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