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 /**
  56  * Returns the box which the chart should be drawn in. This is the canvas's
  57  * box, less space needed for the axis and chart labels.
  58  *
  59  * @return {{ x : numer, y : number, w : number, h : number }}
  60  */
  61 DygraphLayout.prototype.getPlotArea = function() {
  62   return this.area_;
  63 };
  64
  65 // Compute the box which the chart should be drawn in. This is the canvas's
  66 // box, less space needed for axis and chart labels.
  67 // NOTE: This should only be called by Dygraph.predraw_().
  68 DygraphLayout.prototype.computePlotArea = function() {
  69   var area = {
  70     // TODO(danvk): per-axis setting.
  71     x: 0,
  72     y: 0
  73   };
  74
  75   area.w = this.dygraph_.width_ - area.x - this.attr_('rightGap');
  76   area.h = this.dygraph_.height_;
  77
  78   // Let plugins reserve space.
  79   var e = {
  80     chart_div: this.dygraph_.graphDiv,
  81     reserveSpaceLeft: function(px) {
  82       var r = {
  83         x: area.x,
  84         y: area.y,
  85         w: px,
  86         h: area.h
  87       };
  88       area.x += px;
  89       area.w -= px;
  90       return r;
  91     },
  92     reserveSpaceRight: function(px) {
  93       var r = {
  94         x: area.x + area.w - px,
  95         y: area.y,
  96         w: px,
  97         h: area.h
  98       };
  99       area.w -= px;
 100       return r;
 101     },
 102     reserveSpaceTop: function(px) {
 103       var r = {
 104         x: area.x,
 105         y: area.y,
 106         w: area.w,
 107         h: px
 108       };
 109       area.y += px;
 110       area.h -= px;
 111       return r;
 112     },
 113     reserveSpaceBottom: function(px) {
 114       var r = {
 115         x: area.x,
 116         y: area.y + area.h - px,
 117         w: area.w,
 118         h: px
 119       };
 120       area.h -= px;
 121       return r;
 122     },
 123     chartRect: function() {
 124       return {x:area.x, y:area.y, w:area.w, h:area.h};
 125     }
 126   };
 127   this.dygraph_.cascadeEvents_('layout', e);
 128
 129   this.area_ = area;
 130 };
 131
 132 DygraphLayout.prototype.setAnnotations = function(ann) {
 133   // The Dygraph object's annotations aren't parsed. We parse them here and
 134   // save a copy. If there is no parser, then the user must be using raw format.
 135   this.annotations = [];
 136   var parse = this.attr_('xValueParser') || function(x) { return x; };
 137   for (var i = 0; i < ann.length; i++) {
 138     var a = {};
 139     if (!ann[i].xval && ann[i].x === undefined) {
 140       this.dygraph_.error("Annotations must have an 'x' property");
 141       return;
 142     }
 143     if (ann[i].icon &&
 144         !(ann[i].hasOwnProperty('width') &&
 145           ann[i].hasOwnProperty('height'))) {
 146       this.dygraph_.error("Must set width and height when setting " +
 147                           "annotation.icon property");
 148       return;
 149     }
 150     Dygraph.update(a, ann[i]);
 151     if (!a.xval) a.xval = parse(a.x);
 152     this.annotations.push(a);
 153   }
 154 };
 155
 156 DygraphLayout.prototype.setXTicks = function(xTicks) {
 157   this.xTicks_ = xTicks;
 158 };
 159
 160 // TODO(danvk): add this to the Dygraph object's API or move it into Layout.
 161 DygraphLayout.prototype.setYAxes = function (yAxes) {
 162   this.yAxes_ = yAxes;
 163 };
 164
 165 DygraphLayout.prototype.setDateWindow = function(dateWindow) {
 166   this.dateWindow_ = dateWindow;
 167 };
 168
 169 DygraphLayout.prototype.evaluate = function() {
 170   this._evaluateLimits();
 171   this._evaluateLineCharts();
 172   this._evaluateLineTicks();
 173   this._evaluateAnnotations();
 174 };
 175
 176 DygraphLayout.prototype._evaluateLimits = function() {
 177   var xlimits = this.dygraph_.xAxisRange();
 178   this.minxval = xlimits[0];
 179   this.maxxval = xlimits[1];
 180   var xrange = xlimits[1] - xlimits[0];
 181   this.xscale = (xrange !== 0 ? 1 / xrange : 1.0);
 182
 183   for (var i = 0; i < this.yAxes_.length; i++) {
 184     var axis = this.yAxes_[i];
 185     axis.minyval = axis.computedValueRange[0];
 186     axis.maxyval = axis.computedValueRange[1];
 187     axis.yrange = axis.maxyval - axis.minyval;
 188     axis.yscale = (axis.yrange !== 0 ? 1.0 / axis.yrange : 1.0);
 189
 190     if (axis.g.attr_("logscale")) {
 191       axis.ylogrange = Dygraph.log10(axis.maxyval) - Dygraph.log10(axis.minyval);
 192       axis.ylogscale = (axis.ylogrange !== 0 ? 1.0 / axis.ylogrange : 1.0);
 193       if (!isFinite(axis.ylogrange) || isNaN(axis.ylogrange)) {
 194         axis.g.error('axis ' + i + ' of graph at ' + axis.g +
 195             ' can\'t be displayed in log scale for range [' +
 196             axis.minyval + ' - ' + axis.maxyval + ']');
 197       }
 198     }
 199   }
 200 };
 201
 202 DygraphLayout._calcYNormal = function(axis, value, logscale) {
 203   if (logscale) {
 204     return 1.0 - ((Dygraph.log10(value) - Dygraph.log10(axis.minyval)) * axis.ylogscale);
 205   } else {
 206     return 1.0 - ((value - axis.minyval) * axis.yscale);
 207   }
 208 };
 209
 210 DygraphLayout.prototype._evaluateLineCharts = function() {
 211   var connectSeparated = this.attr_('connectSeparatedPoints');
 212
 213   // series index -> point index in series -> |point| structure
 214   this.points = new Array(this.datasets.length);
 215
 216   // TODO(bhs): these loops are a hot-spot for high-point-count charts. In fact,
 217   // on chrome+linux, they are 6 times more expensive than iterating through the
 218   // points and drawing the lines. The brunt of the cost comes from allocating
 219   // the |point| structures.
 220   for (var setIdx = 0; setIdx < this.datasets.length; setIdx++) {
 221     var dataset = this.datasets[setIdx];
 222     var setName = this.setNames[setIdx];
 223     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 224     // TODO (konigsberg): use optionsForAxis instead.
 225     var logscale = this.dygraph_.attributes_.getForSeries("logscale", setName);
 226
 227     // Preallocating the size of points reduces reallocations, and therefore,
 228     // calls to collect garbage.
 229     var seriesPoints = new Array(dataset.length);
 230
 231     for (var j = 0; j < dataset.length; j++) {
 232       var item = dataset[j];
 233       var xValue = DygraphLayout.parseFloat_(item[0]);
 234       var yValue = DygraphLayout.parseFloat_(item[1]);
 235
 236       // Range from 0-1 where 0 represents left and 1 represents right.
 237       var xNormal = (xValue - this.minxval) * this.xscale;
 238       // Range from 0-1 where 0 represents top and 1 represents bottom
 239       var yNormal = DygraphLayout._calcYNormal(axis, yValue, logscale);
 240
 241       // TODO(danvk): drop the point in this case, don't null it.
 242       // The nulls create complexity in DygraphCanvasRenderer._drawSeries.
 243       if (connectSeparated && item[1] === null) {
 244         yValue = null;
 245       }
 246       seriesPoints[j] = {
 247         x: xNormal,
 248         y: yNormal,
 249         xval: xValue,
 250         yval: yValue,
 251         name: setName  // TODO(danvk): is this really necessary?
 252       };
 253     }
 254
 255     this.points[setIdx] = seriesPoints;
 256   }
 257 };
 258
 259 /**
 260  * Optimized replacement for parseFloat, which was way too slow when almost
 261  * all values were type number, with few edge cases, none of which were strings.
 262  */
 263 DygraphLayout.parseFloat_ = function(val) {
 264   // parseFloat(null) is NaN
 265   if (val === null) {
 266     return NaN;
 267   }
 268
 269   // Assume it's a number or NaN. If it's something else, I'll be shocked.
 270   return val;
 271 };
 272
 273 DygraphLayout.prototype._evaluateLineTicks = function() {
 274   var i, tick, label, pos;
 275   this.xticks = [];
 276   for (i = 0; i < this.xTicks_.length; i++) {
 277     tick = this.xTicks_[i];
 278     label = tick.label;
 279     pos = this.xscale * (tick.v - this.minxval);
 280     if ((pos >= 0.0) && (pos <= 1.0)) {
 281       this.xticks.push([pos, label]);
 282     }
 283   }
 284
 285   this.yticks = [];
 286   for (i = 0; i < this.yAxes_.length; i++ ) {
 287     var axis = this.yAxes_[i];
 288     for (var j = 0; j < axis.ticks.length; j++) {
 289       tick = axis.ticks[j];
 290       label = tick.label;
 291       pos = this.dygraph_.toPercentYCoord(tick.v, i);
 292       if ((pos >= 0.0) && (pos <= 1.0)) {
 293         this.yticks.push([i, pos, label]);
 294       }
 295     }
 296   }
 297 };
 298
 299
 300 /**
 301  * Behaves the same way as PlotKit.Layout, but also copies the errors
 302  * @private
 303  */
 304 DygraphLayout.prototype.evaluateWithError = function() {
 305   this.evaluate();
 306   if (!(this.attr_('errorBars') || this.attr_('customBars'))) return;
 307
 308   // Copy over the error terms
 309   var i = 0;  // index in this.points
 310   for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 311     var points = this.points[setIdx];
 312     var j = 0;
 313     var dataset = this.datasets[setIdx];
 314     var setName = this.setNames[setIdx];
 315     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 316     // TODO (konigsberg): use optionsForAxis instead.
 317     var logscale = this.dygraph_.attributes_.getForSeries("logscale", setName);
 318
 319     for (j = 0; j < dataset.length; j++, i++) {
 320       var item = dataset[j];
 321       var xv = DygraphLayout.parseFloat_(item[0]);
 322       var yv = DygraphLayout.parseFloat_(item[1]);
 323
 324       if (xv == points[j].xval &&
 325           yv == points[j].yval) {
 326         var errorMinus = DygraphLayout.parseFloat_(item[2]);
 327         var errorPlus = DygraphLayout.parseFloat_(item[3]);
 328
 329         var yv_minus = yv - errorMinus;
 330         var yv_plus = yv + errorPlus;
 331         points[j].y_top = DygraphLayout._calcYNormal(axis, yv_minus, logscale);
 332         points[j].y_bottom = DygraphLayout._calcYNormal(axis, yv_plus, logscale);
 333       }
 334     }
 335   }
 336 };
 337
 338 DygraphLayout.prototype._evaluateAnnotations = function() {
 339   // Add the annotations to the point to which they belong.
 340   // Make a map from (setName, xval) to annotation for quick lookups.
 341   var i;
 342   var annotations = {};
 343   for (i = 0; i < this.annotations.length; i++) {
 344     var a = this.annotations[i];
 345     annotations[a.xval + "," + a.series] = a;
 346   }
 347
 348   this.annotated_points = [];
 349
 350   // Exit the function early if there are no annotations.
 351   if (!this.annotations || !this.annotations.length) {
 352     return;
 353   }
 354
 355   // TODO(antrob): loop through annotations not points.
 356   for (var setIdx = 0; setIdx < this.points.length; setIdx++) {
 357     var points = this.points[setIdx];
 358     for (i = 0; i < points.length; i++) {
 359       var p = points[i];
 360       var k = p.xval + "," + p.name;
 361       if (k in annotations) {
 362         p.annotation = annotations[k];
 363         this.annotated_points.push(p);
 364       }
 365     }
 366   }
 367 };
 368
 369 /**
 370  * Convenience function to remove all the data sets from a graph
 371  */
 372 DygraphLayout.prototype.removeAllDatasets = function() {
 373   delete this.datasets;
 374   delete this.setNames;
 375   delete this.setPointsLengths;
 376   delete this.setPointsOffsets;
 377   this.datasets = [];
 378   this.setNames = [];
 379   this.setPointsLengths = [];
 380   this.setPointsOffsets = [];
 381 };
 382
 383 /**
 384  * Return a copy of the point at the indicated index, with its yval unstacked.
 385  * @param int index of point in layout_.points
 386  */
 387 DygraphLayout.prototype.unstackPointAtIndex = function(setIdx, row) {
 388   var point = this.points[setIdx][row];
 389   // If the point is missing, no unstacking is necessary
 390   if (!Dygraph.isValidPoint(point)) {
 391     return point;
 392   }
 393
 394   // Clone the point since we modify it
 395   var unstackedPoint = {};
 396   for (var pt in point) {
 397     unstackedPoint[pt] = point[pt];
 398   }
 399
 400   if (!this.attr_("stackedGraph")) {
 401     return unstackedPoint;
 402   }
 403
 404   // The unstacked yval is equal to the current yval minus the yval of the
 405   // next point at the same xval.
 406   // We need to iterate over setIdx just in case some series have invalid values
 407   // at current row
 408   for(setIdx++; setIdx < this.points.length; setIdx++) {
 409     var nextPoint = this.points[setIdx][row];
 410     if (nextPoint.xval == point.xval &&  // should always be true?
 411         Dygraph.isValidPoint(nextPoint)) {
 412       unstackedPoint.yval -= nextPoint.yval;
 413       break; // stop at first valid point
 414     }
 415   }
 416
 417   return unstackedPoint;
 418 };