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 // NOTE: This should only be called by Dygraph.predraw_().
  62 DygraphLayout.prototype.computePlotArea = function() {
  63   var area = {
  64     // TODO(danvk): per-axis setting.
  65     x: 0,
  66     y: 0
  67   };
  68
  69   area.w = this.dygraph_.width_ - area.x - this.attr_('rightGap');
  70   area.h = this.dygraph_.height_;
  71
  72   // Let plugins reserve space.
  73   var e = {
  74     chart_div: this.dygraph_.graphDiv,
  75     reserveSpaceLeft: function(px) {
  76       var r = {
  77         x: area.x,
  78         y: area.y,
  79         w: px,
  80         h: area.h
  81       };
  82       area.x += px;
  83       area.w -= px;
  84       return r;
  85     },
  86     reserveSpaceRight: function(px) {
  87       var r = {
  88         x: area.x + area.w - px,
  89         y: area.y,
  90         w: px,
  91         h: area.h
  92       };
  93       area.w -= px;
  94       return r;
  95     },
  96     reserveSpaceTop: function(px) {
  97       var r = {
  98         x: area.x,
  99         y: area.y,
 100         w: area.w,
 101         h: px
 102       };
 103       area.y += px;
 104       area.h -= px;
 105       return r;
 106     },
 107     reserveSpaceBottom: function(px) {
 108       var r = {
 109         x: area.x,
 110         y: area.y + area.h - px,
 111         w: area.w,
 112         h: px
 113       };
 114       area.h -= px;
 115       return r;
 116     },
 117     chartRect: function() {
 118       return {x:area.x, y:area.y, w:area.w, h:area.h};
 119     }
 120   };
 121   this.dygraph_.cascadeEvents_('layout', e);
 122
 123   this.area_ = area;
 124 };
 125
 126 DygraphLayout.prototype.setAnnotations = function(ann) {
 127   // The Dygraph object's annotations aren't parsed. We parse them here and
 128   // save a copy. If there is no parser, then the user must be using raw format.
 129   this.annotations = [];
 130   var parse = this.attr_('xValueParser') || function(x) { return x; };
 131   for (var i = 0; i < ann.length; i++) {
 132     var a = {};
 133     if (!ann[i].xval && !ann[i].x) {
 134       this.dygraph_.error("Annotations must have an 'x' property");
 135       return;
 136     }
 137     if (ann[i].icon &&
 138         !(ann[i].hasOwnProperty('width') &&
 139           ann[i].hasOwnProperty('height'))) {
 140       this.dygraph_.error("Must set width and height when setting " +
 141                           "annotation.icon property");
 142       return;
 143     }
 144     Dygraph.update(a, ann[i]);
 145     if (!a.xval) a.xval = parse(a.x);
 146     this.annotations.push(a);
 147   }
 148 };
 149
 150 DygraphLayout.prototype.setXTicks = function(xTicks) {
 151   this.xTicks_ = xTicks;
 152 };
 153
 154 // TODO(danvk): add this to the Dygraph object's API or move it into Layout.
 155 DygraphLayout.prototype.setYAxes = function (yAxes) {
 156   this.yAxes_ = yAxes;
 157 };
 158
 159 DygraphLayout.prototype.setDateWindow = function(dateWindow) {
 160   this.dateWindow_ = dateWindow;
 161 };
 162
 163 DygraphLayout.prototype.evaluate = function() {
 164   this._evaluateLimits();
 165   this._evaluateLineCharts();
 166   this._evaluateLineTicks();
 167   this._evaluateAnnotations();
 168 };
 169
 170 DygraphLayout.prototype._evaluateLimits = function() {
 171   this.minxval = this.maxxval = null;
 172   if (this.dateWindow_) {
 173     this.minxval = this.dateWindow_[0];
 174     this.maxxval = this.dateWindow_[1];
 175   } else {
 176     for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 177       var series = this.datasets[setIdx];
 178       if (series.length > 1) {
 179         var x1 = series[0][0];
 180         if (!this.minxval || x1 < this.minxval) this.minxval = x1;
 181
 182         var x2 = series[series.length - 1][0];
 183         if (!this.maxxval || x2 > this.maxxval) this.maxxval = x2;
 184       }
 185     }
 186   }
 187   this.xrange = this.maxxval - this.minxval;
 188   this.xscale = (this.xrange !== 0 ? 1/this.xrange : 1.0);
 189
 190   for (var i = 0; i < this.yAxes_.length; i++) {
 191     var axis = this.yAxes_[i];
 192     axis.minyval = axis.computedValueRange[0];
 193     axis.maxyval = axis.computedValueRange[1];
 194     axis.yrange = axis.maxyval - axis.minyval;
 195     axis.yscale = (axis.yrange !== 0 ? 1.0 / axis.yrange : 1.0);
 196
 197     if (axis.g.attr_("logscale")) {
 198       axis.ylogrange = Dygraph.log10(axis.maxyval) - Dygraph.log10(axis.minyval);
 199       axis.ylogscale = (axis.ylogrange !== 0 ? 1.0 / axis.ylogrange : 1.0);
 200       if (!isFinite(axis.ylogrange) || isNaN(axis.ylogrange)) {
 201         axis.g.error('axis ' + i + ' of graph at ' + axis.g +
 202             ' can\'t be displayed in log scale for range [' +
 203             axis.minyval + ' - ' + axis.maxyval + ']');
 204       }
 205     }
 206   }
 207 };
 208
 209 DygraphLayout._calcYNormal = function(axis, value, logscale) {
 210   if (logscale) {
 211     return 1.0 - ((Dygraph.log10(value) - Dygraph.log10(axis.minyval)) * axis.ylogscale);
 212   } else {
 213     return 1.0 - ((value - axis.minyval) * axis.yscale);
 214   }
 215 };
 216
 217 DygraphLayout.prototype._evaluateLineCharts = function() {
 218   var connectSeparated = this.attr_('connectSeparatedPoints');
 219
 220   // series index -> point index in series -> |point| structure
 221   this.points = new Array(this.datasets.length);
 222
 223   // TODO(bhs): these loops are a hot-spot for high-point-count charts. In fact,
 224   // on chrome+linux, they are 6 times more expensive than iterating through the
 225   // points and drawing the lines. The brunt of the cost comes from allocating
 226   // the |point| structures.
 227   for (var setIdx = 0; setIdx < this.datasets.length; setIdx++) {
 228     var dataset = this.datasets[setIdx];
 229     var setName = this.setNames[setIdx];
 230     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 231     // TODO (konigsberg): use optionsForAxis instead.
 232     var logscale = this.dygraph_.attributes_.getForSeries("logscale", setName);
 233
 234     // Preallocating the size of points reduces reallocations, and therefore,
 235     // calls to collect garbage.
 236     var seriesPoints = new Array(dataset.length);
 237
 238     for (var j = 0; j < dataset.length; j++) {
 239       var item = dataset[j];
 240       var xValue = DygraphLayout.parseFloat_(item[0]);
 241       var yValue = DygraphLayout.parseFloat_(item[1]);
 242
 243       // Range from 0-1 where 0 represents left and 1 represents right.
 244       var xNormal = (xValue - this.minxval) * this.xscale;
 245       // Range from 0-1 where 0 represents top and 1 represents bottom
 246       var yNormal = DygraphLayout._calcYNormal(axis, yValue, logscale);
 247
 248       // TODO(danvk): drop the point in this case, don't null it.
 249       // The nulls create complexity in DygraphCanvasRenderer._drawSeries.
 250       if (connectSeparated && item[1] === null) {
 251         yValue = null;
 252       }
 253       seriesPoints[j] = {
 254         x: xNormal,
 255         y: yNormal,
 256         xval: xValue,
 257         yval: yValue,
 258         name: setName  // TODO(danvk): is this really necessary?
 259       };
 260     }
 261
 262     this.points[setIdx] = seriesPoints;
 263   }
 264 };
 265
 266 /**
 267  * Optimized replacement for parseFloat, which was way too slow when almost
 268  * all values were type number, with few edge cases, none of which were strings.
 269  */
 270 DygraphLayout.parseFloat_ = function(val) {
 271   // parseFloat(null) is NaN
 272   if (val === null) {
 273     return NaN;
 274   }
 275
 276   // Assume it's a number or NaN. If it's something else, I'll be shocked.
 277   return val;
 278 };
 279
 280 DygraphLayout.prototype._evaluateLineTicks = function() {
 281   var i, tick, label, pos;
 282   this.xticks = [];
 283   for (i = 0; i < this.xTicks_.length; i++) {
 284     tick = this.xTicks_[i];
 285     label = tick.label;
 286     pos = this.xscale * (tick.v - this.minxval);
 287     if ((pos >= 0.0) && (pos <= 1.0)) {
 288       this.xticks.push([pos, label]);
 289     }
 290   }
 291
 292   this.yticks = [];
 293   for (i = 0; i < this.yAxes_.length; i++ ) {
 294     var axis = this.yAxes_[i];
 295     for (var j = 0; j < axis.ticks.length; j++) {
 296       tick = axis.ticks[j];
 297       label = tick.label;
 298       pos = this.dygraph_.toPercentYCoord(tick.v, i);
 299       if ((pos >= 0.0) && (pos <= 1.0)) {
 300         this.yticks.push([i, pos, label]);
 301       }
 302     }
 303   }
 304 };
 305
 306
 307 /**
 308  * Behaves the same way as PlotKit.Layout, but also copies the errors
 309  * @private
 310  */
 311 DygraphLayout.prototype.evaluateWithError = function() {
 312   this.evaluate();
 313   if (!(this.attr_('errorBars') || this.attr_('customBars'))) return;
 314
 315   // Copy over the error terms
 316   var i = 0;  // index in this.points
 317   for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 318     var points = this.points[setIdx];
 319     var j = 0;
 320     var dataset = this.datasets[setIdx];
 321     var setName = this.setNames[setIdx];
 322     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 323     // TODO (konigsberg): use optionsForAxis instead.
 324     var logscale = this.dygraph_.attributes_.getForSeries("logscale", setName);
 325
 326     for (j = 0; j < dataset.length; j++, i++) {
 327       var item = dataset[j];
 328       var xv = DygraphLayout.parseFloat_(item[0]);
 329       var yv = DygraphLayout.parseFloat_(item[1]);
 330
 331       if (xv == points[j].xval &&
 332           yv == points[j].yval) {
 333         var errorMinus = DygraphLayout.parseFloat_(item[2]);
 334         var errorPlus = DygraphLayout.parseFloat_(item[3]);
 335
 336         var yv_minus = yv - errorMinus;
 337         var yv_plus = yv + errorPlus;
 338         points[j].y_top = DygraphLayout._calcYNormal(axis, yv_minus, logscale);
 339         points[j].y_bottom = DygraphLayout._calcYNormal(axis, yv_plus, logscale);
 340       }
 341     }
 342   }
 343 };
 344
 345 DygraphLayout.prototype._evaluateAnnotations = function() {
 346   // Add the annotations to the point to which they belong.
 347   // Make a map from (setName, xval) to annotation for quick lookups.
 348   var i;
 349   var annotations = {};
 350   for (i = 0; i < this.annotations.length; i++) {
 351     var a = this.annotations[i];
 352     annotations[a.xval + "," + a.series] = a;
 353   }
 354
 355   this.annotated_points = [];
 356
 357   // Exit the function early if there are no annotations.
 358   if (!this.annotations || !this.annotations.length) {
 359     return;
 360   }
 361
 362   // TODO(antrob): loop through annotations not points.
 363   for (var setIdx = 0; setIdx < this.points.length; setIdx++) {
 364     var points = this.points[setIdx];
 365     for (i = 0; i < points.length; i++) {
 366       var p = points[i];
 367       var k = p.xval + "," + p.name;
 368       if (k in annotations) {
 369         p.annotation = annotations[k];
 370         this.annotated_points.push(p);
 371       }
 372     }
 373   }
 374 };
 375
 376 /**
 377  * Convenience function to remove all the data sets from a graph
 378  */
 379 DygraphLayout.prototype.removeAllDatasets = function() {
 380   delete this.datasets;
 381   delete this.setNames;
 382   delete this.setPointsLengths;
 383   delete this.setPointsOffsets;
 384   this.datasets = [];
 385   this.setNames = [];
 386   this.setPointsLengths = [];
 387   this.setPointsOffsets = [];
 388 };
 389
 390 /**
 391  * Return a copy of the point at the indicated index, with its yval unstacked.
 392  * @param int index of point in layout_.points
 393  */
 394 DygraphLayout.prototype.unstackPointAtIndex = function(setIdx, row) {
 395   var point = this.points[setIdx][row];
 396   // If the point is missing, no unstacking is necessary
 397   if (!point.yval) {
 398     return point;
 399   }
 400
 401   // Clone the point since we modify it
 402   var unstackedPoint = {};
 403   for (var pt in point) {
 404     unstackedPoint[pt] = point[pt];
 405   }
 406
 407   if (!this.attr_("stackedGraph")) {
 408     return unstackedPoint;
 409   }
 410
 411   // The unstacked yval is equal to the current yval minus the yval of the
 412   // next point at the same xval.
 413   if (setIdx == this.points.length - 1) {
 414     // We're the last series, so no unstacking is necessary.
 415     return unstackedPoint;
 416   }
 417
 418   var points = this.points[setIdx + 1];
 419   if (points[row].xval == point.xval &&  // should always be true?
 420       points[row].yval) {
 421     unstackedPoint.yval -= points[row].yval;
 422   }
 423
 424   return unstackedPoint;
 425 };