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