  76     reserveSpaceLeft: function(px) {
  77       var r = {
  78         x: area.x,
  79         y: area.y,
  80         w: px,
  81         h: area.h
  82       };
  83       area.x += px;
  84       area.w -= px;
  85       return r;
  86     },
  87     reserveSpaceRight: function(px) {
  88       var r = {
  89         x: area.x + area.w - px,
  90         y: area.y,
  91         w: px,
  92         h: area.h
  93       };
  94       area.w -= px;
  95       return r;
  96     },
  97     reserveSpaceTop: function(px) {
  98       var r = {
  99         x: area.x,
 100         y: area.y,
 101         w: area.w,
 102         h: px
 103       };
 104       area.y += px;
 105       area.h -= px;
 106       return r;
 107     },
 108     reserveSpaceBottom: function(px) {
 109       var r = {
 110         x: area.x,
 111         y: area.y + area.h - px,
 112         w: area.w,
 113         h: px
 114       };
 115       area.h -= px;
 116       return r;
 117     },
 118     chartRect: function() {
 119       return {x:area.x, y:area.y, w:area.w, h:area.h};
 120     }
 121   };
 122   this.dygraph_.cascadeEvents_('layout', e);
 123
 124   if (this.attr_('drawXAxis')) {
 125     if (this.attr_('xAxisHeight')) {
 126       area.h -= this.attr_('xAxisHeight');
 127     } else {
 128       area.h -= this.attr_('axisLabelFontSize') + 2 * this.attr_('axisTickSize');
 129     }
 130   }
 131
 132   // Shrink the drawing area to accomodate additional y-axes.
 133   if (this.dygraph_.numAxes() == 2) {
 134     // TODO(danvk): per-axis setting.
 135     area.w -= (this.attr_('yAxisLabelWidth') + 2 * this.attr_('axisTickSize'));
 136   } else if (this.dygraph_.numAxes() > 2) {
 137     this.dygraph_.error("Only two y-axes are supported at this time. (Trying " +
 138                         "to use " + this.dygraph_.numAxes() + ")");
 139   }
 140
 141 /*
 142   // Add space for chart labels: title, xlabel and ylabel.
 143   if (this.attr_('title')) {
 144     area.h -= this.attr_('titleHeight');
 145     area.y += this.attr_('titleHeight');
 146   }
 147   if (this.attr_('xlabel')) {
 148     area.h -= this.attr_('xLabelHeight');
 149   }
 150   if (this.attr_('ylabel')) {
 151     // It would make sense to shift the chart here to make room for the y-axis
 152     // label, but the default yAxisLabelWidth is large enough that this results
 153     // in overly-padded charts. The y-axis label should fit fine. If it
 154     // doesn't, the yAxisLabelWidth option can be increased.
 155   }
 156
 157   if (this.attr_('y2label')) {
 158     // same logic applies here as for ylabel.
 159     // TODO(danvk): make yAxisLabelWidth a per-axis property
 160   }
 161 */
 162
 163   // Add space for range selector, if needed.
 164   if (this.attr_('showRangeSelector')) {
 165     area.h -= this.attr_('rangeSelectorHeight') + 4;
 166   }
 167
 168   return area;
 169 };
 170
 171 DygraphLayout.prototype.setAnnotations = function(ann) {
 172   // The Dygraph object's annotations aren't parsed. We parse them here and
 173   // save a copy. If there is no parser, then the user must be using raw format.
 174   this.annotations = [];
 175   var parse = this.attr_('xValueParser') || function(x) { return x; };
 176   for (var i = 0; i < ann.length; i++) {
 177     var a = {};
 178     if (!ann[i].xval && !ann[i].x) {
 179       this.dygraph_.error("Annotations must have an 'x' property");
 180       return;
 181     }
 182     if (ann[i].icon &&
 183         !(ann[i].hasOwnProperty('width') &&
 184           ann[i].hasOwnProperty('height'))) {
 185       this.dygraph_.error("Must set width and height when setting " +
 186                           "annotation.icon property");
 187       return;
 188     }
 189     Dygraph.update(a, ann[i]);
 190     if (!a.xval) a.xval = parse(a.x);
 191     this.annotations.push(a);
 192   }
 193 };
 194
 195 DygraphLayout.prototype.setXTicks = function(xTicks) {
 196   this.xTicks_ = xTicks;
 197 };
 198
 199 // TODO(danvk): add this to the Dygraph object's API or move it into Layout.
 200 DygraphLayout.prototype.setYAxes = function (yAxes) {
 201   this.yAxes_ = yAxes;
 202 };
 203
 204 DygraphLayout.prototype.setDateWindow = function(dateWindow) {
 205   this.dateWindow_ = dateWindow;
 206 };
 207
 208 DygraphLayout.prototype.evaluate = function() {
 209   this._evaluateLimits();
 210   this._evaluateLineCharts();
 211   this._evaluateLineTicks();
 212   this._evaluateAnnotations();
 213 };
 214
 215 DygraphLayout.prototype._evaluateLimits = function() {
 216   this.minxval = this.maxxval = null;
 217   if (this.dateWindow_) {
 218     this.minxval = this.dateWindow_[0];
 219     this.maxxval = this.dateWindow_[1];
 220   } else {
 221     for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 222       var series = this.datasets[setIdx];
 223       if (series.length > 1) {
 224         var x1 = series[0][0];
 225         if (!this.minxval || x1 < this.minxval) this.minxval = x1;
 226
 227         var x2 = series[series.length - 1][0];
 228         if (!this.maxxval || x2 > this.maxxval) this.maxxval = x2;
 229       }
 230     }
 231   }
 232   this.xrange = this.maxxval - this.minxval;
 233   this.xscale = (this.xrange !== 0 ? 1/this.xrange : 1.0);
 234
 235   for (var i = 0; i < this.yAxes_.length; i++) {
 236     var axis = this.yAxes_[i];
 237     axis.minyval = axis.computedValueRange[0];
 238     axis.maxyval = axis.computedValueRange[1];
 239     axis.yrange = axis.maxyval - axis.minyval;
 240     axis.yscale = (axis.yrange !== 0 ? 1.0 / axis.yrange : 1.0);
 241
 242     if (axis.g.attr_("logscale")) {
 243       axis.ylogrange = Dygraph.log10(axis.maxyval) - Dygraph.log10(axis.minyval);
 244       axis.ylogscale = (axis.ylogrange !== 0 ? 1.0 / axis.ylogrange : 1.0);
 245       if (!isFinite(axis.ylogrange) || isNaN(axis.ylogrange)) {
 246         axis.g.error('axis ' + i + ' of graph at ' + axis.g +
 247             ' can\'t be displayed in log scale for range [' +
 248             axis.minyval + ' - ' + axis.maxyval + ']');
 249       }
 250     }
 251   }
 252 };
 253
 254 DygraphLayout._calcYNormal = function(axis, value) {
 255   if (axis.logscale) {
 256     return 1.0 - ((Dygraph.log10(value) - Dygraph.log10(axis.minyval)) * axis.ylogscale);
 257   } else {
 258     return 1.0 - ((value - axis.minyval) * axis.yscale);
 259   }
 260 };
 261
 262 DygraphLayout.prototype._evaluateLineCharts = function() {
 263   // An array to keep track of how many points will be drawn for each set.
 264   // This will allow for the canvas renderer to not have to check every point
 265   // for every data set since the points are added in order of the sets in
 266   // datasets.
 267   this.setPointsLengths = [];
 268   this.setPointsOffsets = [];
 269
 270   var connectSeparated = this.attr_('connectSeparatedPoints');
 271   // TODO(bhs): these loops are a hot-spot for high-point-count charts. In fact,
 272   // on chrome+linux, they are 6 times more expensive than iterating through the
 273   // points and drawing the lines. The brunt of the cost comes from allocating
 274   // the |point| structures.
 275   var i = 0;
 276   var setIdx;
 277
 278   // Preallocating the size of points reduces reallocations, and therefore,
 279   // calls to collect garbage.
 280   var totalPoints = 0;
 281   for (setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 282     totalPoints += this.datasets[setIdx].length;
 283   }
 284   this.points = new Array(totalPoints);
 285
 286   for (setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 287     this.setPointsOffsets.push(i);
 288     var dataset = this.datasets[setIdx];
 289     var setName = this.setNames[setIdx];
 290     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 291
 292     for (var j = 0; j < dataset.length; j++) {
 293       var item = dataset[j];
 294       var xValue = DygraphLayout.parseFloat_(item[0]);
 295       var yValue = DygraphLayout.parseFloat_(item[1]);
 296
 297       // Range from 0-1 where 0 represents left and 1 represents right.
 298       var xNormal = (xValue - this.minxval) * this.xscale;
 299       // Range from 0-1 where 0 represents top and 1 represents bottom
 300       var yNormal = DygraphLayout._calcYNormal(axis, yValue);
 301
 302       if (connectSeparated && item[1] === null) {
 303         yValue = null;
 304       }
 305       this.points[i] = {
 306         // TODO(danvk): here
 307         x: xNormal,
 308         y: yNormal,
 309         xval: xValue,
 310         yval: yValue,
 311         name: setName
 312       };
 313       i++;
 314     }
 315     this.setPointsLengths.push(i - this.setPointsOffsets[setIdx]);
 316   }
 317 };
 318
 319 /**
 320  * Optimized replacement for parseFloat, which was way too slow when almost
 321  * all values were type number, with few edge cases, none of which were strings.
 322  */
 323 DygraphLayout.parseFloat_ = function(val) {
 324   // parseFloat(null) is NaN
 325   if (val === null) {
 326     return NaN;
 327   }
 328
 329   // Assume it's a number or NaN. If it's something else, I'll be shocked.
 330   return val;
 331 }
 332
 333 DygraphLayout.prototype._evaluateLineTicks = function() {
 334   var i, tick, label, pos;
 335   this.xticks = [];
 336   for (i = 0; i < this.xTicks_.length; i++) {
 337     tick = this.xTicks_[i];
 338     label = tick.label;
 339     pos = this.xscale * (tick.v - this.minxval);
 340     if ((pos >= 0.0) && (pos <= 1.0)) {
 341       this.xticks.push([pos, label]);
 342     }
 343   }
 344
 345   this.yticks = [];
 346   for (i = 0; i < this.yAxes_.length; i++ ) {
 347     var axis = this.yAxes_[i];
 348     for (var j = 0; j < axis.ticks.length; j++) {
 349       tick = axis.ticks[j];
 350       label = tick.label;
 351       pos = this.dygraph_.toPercentYCoord(tick.v, i);
 352       if ((pos >= 0.0) && (pos <= 1.0)) {
 353         this.yticks.push([i, pos, label]);
 354       }
 355     }
 356   }
 357 };
 358
 359
 360 /**
 361  * Behaves the same way as PlotKit.Layout, but also copies the errors
 362  * @private
 363  */
 364 DygraphLayout.prototype.evaluateWithError = function() {
 365   this.evaluate();
 366   if (!(this.attr_('errorBars') || this.attr_('customBars'))) return;
 367
 368   // Copy over the error terms
 369   var i = 0;  // index in this.points
 370   for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 371     var j = 0;
 372     var dataset = this.datasets[setIdx];
 373     var setName = this.setNames[setIdx];
 374     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 375     for (j = 0; j < dataset.length; j++, i++) {
 376       var item = dataset[j];
 377       var xv = DygraphLayout.parseFloat_(item[0]);
 378       var yv = DygraphLayout.parseFloat_(item[1]);
 379
 380       if (xv == this.points[i].xval &&
 381           yv == this.points[i].yval) {
 382         var errorMinus = DygraphLayout.parseFloat_(item[2]);
 383         var errorPlus = DygraphLayout.parseFloat_(item[3]);
 384
 385         var yv_minus = yv - errorMinus;
 386         var yv_plus = yv + errorPlus;
 387         this.points[i].y_top = DygraphLayout._calcYNormal(axis, yv_minus);
 388         this.points[i].y_bottom = DygraphLayout._calcYNormal(axis, yv_plus);
 389       }
 390     }
 391   }
 392 };
 393
 394 DygraphLayout.prototype._evaluateAnnotations = function() {
 395   // Add the annotations to the point to which they belong.
 396   // Make a map from (setName, xval) to annotation for quick lookups.
 397   var i;
 398   var annotations = {};
 399   for (i = 0; i < this.annotations.length; i++) {
 400     var a = this.annotations[i];
 401     annotations[a.xval + "," + a.series] = a;
 402   }
 403
 404   this.annotated_points = [];
 405
 406   // Exit the function early if there are no annotations.
 407   if (!this.annotations || !this.annotations.length) {
 408     return;
 409   }
 410
 411   // TODO(antrob): loop through annotations not points.
 412   for (i = 0; i < this.points.length; i++) {
 413     var p = this.points[i];
 414     var k = p.xval + "," + p.name;
 415     if (k in annotations) {
 416       p.annotation = annotations[k];
 417       this.annotated_points.push(p);
 418     }
 419   }
 420 };
 421
 422 /**
 423  * Convenience function to remove all the data sets from a graph
 424  */
 425 DygraphLayout.prototype.removeAllDatasets = function() {
 426   delete this.datasets;
 427   delete this.setNames;
 428   delete this.setPointsLengths;
 429   delete this.setPointsOffsets;
 430   this.datasets = [];
 431   this.setNames = [];
 432   this.setPointsLengths = [];
 433   this.setPointsOffsets = [];
 434 };
 435
 436 /**
 437  * Return a copy of the point at the indicated index, with its yval unstacked.
 438  * @param int index of point in layout_.points
 439  */
 440 DygraphLayout.prototype.unstackPointAtIndex = function(idx) {
 441   var point = this.points[idx];
 442   // If the point is missing, no unstacking is necessary
 443   if (!point.yval) {
 444     return point;
 445   }
 446
 447   // Clone the point since we modify it
 448   var unstackedPoint = {};
 449   for (var pt in point) {
 450     unstackedPoint[pt] = point[pt];
 451   }
 452
 453   if (!this.attr_("stackedGraph")) {
 454     return unstackedPoint;
 455   }
 456
 457   // The unstacked yval is equal to the current yval minus the yval of the
 458   // next point at the same xval.
 459   for (var i = idx+1; i < this.points.length; i++) {
 460     if ((this.points[i].xval == point.xval) && this.points[i].yval) {
 461       unstackedPoint.yval -= this.points[i].yval;
 462       break;
 463     }
 464   }
 465
 466   return unstackedPoint;
 467 };