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   if (this.attr_('drawXAxis')) {
  73     if (this.attr_('xAxisHeight')) {
  74       area.h -= this.attr_('xAxisHeight');
  75     } else {
  76       area.h -= this.attr_('axisLabelFontSize') + 2 * this.attr_('axisTickSize');
  77     }
  78   }
  79
  80   // Shrink the drawing area to accomodate additional y-axes.
  81   if (this.dygraph_.numAxes() == 2) {
  82     // TODO(danvk): per-axis setting.
  83     area.w -= (this.attr_('yAxisLabelWidth') + 2 * this.attr_('axisTickSize'));
  84   } else if (this.dygraph_.numAxes() > 2) {
  85     this.dygraph_.error("Only two y-axes are supported at this time. (Trying " +
  86                         "to use " + this.dygraph_.numAxes() + ")");
  87   }
  88
  89   // Add space for chart labels: title, xlabel and ylabel.
  90   if (this.attr_('title')) {
  91     area.h -= this.attr_('titleHeight');
  92     area.y += this.attr_('titleHeight');
  93   }
  94   if (this.attr_('xlabel')) {
  95     area.h -= this.attr_('xLabelHeight');
  96   }
  97   if (this.attr_('ylabel')) {
  98     // It would make sense to shift the chart here to make room for the y-axis
  99     // label, but the default yAxisLabelWidth is large enough that this results
 100     // in overly-padded charts. The y-axis label should fit fine. If it
 101     // doesn't, the yAxisLabelWidth option can be increased.
 102   }
 103
 104   if (this.attr_('y2label')) {
 105     // same logic applies here as for ylabel.
 106     // TODO(danvk): make yAxisLabelWidth a per-axis property
 107   }
 108
 109   // Add space for range selector, if needed.
 110   if (this.attr_('showRangeSelector')) {
 111     area.h -= this.attr_('rangeSelectorHeight') + 4;
 112   }
 113
 114   return area;
 115 };
 116
 117 DygraphLayout.prototype.setAnnotations = function(ann) {
 118   // The Dygraph object's annotations aren't parsed. We parse them here and
 119   // save a copy. If there is no parser, then the user must be using raw format.
 120   this.annotations = [];
 121   var parse = this.attr_('xValueParser') || function(x) { return x; };
 122   for (var i = 0; i < ann.length; i++) {
 123     var a = {};
 124     if (!ann[i].xval && !ann[i].x) {
 125       this.dygraph_.error("Annotations must have an 'x' property");
 126       return;
 127     }
 128     if (ann[i].icon &&
 129         !(ann[i].hasOwnProperty('width') &&
 130           ann[i].hasOwnProperty('height'))) {
 131       this.dygraph_.error("Must set width and height when setting " +
 132                           "annotation.icon property");
 133       return;
 134     }
 135     Dygraph.update(a, ann[i]);
 136     if (!a.xval) a.xval = parse(a.x);
 137     this.annotations.push(a);
 138   }
 139 };
 140
 141 DygraphLayout.prototype.setXTicks = function(xTicks) {
 142   this.xTicks_ = xTicks;
 143 };
 144
 145 // TODO(danvk): add this to the Dygraph object's API or move it into Layout.
 146 DygraphLayout.prototype.setYAxes = function (yAxes) {
 147   this.yAxes_ = yAxes;
 148 };
 149
 150 DygraphLayout.prototype.setDateWindow = function(dateWindow) {
 151   this.dateWindow_ = dateWindow;
 152 };
 153
 154 DygraphLayout.prototype.evaluate = function() {
 155   this._evaluateLimits();
 156   this._evaluateLineCharts();
 157   this._evaluateLineTicks();
 158   this._evaluateAnnotations();
 159 };
 160
 161 DygraphLayout.prototype._evaluateLimits = function() {
 162   this.minxval = this.maxxval = null;
 163   if (this.dateWindow_) {
 164     this.minxval = this.dateWindow_[0];
 165     this.maxxval = this.dateWindow_[1];
 166   } else {
 167     for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 168       var series = this.datasets[setIdx];
 169       if (series.length > 1) {
 170         var x1 = series[0][0];
 171         if (!this.minxval || x1 < this.minxval) this.minxval = x1;
 172
 173         var x2 = series[series.length - 1][0];
 174         if (!this.maxxval || x2 > this.maxxval) this.maxxval = x2;
 175       }
 176     }
 177   }
 178   this.xrange = this.maxxval - this.minxval;
 179   this.xscale = (this.xrange !== 0 ? 1/this.xrange : 1.0);
 180
 181   for (var i = 0; i < this.yAxes_.length; i++) {
 182     var axis = this.yAxes_[i];
 183     axis.minyval = axis.computedValueRange[0];
 184     axis.maxyval = axis.computedValueRange[1];
 185     axis.yrange = axis.maxyval - axis.minyval;
 186     axis.yscale = (axis.yrange !== 0 ? 1.0 / axis.yrange : 1.0);
 187
 188     if (axis.g.attr_("logscale")) {
 189       axis.ylogrange = Dygraph.log10(axis.maxyval) - Dygraph.log10(axis.minyval);
 190       axis.ylogscale = (axis.ylogrange !== 0 ? 1.0 / axis.ylogrange : 1.0);
 191       if (!isFinite(axis.ylogrange) || isNaN(axis.ylogrange)) {
 192         axis.g.error('axis ' + i + ' of graph at ' + axis.g +
 193             ' can\'t be displayed in log scale for range [' +
 194             axis.minyval + ' - ' + axis.maxyval + ']');
 195       }
 196     }
 197   }
 198 };
 199
 200 DygraphLayout._calcYNormal = function(axis, value) {
 201   if (axis.logscale) {
 202     return 1.0 - ((Dygraph.log10(value) - Dygraph.log10(axis.minyval)) * axis.ylogscale);
 203   } else {
 204     return 1.0 - ((value - axis.minyval) * axis.yscale);
 205   }
 206 };
 207
 208 DygraphLayout.prototype._evaluateLineCharts = function() {
 209   // An array to keep track of how many points will be drawn for each set.
 210   // This will allow for the canvas renderer to not have to check every point
 211   // for every data set since the points are added in order of the sets in
 212   // datasets.
 213   this.setPointsLengths = [];
 214   this.setPointsOffsets = [];
 215
 216   var connectSeparated = this.attr_('connectSeparatedPoints');
 217   // TODO(bhs): these loops are a hot-spot for high-point-count charts. In fact,
 218   // on chrome+linux, they are 6 times more expensive than iterating through the
 219   // points and drawing the lines. The brunt of the cost comes from allocating
 220   // the |point| structures.
 221   var i = 0;
 222   var setIdx;
 223
 224   // Preallocating the size of points reduces reallocations, and therefore,
 225   // calls to collect garbage.
 226   var totalPoints = 0;
 227   for (setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 228     totalPoints += this.datasets[setIdx].length;
 229   }
 230   this.points = new Array(totalPoints);
 231
 232   for (setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 233     this.setPointsOffsets.push(i);
 234     var dataset = this.datasets[setIdx];
 235     var setName = this.setNames[setIdx];
 236     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 237
 238     for (var j = 0; j < dataset.length; j++) {
 239       var item = dataset[j];
 240       var xValue = DygraphLayout.parseFloat_(item[0]);
 241       var yValue = DygraphLayout.parseFloat_(item[1]);
 242
 243       // Range from 0-1 where 0 represents left and 1 represents right.
 244       var xNormal = (xValue - this.minxval) * this.xscale;
 245       // Range from 0-1 where 0 represents top and 1 represents bottom
 246       var yNormal = DygraphLayout._calcYNormal(axis, yValue);
 247
 248       if (connectSeparated && item[1] === null) {
 249         yValue = null;
 250       }
 251       this.points[i] = {
 252         // TODO(danvk): here
 253         x: xNormal,
 254         y: yNormal,
 255         xval: xValue,
 256         yval: yValue,
 257         name: setName
 258       };
 259       i++;
 260     }
 261     this.setPointsLengths.push(i - this.setPointsOffsets[setIdx]);
 262   }
 263 };
 264
 265 /**
 266  * Optimized replacement for parseFloat, which was way too slow when almost
 267  * all values were type number, with few edge cases, none of which were strings.
 268  */
 269 DygraphLayout.parseFloat_ = function(val) {
 270   // parseFloat(null) is NaN
 271   if (val === null) {
 272     return NaN;
 273   }
 274
 275   // Assume it's a number or NaN. If it's something else, I'll be shocked.
 276   return val;
 277 }
 278
 279 DygraphLayout.prototype._evaluateLineTicks = function() {
 280   var i, tick, label, pos;
 281   this.xticks = [];
 282   for (i = 0; i < this.xTicks_.length; i++) {
 283     tick = this.xTicks_[i];
 284     label = tick.label;
 285     pos = this.xscale * (tick.v - this.minxval);
 286     if ((pos >= 0.0) && (pos <= 1.0)) {
 287       this.xticks.push([pos, label]);
 288     }
 289   }
 290
 291   this.yticks = [];
 292   for (i = 0; i < this.yAxes_.length; i++ ) {
 293     var axis = this.yAxes_[i];
 294     for (var j = 0; j < axis.ticks.length; j++) {
 295       tick = axis.ticks[j];
 296       label = tick.label;
 297       pos = this.dygraph_.toPercentYCoord(tick.v, i);
 298       if ((pos >= 0.0) && (pos <= 1.0)) {
 299         this.yticks.push([i, pos, label]);
 300       }
 301     }
 302   }
 303 };
 304
 305
 306 /**
 307  * Behaves the same way as PlotKit.Layout, but also copies the errors
 308  * @private
 309  */
 310 DygraphLayout.prototype.evaluateWithError = function() {
 311   this.evaluate();
 312   if (!(this.attr_('errorBars') || this.attr_('customBars'))) return;
 313
 314   // Copy over the error terms
 315   var i = 0;  // index in this.points
 316   for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 317     var j = 0;
 318     var dataset = this.datasets[setIdx];
 319     var setName = this.setNames[setIdx];
 320     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 321     for (j = 0; j < dataset.length; j++, i++) {
 322       var item = dataset[j];
 323       var xv = DygraphLayout.parseFloat_(item[0]);
 324       var yv = DygraphLayout.parseFloat_(item[1]);
 325
 326       if (xv == this.points[i].xval &&
 327           yv == this.points[i].yval) {
 328         var errorMinus = DygraphLayout.parseFloat_(item[2]);
 329         var errorPlus = DygraphLayout.parseFloat_(item[3]);
 330
 331         var yv_minus = yv - errorMinus;
 332         var yv_plus = yv + errorPlus;
 333         this.points[i].y_top = DygraphLayout._calcYNormal(axis, yv_minus);
 334         this.points[i].y_bottom = DygraphLayout._calcYNormal(axis, yv_plus);
 335       }
 336     }
 337   }
 338 };
 339
 340 DygraphLayout.prototype._evaluateAnnotations = function() {
 341   // Add the annotations to the point to which they belong.
 342   // Make a map from (setName, xval) to annotation for quick lookups.
 343   var i;
 344   var annotations = {};
 345   for (i = 0; i < this.annotations.length; i++) {
 346     var a = this.annotations[i];
 347     annotations[a.xval + "," + a.series] = a;
 348   }
 349
 350   this.annotated_points = [];
 351
 352   // Exit the function early if there are no annotations.
 353   if (!this.annotations || !this.annotations.length) {
 354     return;
 355   }
 356
 357   // TODO(antrob): loop through annotations not points.
 358   for (i = 0; i < this.points.length; i++) {
 359     var p = this.points[i];
 360     var k = p.xval + "," + p.name;
 361     if (k in annotations) {
 362       p.annotation = annotations[k];
 363       this.annotated_points.push(p);
 364     }
 365   }
 366 };
 367
 368 /**
 369  * Convenience function to remove all the data sets from a graph
 370  */
 371 DygraphLayout.prototype.removeAllDatasets = function() {
 372   delete this.datasets;
 373   delete this.setNames;
 374   delete this.setPointsLengths;
 375   delete this.setPointsOffsets;
 376   this.datasets = [];
 377   this.setNames = [];
 378   this.setPointsLengths = [];
 379   this.setPointsOffsets = [];
 380 };
 381
 382 /**
 383  * Return a copy of the point at the indicated index, with its yval unstacked.
 384  * @param int index of point in layout_.points
 385  */
 386 DygraphLayout.prototype.unstackPointAtIndex = function(idx) {
 387   var point = this.points[idx];
 388   // If the point is missing, no unstacking is necessary
 389   if (!point.yval) {
 390     return point;
 391   }
 392
 393   // Clone the point since we modify it
 394   var unstackedPoint = {};
 395   for (var pt in point) {
 396     unstackedPoint[pt] = point[pt];
 397   }
 398
 399   if (!this.attr_("stackedGraph")) {
 400     return unstackedPoint;
 401   }
 402
 403   // The unstacked yval is equal to the current yval minus the yval of the
 404   // next point at the same xval.
 405   for (var i = idx+1; i < this.points.length; i++) {
 406     if ((this.points[i].xval == point.xval) && this.points[i].yval) {
 407       unstackedPoint.yval -= this.points[i].yval;
 408       break;
 409     }
 410   }
 411
 412   return unstackedPoint;
 413 };