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