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 totalPoints = 0;
 223   for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 224     totalPoints += this.datasets[setIdx].length;
 225   }
 226   this.points = new Array(totalPoints);
 227
 228   for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 229     this.setPointsOffsets.push(i);
 230     var dataset = this.datasets[setIdx];
 231     var setName = this.setNames[setIdx];
 232     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 233
 234     for (var j = 0; j < dataset.length; j++) {
 235       var item = dataset[j];
 236       var xValue = item[0];
 237       var yValue = item[1];
 238
 239       // Range from 0-1 where 0 represents left and 1 represents right.
 240       var xNormal = (xValue - this.minxval) * this.xscale;
 241       // Range from 0-1 where 0 represents top and 1 represents bottom
 242       var yNormal = DygraphLayout._calcYNormal(axis, yValue);
 243
 244       if (connectSeparated && item[1] === null) {
 245         yValue = null;
 246       }
 247       this.points[i] = {
 248         // TODO(danvk): here
 249         x: xNormal,
 250         y: yNormal,
 251         xval: xValue,
 252         yval: yValue,
 253         name: setName
 254       };
 255       i++;
 256     }
 257     this.setPointsLengths.push(i - this.setPointsOffsets[setIdx]);
 258   }
 259 };
 260
 261 DygraphLayout.prototype._evaluateLineTicks = function() {
 262   var i, tick, label, pos;
 263   this.xticks = [];
 264   for (i = 0; i < this.xTicks_.length; i++) {
 265     tick = this.xTicks_[i];
 266     label = tick.label;
 267     pos = this.xscale * (tick.v - this.minxval);
 268     if ((pos >= 0.0) && (pos <= 1.0)) {
 269       this.xticks.push([pos, label]);
 270     }
 271   }
 272
 273   this.yticks = [];
 274   for (i = 0; i < this.yAxes_.length; i++ ) {
 275     var axis = this.yAxes_[i];
 276     for (var j = 0; j < axis.ticks.length; j++) {
 277       tick = axis.ticks[j];
 278       label = tick.label;
 279       pos = this.dygraph_.toPercentYCoord(tick.v, i);
 280       if ((pos >= 0.0) && (pos <= 1.0)) {
 281         this.yticks.push([i, pos, label]);
 282       }
 283     }
 284   }
 285 };
 286
 287
 288 /**
 289  * Behaves the same way as PlotKit.Layout, but also copies the errors
 290  * @private
 291  */
 292 DygraphLayout.prototype.evaluateWithError = function() {
 293   this.evaluate();
 294   if (!(this.attr_('errorBars') || this.attr_('customBars'))) return;
 295
 296   // Copy over the error terms
 297   var i = 0;  // index in this.points
 298   for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 299     var j = 0;
 300     var dataset = this.datasets[setIdx];
 301     var setName = this.setNames[setIdx];
 302     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 303     for (j = 0; j < dataset.length; j++, i++) {
 304       var item = dataset[j];
 305       var xv = item[0];
 306       var yv = item[1];
 307
 308       if (xv == this.points[i].xval &&
 309           yv == this.points[i].yval) {
 310         var errorMinus = item[2];
 311         var errorPlus = item[3];
 312
 313         var yv_minus = yv - errorMinus;
 314         var yv_plus = yv + errorPlus;
 315         this.points[i].y_top = DygraphLayout._calcYNormal(axis, yv_minus);
 316         this.points[i].y_bottom = DygraphLayout._calcYNormal(axis, yv_plus);
 317       }
 318     }
 319   }
 320 };
 321
 322 DygraphLayout.prototype._evaluateAnnotations = function() {
 323   // Add the annotations to the point to which they belong.
 324   // Make a map from (setName, xval) to annotation for quick lookups.
 325   var i;
 326   var annotations = {};
 327   for (i = 0; i < this.annotations.length; i++) {
 328     var a = this.annotations[i];
 329     annotations[a.xval + "," + a.series] = a;
 330   }
 331
 332   this.annotated_points = [];
 333
 334   // Exit the function early if there are no annotations.
 335   if (!this.annotations || !this.annotations.length) {
 336     return;
 337   }
 338
 339   // TODO(antrob): loop through annotations not points.
 340   for (i = 0; i < this.points.length; i++) {
 341     var p = this.points[i];
 342     var k = p.xval + "," + p.name;
 343     if (k in annotations) {
 344       p.annotation = annotations[k];
 345       this.annotated_points.push(p);
 346     }
 347   }
 348 };
 349
 350 /**
 351  * Convenience function to remove all the data sets from a graph
 352  */
 353 DygraphLayout.prototype.removeAllDatasets = function() {
 354   delete this.datasets;
 355   delete this.setNames;
 356   delete this.setPointsLengths;
 357   delete this.setPointsOffsets;
 358   this.datasets = [];
 359   this.setNames = [];
 360   this.setPointsLengths = [];
 361   this.setPointsOffsets = [];
 362 };
 363
 364 /**
 365  * Return a copy of the point at the indicated index, with its yval unstacked.
 366  * @param int index of point in layout_.points
 367  */
 368 DygraphLayout.prototype.unstackPointAtIndex = function(idx) {
 369   var point = this.points[idx];
 370   // If the point is missing, no unstacking is necessary
 371   if (!point.yval) {
 372     return point;
 373   }
 374
 375   // Clone the point since we modify it
 376   var unstackedPoint = {};
 377   for (var pt in point) {
 378     unstackedPoint[pt] = point[pt];
 379   }
 380
 381   if (!this.attr_("stackedGraph")) {
 382     return unstackedPoint;
 383   }
 384
 385   // The unstacked yval is equal to the current yval minus the yval of the
 386   // next point at the same xval.
 387   for (var i = idx+1; i < this.points.length; i++) {
 388     if ((this.points[i].xval == point.xval) && this.points[i].yval) {
 389       unstackedPoint.yval -= this.points[i].yval;
 390       break;
 391     }
 392   }
 393
 394   return unstackedPoint;
 395 };