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   this.points = null;
  39
  40   // TODO(danvk): it's odd that xTicks_ and yTicks_ are inputs, but xticks and
  41   // yticks are outputs. Clean this up.
  42   this.xTicks_ = null;
  43   this.yTicks_ = null;
  44 };
  45
  46 DygraphLayout.prototype.attr_ = function(name) {
  47   return this.dygraph_.attr_(name);
  48 };
  49
  50 DygraphLayout.prototype.addDataset = function(setname, set_xy) {
  51   this.datasets.push(set_xy);
  52   this.setNames.push(setname);
  53 };
  54
  55 DygraphLayout.prototype.getPlotArea = function() {
  56   return this.area_;
  57 };
  58
  59 // Compute the box which the chart should be drawn in. This is the canvas's
  60 // box, less space needed for axis and chart labels.
  61 DygraphLayout.prototype.computePlotArea = function() {
  62   var area = {
  63     // TODO(danvk): per-axis setting.
  64     x: 0,
  65     y: 0
  66   };
  67
  68   area.w = this.dygraph_.width_ - area.x - this.attr_('rightGap');
  69   area.h = this.dygraph_.height_;
  70
  71   // Let plugins reserve space.
  72   var e = {
  73     chart_div: this.dygraph_.graphDiv,
  74     reserveSpaceLeft: function(px) {
  75       var r = {
  76         x: area.x,
  77         y: area.y,
  78         w: px,
  79         h: area.h
  80       };
  81       area.x += px;
  82       area.w -= px;
  83       return r;
  84     },
  85     reserveSpaceRight: function(px) {
  86       var r = {
  87         x: area.x + area.w - px,
  88         y: area.y,
  89         w: px,
  90         h: area.h
  91       };
  92       area.w -= px;
  93       return r;
  94     },
  95     reserveSpaceTop: function(px) {
  96       var r = {
  97         x: area.x,
  98         y: area.y,
  99         w: area.w,
 100         h: px
 101       };
 102       area.y += px;
 103       area.h -= px;
 104       return r;
 105     },
 106     reserveSpaceBottom: function(px) {
 107       var r = {
 108         x: area.x,
 109         y: area.y + area.h - px,
 110         w: area.w,
 111         h: px
 112       };
 113       area.h -= px;
 114       return r;
 115     },
 116     chartRect: function() {
 117       return {x:area.x, y:area.y, w:area.w, h:area.h};
 118     }
 119   };
 120   this.dygraph_.cascadeEvents_('layout', e);
 121
 122   this.area_ = area;
 123 };
 124
 125 DygraphLayout.prototype.setAnnotations = function(ann) {
 126   // The Dygraph object's annotations aren't parsed. We parse them here and
 127   // save a copy. If there is no parser, then the user must be using raw format.
 128   this.annotations = [];
 129   var parse = this.attr_('xValueParser') || function(x) { return x; };
 130   for (var i = 0; i < ann.length; i++) {
 131     var a = {};
 132     if (!ann[i].xval && !ann[i].x) {
 133       this.dygraph_.error("Annotations must have an 'x' property");
 134       return;
 135     }
 136     if (ann[i].icon &&
 137         !(ann[i].hasOwnProperty('width') &&
 138           ann[i].hasOwnProperty('height'))) {
 139       this.dygraph_.error("Must set width and height when setting " +
 140                           "annotation.icon property");
 141       return;
 142     }
 143     Dygraph.update(a, ann[i]);
 144     if (!a.xval) a.xval = parse(a.x);
 145     this.annotations.push(a);
 146   }
 147 };
 148
 149 DygraphLayout.prototype.setXTicks = function(xTicks) {
 150   this.xTicks_ = xTicks;
 151 };
 152
 153 // TODO(danvk): add this to the Dygraph object's API or move it into Layout.
 154 DygraphLayout.prototype.setYAxes = function (yAxes) {
 155   this.yAxes_ = yAxes;
 156 };
 157
 158 DygraphLayout.prototype.setDateWindow = function(dateWindow) {
 159   this.dateWindow_ = dateWindow;
 160 };
 161
 162 DygraphLayout.prototype.evaluate = function() {
 163   this._evaluateLimits();
 164   this._evaluateLineCharts();
 165   this._evaluateLineTicks();
 166   this._evaluateAnnotations();
 167 };
 168
 169 DygraphLayout.prototype._evaluateLimits = function() {
 170   this.minxval = this.maxxval = null;
 171   if (this.dateWindow_) {
 172     this.minxval = this.dateWindow_[0];
 173     this.maxxval = this.dateWindow_[1];
 174   } else {
 175     for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 176       var series = this.datasets[setIdx];
 177       if (series.length > 1) {
 178         var x1 = series[0][0];
 179         if (!this.minxval || x1 < this.minxval) this.minxval = x1;
 180
 181         var x2 = series[series.length - 1][0];
 182         if (!this.maxxval || x2 > this.maxxval) this.maxxval = x2;
 183       }
 184     }
 185   }
 186   this.xrange = this.maxxval - this.minxval;
 187   this.xscale = (this.xrange !== 0 ? 1/this.xrange : 1.0);
 188
 189   for (var i = 0; i < this.yAxes_.length; i++) {
 190     var axis = this.yAxes_[i];
 191     axis.minyval = axis.computedValueRange[0];
 192     axis.maxyval = axis.computedValueRange[1];
 193     axis.yrange = axis.maxyval - axis.minyval;
 194     axis.yscale = (axis.yrange !== 0 ? 1.0 / axis.yrange : 1.0);
 195
 196     if (axis.g.attr_("logscale")) {
 197       axis.ylogrange = Dygraph.log10(axis.maxyval) - Dygraph.log10(axis.minyval);
 198       axis.ylogscale = (axis.ylogrange !== 0 ? 1.0 / axis.ylogrange : 1.0);
 199       if (!isFinite(axis.ylogrange) || isNaN(axis.ylogrange)) {
 200         axis.g.error('axis ' + i + ' of graph at ' + axis.g +
 201             ' can\'t be displayed in log scale for range [' +
 202             axis.minyval + ' - ' + axis.maxyval + ']');
 203       }
 204     }
 205   }
 206 };
 207
 208 DygraphLayout._calcYNormal = function(axis, value, logscale) {
 209   if (logscale) {
 210     return 1.0 - ((Dygraph.log10(value) - Dygraph.log10(axis.minyval)) * axis.ylogscale);
 211   } else {
 212     return 1.0 - ((value - axis.minyval) * axis.yscale);
 213   }
 214 };
 215
 216 DygraphLayout.prototype._evaluateLineCharts = function() {
 217   var connectSeparated = this.attr_('connectSeparatedPoints');
 218
 219   // series index -> point index in series -> |point| structure
 220   this.points = new Array(this.datasets.length);
 221
 222   // TODO(bhs): these loops are a hot-spot for high-point-count charts. In fact,
 223   // on chrome+linux, they are 6 times more expensive than iterating through the
 224   // points and drawing the lines. The brunt of the cost comes from allocating
 225   // the |point| structures.
 226   for (var setIdx = 0; setIdx < this.datasets.length; setIdx++) {
 227     var dataset = this.datasets[setIdx];
 228     var setName = this.setNames[setIdx];
 229     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 230     // TODO (konigsberg): use optionsForAxis instead.
 231     var logscale = this.dygraph_.attributes_.getForSeries("logscale", setName);
 232
 233     // Preallocating the size of points reduces reallocations, and therefore,
 234     // calls to collect garbage.
 235     var seriesPoints = new Array(dataset.length);
 236
 237     for (var j = 0; j < dataset.length; j++) {
 238       var item = dataset[j];
 239       var xValue = DygraphLayout.parseFloat_(item[0]);
 240       var yValue = DygraphLayout.parseFloat_(item[1]);
 241
 242       // Range from 0-1 where 0 represents left and 1 represents right.
 243       var xNormal = (xValue - this.minxval) * this.xscale;
 244       // Range from 0-1 where 0 represents top and 1 represents bottom
 245       var yNormal = DygraphLayout._calcYNormal(axis, yValue, logscale);
 246
 247       // TODO(danvk): drop the point in this case, don't null it.
 248       // The nulls create complexity in DygraphCanvasRenderer._drawSeries.
 249       if (connectSeparated && item[1] === null) {
 250         yValue = null;
 251       }
 252       seriesPoints[j] = {
 253         x: xNormal,
 254         y: yNormal,
 255         xval: xValue,
 256         yval: yValue,
 257         name: setName  // TODO(danvk): is this really necessary?
 258       };
 259     }
 260
 261     this.points[setIdx] = seriesPoints;
 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 points = this.points[setIdx];
 318     var j = 0;
 319     var dataset = this.datasets[setIdx];
 320     var setName = this.setNames[setIdx];
 321     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 322     // TODO (konigsberg): use optionsForAxis instead.
 323     var logscale = this.dygraph_.attributes_.getForSeries("logscale", setName);
 324
 325     for (j = 0; j < dataset.length; j++, i++) {
 326       var item = dataset[j];
 327       var xv = DygraphLayout.parseFloat_(item[0]);
 328       var yv = DygraphLayout.parseFloat_(item[1]);
 329
 330       if (xv == points[j].xval &&
 331           yv == points[j].yval) {
 332         var errorMinus = DygraphLayout.parseFloat_(item[2]);
 333         var errorPlus = DygraphLayout.parseFloat_(item[3]);
 334
 335         var yv_minus = yv - errorMinus;
 336         var yv_plus = yv + errorPlus;
 337         points[j].y_top = DygraphLayout._calcYNormal(axis, yv_minus, logscale);
 338         points[j].y_bottom = DygraphLayout._calcYNormal(axis, yv_plus, logscale);
 339       }
 340     }
 341   }
 342 };
 343
 344 DygraphLayout.prototype._evaluateAnnotations = function() {
 345   // Add the annotations to the point to which they belong.
 346   // Make a map from (setName, xval) to annotation for quick lookups.
 347   var i;
 348   var annotations = {};
 349   for (i = 0; i < this.annotations.length; i++) {
 350     var a = this.annotations[i];
 351     annotations[a.xval + "," + a.series] = a;
 352   }
 353
 354   this.annotated_points = [];
 355
 356   // Exit the function early if there are no annotations.
 357   if (!this.annotations || !this.annotations.length) {
 358     return;
 359   }
 360
 361   // TODO(antrob): loop through annotations not points.
 362   for (var setIdx = 0; setIdx < this.points.length; setIdx++) {
 363     var points = this.points[setIdx];
 364     for (i = 0; i < points.length; i++) {
 365       var p = points[i];
 366       var k = p.xval + "," + p.name;
 367       if (k in annotations) {
 368         p.annotation = annotations[k];
 369         this.annotated_points.push(p);
 370       }
 371     }
 372   }
 373 };
 374
 375 /**
 376  * Convenience function to remove all the data sets from a graph
 377  */
 378 DygraphLayout.prototype.removeAllDatasets = function() {
 379   delete this.datasets;
 380   delete this.setNames;
 381   delete this.setPointsLengths;
 382   delete this.setPointsOffsets;
 383   this.datasets = [];
 384   this.setNames = [];
 385   this.setPointsLengths = [];
 386   this.setPointsOffsets = [];
 387 };
 388
 389 /**
 390  * Return a copy of the point at the indicated index, with its yval unstacked.
 391  * @param int index of point in layout_.points
 392  */
 393 DygraphLayout.prototype.unstackPointAtIndex = function(setIdx, row) {
 394   var point = this.points[setIdx][row];
 395   // If the point is missing, no unstacking is necessary
 396   if (!point.yval) {
 397     return point;
 398   }
 399
 400   // Clone the point since we modify it
 401   var unstackedPoint = {};
 402   for (var pt in point) {
 403     unstackedPoint[pt] = point[pt];
 404   }
 405
 406   if (!this.attr_("stackedGraph")) {
 407     return unstackedPoint;
 408   }
 409
 410   // The unstacked yval is equal to the current yval minus the yval of the
 411   // next point at the same xval.
 412   if (setIdx == this.points.length - 1) {
 413     // We're the last series, so no unstacking is necessary.
 414     return unstackedPoint;
 415   }
 416
 417   var points = this.points[setIdx + 1];
 418   if (points[row].xval == point.xval &&  // should always be true?
 419       points[row].yval) {
 420     unstackedPoint.yval -= points[row].yval;
 421   }
 422
 423   return unstackedPoint;
 424 };