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