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