dygraph-canvas.js

   1 // Copyright 2006 Dan Vanderkam (danvdk@gmail.com)
   2 // All Rights Reserved.
   3
   4 /**
   5  * @fileoverview Based on PlotKit.CanvasRenderer, but modified to meet the
   6  * needs of dygraphs.
   7  *
   8  * In particular, support for:
   9  * - grid overlays
  10  * - error bars
  11  * - dygraphs attribute system
  12  */
  13
  14 /**
  15  * This class determines the charting area (in pixel coordinates), maps the
  16  * percentage coordinates in the DygraphLayout to pixels and draws them.
  17  * It's also responsible for creating chart DOM elements, i.e. annotations,
  18  * tick mark labels, the title and the x/y-axis labels.
  19  * This class is based on PlotKit.CanvasRenderer.
  20  *
  21  * @param {Object} element The canvas to attach to
  22  * @param {Object} elementContext The 2d context of the canvas (injected so it
  23  * can be mocked for testing.)
  24  * @param {Layout} layout The DygraphLayout object for this graph.
  25  * @constructor
  26  */
  27 DygraphCanvasRenderer = function(dygraph, element, elementContext, layout) {
  28   this.dygraph_ = dygraph;
  29
  30   this.layout = layout;
  31   this.element = element;
  32   this.elementContext = elementContext;
  33   this.container = this.element.parentNode;
  34
  35   this.height = this.element.height;
  36   this.width = this.element.width;
  37
  38   // --- check whether everything is ok before we return
  39   if (!this.isIE && !(DygraphCanvasRenderer.isSupported(this.element)))
  40       throw "Canvas is not supported.";
  41
  42   // internal state
  43   this.xlabels = new Array();
  44   this.ylabels = new Array();
  45   this.annotations = new Array();
  46   this.chartLabels = {};
  47
  48   this.area = this.computeArea_();
  49   this.container.style.position = "relative";
  50   this.container.style.width = this.width + "px";
  51
  52   // Set up a clipping area for the canvas (and the interaction canvas).
  53   // This ensures that we don't overdraw.
  54   var ctx = this.dygraph_.canvas_ctx_;
  55   ctx.beginPath();
  56   ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
  57   ctx.clip();
  58
  59   ctx = this.dygraph_.hidden_ctx_;
  60   ctx.beginPath();
  61   ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
  62   ctx.clip();
  63 };
  64
  65 DygraphCanvasRenderer.prototype.attr_ = function(x) {
  66   return this.dygraph_.attr_(x);
  67 };
  68
  69 // Compute the box which the chart should be drawn in. This is the canvas's
  70 // box, less space needed for axis and chart labels.
  71 // TODO(danvk): this belongs in DygraphLayout.
  72 DygraphCanvasRenderer.prototype.computeArea_ = function() {
  73   var area = {
  74     // TODO(danvk): per-axis setting.
  75     x: 0,
  76     y: 0
  77   };
  78   if (this.attr_('drawYAxis')) {
  79    area.x = this.attr_('yAxisLabelWidth') + 2 * this.attr_('axisTickSize');
  80   }
  81
  82   area.w = this.width - area.x - this.attr_('rightGap');
  83   area.h = this.height;
  84   if (this.attr_('drawXAxis')) {
  85     if (this.attr_('xAxisHeight')) {
  86       area.h -= this.attr_('xAxisHeight');
  87     } else {
  88       area.h -= this.attr_('axisLabelFontSize') + 2 * this.attr_('axisTickSize');
  89     }
  90   }
  91
  92   // Shrink the drawing area to accomodate additional y-axes.
  93   if (this.dygraph_.numAxes() == 2) {
  94     // TODO(danvk): per-axis setting.
  95     area.w -= (this.attr_('yAxisLabelWidth') + 2 * this.attr_('axisTickSize'));
  96   } else if (this.dygraph_.numAxes() > 2) {
  97     this.dygraph_.error("Only two y-axes are supported at this time. (Trying " +
  98                         "to use " + this.dygraph_.numAxes() + ")");
  99   }
 100
 101   // Add space for chart labels: title, xlabel and ylabel.
 102   if (this.attr_('title')) {
 103     area.h -= this.attr_('titleHeight');
 104     area.y += this.attr_('titleHeight');
 105   }
 106   if (this.attr_('xlabel')) {
 107     area.h -= this.attr_('xLabelHeight');
 108   }
 109   if (this.attr_('ylabel')) {
 110     // It would make sense to shift the chart here to make room for the y-axis
 111     // label, but the default yAxisLabelWidth is large enough that this results
 112     // in overly-padded charts. The y-axis label should fit fine. If it
 113     // doesn't, the yAxisLabelWidth option can be increased.
 114   }
 115
 116   return area;
 117 };
 118
 119 DygraphCanvasRenderer.prototype.clear = function() {
 120   if (this.isIE) {
 121     // VML takes a while to start up, so we just poll every this.IEDelay
 122     try {
 123       if (this.clearDelay) {
 124         this.clearDelay.cancel();
 125         this.clearDelay = null;
 126       }
 127       var context = this.elementContext;
 128     }
 129     catch (e) {
 130       // TODO(danvk): this is broken, since MochiKit.Async is gone.
 131       this.clearDelay = MochiKit.Async.wait(this.IEDelay);
 132       this.clearDelay.addCallback(bind(this.clear, this));
 133       return;
 134     }
 135   }
 136
 137   var context = this.elementContext;
 138   context.clearRect(0, 0, this.width, this.height);
 139
 140   for (var i = 0; i < this.xlabels.length; i++) {
 141     var el = this.xlabels[i];
 142     if (el.parentNode) el.parentNode.removeChild(el);
 143   }
 144   for (var i = 0; i < this.ylabels.length; i++) {
 145     var el = this.ylabels[i];
 146     if (el.parentNode) el.parentNode.removeChild(el);
 147   }
 148   for (var i = 0; i < this.annotations.length; i++) {
 149     var el = this.annotations[i];
 150     if (el.parentNode) el.parentNode.removeChild(el);
 151   }
 152   for (var k in this.chartLabels) {
 153     if (!this.chartLabels.hasOwnProperty(k)) continue;
 154     var el = this.chartLabels[k];
 155     if (el.parentNode) el.parentNode.removeChild(el);
 156   }
 157   this.xlabels = new Array();
 158   this.ylabels = new Array();
 159   this.annotations = new Array();
 160   this.chartLabels = {};
 161 };
 162
 163
 164 DygraphCanvasRenderer.isSupported = function(canvasName) {
 165   var canvas = null;
 166   try {
 167     if (typeof(canvasName) == 'undefined' || canvasName == null)
 168       canvas = document.createElement("canvas");
 169     else
 170       canvas = canvasName;
 171     var context = canvas.getContext("2d");
 172   }
 173   catch (e) {
 174     var ie = navigator.appVersion.match(/MSIE (\d\.\d)/);
 175     var opera = (navigator.userAgent.toLowerCase().indexOf("opera") != -1);
 176     if ((!ie) || (ie[1] < 6) || (opera))
 177       return false;
 178     return true;
 179   }
 180   return true;
 181 };
 182
 183 /**
 184  * @param { [String] } colors Array of color strings. Should have one entry for
 185  * each series to be rendered.
 186  */
 187 DygraphCanvasRenderer.prototype.setColors = function(colors) {
 188   this.colorScheme_ = colors;
 189 };
 190
 191 /**
 192  * Draw an X/Y grid on top of the existing plot
 193  */
 194 DygraphCanvasRenderer.prototype.render = function() {
 195   // Draw the new X/Y grid. Lines appear crisper when pixels are rounded to
 196   // half-integers. This prevents them from drawing in two rows/cols.
 197   var ctx = this.elementContext;
 198   function halfUp(x){return Math.round(x)+0.5};
 199   function halfDown(y){return Math.round(y)-0.5};
 200
 201   if (this.attr_('underlayCallback')) {
 202     // NOTE: we pass the dygraph object to this callback twice to avoid breaking
 203     // users who expect a deprecated form of this callback.
 204     this.attr_('underlayCallback')(ctx, this.area, this.dygraph_, this.dygraph_);
 205   }
 206
 207   if (this.attr_('drawYGrid')) {
 208     var ticks = this.layout.yticks;
 209     ctx.save();
 210     ctx.strokeStyle = this.attr_('gridLineColor');
 211     ctx.lineWidth = this.attr_('gridLineWidth');
 212     for (var i = 0; i < ticks.length; i++) {
 213       // TODO(danvk): allow secondary axes to draw a grid, too.
 214       if (ticks[i][0] != 0) continue;
 215       var x = halfUp(this.area.x);
 216       var y = halfDown(this.area.y + ticks[i][1] * this.area.h);
 217       ctx.beginPath();
 218       ctx.moveTo(x, y);
 219       ctx.lineTo(x + this.area.w, y);
 220       ctx.closePath();
 221       ctx.stroke();
 222     }
 223   }
 224
 225   if (this.attr_('drawXGrid')) {
 226     var ticks = this.layout.xticks;
 227     ctx.save();
 228     ctx.strokeStyle = this.attr_('gridLineColor');
 229     ctx.lineWidth = this.attr_('gridLineWidth');
 230     for (var i=0; i<ticks.length; i++) {
 231       var x = halfUp(this.area.x + ticks[i][0] * this.area.w);
 232       var y = halfDown(this.area.y + this.area.h);
 233       ctx.beginPath();
 234       ctx.moveTo(x, y);
 235       ctx.lineTo(x, this.area.y);
 236       ctx.closePath();
 237       ctx.stroke();
 238     }
 239   }
 240
 241   // Do the ordinary rendering, as before
 242   this._renderLineChart();
 243   this._renderAxis();
 244   this._renderChartLabels();
 245   this._renderAnnotations();
 246 };
 247
 248
 249 DygraphCanvasRenderer.prototype._renderAxis = function() {
 250   if (!this.attr_('drawXAxis') && !this.attr_('drawYAxis')) return;
 251
 252   // Round pixels to half-integer boundaries for crisper drawing.
 253   function halfUp(x){return Math.round(x)+0.5};
 254   function halfDown(y){return Math.round(y)-0.5};
 255
 256   var context = this.elementContext;
 257
 258   var labelStyle = {
 259     position: "absolute",
 260     fontSize: this.attr_('axisLabelFontSize') + "px",
 261     zIndex: 10,
 262     color: this.attr_('axisLabelColor'),
 263     width: this.attr_('axisLabelWidth') + "px",
 264     // height: this.attr_('axisLabelFontSize') + 2 + "px",
 265     overflow: "hidden"
 266   };
 267   var makeDiv = function(txt, axis) {
 268     var div = document.createElement("div");
 269     for (var name in labelStyle) {
 270       if (labelStyle.hasOwnProperty(name)) {
 271         div.style[name] = labelStyle[name];
 272       }
 273     }
 274     var inner_div = document.createElement("div");
 275     // TODO(danvk): separate class for secondary y-axis
 276     inner_div.className = 'dygraph-axis-label dygraph-axis-label-' + axis;
 277     inner_div.appendChild(document.createTextNode(txt));
 278     div.appendChild(inner_div);
 279     return div;
 280   };
 281
 282   // axis lines
 283   context.save();
 284   context.strokeStyle = this.attr_('axisLineColor');
 285   context.lineWidth = this.attr_('axisLineWidth');
 286
 287   if (this.attr_('drawYAxis')) {
 288     if (this.layout.yticks && this.layout.yticks.length > 0) {
 289       for (var i = 0; i < this.layout.yticks.length; i++) {
 290         var tick = this.layout.yticks[i];
 291         if (typeof(tick) == "function") return;
 292         var x = this.area.x;
 293         var sgn = 1;
 294         if (tick[0] == 1) {  // right-side y-axis
 295           x = this.area.x + this.area.w;
 296           sgn = -1;
 297         }
 298         var y = this.area.y + tick[1] * this.area.h;
 299         context.beginPath();
 300         context.moveTo(halfUp(x), halfDown(y));
 301         context.lineTo(halfUp(x - sgn * this.attr_('axisTickSize')), halfDown(y));
 302         context.closePath();
 303         context.stroke();
 304
 305         var label = makeDiv(tick[2], 'y');
 306         var top = (y - this.attr_('axisLabelFontSize') / 2);
 307         if (top < 0) top = 0;
 308
 309         if (top + this.attr_('axisLabelFontSize') + 3 > this.height) {
 310           label.style.bottom = "0px";
 311         } else {
 312           label.style.top = top + "px";
 313         }
 314         if (tick[0] == 0) {
 315           label.style.left = (this.area.x - this.attr_('yAxisLabelWidth') - this.attr_('axisTickSize')) + "px";
 316           label.style.textAlign = "right";
 317         } else if (tick[0] == 1) {
 318           label.style.left = (this.area.x + this.area.w +
 319                               this.attr_('axisTickSize')) + "px";
 320           label.style.textAlign = "left";
 321         }
 322         label.style.width = this.attr_('yAxisLabelWidth') + "px";
 323         this.container.appendChild(label);
 324         this.ylabels.push(label);
 325       }
 326
 327       // The lowest tick on the y-axis often overlaps with the leftmost
 328       // tick on the x-axis. Shift the bottom tick up a little bit to
 329       // compensate if necessary.
 330       var bottomTick = this.ylabels[0];
 331       var fontSize = this.attr_('axisLabelFontSize');
 332       var bottom = parseInt(bottomTick.style.top) + fontSize;
 333       if (bottom > this.height - fontSize) {
 334         bottomTick.style.top = (parseInt(bottomTick.style.top) -
 335             fontSize / 2) + "px";
 336       }
 337     }
 338
 339     // draw a vertical line on the left to separate the chart from the labels.
 340     context.beginPath();
 341     context.moveTo(halfUp(this.area.x), halfDown(this.area.y));
 342     context.lineTo(halfUp(this.area.x), halfDown(this.area.y + this.area.h));
 343     context.closePath();
 344     context.stroke();
 345
 346     // if there's a secondary y-axis, draw a vertical line for that, too.
 347     if (this.dygraph_.numAxes() == 2) {
 348       context.beginPath();
 349       context.moveTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y));
 350       context.lineTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
 351       context.closePath();
 352       context.stroke();
 353     }
 354   }
 355
 356   if (this.attr_('drawXAxis')) {
 357     if (this.layout.xticks) {
 358       for (var i = 0; i < this.layout.xticks.length; i++) {
 359         var tick = this.layout.xticks[i];
 360         if (typeof(dataset) == "function") return;
 361
 362         var x = this.area.x + tick[0] * this.area.w;
 363         var y = this.area.y + this.area.h;
 364         context.beginPath();
 365         context.moveTo(halfUp(x), halfDown(y));
 366         context.lineTo(halfUp(x), halfDown(y + this.attr_('axisTickSize')));
 367         context.closePath();
 368         context.stroke();
 369
 370         var label = makeDiv(tick[1], 'x');
 371         label.style.textAlign = "center";
 372         label.style.top = (y + this.attr_('axisTickSize')) + 'px';
 373
 374         var left = (x - this.attr_('axisLabelWidth')/2);
 375         if (left + this.attr_('axisLabelWidth') > this.width) {
 376           left = this.width - this.attr_('xAxisLabelWidth');
 377           label.style.textAlign = "right";
 378         }
 379         if (left < 0) {
 380           left = 0;
 381           label.style.textAlign = "left";
 382         }
 383
 384         label.style.left = left + "px";
 385         label.style.width = this.attr_('xAxisLabelWidth') + "px";
 386         this.container.appendChild(label);
 387         this.xlabels.push(label);
 388       }
 389     }
 390
 391     context.beginPath();
 392     context.moveTo(halfUp(this.area.x), halfDown(this.area.y + this.area.h));
 393     context.lineTo(halfUp(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
 394     context.closePath();
 395     context.stroke();
 396   }
 397
 398   context.restore();
 399 };
 400
 401
 402 DygraphCanvasRenderer.prototype._renderChartLabels = function() {
 403   // Generate divs for the chart title, xlabel and ylabel.
 404   // Space for these divs has already been taken away from the charting area in
 405   // the DygraphCanvasRenderer constructor.
 406   if (this.attr_('title')) {
 407     var div = document.createElement("div");
 408     div.style.position = 'absolute';
 409     div.style.top = '0px';
 410     div.style.left = this.area.x + 'px';
 411     div.style.width = this.area.w + 'px';
 412     div.style.height = this.attr_('titleHeight') + 'px';
 413     div.style.textAlign = 'center';
 414     div.style.fontSize = (this.attr_('titleHeight') - 8) + 'px';
 415     div.style.fontWeight = 'bold';
 416     var class_div = document.createElement("div");
 417     class_div.className = 'dygraph-label dygraph-title';
 418     class_div.innerHTML = this.attr_('title');
 419     div.appendChild(class_div);
 420     this.container.appendChild(div);
 421     this.chartLabels.title = div;
 422   }
 423
 424   if (this.attr_('xlabel')) {
 425     var div = document.createElement("div");
 426     div.style.position = 'absolute';
 427     div.style.bottom = 0;  // TODO(danvk): this is lazy. Calculate style.top.
 428     div.style.left = this.area.x + 'px';
 429     div.style.width = this.area.w + 'px';
 430     div.style.height = this.attr_('xLabelHeight') + 'px';
 431     div.style.textAlign = 'center';
 432     div.style.fontSize = (this.attr_('xLabelHeight') - 2) + 'px';
 433
 434     var class_div = document.createElement("div");
 435     class_div.className = 'dygraph-label dygraph-xlabel';
 436     class_div.innerHTML = this.attr_('xlabel');
 437     div.appendChild(class_div);
 438     this.container.appendChild(div);
 439     this.chartLabels.xlabel = div;
 440   }
 441
 442   if (this.attr_('ylabel')) {
 443     var box = {
 444       left: 0,
 445       top: this.area.y,
 446       width: this.attr_('yLabelWidth'),
 447       height: this.area.h
 448     };
 449     // TODO(danvk): is this outer div actually necessary?
 450     var div = document.createElement("div");
 451     div.style.position = 'absolute';
 452     div.style.left = box.left;
 453     div.style.top = box.top + 'px';
 454     div.style.width = box.width + 'px';
 455     div.style.height = box.height + 'px';
 456     div.style.fontSize = (this.attr_('yLabelWidth') - 2) + 'px';
 457
 458     var inner_div = document.createElement("div");
 459     inner_div.style.position = 'absolute';
 460     inner_div.style.width = box.height + 'px';
 461     inner_div.style.height = box.width + 'px';
 462     inner_div.style.top = (box.height / 2 - box.width / 2) + 'px';
 463     inner_div.style.left = (box.width / 2 - box.height / 2) + 'px';
 464     inner_div.style.textAlign = 'center';
 465
 466     // CSS rotation is an HTML5 feature which is not standardized. Hence every
 467     // browser has its own name for the CSS style.
 468     inner_div.style.transform = 'rotate(-90deg)';        // HTML5
 469     inner_div.style.WebkitTransform = 'rotate(-90deg)';  // Safari/Chrome
 470     inner_div.style.MozTransform = 'rotate(-90deg)';     // Firefox
 471     inner_div.style.OTransform = 'rotate(-90deg)';       // Opera
 472     inner_div.style.msTransform = 'rotate(-90deg)';      // IE9
 473
 474     if (typeof(document.documentMode) !== 'undefined' &&
 475         document.documentMode < 9) {
 476       // We're dealing w/ an old version of IE, so we have to rotate the text
 477       // using a BasicImage transform. This uses a different origin of rotation
 478       // than HTML5 rotation (top left of div vs. its center).
 479       inner_div.style.filter =
 480        'progid:DXImageTransform.Microsoft.BasicImage(rotation=3)';
 481       inner_div.style.left = '0px';
 482       inner_div.style.top = '0px';
 483     }
 484
 485     var class_div = document.createElement("div");
 486     class_div.className = 'dygraph-label dygraph-ylabel';
 487     class_div.innerHTML = this.attr_('ylabel');
 488
 489     inner_div.appendChild(class_div);
 490     div.appendChild(inner_div);
 491     this.container.appendChild(div);
 492     this.chartLabels.ylabel = div;
 493   }
 494 };
 495
 496
 497 DygraphCanvasRenderer.prototype._renderAnnotations = function() {
 498   var annotationStyle = {
 499     "position": "absolute",
 500     "fontSize": this.attr_('axisLabelFontSize') + "px",
 501     "zIndex": 10,
 502     "overflow": "hidden"
 503   };
 504
 505   var bindEvt = function(eventName, classEventName, p, self) {
 506     return function(e) {
 507       var a = p.annotation;
 508       if (a.hasOwnProperty(eventName)) {
 509         a[eventName](a, p, self.dygraph_, e);
 510       } else if (self.dygraph_.attr_(classEventName)) {
 511         self.dygraph_.attr_(classEventName)(a, p, self.dygraph_,e );
 512       }
 513     };
 514   }
 515
 516   // Get a list of point with annotations.
 517   var points = this.layout.annotated_points;
 518   for (var i = 0; i < points.length; i++) {
 519     var p = points[i];
 520     if (p.canvasx < this.area.x || p.canvasx > this.area.x + this.area.w) {
 521       continue;
 522     }
 523
 524     var a = p.annotation;
 525     var tick_height = 6;
 526     if (a.hasOwnProperty("tickHeight")) {
 527       tick_height = a.tickHeight;
 528     }
 529
 530     var div = document.createElement("div");
 531     for (var name in annotationStyle) {
 532       if (annotationStyle.hasOwnProperty(name)) {
 533         div.style[name] = annotationStyle[name];
 534       }
 535     }
 536     if (!a.hasOwnProperty('icon')) {
 537       div.className = "dygraphDefaultAnnotation";
 538     }
 539     if (a.hasOwnProperty('cssClass')) {
 540       div.className += " " + a.cssClass;
 541     }
 542
 543     var width = a.hasOwnProperty('width') ? a.width : 16;
 544     var height = a.hasOwnProperty('height') ? a.height : 16;
 545     if (a.hasOwnProperty('icon')) {
 546       var img = document.createElement("img");
 547       img.src = a.icon;
 548       img.width = width;
 549       img.height = height;
 550       div.appendChild(img);
 551     } else if (p.annotation.hasOwnProperty('shortText')) {
 552       div.appendChild(document.createTextNode(p.annotation.shortText));
 553     }
 554     div.style.left = (p.canvasx - width / 2) + "px";
 555     if (a.attachAtBottom) {
 556       div.style.top = (this.area.h - height - tick_height) + "px";
 557     } else {
 558       div.style.top = (p.canvasy - height - tick_height) + "px";
 559     }
 560     div.style.width = width + "px";
 561     div.style.height = height + "px";
 562     div.title = p.annotation.text;
 563     div.style.color = this.colors[p.name];
 564     div.style.borderColor = this.colors[p.name];
 565     a.div = div;
 566
 567     Dygraph.addEvent(div, 'click',
 568         bindEvt('clickHandler', 'annotationClickHandler', p, this));
 569     Dygraph.addEvent(div, 'mouseover',
 570         bindEvt('mouseOverHandler', 'annotationMouseOverHandler', p, this));
 571     Dygraph.addEvent(div, 'mouseout',
 572         bindEvt('mouseOutHandler', 'annotationMouseOutHandler', p, this));
 573     Dygraph.addEvent(div, 'dblclick',
 574         bindEvt('dblClickHandler', 'annotationDblClickHandler', p, this));
 575
 576     this.container.appendChild(div);
 577     this.annotations.push(div);
 578
 579     var ctx = this.elementContext;
 580     ctx.strokeStyle = this.colors[p.name];
 581     ctx.beginPath();
 582     if (!a.attachAtBottom) {
 583       ctx.moveTo(p.canvasx, p.canvasy);
 584       ctx.lineTo(p.canvasx, p.canvasy - 2 - tick_height);
 585     } else {
 586       ctx.moveTo(p.canvasx, this.area.h);
 587       ctx.lineTo(p.canvasx, this.area.h - 2 - tick_height);
 588     }
 589     ctx.closePath();
 590     ctx.stroke();
 591   }
 592 };
 593
 594
 595 /**
 596  * Overrides the CanvasRenderer method to draw error bars
 597  */
 598 DygraphCanvasRenderer.prototype._renderLineChart = function() {
 599   // TODO(danvk): use this.attr_ for many of these.
 600   var context = this.elementContext;
 601   var fillAlpha = this.attr_('fillAlpha');
 602   var errorBars = this.attr_("errorBars") || this.attr_("customBars");
 603   var fillGraph = this.attr_("fillGraph");
 604   var stackedGraph = this.attr_("stackedGraph");
 605   var stepPlot = this.attr_("stepPlot");
 606
 607   var setNames = [];
 608   for (var name in this.layout.datasets) {
 609     if (this.layout.datasets.hasOwnProperty(name)) {
 610       setNames.push(name);
 611     }
 612   }
 613   var setCount = setNames.length;
 614
 615   // TODO(danvk): Move this mapping into Dygraph and get it out of here.
 616   this.colors = {}
 617   for (var i = 0; i < setCount; i++) {
 618     this.colors[setNames[i]] = this.colorScheme_[i % this.colorScheme_.length];
 619   }
 620
 621   // Update Points
 622   // TODO(danvk): here
 623   for (var i = 0; i < this.layout.points.length; i++) {
 624     var point = this.layout.points[i];
 625     point.canvasx = this.area.w * point.x + this.area.x;
 626     point.canvasy = this.area.h * point.y + this.area.y;
 627   }
 628
 629   // create paths
 630   var ctx = context;
 631   if (errorBars) {
 632     if (fillGraph) {
 633       this.dygraph_.warn("Can't use fillGraph option with error bars");
 634     }
 635
 636     for (var i = 0; i < setCount; i++) {
 637       var setName = setNames[i];
 638       var axis = this.dygraph_.axisPropertiesForSeries(setName);
 639       var color = this.colors[setName];
 640
 641       // setup graphics context
 642       ctx.save();
 643       var prevX = NaN;
 644       var prevY = NaN;
 645       var prevYs = [-1, -1];
 646       var yscale = axis.yscale;
 647       // should be same color as the lines but only 15% opaque.
 648       var rgb = new RGBColor(color);
 649       var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 650                             fillAlpha + ')';
 651       ctx.fillStyle = err_color;
 652       ctx.beginPath();
 653       for (var j = 0; j < this.layout.points.length; j++) {
 654         var point = this.layout.points[j];
 655         if (point.name == setName) {
 656           if (!Dygraph.isOK(point.y)) {
 657             prevX = NaN;
 658             continue;
 659           }
 660
 661           // TODO(danvk): here
 662           if (stepPlot) {
 663             var newYs = [ prevY - point.errorPlus * yscale,
 664                           prevY + point.errorMinus * yscale ];
 665             prevY = point.y;
 666           } else {
 667             var newYs = [ point.y - point.errorPlus * yscale,
 668                           point.y + point.errorMinus * yscale ];
 669           }
 670           newYs[0] = this.area.h * newYs[0] + this.area.y;
 671           newYs[1] = this.area.h * newYs[1] + this.area.y;
 672           if (!isNaN(prevX)) {
 673             if (stepPlot) {
 674               ctx.moveTo(prevX, newYs[0]);
 675             } else {
 676               ctx.moveTo(prevX, prevYs[0]);
 677             }
 678             ctx.lineTo(point.canvasx, newYs[0]);
 679             ctx.lineTo(point.canvasx, newYs[1]);
 680             if (stepPlot) {
 681               ctx.lineTo(prevX, newYs[1]);
 682             } else {
 683               ctx.lineTo(prevX, prevYs[1]);
 684             }
 685             ctx.closePath();
 686           }
 687           prevYs = newYs;
 688           prevX = point.canvasx;
 689         }
 690       }
 691       ctx.fill();
 692     }
 693   } else if (fillGraph) {
 694     var baseline = []  // for stacked graphs: baseline for filling
 695
 696     // process sets in reverse order (needed for stacked graphs)
 697     for (var i = setCount - 1; i >= 0; i--) {
 698       var setName = setNames[i];
 699       var color = this.colors[setName];
 700       var axis = this.dygraph_.axisPropertiesForSeries(setName);
 701       var axisY = 1.0 + axis.minyval * axis.yscale;
 702       if (axisY < 0.0) axisY = 0.0;
 703       else if (axisY > 1.0) axisY = 1.0;
 704       axisY = this.area.h * axisY + this.area.y;
 705
 706       // setup graphics context
 707       ctx.save();
 708       var prevX = NaN;
 709       var prevYs = [-1, -1];
 710       var yscale = axis.yscale;
 711       // should be same color as the lines but only 15% opaque.
 712       var rgb = new RGBColor(color);
 713       var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 714                             fillAlpha + ')';
 715       ctx.fillStyle = err_color;
 716       ctx.beginPath();
 717       for (var j = 0; j < this.layout.points.length; j++) {
 718         var point = this.layout.points[j];
 719         if (point.name == setName) {
 720           if (!Dygraph.isOK(point.y)) {
 721             prevX = NaN;
 722             continue;
 723           }
 724           var newYs;
 725           if (stackedGraph) {
 726             lastY = baseline[point.canvasx];
 727             if (lastY === undefined) lastY = axisY;
 728             baseline[point.canvasx] = point.canvasy;
 729             newYs = [ point.canvasy, lastY ];
 730           } else {
 731             newYs = [ point.canvasy, axisY ];
 732           }
 733           if (!isNaN(prevX)) {
 734             ctx.moveTo(prevX, prevYs[0]);
 735             if (stepPlot) {
 736               ctx.lineTo(point.canvasx, prevYs[0]);
 737             } else {
 738               ctx.lineTo(point.canvasx, newYs[0]);
 739             }
 740             ctx.lineTo(point.canvasx, newYs[1]);
 741             ctx.lineTo(prevX, prevYs[1]);
 742             ctx.closePath();
 743           }
 744           prevYs = newYs;
 745           prevX = point.canvasx;
 746         }
 747       }
 748       ctx.fill();
 749     }
 750   }
 751
 752   var isNullOrNaN = function(x) {
 753     return (x === null || isNaN(x));
 754   };
 755
 756   for (var i = 0; i < setCount; i++) {
 757     var setName = setNames[i];
 758     var color = this.colors[setName];
 759     var strokeWidth = this.dygraph_.attr_("strokeWidth", setName);
 760
 761     // setup graphics context
 762     context.save();
 763     var point = this.layout.points[0];
 764     var pointSize = this.dygraph_.attr_("pointSize", setName);
 765     var prevX = null, prevY = null;
 766     var drawPoints = this.dygraph_.attr_("drawPoints", setName);
 767     var points = this.layout.points;
 768     for (var j = 0; j < points.length; j++) {
 769       var point = points[j];
 770       if (point.name == setName) {
 771         if (isNullOrNaN(point.canvasy)) {
 772           if (stepPlot && prevX != null) {
 773             // Draw a horizontal line to the start of the missing data
 774             ctx.beginPath();
 775             ctx.strokeStyle = color;
 776             ctx.lineWidth = this.attr_('strokeWidth');
 777             ctx.moveTo(prevX, prevY);
 778             ctx.lineTo(point.canvasx, prevY);
 779             ctx.stroke();
 780           }
 781           // this will make us move to the next point, not draw a line to it.
 782           prevX = prevY = null;
 783         } else {
 784           // A point is "isolated" if it is non-null but both the previous
 785           // and next points are null.
 786           var isIsolated = (!prevX && (j == points.length - 1 ||
 787                                        isNullOrNaN(points[j+1].canvasy)));
 788
 789           if (prevX === null) {
 790             prevX = point.canvasx;
 791             prevY = point.canvasy;
 792           } else {
 793             // TODO(danvk): figure out why this conditional is necessary.
 794             if (strokeWidth) {
 795               ctx.beginPath();
 796               ctx.strokeStyle = color;
 797               ctx.lineWidth = strokeWidth;
 798               ctx.moveTo(prevX, prevY);
 799               if (stepPlot) {
 800                 ctx.lineTo(point.canvasx, prevY);
 801               }
 802               prevX = point.canvasx;
 803               prevY = point.canvasy;
 804               ctx.lineTo(prevX, prevY);
 805               ctx.stroke();
 806             }
 807           }
 808
 809           if (drawPoints || isIsolated) {
 810            ctx.beginPath();
 811            ctx.fillStyle = color;
 812            ctx.arc(point.canvasx, point.canvasy, pointSize,
 813                    0, 2 * Math.PI, false);
 814            ctx.fill();
 815           }
 816         }
 817       }
 818     }
 819   }
 820
 821   context.restore();
 822 };