dygraph-canvas.js

   1 // Copyright 2006 Dan Vanderkam (danvdk@gmail.com)
   2 // All Rights Reserved.
   3
   4 /**
   5  * @fileoverview Based on PlotKit, but modified to meet the needs of dygraphs.
   6  * In particular, support for:
   7  * - grid overlays
   8  * - error bars
   9  * - dygraphs attribute system
  10  */
  11
  12 /**
  13  * Creates a new DygraphLayout object.
  14  * @param {Object} options Options for PlotKit.Layout
  15  * @return {Object} The DygraphLayout object
  16  */
  17 DygraphLayout = function(dygraph, options) {
  18   this.dygraph_ = dygraph;
  19   this.options = {};  // TODO(danvk): remove, use attr_ instead.
  20   Dygraph.update(this.options, options ? options : {});
  21   this.datasets = new Array();
  22   this.annotations = new Array()
  23 };
  24
  25 DygraphLayout.prototype.attr_ = function(name) {
  26   return this.dygraph_.attr_(name);
  27 };
  28
  29 DygraphLayout.prototype.addDataset = function(setname, set_xy) {
  30   this.datasets[setname] = set_xy;
  31 };
  32
  33 DygraphLayout.prototype.setAnnotations = function(ann) {
  34   // The Dygraph object's annotations aren't parsed. We parse them here and
  35   // save a copy.
  36   this.annotations = [];
  37   var parse = this.attr_('xValueParser');
  38   for (var i = 0; i < ann.length; i++) {
  39     var a = {};
  40     if (!ann[i].xval && !ann[i].x) {
  41       this.dygraph_.error("Annotations must have an 'x' property");
  42       return;
  43     }
  44     if (ann[i].icon &&
  45         !(ann[i].hasOwnProperty('width') &&
  46           ann[i].hasOwnProperty('height'))) {
  47       this.dygraph_.error("Must set width and height when setting " +
  48                           "annotation.icon property");
  49       return;
  50     }
  51     Dygraph.update(a, ann[i]);
  52     if (!a.xval) a.xval = parse(a.x);
  53     this.annotations.push(a);
  54   }
  55 };
  56
  57 DygraphLayout.prototype.evaluate = function() {
  58   this._evaluateLimits();
  59   this._evaluateLineCharts();
  60   this._evaluateLineTicks();
  61   this._evaluateAnnotations();
  62 };
  63
  64 DygraphLayout.prototype._evaluateLimits = function() {
  65   this.minxval = this.maxxval = null;
  66   if (this.options.dateWindow) {
  67     this.minxval = this.options.dateWindow[0];
  68     this.maxxval = this.options.dateWindow[1];
  69   } else {
  70     for (var name in this.datasets) {
  71       if (!this.datasets.hasOwnProperty(name)) continue;
  72       var series = this.datasets[name];
  73       if (series.length > 1) {
  74         var x1 = series[0][0];
  75         if (!this.minxval || x1 < this.minxval) this.minxval = x1;
  76
  77         var x2 = series[series.length - 1][0];
  78         if (!this.maxxval || x2 > this.maxxval) this.maxxval = x2;
  79       }
  80     }
  81   }
  82   this.xrange = this.maxxval - this.minxval;
  83   this.xscale = (this.xrange != 0 ? 1/this.xrange : 1.0);
  84
  85   for (var i = 0; i < this.options.yAxes.length; i++) {
  86     var axis = this.options.yAxes[i];
  87     axis.minyval = axis.computedValueRange[0];
  88     axis.maxyval = axis.computedValueRange[1];
  89     axis.yrange = axis.maxyval - axis.minyval;
  90     axis.yscale = (axis.yrange != 0 ? 1.0 / axis.yrange : 1.0);
  91   }
  92 };
  93
  94 DygraphLayout.prototype._evaluateLineCharts = function() {
  95   // add all the rects
  96   this.points = new Array();
  97   for (var setName in this.datasets) {
  98     if (!this.datasets.hasOwnProperty(setName)) continue;
  99
 100     var dataset = this.datasets[setName];
 101     var axis = this.options.yAxes[this.options.seriesToAxisMap[setName]];
 102
 103     for (var j = 0; j < dataset.length; j++) {
 104       var item = dataset[j];
 105       var point = {
 106         // TODO(danvk): here
 107         x: ((parseFloat(item[0]) - this.minxval) * this.xscale),
 108         y: 1.0 - ((parseFloat(item[1]) - axis.minyval) * axis.yscale),
 109         xval: parseFloat(item[0]),
 110         yval: parseFloat(item[1]),
 111         name: setName
 112       };
 113
 114       // limit the x, y values so they do not overdraw
 115       if (point.y <= 0.0) {
 116         point.y = 0.0;
 117       }
 118       if (point.y >= 1.0) {
 119         point.y = 1.0;
 120       }
 121       this.points.push(point);
 122     }
 123   }
 124 };
 125
 126 DygraphLayout.prototype._evaluateLineTicks = function() {
 127   this.xticks = new Array();
 128   for (var i = 0; i < this.options.xTicks.length; i++) {
 129     var tick = this.options.xTicks[i];
 130     var label = tick.label;
 131     var pos = this.xscale * (tick.v - this.minxval);
 132     if ((pos >= 0.0) && (pos <= 1.0)) {
 133       this.xticks.push([pos, label]);
 134     }
 135   }
 136
 137   this.yticks = new Array();
 138   for (var i = 0; i < this.options.yAxes.length; i++ ) {
 139     var axis = this.options.yAxes[i];
 140     for (var j = 0; j < axis.ticks.length; j++) {
 141       var tick = axis.ticks[j];
 142       var label = tick.label;
 143       var pos = 1.0 - (axis.yscale * (tick.v - axis.minyval));
 144       if ((pos >= 0.0) && (pos <= 1.0)) {
 145         this.yticks.push([i, pos, label]);
 146       }
 147     }
 148   }
 149 };
 150
 151
 152 /**
 153  * Behaves the same way as PlotKit.Layout, but also copies the errors
 154  * @private
 155  */
 156 DygraphLayout.prototype.evaluateWithError = function() {
 157   this.evaluate();
 158   if (!this.options.errorBars) return;
 159
 160   // Copy over the error terms
 161   var i = 0; // index in this.points
 162   for (var setName in this.datasets) {
 163     if (!this.datasets.hasOwnProperty(setName)) continue;
 164     var j = 0;
 165     var dataset = this.datasets[setName];
 166     for (var j = 0; j < dataset.length; j++, i++) {
 167       var item = dataset[j];
 168       var xv = parseFloat(item[0]);
 169       var yv = parseFloat(item[1]);
 170
 171       if (xv == this.points[i].xval &&
 172           yv == this.points[i].yval) {
 173         this.points[i].errorMinus = parseFloat(item[2]);
 174         this.points[i].errorPlus = parseFloat(item[3]);
 175       }
 176     }
 177   }
 178 };
 179
 180 DygraphLayout.prototype._evaluateAnnotations = function() {
 181   // Add the annotations to the point to which they belong.
 182   // Make a map from (setName, xval) to annotation for quick lookups.
 183   var annotations = {};
 184   for (var i = 0; i < this.annotations.length; i++) {
 185     var a = this.annotations[i];
 186     annotations[a.xval + "," + a.series] = a;
 187   }
 188
 189   this.annotated_points = [];
 190   for (var i = 0; i < this.points.length; i++) {
 191     var p = this.points[i];
 192     var k = p.xval + "," + p.name;
 193     if (k in annotations) {
 194       p.annotation = annotations[k];
 195       this.annotated_points.push(p);
 196     }
 197   }
 198 };
 199
 200 /**
 201  * Convenience function to remove all the data sets from a graph
 202  */
 203 DygraphLayout.prototype.removeAllDatasets = function() {
 204   delete this.datasets;
 205   this.datasets = new Array();
 206 };
 207
 208 /**
 209  * Change the values of various layout options
 210  * @param {Object} new_options an associative array of new properties
 211  */
 212 DygraphLayout.prototype.updateOptions = function(new_options) {
 213   Dygraph.update(this.options, new_options ? new_options : {});
 214 };
 215
 216 /**
 217  * Return a copy of the point at the indicated index, with its yval unstacked.
 218  * @param int index of point in layout_.points
 219  */
 220 DygraphLayout.prototype.unstackPointAtIndex = function(idx) {
 221   var point = this.points[idx];
 222
 223   // Clone the point since we modify it
 224   var unstackedPoint = {};
 225   for (var i in point) {
 226     unstackedPoint[i] = point[i];
 227   }
 228
 229   if (!this.attr_("stackedGraph")) {
 230     return unstackedPoint;
 231   }
 232
 233   // The unstacked yval is equal to the current yval minus the yval of the
 234   // next point at the same xval.
 235   for (var i = idx+1; i < this.points.length; i++) {
 236     if (this.points[i].xval == point.xval) {
 237       unstackedPoint.yval -= this.points[i].yval;
 238       break;
 239     }
 240   }
 241
 242   return unstackedPoint;
 243 }
 244
 245 // Subclass PlotKit.CanvasRenderer to add:
 246 // 1. X/Y grid overlay
 247 // 2. Ability to draw error bars (if required)
 248
 249 /**
 250  * Sets some PlotKit.CanvasRenderer options
 251  * @param {Object} element The canvas to attach to
 252  * @param {Layout} layout The DygraphLayout object for this graph.
 253  * @param {Object} options Options to pass on to CanvasRenderer
 254  */
 255 DygraphCanvasRenderer = function(dygraph, element, layout, options) {
 256   // TODO(danvk): remove options, just use dygraph.attr_.
 257   this.dygraph_ = dygraph;
 258
 259   // default options
 260   this.options = {
 261     "strokeWidth": 0.5,
 262     "drawXAxis": true,
 263     "drawYAxis": true,
 264     "axisLineColor": "black",
 265     "axisLineWidth": 0.5,
 266     "axisTickSize": 3,
 267     "axisLabelColor": "black",
 268     "axisLabelFont": "Arial",
 269     "axisLabelFontSize": 9,
 270     "axisLabelWidth": 50,
 271     "drawYGrid": true,
 272     "drawXGrid": true,
 273     "gridLineColor": "rgb(128,128,128)",
 274     "fillAlpha": 0.15,
 275     "underlayCallback": null
 276   };
 277   Dygraph.update(this.options, options);
 278
 279   this.layout = layout;
 280   this.element = element;
 281   this.container = this.element.parentNode;
 282
 283   this.height = this.element.height;
 284   this.width = this.element.width;
 285
 286   // --- check whether everything is ok before we return
 287   if (!this.isIE && !(DygraphCanvasRenderer.isSupported(this.element)))
 288       throw "Canvas is not supported.";
 289
 290   // internal state
 291   this.xlabels = new Array();
 292   this.ylabels = new Array();
 293   this.annotations = new Array();
 294
 295   // TODO(danvk): consider all axes in this computation.
 296   this.area = {
 297     // TODO(danvk): per-axis setting.
 298     x: this.options.yAxisLabelWidth + 2 * this.options.axisTickSize,
 299     y: 0
 300   };
 301   this.area.w = this.width - this.area.x - this.options.rightGap;
 302   this.area.h = this.height - this.options.axisLabelFontSize -
 303                 2 * this.options.axisTickSize;
 304
 305   // Shrink the drawing area to accomodate additional y-axes.
 306   if (this.dygraph_.numAxes() == 2) {
 307     // TODO(danvk): per-axis setting.
 308     this.area.w -= (this.options.yAxisLabelWidth + 2 * this.options.axisTickSize);
 309   } else if (this.dygraph_.numAxes() > 2) {
 310     this.dygraph_.error("Only two y-axes are supported at this time. (Trying " +
 311                         "to use " + this.layout.yAxes.length + ")");
 312   }
 313
 314   this.container.style.position = "relative";
 315   this.container.style.width = this.width + "px";
 316
 317   // Set up a clipping area for the canvas (and the interaction canvas).
 318   // This ensures that we don't overdraw.
 319   var ctx = this.element.getContext("2d");
 320   ctx.beginPath();
 321   ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
 322   ctx.clip();
 323
 324   var ctx = this.dygraph_.hidden_.getContext("2d");
 325   ctx.beginPath();
 326   ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
 327   ctx.clip();
 328 };
 329
 330 DygraphCanvasRenderer.prototype.clear = function() {
 331   if (this.isIE) {
 332     // VML takes a while to start up, so we just poll every this.IEDelay
 333     try {
 334       if (this.clearDelay) {
 335         this.clearDelay.cancel();
 336         this.clearDelay = null;
 337       }
 338       var context = this.element.getContext("2d");
 339     }
 340     catch (e) {
 341       // TODO(danvk): this is broken, since MochiKit.Async is gone.
 342       this.clearDelay = MochiKit.Async.wait(this.IEDelay);
 343       this.clearDelay.addCallback(bind(this.clear, this));
 344       return;
 345     }
 346   }
 347
 348   var context = this.element.getContext("2d");
 349   context.clearRect(0, 0, this.width, this.height);
 350
 351   for (var i = 0; i < this.xlabels.length; i++) {
 352     var el = this.xlabels[i];
 353     el.parentNode.removeChild(el);
 354   }
 355   for (var i = 0; i < this.ylabels.length; i++) {
 356     var el = this.ylabels[i];
 357     el.parentNode.removeChild(el);
 358   }
 359   for (var i = 0; i < this.annotations.length; i++) {
 360     var el = this.annotations[i];
 361     el.parentNode.removeChild(el);
 362   }
 363   this.xlabels = new Array();
 364   this.ylabels = new Array();
 365   this.annotations = new Array();
 366 };
 367
 368
 369 DygraphCanvasRenderer.isSupported = function(canvasName) {
 370   var canvas = null;
 371   try {
 372     if (typeof(canvasName) == 'undefined' || canvasName == null)
 373       canvas = document.createElement("canvas");
 374     else
 375       canvas = canvasName;
 376     var context = canvas.getContext("2d");
 377   }
 378   catch (e) {
 379     var ie = navigator.appVersion.match(/MSIE (\d\.\d)/);
 380     var opera = (navigator.userAgent.toLowerCase().indexOf("opera") != -1);
 381     if ((!ie) || (ie[1] < 6) || (opera))
 382       return false;
 383     return true;
 384   }
 385   return true;
 386 };
 387
 388 /**
 389  * Draw an X/Y grid on top of the existing plot
 390  */
 391 DygraphCanvasRenderer.prototype.render = function() {
 392   // Draw the new X/Y grid
 393   var ctx = this.element.getContext("2d");
 394
 395   if (this.options.underlayCallback) {
 396     this.options.underlayCallback(ctx, this.area, this.layout, this.dygraph_);
 397   }
 398
 399   if (this.options.drawYGrid) {
 400     var ticks = this.layout.yticks;
 401     ctx.save();
 402     ctx.strokeStyle = this.options.gridLineColor;
 403     ctx.lineWidth = this.options.axisLineWidth;
 404     for (var i = 0; i < ticks.length; i++) {
 405       if (ticks[i][0] != 0) continue;  // TODO(danvk): per-axis property
 406       var x = this.area.x;
 407       var y = this.area.y + ticks[i][1] * this.area.h;
 408       ctx.beginPath();
 409       ctx.moveTo(x, y);
 410       ctx.lineTo(x + this.area.w, y);
 411       ctx.closePath();
 412       ctx.stroke();
 413     }
 414   }
 415
 416   if (this.options.drawXGrid) {
 417     var ticks = this.layout.xticks;
 418     ctx.save();
 419     ctx.strokeStyle = this.options.gridLineColor;
 420     ctx.lineWidth = this.options.axisLineWidth;
 421     for (var i=0; i<ticks.length; i++) {
 422       var x = this.area.x + ticks[i][1] * this.area.w;
 423       var y = this.area.y + this.area.h;
 424       ctx.beginPath();
 425       ctx.moveTo(x, y);
 426       ctx.lineTo(x, this.area.y);
 427       ctx.closePath();
 428       ctx.stroke();
 429     }
 430   }
 431
 432   // Do the ordinary rendering, as before
 433   this._renderLineChart();
 434   this._renderAxis();
 435   this._renderAnnotations();
 436 };
 437
 438
 439 DygraphCanvasRenderer.prototype._renderAxis = function() {
 440   if (!this.options.drawXAxis && !this.options.drawYAxis)
 441     return;
 442
 443   var context = this.element.getContext("2d");
 444
 445   var labelStyle = {
 446     "position": "absolute",
 447     "fontSize": this.options.axisLabelFontSize + "px",
 448     "zIndex": 10,
 449     "color": this.options.axisLabelColor,
 450     "width": this.options.axisLabelWidth + "px",
 451     "overflow": "hidden"
 452   };
 453   var makeDiv = function(txt) {
 454     var div = document.createElement("div");
 455     for (var name in labelStyle) {
 456       if (labelStyle.hasOwnProperty(name)) {
 457         div.style[name] = labelStyle[name];
 458       }
 459     }
 460     div.appendChild(document.createTextNode(txt));
 461     return div;
 462   };
 463
 464   // axis lines
 465   context.save();
 466   context.strokeStyle = this.options.axisLineColor;
 467   context.lineWidth = this.options.axisLineWidth;
 468
 469   if (this.options.drawYAxis) {
 470     if (this.layout.yticks && this.layout.yticks.length > 0) {
 471       for (var i = 0; i < this.layout.yticks.length; i++) {
 472         var tick = this.layout.yticks[i];
 473         if (typeof(tick) == "function") return;
 474         var x = this.area.x;
 475         if (tick[0] == 1) {
 476           x = this.area.x + this.area.w - labelStyle.width;
 477         }
 478         var y = this.area.y + tick[1] * this.area.h;
 479         context.beginPath();
 480         context.moveTo(x, y);
 481         context.lineTo(x - this.options.axisTickSize, y);
 482         context.closePath();
 483         context.stroke();
 484
 485         var label = makeDiv(tick[2]);
 486         var top = (y - this.options.axisLabelFontSize / 2);
 487         if (top < 0) top = 0;
 488
 489         if (top + this.options.axisLabelFontSize + 3 > this.height) {
 490           label.style.bottom = "0px";
 491         } else {
 492           label.style.top = top + "px";
 493         }
 494         if (tick[0] == 0) {
 495           label.style.left = "0px";
 496           label.style.textAlign = "right";
 497         } else if (tick[0] == 1) {
 498           label.style.left = (this.area.x + this.area.w +
 499                               this.options.axisTickSize) + "px";
 500           label.style.textAlign = "left";
 501         }
 502         label.style.width = this.options.yAxisLabelWidth + "px";
 503         this.container.appendChild(label);
 504         this.ylabels.push(label);
 505       }
 506
 507       // The lowest tick on the y-axis often overlaps with the leftmost
 508       // tick on the x-axis. Shift the bottom tick up a little bit to
 509       // compensate if necessary.
 510       var bottomTick = this.ylabels[0];
 511       var fontSize = this.options.axisLabelFontSize;
 512       var bottom = parseInt(bottomTick.style.top) + fontSize;
 513       if (bottom > this.height - fontSize) {
 514         bottomTick.style.top = (parseInt(bottomTick.style.top) -
 515             fontSize / 2) + "px";
 516       }
 517     }
 518
 519     context.beginPath();
 520     context.moveTo(this.area.x, this.area.y);
 521     context.lineTo(this.area.x, this.area.y + this.area.h);
 522     context.closePath();
 523     context.stroke();
 524   }
 525
 526   if (this.options.drawXAxis) {
 527     if (this.layout.xticks) {
 528       for (var i = 0; i < this.layout.xticks.length; i++) {
 529         var tick = this.layout.xticks[i];
 530         if (typeof(dataset) == "function") return;
 531
 532         var x = this.area.x + tick[0] * this.area.w;
 533         var y = this.area.y + this.area.h;
 534         context.beginPath();
 535         context.moveTo(x, y);
 536         context.lineTo(x, y + this.options.axisTickSize);
 537         context.closePath();
 538         context.stroke();
 539
 540         var label = makeDiv(tick[1]);
 541         label.style.textAlign = "center";
 542         label.style.bottom = "0px";
 543
 544         var left = (x - this.options.axisLabelWidth/2);
 545         if (left + this.options.axisLabelWidth > this.width) {
 546           left = this.width - this.options.xAxisLabelWidth;
 547           label.style.textAlign = "right";
 548         }
 549         if (left < 0) {
 550           left = 0;
 551           label.style.textAlign = "left";
 552         }
 553
 554         label.style.left = left + "px";
 555         label.style.width = this.options.xAxisLabelWidth + "px";
 556         this.container.appendChild(label);
 557         this.xlabels.push(label);
 558       }
 559     }
 560
 561     context.beginPath();
 562     context.moveTo(this.area.x, this.area.y + this.area.h);
 563     context.lineTo(this.area.x + this.area.w, this.area.y + this.area.h);
 564     context.closePath();
 565     context.stroke();
 566   }
 567
 568   context.restore();
 569 };
 570
 571
 572 DygraphCanvasRenderer.prototype._renderAnnotations = function() {
 573   var annotationStyle = {
 574     "position": "absolute",
 575     "fontSize": this.options.axisLabelFontSize + "px",
 576     "zIndex": 10,
 577     "overflow": "hidden"
 578   };
 579
 580   var bindEvt = function(eventName, classEventName, p, self) {
 581     return function(e) {
 582       var a = p.annotation;
 583       if (a.hasOwnProperty(eventName)) {
 584         a[eventName](a, p, self.dygraph_, e);
 585       } else if (self.dygraph_.attr_(classEventName)) {
 586         self.dygraph_.attr_(classEventName)(a, p, self.dygraph_,e );
 587       }
 588     };
 589   }
 590
 591   // Get a list of point with annotations.
 592   var points = this.layout.annotated_points;
 593   for (var i = 0; i < points.length; i++) {
 594     var p = points[i];
 595     if (p.canvasx < this.area.x || p.canvasx > this.area.x + this.area.w) {
 596       continue;
 597     }
 598
 599     var a = p.annotation;
 600     var tick_height = 6;
 601     if (a.hasOwnProperty("tickHeight")) {
 602       tick_height = a.tickHeight;
 603     }
 604
 605     var div = document.createElement("div");
 606     for (var name in annotationStyle) {
 607       if (annotationStyle.hasOwnProperty(name)) {
 608         div.style[name] = annotationStyle[name];
 609       }
 610     }
 611     if (!a.hasOwnProperty('icon')) {
 612       div.className = "dygraphDefaultAnnotation";
 613     }
 614     if (a.hasOwnProperty('cssClass')) {
 615       div.className += " " + a.cssClass;
 616     }
 617
 618     var width = a.hasOwnProperty('width') ? a.width : 16;
 619     var height = a.hasOwnProperty('height') ? a.height : 16;
 620     if (a.hasOwnProperty('icon')) {
 621       var img = document.createElement("img");
 622       img.src = a.icon;
 623       img.width = width;
 624       img.height = height;
 625       div.appendChild(img);
 626     } else if (p.annotation.hasOwnProperty('shortText')) {
 627       div.appendChild(document.createTextNode(p.annotation.shortText));
 628     }
 629     div.style.left = (p.canvasx - width / 2) + "px";
 630     if (a.attachAtBottom) {
 631       div.style.top = (this.area.h - height - tick_height) + "px";
 632     } else {
 633       div.style.top = (p.canvasy - height - tick_height) + "px";
 634     }
 635     div.style.width = width + "px";
 636     div.style.height = height + "px";
 637     div.title = p.annotation.text;
 638     div.style.color = this.colors[p.name];
 639     div.style.borderColor = this.colors[p.name];
 640     a.div = div;
 641
 642     Dygraph.addEvent(div, 'click',
 643         bindEvt('clickHandler', 'annotationClickHandler', p, this));
 644     Dygraph.addEvent(div, 'mouseover',
 645         bindEvt('mouseOverHandler', 'annotationMouseOverHandler', p, this));
 646     Dygraph.addEvent(div, 'mouseout',
 647         bindEvt('mouseOutHandler', 'annotationMouseOutHandler', p, this));
 648     Dygraph.addEvent(div, 'dblclick',
 649         bindEvt('dblClickHandler', 'annotationDblClickHandler', p, this));
 650
 651     this.container.appendChild(div);
 652     this.annotations.push(div);
 653
 654     var ctx = this.element.getContext("2d");
 655     ctx.strokeStyle = this.colors[p.name];
 656     ctx.beginPath();
 657     if (!a.attachAtBottom) {
 658       ctx.moveTo(p.canvasx, p.canvasy);
 659       ctx.lineTo(p.canvasx, p.canvasy - 2 - tick_height);
 660     } else {
 661       ctx.moveTo(p.canvasx, this.area.h);
 662       ctx.lineTo(p.canvasx, this.area.h - 2 - tick_height);
 663     }
 664     ctx.closePath();
 665     ctx.stroke();
 666   }
 667 };
 668
 669
 670 /**
 671  * Overrides the CanvasRenderer method to draw error bars
 672  */
 673 DygraphCanvasRenderer.prototype._renderLineChart = function() {
 674   var context = this.element.getContext("2d");
 675   var colorCount = this.options.colorScheme.length;
 676   var colorScheme = this.options.colorScheme;
 677   var fillAlpha = this.options.fillAlpha;
 678   var errorBars = this.layout.options.errorBars;
 679   var fillGraph = this.layout.options.fillGraph;
 680   var stackedGraph = this.layout.options.stackedGraph;
 681   var stepPlot = this.layout.options.stepPlot;
 682
 683   var setNames = [];
 684   for (var name in this.layout.datasets) {
 685     if (this.layout.datasets.hasOwnProperty(name)) {
 686       setNames.push(name);
 687     }
 688   }
 689   var setCount = setNames.length;
 690
 691   this.colors = {}
 692   for (var i = 0; i < setCount; i++) {
 693     this.colors[setNames[i]] = colorScheme[i % colorCount];
 694   }
 695
 696   // Update Points
 697   // TODO(danvk): here
 698   for (var i = 0; i < this.layout.points.length; i++) {
 699     var point = this.layout.points[i];
 700     point.canvasx = this.area.w * point.x + this.area.x;
 701     point.canvasy = this.area.h * point.y + this.area.y;
 702   }
 703
 704   // create paths
 705   var isOK = function(x) { return x && !isNaN(x); };
 706
 707   var ctx = context;
 708   if (errorBars) {
 709     if (fillGraph) {
 710       this.dygraph_.warn("Can't use fillGraph option with error bars");
 711     }
 712
 713     for (var i = 0; i < setCount; i++) {
 714       var setName = setNames[i];
 715       var axis = this.layout.options.yAxes[
 716         this.layout.options.seriesToAxisMap[setName]];
 717       var color = this.colors[setName];
 718
 719       // setup graphics context
 720       ctx.save();
 721       var prevX = NaN;
 722       var prevY = NaN;
 723       var prevYs = [-1, -1];
 724       var yscale = axis.yscale;
 725       // should be same color as the lines but only 15% opaque.
 726       var rgb = new RGBColor(color);
 727       var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 728                             fillAlpha + ')';
 729       ctx.fillStyle = err_color;
 730       ctx.beginPath();
 731       for (var j = 0; j < this.layout.points.length; j++) {
 732         var point = this.layout.points[j];
 733         if (point.name == setName) {
 734           if (!isOK(point.y)) {
 735             prevX = NaN;
 736             continue;
 737           }
 738
 739           // TODO(danvk): here
 740           if (stepPlot) {
 741             var newYs = [ prevY - point.errorPlus * yscale,
 742                           prevY + point.errorMinus * yscale ];
 743             prevY = point.y;
 744           } else {
 745             var newYs = [ point.y - point.errorPlus * yscale,
 746                           point.y + point.errorMinus * yscale ];
 747           }
 748           newYs[0] = this.area.h * newYs[0] + this.area.y;
 749           newYs[1] = this.area.h * newYs[1] + this.area.y;
 750           if (!isNaN(prevX)) {
 751             if (stepPlot) {
 752               ctx.moveTo(prevX, newYs[0]);
 753             } else {
 754               ctx.moveTo(prevX, prevYs[0]);
 755             }
 756             ctx.lineTo(point.canvasx, newYs[0]);
 757             ctx.lineTo(point.canvasx, newYs[1]);
 758             if (stepPlot) {
 759               ctx.lineTo(prevX, newYs[1]);
 760             } else {
 761               ctx.lineTo(prevX, prevYs[1]);
 762             }
 763             ctx.closePath();
 764           }
 765           prevYs = newYs;
 766           prevX = point.canvasx;
 767         }
 768       }
 769       ctx.fill();
 770     }
 771   } else if (fillGraph) {
 772     var baseline = []  // for stacked graphs: baseline for filling
 773
 774     // process sets in reverse order (needed for stacked graphs)
 775     for (var i = setCount - 1; i >= 0; i--) {
 776       var setName = setNames[i];
 777       var color = this.colors[setName];
 778       var axis = this.layout.options.yAxes[
 779         this.layout.options.seriesToAxisMap[setName]];
 780       var axisY = 1.0 + axis.minyval * axis.yscale;
 781       if (axisY < 0.0) axisY = 0.0;
 782       else if (axisY > 1.0) axisY = 1.0;
 783       axisY = this.area.h * axisY + this.area.y;
 784
 785       // setup graphics context
 786       ctx.save();
 787       var prevX = NaN;
 788       var prevYs = [-1, -1];
 789       var yscale = axis.yscale;
 790       // should be same color as the lines but only 15% opaque.
 791       var rgb = new RGBColor(color);
 792       var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 793                             fillAlpha + ')';
 794       ctx.fillStyle = err_color;
 795       ctx.beginPath();
 796       for (var j = 0; j < this.layout.points.length; j++) {
 797         var point = this.layout.points[j];
 798         if (point.name == setName) {
 799           if (!isOK(point.y)) {
 800             prevX = NaN;
 801             continue;
 802           }
 803           var newYs;
 804           if (stackedGraph) {
 805             lastY = baseline[point.canvasx];
 806             if (lastY === undefined) lastY = axisY;
 807             baseline[point.canvasx] = point.canvasy;
 808             newYs = [ point.canvasy, lastY ];
 809           } else {
 810             newYs = [ point.canvasy, axisY ];
 811           }
 812           if (!isNaN(prevX)) {
 813             ctx.moveTo(prevX, prevYs[0]);
 814             if (stepPlot) {
 815               ctx.lineTo(point.canvasx, prevYs[0]);
 816             } else {
 817               ctx.lineTo(point.canvasx, newYs[0]);
 818             }
 819             ctx.lineTo(point.canvasx, newYs[1]);
 820             ctx.lineTo(prevX, prevYs[1]);
 821             ctx.closePath();
 822           }
 823           prevYs = newYs;
 824           prevX = point.canvasx;
 825         }
 826       }
 827       ctx.fill();
 828     }
 829   }
 830
 831   for (var i = 0; i < setCount; i++) {
 832     var setName = setNames[i];
 833     var color = this.colors[setName];
 834     var strokeWidth = this.dygraph_.attr_("strokeWidth", setName);
 835
 836     // setup graphics context
 837     context.save();
 838     var point = this.layout.points[0];
 839     var pointSize = this.dygraph_.attr_("pointSize", setName);
 840     var prevX = null, prevY = null;
 841     var drawPoints = this.dygraph_.attr_("drawPoints", setName);
 842     var points = this.layout.points;
 843     for (var j = 0; j < points.length; j++) {
 844       var point = points[j];
 845       if (point.name == setName) {
 846         if (!isOK(point.canvasy)) {
 847           if (stepPlot && prevX != null) {
 848             // Draw a horizontal line to the start of the missing data
 849             ctx.beginPath();
 850             ctx.strokeStyle = color;
 851             ctx.lineWidth = this.options.strokeWidth;
 852             ctx.moveTo(prevX, prevY);
 853             ctx.lineTo(point.canvasx, prevY);
 854             ctx.stroke();
 855           }
 856           // this will make us move to the next point, not draw a line to it.
 857           prevX = prevY = null;
 858         } else {
 859           // A point is "isolated" if it is non-null but both the previous
 860           // and next points are null.
 861           var isIsolated = (!prevX && (j == points.length - 1 ||
 862                                        !isOK(points[j+1].canvasy)));
 863
 864           if (!prevX) {
 865             prevX = point.canvasx;
 866             prevY = point.canvasy;
 867           } else {
 868             // TODO(danvk): figure out why this conditional is necessary.
 869             if (strokeWidth) {
 870               ctx.beginPath();
 871               ctx.strokeStyle = color;
 872               ctx.lineWidth = strokeWidth;
 873               ctx.moveTo(prevX, prevY);
 874               if (stepPlot) {
 875                 ctx.lineTo(point.canvasx, prevY);
 876               }
 877               prevX = point.canvasx;
 878               prevY = point.canvasy;
 879               ctx.lineTo(prevX, prevY);
 880               ctx.stroke();
 881             }
 882           }
 883
 884           if (drawPoints || isIsolated) {
 885            ctx.beginPath();
 886            ctx.fillStyle = color;
 887            ctx.arc(point.canvasx, point.canvasy, pointSize,
 888                    0, 2 * Math.PI, false);
 889            ctx.fill();
 890           }
 891         }
 892       }
 893     }
 894   }
 895
 896   context.restore();
 897 };