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: number, 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, chart labels, and other plug-ins.
  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.evaluate = function() {
 166   this._evaluateLimits();
 167   this._evaluateLineCharts();
 168   this._evaluateLineTicks();
 169   this._evaluateAnnotations();
 170 };
 171
 172 DygraphLayout.prototype._evaluateLimits = function() {
 173   var xlimits = this.dygraph_.xAxisRange();
 174   this.minxval = xlimits[0];
 175   this.maxxval = xlimits[1];
 176   var xrange = xlimits[1] - xlimits[0];
 177   this.xscale = (xrange !== 0 ? 1 / xrange : 1.0);
 178
 179   for (var i = 0; i < this.yAxes_.length; i++) {
 180     var axis = this.yAxes_[i];
 181     axis.minyval = axis.computedValueRange[0];
 182     axis.maxyval = axis.computedValueRange[1];
 183     axis.yrange = axis.maxyval - axis.minyval;
 184     axis.yscale = (axis.yrange !== 0 ? 1.0 / axis.yrange : 1.0);
 185
 186     if (axis.g.attr_("logscale")) {
 187       axis.ylogrange = Dygraph.log10(axis.maxyval) - Dygraph.log10(axis.minyval);
 188       axis.ylogscale = (axis.ylogrange !== 0 ? 1.0 / axis.ylogrange : 1.0);
 189       if (!isFinite(axis.ylogrange) || isNaN(axis.ylogrange)) {
 190         axis.g.error('axis ' + i + ' of graph at ' + axis.g +
 191             ' can\'t be displayed in log scale for range [' +
 192             axis.minyval + ' - ' + axis.maxyval + ']');
 193       }
 194     }
 195   }
 196 };
 197
 198 DygraphLayout._calcYNormal = function(axis, value, logscale) {
 199   if (logscale) {
 200     return 1.0 - ((Dygraph.log10(value) - Dygraph.log10(axis.minyval)) * axis.ylogscale);
 201   } else {
 202     return 1.0 - ((value - axis.minyval) * axis.yscale);
 203   }
 204 };
 205
 206 DygraphLayout.prototype._evaluateLineCharts = function() {
 207   var connectSeparated = this.attr_('connectSeparatedPoints');
 208
 209   // series index -> point index in series -> |point| structure
 210   this.points = new Array(this.datasets.length);
 211
 212   // TODO(bhs): these loops are a hot-spot for high-point-count charts. In fact,
 213   // on chrome+linux, they are 6 times more expensive than iterating through the
 214   // points and drawing the lines. The brunt of the cost comes from allocating
 215   // the |point| structures.
 216   var boundaryIdStart = this.dygraph_.getLeftBoundary_();
 217   for (var setIdx = 0; setIdx < this.datasets.length; setIdx++) {
 218     var dataset = this.datasets[setIdx];
 219     var setName = this.setNames[setIdx];
 220     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 221     // TODO (konigsberg): use optionsForAxis instead.
 222     var logscale = this.dygraph_.attributes_.getForSeries("logscale", setName);
 223
 224     // Preallocating the size of points reduces reallocations, and therefore,
 225     // calls to collect garbage.
 226     var seriesPoints = new Array(dataset.length);
 227
 228     for (var j = 0; j < dataset.length; j++) {
 229       var item = dataset[j];
 230       var xValue = DygraphLayout.parseFloat_(item[0]);
 231       var yValue = DygraphLayout.parseFloat_(item[1]);
 232
 233       // Range from 0-1 where 0 represents left and 1 represents right.
 234       var xNormal = (xValue - this.minxval) * this.xscale;
 235       // Range from 0-1 where 0 represents top and 1 represents bottom
 236       var yNormal = DygraphLayout._calcYNormal(axis, yValue, logscale);
 237
 238       // TODO(danvk): drop the point in this case, don't null it.
 239       // The nulls create complexity in DygraphCanvasRenderer._drawSeries.
 240       if (connectSeparated && item[1] === null) {
 241         yValue = null;
 242       }
 243       seriesPoints[j] = {
 244         x: xNormal,
 245         y: yNormal,
 246         xval: xValue,
 247         yval: yValue,
 248         name: setName,  // TODO(danvk): is this really necessary?
 249         idx: j + boundaryIdStart
 250       };
 251     }
 252
 253     this.points[setIdx] = seriesPoints;
 254   }
 255 };
 256
 257 /**
 258  * Optimized replacement for parseFloat, which was way too slow when almost
 259  * all values were type number, with few edge cases, none of which were strings.
 260  */
 261 DygraphLayout.parseFloat_ = function(val) {
 262   // parseFloat(null) is NaN
 263   if (val === null) {
 264     return NaN;
 265   }
 266
 267   // Assume it's a number or NaN. If it's something else, I'll be shocked.
 268   return val;
 269 };
 270
 271 DygraphLayout.prototype._evaluateLineTicks = function() {
 272   var i, tick, label, pos;
 273   this.xticks = [];
 274   for (i = 0; i < this.xTicks_.length; i++) {
 275     tick = this.xTicks_[i];
 276     label = tick.label;
 277     pos = this.xscale * (tick.v - this.minxval);
 278     if ((pos >= 0.0) && (pos <= 1.0)) {
 279       this.xticks.push([pos, label]);
 280     }
 281   }
 282
 283   this.yticks = [];
 284   for (i = 0; i < this.yAxes_.length; i++ ) {
 285     var axis = this.yAxes_[i];
 286     for (var j = 0; j < axis.ticks.length; j++) {
 287       tick = axis.ticks[j];
 288       label = tick.label;
 289       pos = this.dygraph_.toPercentYCoord(tick.v, i);
 290       if ((pos >= 0.0) && (pos <= 1.0)) {
 291         this.yticks.push([i, pos, label]);
 292       }
 293     }
 294   }
 295 };
 296
 297
 298 /**
 299  * Behaves the same way as PlotKit.Layout, but also copies the errors
 300  * @private
 301  */
 302 DygraphLayout.prototype.evaluateWithError = function() {
 303   this.evaluate();
 304   if (!(this.attr_('errorBars') || this.attr_('customBars'))) return;
 305
 306   // Copy over the error terms
 307   var i = 0;  // index in this.points
 308   for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 309     var points = this.points[setIdx];
 310     var j = 0;
 311     var dataset = this.datasets[setIdx];
 312     var setName = this.setNames[setIdx];
 313     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 314     // TODO (konigsberg): use optionsForAxis instead.
 315     var logscale = this.dygraph_.attributes_.getForSeries("logscale", setName);
 316
 317     for (j = 0; j < dataset.length; j++, i++) {
 318       var item = dataset[j];
 319       var xv = DygraphLayout.parseFloat_(item[0]);
 320       var yv = DygraphLayout.parseFloat_(item[1]);
 321
 322       if (xv == points[j].xval &&
 323           yv == points[j].yval) {
 324         var errorMinus = DygraphLayout.parseFloat_(item[2]);
 325         var errorPlus = DygraphLayout.parseFloat_(item[3]);
 326
 327         var yv_minus = yv - errorMinus;
 328         var yv_plus = yv + errorPlus;
 329         points[j].y_top = DygraphLayout._calcYNormal(axis, yv_minus, logscale);
 330         points[j].y_bottom = DygraphLayout._calcYNormal(axis, yv_plus, logscale);
 331       }
 332     }
 333   }
 334 };
 335
 336 DygraphLayout.prototype._evaluateAnnotations = function() {
 337   // Add the annotations to the point to which they belong.
 338   // Make a map from (setName, xval) to annotation for quick lookups.
 339   var i;
 340   var annotations = {};
 341   for (i = 0; i < this.annotations.length; i++) {
 342     var a = this.annotations[i];
 343     annotations[a.xval + "," + a.series] = a;
 344   }
 345
 346   this.annotated_points = [];
 347
 348   // Exit the function early if there are no annotations.
 349   if (!this.annotations || !this.annotations.length) {
 350     return;
 351   }
 352
 353   // TODO(antrob): loop through annotations not points.
 354   for (var setIdx = 0; setIdx < this.points.length; setIdx++) {
 355     var points = this.points[setIdx];
 356     for (i = 0; i < points.length; i++) {
 357       var p = points[i];
 358       var k = p.xval + "," + p.name;
 359       if (k in annotations) {
 360         p.annotation = annotations[k];
 361         this.annotated_points.push(p);
 362       }
 363     }
 364   }
 365 };
 366
 367 /**
 368  * Convenience function to remove all the data sets from a graph
 369  */
 370 DygraphLayout.prototype.removeAllDatasets = function() {
 371   delete this.datasets;
 372   delete this.setNames;
 373   delete this.setPointsLengths;
 374   delete this.setPointsOffsets;
 375   this.datasets = [];
 376   this.setNames = [];
 377   this.setPointsLengths = [];
 378   this.setPointsOffsets = [];
 379 };
 380
 381 /**
 382  * Return a copy of the point at the indicated index, with its yval unstacked.
 383  * @param int index of point in layout_.points
 384  */
 385 DygraphLayout.prototype.unstackPointAtIndex = function(setIdx, row) {
 386   var point = this.points[setIdx][row];
 387   // If the point is missing, no unstacking is necessary
 388   if (!Dygraph.isValidPoint(point)) {
 389     return point;
 390   }
 391
 392   // Clone the point since we modify it
 393   var unstackedPoint = {};
 394   for (var pt in point) {
 395     unstackedPoint[pt] = point[pt];
 396   }
 397
 398   if (!this.attr_("stackedGraph")) {
 399     return unstackedPoint;
 400   }
 401
 402   // The unstacked yval is equal to the current yval minus the yval of the
 403   // next point at the same xval.
 404   // We need to iterate over setIdx just in case some series have invalid values
 405   // at current row
 406   for(setIdx++; setIdx < this.points.length; setIdx++) {
 407     var nextPoint = this.points[setIdx][row];
 408     if (nextPoint.xval == point.xval &&  // should always be true?
 409         Dygraph.isValidPoint(nextPoint)) {
 410       unstackedPoint.yval -= nextPoint.yval;
 411       break; // stop at first valid point
 412     }
 413   }
 414
 415   return unstackedPoint;
 416 };