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 === undefined) {
 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   var xlimits = this.dygraph_.xAxisRange();
 172   this.minxval = xlimits[0];
 173   this.maxxval = xlimits[1];
 174   var xrange = xlimits[1] - xlimits[0];
 175   this.xscale = (xrange !== 0 ? 1 / xrange : 1.0);
 176
 177   for (var i = 0; i < this.yAxes_.length; i++) {
 178     var axis = this.yAxes_[i];
 179     axis.minyval = axis.computedValueRange[0];
 180     axis.maxyval = axis.computedValueRange[1];
 181     axis.yrange = axis.maxyval - axis.minyval;
 182     axis.yscale = (axis.yrange !== 0 ? 1.0 / axis.yrange : 1.0);
 183
 184     if (axis.g.attr_("logscale")) {
 185       axis.ylogrange = Dygraph.log10(axis.maxyval) - Dygraph.log10(axis.minyval);
 186       axis.ylogscale = (axis.ylogrange !== 0 ? 1.0 / axis.ylogrange : 1.0);
 187       if (!isFinite(axis.ylogrange) || isNaN(axis.ylogrange)) {
 188         axis.g.error('axis ' + i + ' of graph at ' + axis.g +
 189             ' can\'t be displayed in log scale for range [' +
 190             axis.minyval + ' - ' + axis.maxyval + ']');
 191       }
 192     }
 193   }
 194 };
 195
 196 DygraphLayout._calcYNormal = function(axis, value, logscale) {
 197   if (logscale) {
 198     return 1.0 - ((Dygraph.log10(value) - Dygraph.log10(axis.minyval)) * axis.ylogscale);
 199   } else {
 200     return 1.0 - ((value - axis.minyval) * axis.yscale);
 201   }
 202 };
 203
 204 DygraphLayout.prototype._evaluateLineCharts = function() {
 205   var connectSeparated = this.attr_('connectSeparatedPoints');
 206
 207   // series index -> point index in series -> |point| structure
 208   this.points = new Array(this.datasets.length);
 209
 210   // TODO(bhs): these loops are a hot-spot for high-point-count charts. In fact,
 211   // on chrome+linux, they are 6 times more expensive than iterating through the
 212   // points and drawing the lines. The brunt of the cost comes from allocating
 213   // the |point| structures.
 214   var boundaryIdStart = 0;
 215   if (this.dygraph_.boundaryIds_.length > 0) {
 216     boundaryIdStart = this.dygraph_.boundaryIds_[this.dygraph_.boundaryIds_.length-1][0]
 217   }
 218   for (var setIdx = 0; setIdx < this.datasets.length; setIdx++) {
 219     var dataset = this.datasets[setIdx];
 220     var setName = this.setNames[setIdx];
 221     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 222     // TODO (konigsberg): use optionsForAxis instead.
 223     var logscale = this.dygraph_.attributes_.getForSeries("logscale", setName);
 224
 225     // Preallocating the size of points reduces reallocations, and therefore,
 226     // calls to collect garbage.
 227     var seriesPoints = new Array(dataset.length);
 228
 229     for (var j = 0; j < dataset.length; j++) {
 230       var item = dataset[j];
 231       var xValue = DygraphLayout.parseFloat_(item[0]);
 232       var yValue = DygraphLayout.parseFloat_(item[1]);
 233
 234       // Range from 0-1 where 0 represents left and 1 represents right.
 235       var xNormal = (xValue - this.minxval) * this.xscale;
 236       // Range from 0-1 where 0 represents top and 1 represents bottom
 237       var yNormal = DygraphLayout._calcYNormal(axis, yValue, logscale);
 238
 239       // TODO(danvk): drop the point in this case, don't null it.
 240       // The nulls create complexity in DygraphCanvasRenderer._drawSeries.
 241       if (connectSeparated && item[1] === null) {
 242         yValue = null;
 243       }
 244       seriesPoints[j] = {
 245         x: xNormal,
 246         y: yNormal,
 247         xval: xValue,
 248         yval: yValue,
 249         name: setName,  // TODO(danvk): is this really necessary?
 250         idx: j + boundaryIdStart
 251       };
 252     }
 253
 254     this.points[setIdx] = seriesPoints;
 255   }
 256 };
 257
 258 /**
 259  * Optimized replacement for parseFloat, which was way too slow when almost
 260  * all values were type number, with few edge cases, none of which were strings.
 261  */
 262 DygraphLayout.parseFloat_ = function(val) {
 263   // parseFloat(null) is NaN
 264   if (val === null) {
 265     return NaN;
 266   }
 267
 268   // Assume it's a number or NaN. If it's something else, I'll be shocked.
 269   return val;
 270 };
 271
 272 DygraphLayout.prototype._evaluateLineTicks = function() {
 273   var i, tick, label, pos;
 274   this.xticks = [];
 275   for (i = 0; i < this.xTicks_.length; i++) {
 276     tick = this.xTicks_[i];
 277     label = tick.label;
 278     pos = this.xscale * (tick.v - this.minxval);
 279     if ((pos >= 0.0) && (pos <= 1.0)) {
 280       this.xticks.push([pos, label]);
 281     }
 282   }
 283
 284   this.yticks = [];
 285   for (i = 0; i < this.yAxes_.length; i++ ) {
 286     var axis = this.yAxes_[i];
 287     for (var j = 0; j < axis.ticks.length; j++) {
 288       tick = axis.ticks[j];
 289       label = tick.label;
 290       pos = this.dygraph_.toPercentYCoord(tick.v, i);
 291       if ((pos >= 0.0) && (pos <= 1.0)) {
 292         this.yticks.push([i, pos, label]);
 293       }
 294     }
 295   }
 296 };
 297
 298
 299 /**
 300  * Behaves the same way as PlotKit.Layout, but also copies the errors
 301  * @private
 302  */
 303 DygraphLayout.prototype.evaluateWithError = function() {
 304   this.evaluate();
 305   if (!(this.attr_('errorBars') || this.attr_('customBars'))) return;
 306
 307   // Copy over the error terms
 308   var i = 0;  // index in this.points
 309   for (var setIdx = 0; setIdx < this.datasets.length; ++setIdx) {
 310     var points = this.points[setIdx];
 311     var j = 0;
 312     var dataset = this.datasets[setIdx];
 313     var setName = this.setNames[setIdx];
 314     var axis = this.dygraph_.axisPropertiesForSeries(setName);
 315     // TODO (konigsberg): use optionsForAxis instead.
 316     var logscale = this.dygraph_.attributes_.getForSeries("logscale", setName);
 317
 318     for (j = 0; j < dataset.length; j++, i++) {
 319       var item = dataset[j];
 320       var xv = DygraphLayout.parseFloat_(item[0]);
 321       var yv = DygraphLayout.parseFloat_(item[1]);
 322
 323       if (xv == points[j].xval &&
 324           yv == points[j].yval) {
 325         var errorMinus = DygraphLayout.parseFloat_(item[2]);
 326         var errorPlus = DygraphLayout.parseFloat_(item[3]);
 327
 328         var yv_minus = yv - errorMinus;
 329         var yv_plus = yv + errorPlus;
 330         points[j].y_top = DygraphLayout._calcYNormal(axis, yv_minus, logscale);
 331         points[j].y_bottom = DygraphLayout._calcYNormal(axis, yv_plus, logscale);
 332       }
 333     }
 334   }
 335 };
 336
 337 DygraphLayout.prototype._evaluateAnnotations = function() {
 338   // Add the annotations to the point to which they belong.
 339   // Make a map from (setName, xval) to annotation for quick lookups.
 340   var i;
 341   var annotations = {};
 342   for (i = 0; i < this.annotations.length; i++) {
 343     var a = this.annotations[i];
 344     annotations[a.xval + "," + a.series] = a;
 345   }
 346
 347   this.annotated_points = [];
 348
 349   // Exit the function early if there are no annotations.
 350   if (!this.annotations || !this.annotations.length) {
 351     return;
 352   }
 353
 354   // TODO(antrob): loop through annotations not points.
 355   for (var setIdx = 0; setIdx < this.points.length; setIdx++) {
 356     var points = this.points[setIdx];
 357     for (i = 0; i < points.length; i++) {
 358       var p = points[i];
 359       var k = p.xval + "," + p.name;
 360       if (k in annotations) {
 361         p.annotation = annotations[k];
 362         this.annotated_points.push(p);
 363       }
 364     }
 365   }
 366 };
 367
 368 /**
 369  * Convenience function to remove all the data sets from a graph
 370  */
 371 DygraphLayout.prototype.removeAllDatasets = function() {
 372   delete this.datasets;
 373   delete this.setNames;
 374   delete this.setPointsLengths;
 375   delete this.setPointsOffsets;
 376   this.datasets = [];
 377   this.setNames = [];
 378   this.setPointsLengths = [];
 379   this.setPointsOffsets = [];
 380 };
 381
 382 /**
 383  * Return a copy of the point at the indicated index, with its yval unstacked.
 384  * @param int index of point in layout_.points
 385  */
 386 DygraphLayout.prototype.unstackPointAtIndex = function(setIdx, row) {
 387   var point = this.points[setIdx][row];
 388   // If the point is missing, no unstacking is necessary
 389   if (!Dygraph.isValidPoint(point)) {
 390     return point;
 391   }
 392
 393   // Clone the point since we modify it
 394   var unstackedPoint = {};
 395   for (var pt in point) {
 396     unstackedPoint[pt] = point[pt];
 397   }
 398
 399   if (!this.attr_("stackedGraph")) {
 400     return unstackedPoint;
 401   }
 402
 403   // The unstacked yval is equal to the current yval minus the yval of the
 404   // next point at the same xval.
 405   // We need to iterate over setIdx just in case some series have invalid values
 406   // at current row
 407   for(setIdx++; setIdx < this.points.length; setIdx++) {
 408     var nextPoint = this.points[setIdx][row];
 409     if (nextPoint.xval == point.xval &&  // should always be true?
 410         Dygraph.isValidPoint(nextPoint)) {
 411       unstackedPoint.yval -= nextPoint.yval;
 412       break; // stop at first valid point
 413     }
 414   }
 415
 416   return unstackedPoint;
 417 };