dygraph-canvas.js

   1 /**
   2  * @license
   3  * Copyright 2006 Dan Vanderkam (danvdk@gmail.com)
   4  * MIT-licensed (http://opensource.org/licenses/MIT)
   5  */
   6
   7 /**
   8  * @fileoverview Based on PlotKit.CanvasRenderer, but modified to meet the
   9  * needs of dygraphs.
  10  *
  11  * In particular, support for:
  12  * - grid overlays
  13  * - error bars
  14  * - dygraphs attribute system
  15  */
  16
  17 /**
  18  * The DygraphCanvasRenderer class does the actual rendering of the chart onto
  19  * a canvas. It's based on PlotKit.CanvasRenderer.
  20  * @param {Object} element The canvas to attach to
  21  * @param {Object} elementContext The 2d context of the canvas (injected so it
  22  * can be mocked for testing.)
  23  * @param {Layout} layout The DygraphLayout object for this graph.
  24  * @constructor
  25  */
  26
  27 /*jshint globalstrict: true */
  28 /*global Dygraph:false,RGBColor:false */
  29 "use strict";
  30
  31
  32 var DygraphCanvasRenderer = function(dygraph, element, elementContext, layout) {
  33   this.dygraph_ = dygraph;
  34
  35   this.layout = layout;
  36   this.element = element;
  37   this.elementContext = elementContext;
  38   this.container = this.element.parentNode;
  39
  40   this.height = this.element.height;
  41   this.width = this.element.width;
  42
  43   // --- check whether everything is ok before we return
  44   if (!this.isIE && !(DygraphCanvasRenderer.isSupported(this.element)))
  45       throw "Canvas is not supported.";
  46
  47   // internal state
  48   this.xlabels = [];
  49   this.ylabels = [];
  50   this.annotations = [];
  51   this.chartLabels = {};
  52
  53   this.area = layout.getPlotArea();
  54   this.container.style.position = "relative";
  55   this.container.style.width = this.width + "px";
  56
  57   // Set up a clipping area for the canvas (and the interaction canvas).
  58   // This ensures that we don't overdraw.
  59   if (this.dygraph_.isUsingExcanvas_) {
  60     this._createIEClipArea();
  61   } else {
  62     // on Android 3 and 4, setting a clipping area on a canvas prevents it from
  63     // displaying anything.
  64     if (!Dygraph.isAndroid()) {
  65       var ctx = this.dygraph_.canvas_ctx_;
  66       ctx.beginPath();
  67       ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
  68       ctx.clip();
  69
  70       ctx = this.dygraph_.hidden_ctx_;
  71       ctx.beginPath();
  72       ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
  73       ctx.clip();
  74     }
  75   }
  76 };
  77
  78 DygraphCanvasRenderer.prototype.attr_ = function(x) {
  79   return this.dygraph_.attr_(x);
  80 };
  81
  82 DygraphCanvasRenderer.prototype.clear = function() {
  83   var context;
  84   if (this.isIE) {
  85     // VML takes a while to start up, so we just poll every this.IEDelay
  86     try {
  87       if (this.clearDelay) {
  88         this.clearDelay.cancel();
  89         this.clearDelay = null;
  90       }
  91       context = this.elementContext;
  92     }
  93     catch (e) {
  94       // TODO(danvk): this is broken, since MochiKit.Async is gone.
  95       // this.clearDelay = MochiKit.Async.wait(this.IEDelay);
  96       // this.clearDelay.addCallback(bind(this.clear, this));
  97       return;
  98     }
  99   }
 100
 101   context = this.elementContext;
 102   context.clearRect(0, 0, this.width, this.height);
 103
 104   function removeArray(ary) {
 105     for (var i = 0; i < ary.length; i++) {
 106       var el = ary[i];
 107       if (el.parentNode) el.parentNode.removeChild(el);
 108     }
 109   }
 110
 111   removeArray(this.xlabels);
 112   removeArray(this.ylabels);
 113   removeArray(this.annotations);
 114
 115   for (var k in this.chartLabels) {
 116     if (!this.chartLabels.hasOwnProperty(k)) continue;
 117     var el = this.chartLabels[k];
 118     if (el.parentNode) el.parentNode.removeChild(el);
 119   }
 120   this.xlabels = [];
 121   this.ylabels = [];
 122   this.annotations = [];
 123   this.chartLabels = {};
 124 };
 125
 126
 127 DygraphCanvasRenderer.isSupported = function(canvasName) {
 128   var canvas = null;
 129   try {
 130     if (typeof(canvasName) == 'undefined' || canvasName === null) {
 131       canvas = document.createElement("canvas");
 132     } else {
 133       canvas = canvasName;
 134     }
 135     canvas.getContext("2d");
 136   }
 137   catch (e) {
 138     var ie = navigator.appVersion.match(/MSIE (\d\.\d)/);
 139     var opera = (navigator.userAgent.toLowerCase().indexOf("opera") != -1);
 140     if ((!ie) || (ie[1] < 6) || (opera))
 141       return false;
 142     return true;
 143   }
 144   return true;
 145 };
 146
 147 /**
 148  * @param { [String] } colors Array of color strings. Should have one entry for
 149  * each series to be rendered.
 150  */
 151 DygraphCanvasRenderer.prototype.setColors = function(colors) {
 152   this.colorScheme_ = colors;
 153 };
 154
 155 /**
 156  * Draw an X/Y grid on top of the existing plot
 157  */
 158 DygraphCanvasRenderer.prototype.render = function() {
 159   // Draw the new X/Y grid. Lines appear crisper when pixels are rounded to
 160   // half-integers. This prevents them from drawing in two rows/cols.
 161   var ctx = this.elementContext;
 162   function halfUp(x)  { return Math.round(x) + 0.5; }
 163   function halfDown(y){ return Math.round(y) - 0.5; }
 164
 165   if (this.attr_('underlayCallback')) {
 166     // NOTE: we pass the dygraph object to this callback twice to avoid breaking
 167     // users who expect a deprecated form of this callback.
 168     this.attr_('underlayCallback')(ctx, this.area, this.dygraph_, this.dygraph_);
 169   }
 170
 171   var x, y, i, ticks;
 172   if (this.attr_('drawYGrid')) {
 173     ticks = this.layout.yticks;
 174     // TODO(konigsberg): I don't think these calls to save() have a corresponding restore().
 175     ctx.save();
 176     ctx.strokeStyle = this.attr_('gridLineColor');
 177     ctx.lineWidth = this.attr_('gridLineWidth');
 178     for (i = 0; i < ticks.length; i++) {
 179       // TODO(danvk): allow secondary axes to draw a grid, too.
 180       if (ticks[i][0] !== 0) continue;
 181       x = halfUp(this.area.x);
 182       y = halfDown(this.area.y + ticks[i][1] * this.area.h);
 183       ctx.beginPath();
 184       ctx.moveTo(x, y);
 185       ctx.lineTo(x + this.area.w, y);
 186       ctx.closePath();
 187       ctx.stroke();
 188     }
 189     ctx.restore();
 190   }
 191
 192   if (this.attr_('drawXGrid')) {
 193     ticks = this.layout.xticks;
 194     ctx.save();
 195     ctx.strokeStyle = this.attr_('gridLineColor');
 196     ctx.lineWidth = this.attr_('gridLineWidth');
 197     for (i=0; i<ticks.length; i++) {
 198       x = halfUp(this.area.x + ticks[i][0] * this.area.w);
 199       y = halfDown(this.area.y + this.area.h);
 200       ctx.beginPath();
 201       ctx.moveTo(x, y);
 202       ctx.lineTo(x, this.area.y);
 203       ctx.closePath();
 204       ctx.stroke();
 205     }
 206     ctx.restore();
 207   }
 208
 209   // Do the ordinary rendering, as before
 210   this._renderLineChart();
 211   this._renderAxis();
 212   this._renderChartLabels();
 213   this._renderAnnotations();
 214 };
 215
 216 DygraphCanvasRenderer.prototype._createIEClipArea = function() {
 217   var className = 'dygraph-clip-div';
 218   var graphDiv = this.dygraph_.graphDiv;
 219
 220   // Remove old clip divs.
 221   for (var i = graphDiv.childNodes.length-1; i >= 0; i--) {
 222     if (graphDiv.childNodes[i].className == className) {
 223       graphDiv.removeChild(graphDiv.childNodes[i]);
 224     }
 225   }
 226
 227   // Determine background color to give clip divs.
 228   var backgroundColor = document.bgColor;
 229   var element = this.dygraph_.graphDiv;
 230   while (element != document) {
 231     var bgcolor = element.currentStyle.backgroundColor;
 232     if (bgcolor && bgcolor != 'transparent') {
 233       backgroundColor = bgcolor;
 234       break;
 235     }
 236     element = element.parentNode;
 237   }
 238
 239   function createClipDiv(area) {
 240     if (area.w === 0 || area.h === 0) {
 241       return;
 242     }
 243     var elem = document.createElement('div');
 244     elem.className = className;
 245     elem.style.backgroundColor = backgroundColor;
 246     elem.style.position = 'absolute';
 247     elem.style.left = area.x + 'px';
 248     elem.style.top = area.y + 'px';
 249     elem.style.width = area.w + 'px';
 250     elem.style.height = area.h + 'px';
 251     graphDiv.appendChild(elem);
 252   }
 253
 254   var plotArea = this.area;
 255   // Left side
 256   createClipDiv({
 257     x:0, y:0,
 258     w:plotArea.x,
 259     h:this.height
 260   });
 261
 262   // Top
 263   createClipDiv({
 264     x: plotArea.x, y: 0,
 265     w: this.width - plotArea.x,
 266     h: plotArea.y
 267   });
 268
 269   // Right side
 270   createClipDiv({
 271     x: plotArea.x + plotArea.w, y: 0,
 272     w: this.width-plotArea.x - plotArea.w,
 273     h: this.height
 274   });
 275
 276   // Bottom
 277   createClipDiv({
 278     x: plotArea.x,
 279     y: plotArea.y + plotArea.h,
 280     w: this.width - plotArea.x,
 281     h: this.height - plotArea.h - plotArea.y
 282   });
 283 };
 284
 285 DygraphCanvasRenderer.prototype._renderAxis = function() {
 286   if (!this.attr_('drawXAxis') && !this.attr_('drawYAxis')) return;
 287
 288   // Round pixels to half-integer boundaries for crisper drawing.
 289   function halfUp(x)  { return Math.round(x) + 0.5; }
 290   function halfDown(y){ return Math.round(y) - 0.5; }
 291
 292   var context = this.elementContext;
 293
 294   var label, x, y, tick, i;
 295
 296   var labelStyle = {
 297     position: "absolute",
 298     fontSize: this.attr_('axisLabelFontSize') + "px",
 299     zIndex: 10,
 300     color: this.attr_('axisLabelColor'),
 301     width: this.attr_('axisLabelWidth') + "px",
 302     // height: this.attr_('axisLabelFontSize') + 2 + "px",
 303     lineHeight: "normal",  // Something other than "normal" line-height screws up label positioning.
 304     overflow: "hidden"
 305   };
 306   var makeDiv = function(txt, axis, prec_axis) {
 307     var div = document.createElement("div");
 308     for (var name in labelStyle) {
 309       if (labelStyle.hasOwnProperty(name)) {
 310         div.style[name] = labelStyle[name];
 311       }
 312     }
 313     var inner_div = document.createElement("div");
 314     inner_div.className = 'dygraph-axis-label' +
 315                           ' dygraph-axis-label-' + axis +
 316                           (prec_axis ? ' dygraph-axis-label-' + prec_axis : '');
 317     inner_div.innerHTML=txt;
 318     div.appendChild(inner_div);
 319     return div;
 320   };
 321
 322   // axis lines
 323   context.save();
 324   context.strokeStyle = this.attr_('axisLineColor');
 325   context.lineWidth = this.attr_('axisLineWidth');
 326
 327   if (this.attr_('drawYAxis')) {
 328     if (this.layout.yticks && this.layout.yticks.length > 0) {
 329       var num_axes = this.dygraph_.numAxes();
 330       for (i = 0; i < this.layout.yticks.length; i++) {
 331         tick = this.layout.yticks[i];
 332         if (typeof(tick) == "function") return;
 333         x = this.area.x;
 334         var sgn = 1;
 335         var prec_axis = 'y1';
 336         if (tick[0] == 1) {  // right-side y-axis
 337           x = this.area.x + this.area.w;
 338           sgn = -1;
 339           prec_axis = 'y2';
 340         }
 341         y = this.area.y + tick[1] * this.area.h;
 342
 343         /* Tick marks are currently clipped, so don't bother drawing them.
 344         context.beginPath();
 345         context.moveTo(halfUp(x), halfDown(y));
 346         context.lineTo(halfUp(x - sgn * this.attr_('axisTickSize')), halfDown(y));
 347         context.closePath();
 348         context.stroke();
 349         */
 350
 351         label = makeDiv(tick[2], 'y', num_axes == 2 ? prec_axis : null);
 352         var top = (y - this.attr_('axisLabelFontSize') / 2);
 353         if (top < 0) top = 0;
 354
 355         if (top + this.attr_('axisLabelFontSize') + 3 > this.height) {
 356           label.style.bottom = "0px";
 357         } else {
 358           label.style.top = top + "px";
 359         }
 360         if (tick[0] === 0) {
 361           label.style.left = (this.area.x - this.attr_('yAxisLabelWidth') - this.attr_('axisTickSize')) + "px";
 362           label.style.textAlign = "right";
 363         } else if (tick[0] == 1) {
 364           label.style.left = (this.area.x + this.area.w +
 365                               this.attr_('axisTickSize')) + "px";
 366           label.style.textAlign = "left";
 367         }
 368         label.style.width = this.attr_('yAxisLabelWidth') + "px";
 369         this.container.appendChild(label);
 370         this.ylabels.push(label);
 371       }
 372
 373       // The lowest tick on the y-axis often overlaps with the leftmost
 374       // tick on the x-axis. Shift the bottom tick up a little bit to
 375       // compensate if necessary.
 376       var bottomTick = this.ylabels[0];
 377       var fontSize = this.attr_('axisLabelFontSize');
 378       var bottom = parseInt(bottomTick.style.top, 10) + fontSize;
 379       if (bottom > this.height - fontSize) {
 380         bottomTick.style.top = (parseInt(bottomTick.style.top, 10) -
 381             fontSize / 2) + "px";
 382       }
 383     }
 384
 385     // draw a vertical line on the left to separate the chart from the labels.
 386     context.beginPath();
 387     context.moveTo(halfUp(this.area.x), halfDown(this.area.y));
 388     context.lineTo(halfUp(this.area.x), halfDown(this.area.y + this.area.h));
 389     context.closePath();
 390     context.stroke();
 391
 392     // if there's a secondary y-axis, draw a vertical line for that, too.
 393     if (this.dygraph_.numAxes() == 2) {
 394       context.beginPath();
 395       context.moveTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y));
 396       context.lineTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
 397       context.closePath();
 398       context.stroke();
 399     }
 400   }
 401
 402   if (this.attr_('drawXAxis')) {
 403     if (this.layout.xticks) {
 404       for (i = 0; i < this.layout.xticks.length; i++) {
 405         tick = this.layout.xticks[i];
 406         x = this.area.x + tick[0] * this.area.w;
 407         y = this.area.y + this.area.h;
 408
 409         /* Tick marks are currently clipped, so don't bother drawing them.
 410         context.beginPath();
 411         context.moveTo(halfUp(x), halfDown(y));
 412         context.lineTo(halfUp(x), halfDown(y + this.attr_('axisTickSize')));
 413         context.closePath();
 414         context.stroke();
 415         */
 416
 417         label = makeDiv(tick[1], 'x');
 418         label.style.textAlign = "center";
 419         label.style.top = (y + this.attr_('axisTickSize')) + 'px';
 420
 421         var left = (x - this.attr_('axisLabelWidth')/2);
 422         if (left + this.attr_('axisLabelWidth') > this.width) {
 423           left = this.width - this.attr_('xAxisLabelWidth');
 424           label.style.textAlign = "right";
 425         }
 426         if (left < 0) {
 427           left = 0;
 428           label.style.textAlign = "left";
 429         }
 430
 431         label.style.left = left + "px";
 432         label.style.width = this.attr_('xAxisLabelWidth') + "px";
 433         this.container.appendChild(label);
 434         this.xlabels.push(label);
 435       }
 436     }
 437
 438     context.beginPath();
 439     context.moveTo(halfUp(this.area.x), halfDown(this.area.y + this.area.h));
 440     context.lineTo(halfUp(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
 441     context.closePath();
 442     context.stroke();
 443   }
 444
 445   context.restore();
 446 };
 447
 448
 449 DygraphCanvasRenderer.prototype._renderChartLabels = function() {
 450   var div, class_div;
 451
 452   // Generate divs for the chart title, xlabel and ylabel.
 453   // Space for these divs has already been taken away from the charting area in
 454   // the DygraphCanvasRenderer constructor.
 455   if (this.attr_('title')) {
 456     div = document.createElement("div");
 457     div.style.position = 'absolute';
 458     div.style.top = '0px';
 459     div.style.left = this.area.x + 'px';
 460     div.style.width = this.area.w + 'px';
 461     div.style.height = this.attr_('titleHeight') + 'px';
 462     div.style.textAlign = 'center';
 463     div.style.fontSize = (this.attr_('titleHeight') - 8) + 'px';
 464     div.style.fontWeight = 'bold';
 465     class_div = document.createElement("div");
 466     class_div.className = 'dygraph-label dygraph-title';
 467     class_div.innerHTML = this.attr_('title');
 468     div.appendChild(class_div);
 469     this.container.appendChild(div);
 470     this.chartLabels.title = div;
 471   }
 472
 473   if (this.attr_('xlabel')) {
 474     div = document.createElement("div");
 475     div.style.position = 'absolute';
 476     div.style.bottom = 0;  // TODO(danvk): this is lazy. Calculate style.top.
 477     div.style.left = this.area.x + 'px';
 478     div.style.width = this.area.w + 'px';
 479     div.style.height = this.attr_('xLabelHeight') + 'px';
 480     div.style.textAlign = 'center';
 481     div.style.fontSize = (this.attr_('xLabelHeight') - 2) + 'px';
 482
 483     class_div = document.createElement("div");
 484     class_div.className = 'dygraph-label dygraph-xlabel';
 485     class_div.innerHTML = this.attr_('xlabel');
 486     div.appendChild(class_div);
 487     this.container.appendChild(div);
 488     this.chartLabels.xlabel = div;
 489   }
 490
 491   var that = this;
 492   function createRotatedDiv(axis, classes, html) {
 493     var box = {
 494       left: 0,
 495       top: that.area.y,
 496       width: that.attr_('yLabelWidth'),
 497       height: that.area.h
 498     };
 499     // TODO(danvk): is this outer div actually necessary?
 500     div = document.createElement("div");
 501     div.style.position = 'absolute';
 502     if (axis == 1) {
 503       div.style.left = box.left;
 504     } else {
 505       div.style.right = box.left;
 506     }
 507     div.style.top = box.top + 'px';
 508     div.style.width = box.width + 'px';
 509     div.style.height = box.height + 'px';
 510     div.style.fontSize = (that.attr_('yLabelWidth') - 2) + 'px';
 511
 512     var inner_div = document.createElement("div");
 513     inner_div.style.position = 'absolute';
 514     inner_div.style.width = box.height + 'px';
 515     inner_div.style.height = box.width + 'px';
 516     inner_div.style.top = (box.height / 2 - box.width / 2) + 'px';
 517     inner_div.style.left = (box.width / 2 - box.height / 2) + 'px';
 518     inner_div.style.textAlign = 'center';
 519
 520     // CSS rotation is an HTML5 feature which is not standardized. Hence every
 521     // browser has its own name for the CSS style.
 522     var val = 'rotate(' + (axis == 1 ? '-' : '') + '90deg)';
 523     inner_div.style.transform = val;        // HTML5
 524     inner_div.style.WebkitTransform = val;  // Safari/Chrome
 525     inner_div.style.MozTransform = val;     // Firefox
 526     inner_div.style.OTransform = val;       // Opera
 527     inner_div.style.msTransform = val;      // IE9
 528
 529     if (typeof(document.documentMode) !== 'undefined' &&
 530         document.documentMode < 9) {
 531       // We're dealing w/ an old version of IE, so we have to rotate the text
 532       // using a BasicImage transform. This uses a different origin of rotation
 533       // than HTML5 rotation (top left of div vs. its center).
 534       inner_div.style.filter =
 535           'progid:DXImageTransform.Microsoft.BasicImage(rotation=' +
 536           (axis == 1 ? '3' : '1') + ')';
 537       inner_div.style.left = '0px';
 538       inner_div.style.top = '0px';
 539     }
 540
 541     class_div = document.createElement("div");
 542     class_div.className = classes;
 543     class_div.innerHTML = html;
 544
 545     inner_div.appendChild(class_div);
 546     div.appendChild(inner_div);
 547     return div;
 548   }
 549
 550   var div;
 551   if (this.attr_('ylabel')) {
 552     div = createRotatedDiv(1, 'dygraph-label dygraph-ylabel',
 553                            this.attr_('ylabel'));
 554     this.container.appendChild(div);
 555     this.chartLabels.ylabel = div;
 556   }
 557   if (this.attr_('y2label') && this.dygraph_.numAxes() == 2) {
 558     div = createRotatedDiv(2, 'dygraph-label dygraph-y2label',
 559                            this.attr_('y2label'));
 560     this.container.appendChild(div);
 561     this.chartLabels.y2label = div;
 562   }
 563 };
 564
 565
 566 DygraphCanvasRenderer.prototype._renderAnnotations = function() {
 567   var annotationStyle = {
 568     "position": "absolute",
 569     "fontSize": this.attr_('axisLabelFontSize') + "px",
 570     "zIndex": 10,
 571     "overflow": "hidden"
 572   };
 573
 574   var bindEvt = function(eventName, classEventName, p, self) {
 575     return function(e) {
 576       var a = p.annotation;
 577       if (a.hasOwnProperty(eventName)) {
 578         a[eventName](a, p, self.dygraph_, e);
 579       } else if (self.dygraph_.attr_(classEventName)) {
 580         self.dygraph_.attr_(classEventName)(a, p, self.dygraph_,e );
 581       }
 582     };
 583   };
 584
 585   // Get a list of point with annotations.
 586   var points = this.layout.annotated_points;
 587   for (var i = 0; i < points.length; i++) {
 588     var p = points[i];
 589     if (p.canvasx < this.area.x || p.canvasx > this.area.x + this.area.w) {
 590       continue;
 591     }
 592
 593     var a = p.annotation;
 594     var tick_height = 6;
 595     if (a.hasOwnProperty("tickHeight")) {
 596       tick_height = a.tickHeight;
 597     }
 598
 599     var div = document.createElement("div");
 600     for (var name in annotationStyle) {
 601       if (annotationStyle.hasOwnProperty(name)) {
 602         div.style[name] = annotationStyle[name];
 603       }
 604     }
 605     if (!a.hasOwnProperty('icon')) {
 606       div.className = "dygraphDefaultAnnotation";
 607     }
 608     if (a.hasOwnProperty('cssClass')) {
 609       div.className += " " + a.cssClass;
 610     }
 611
 612     var width = a.hasOwnProperty('width') ? a.width : 16;
 613     var height = a.hasOwnProperty('height') ? a.height : 16;
 614     if (a.hasOwnProperty('icon')) {
 615       var img = document.createElement("img");
 616       img.src = a.icon;
 617       img.width = width;
 618       img.height = height;
 619       div.appendChild(img);
 620     } else if (p.annotation.hasOwnProperty('shortText')) {
 621       div.appendChild(document.createTextNode(p.annotation.shortText));
 622     }
 623     div.style.left = (p.canvasx - width / 2) + "px";
 624     if (a.attachAtBottom) {
 625       div.style.top = (this.area.h - height - tick_height) + "px";
 626     } else {
 627       div.style.top = (p.canvasy - height - tick_height) + "px";
 628     }
 629     div.style.width = width + "px";
 630     div.style.height = height + "px";
 631     div.title = p.annotation.text;
 632     div.style.color = this.colors[p.name];
 633     div.style.borderColor = this.colors[p.name];
 634     a.div = div;
 635
 636     Dygraph.addEvent(div, 'click',
 637         bindEvt('clickHandler', 'annotationClickHandler', p, this));
 638     Dygraph.addEvent(div, 'mouseover',
 639         bindEvt('mouseOverHandler', 'annotationMouseOverHandler', p, this));
 640     Dygraph.addEvent(div, 'mouseout',
 641         bindEvt('mouseOutHandler', 'annotationMouseOutHandler', p, this));
 642     Dygraph.addEvent(div, 'dblclick',
 643         bindEvt('dblClickHandler', 'annotationDblClickHandler', p, this));
 644
 645     this.container.appendChild(div);
 646     this.annotations.push(div);
 647
 648     var ctx = this.elementContext;
 649     ctx.strokeStyle = this.colors[p.name];
 650     ctx.beginPath();
 651     if (!a.attachAtBottom) {
 652       ctx.moveTo(p.canvasx, p.canvasy);
 653       ctx.lineTo(p.canvasx, p.canvasy - 2 - tick_height);
 654     } else {
 655       ctx.moveTo(p.canvasx, this.area.h);
 656       ctx.lineTo(p.canvasx, this.area.h - 2 - tick_height);
 657     }
 658     ctx.closePath();
 659     ctx.stroke();
 660   }
 661 };
 662
 663 DygraphCanvasRenderer.makeNextPointStep_ = function(connect, points, end) {
 664   if (connect) {
 665     return function(j) {
 666       while (++j < end) {
 667         if (!(points[j].yval === null)) break;
 668       }
 669       return j;
 670     }
 671   } else {
 672     return function(j) { return j + 1 };
 673   }
 674 };
 675
 676 DygraphCanvasRenderer.prototype._drawStyledLine = function(
 677     ctx, i, setName, color, strokeWidth, strokePattern, drawPoints,
 678     drawPointCallback, pointSize) {
 679   var isNullOrNaN = function(x) {
 680     return (x === null || isNaN(x));
 681   };
 682
 683   var stepPlot = this.attr_("stepPlot");
 684   var firstIndexInSet = this.layout.setPointsOffsets[i];
 685   var setLength = this.layout.setPointsLengths[i];
 686   var afterLastIndexInSet = firstIndexInSet + setLength;
 687   var points = this.layout.points;
 688   var prevX = null;
 689   var prevY = null;
 690   var pointsOnLine = []; // Array of [canvasx, canvasy] pairs.
 691   if (!Dygraph.isArrayLike(strokePattern)) {
 692     strokePattern = null;
 693   }
 694
 695   var point;
 696   var next = DygraphCanvasRenderer.makeNextPointStep_(
 697       this.attr_('connectSeparatedPoints'), points, afterLastIndexInSet);
 698   ctx.save();
 699   for (var j = firstIndexInSet; j < afterLastIndexInSet; j = next(j)) {
 700     point = points[j];
 701     if (isNullOrNaN(point.canvasy)) {
 702       if (stepPlot && prevX !== null) {
 703         // Draw a horizontal line to the start of the missing data
 704         ctx.beginPath();
 705         ctx.strokeStyle = color;
 706         ctx.lineWidth = this.attr_('strokeWidth');
 707         this._dashedLine(ctx, prevX, prevY, point.canvasx, prevY, strokePattern);
 708         ctx.stroke();
 709       }
 710       // this will make us move to the next point, not draw a line to it.
 711       prevX = prevY = null;
 712     } else {
 713       // A point is "isolated" if it is non-null but both the previous
 714       // and next points are null.
 715       var isIsolated = (!prevX && (j == points.length - 1 ||
 716                                    isNullOrNaN(points[j+1].canvasy)));
 717       if (prevX === null) {
 718         prevX = point.canvasx;
 719         prevY = point.canvasy;
 720       } else {
 721         // Skip over points that will be drawn in the same pixel.
 722         if (Math.round(prevX) == Math.round(point.canvasx) &&
 723             Math.round(prevY) == Math.round(point.canvasy)) {
 724           continue;
 725         }
 726         // TODO(antrob): skip over points that lie on a line that is already
 727         // going to be drawn. There is no need to have more than 2
 728         // consecutive points that are collinear.
 729         if (strokeWidth) {
 730           ctx.beginPath();
 731           ctx.strokeStyle = color;
 732           ctx.lineWidth = strokeWidth;
 733           if (stepPlot) {
 734             this._dashedLine(ctx, prevX, prevY, point.canvasx, prevY, strokePattern);
 735             prevX = point.canvasx;
 736           }
 737           this._dashedLine(ctx, prevX, prevY, point.canvasx, point.canvasy, strokePattern);
 738           prevX = point.canvasx;
 739           prevY = point.canvasy;
 740           ctx.stroke();
 741         }
 742       }
 743
 744       if (drawPoints || isIsolated) {
 745         pointsOnLine.push([point.canvasx, point.canvasy]);
 746       }
 747     }
 748   }
 749   for (var idx = 0; idx < pointsOnLine.length; idx++) {
 750     var cb = pointsOnLine[idx];
 751     ctx.save();
 752     drawPointCallback(
 753         this.dygraph_, setName, ctx, cb[0], cb[1], color, pointSize);
 754     ctx.restore();
 755   }
 756   ctx.restore();
 757 };
 758
 759 DygraphCanvasRenderer.prototype._drawLine = function(ctx, i) {
 760   var setNames = this.layout.setNames;
 761   var setName = setNames[i];
 762
 763   var strokeWidth = this.dygraph_.attr_("strokeWidth", setName);
 764   var borderWidth = this.dygraph_.attr_("strokeBorderWidth", setName);
 765   var drawPointCallback = this.dygraph_.attr_("drawPointCallback", setName) ||
 766       Dygraph.Circles.DEFAULT;
 767   if (borderWidth && strokeWidth) {
 768     this._drawStyledLine(ctx, i, setName,
 769         this.dygraph_.attr_("strokeBorderColor", setName),
 770         strokeWidth + 2 * borderWidth,
 771         this.dygraph_.attr_("strokePattern", setName),
 772         this.dygraph_.attr_("drawPoints", setName),
 773         drawPointCallback,
 774         this.dygraph_.attr_("pointSize", setName));
 775   }
 776
 777   this._drawStyledLine(ctx, i, setName,
 778       this.colors[setName],
 779       strokeWidth,
 780       this.dygraph_.attr_("strokePattern", setName),
 781       this.dygraph_.attr_("drawPoints", setName),
 782       drawPointCallback,
 783       this.dygraph_.attr_("pointSize", setName));
 784 };
 785
 786 /**
 787  * Actually draw the lines chart, including error bars.
 788  * TODO(danvk): split this into several smaller functions.
 789  * @private
 790  */
 791 DygraphCanvasRenderer.prototype._renderLineChart = function() {
 792   // TODO(danvk): use this.attr_ for many of these.
 793   var ctx = this.elementContext;
 794   var fillAlpha = this.attr_('fillAlpha');
 795   var errorBars = this.attr_("errorBars") || this.attr_("customBars");
 796   var fillGraph = this.attr_("fillGraph");
 797   var stackedGraph = this.attr_("stackedGraph");
 798   var stepPlot = this.attr_("stepPlot");
 799   var points = this.layout.points;
 800   var pointsLength = points.length;
 801   var point, i, j, prevX, prevY, prevYs, color, setName, newYs, err_color, rgb, yscale, axis;
 802
 803   var setNames = this.layout.setNames;
 804   var setCount = setNames.length;
 805
 806   // TODO(danvk): Move this mapping into Dygraph and get it out of here.
 807   this.colors = {};
 808   for (i = 0; i < setCount; i++) {
 809     this.colors[setNames[i]] = this.colorScheme_[i % this.colorScheme_.length];
 810   }
 811
 812   // Update Points
 813   // TODO(danvk): here
 814   for (i = pointsLength; i--;) {
 815     point = points[i];
 816     point.canvasx = this.area.w * point.x + this.area.x;
 817     point.canvasy = this.area.h * point.y + this.area.y;
 818   }
 819
 820   // create paths
 821   if (errorBars) {
 822     ctx.save();
 823     if (fillGraph) {
 824       this.dygraph_.warn("Can't use fillGraph option with error bars");
 825     }
 826
 827     for (i = 0; i < setCount; i++) {
 828       setName = setNames[i];
 829       axis = this.dygraph_.axisPropertiesForSeries(setName);
 830       color = this.colors[setName];
 831
 832       var firstIndexInSet = this.layout.setPointsOffsets[i];
 833       var setLength = this.layout.setPointsLengths[i];
 834       var afterLastIndexInSet = firstIndexInSet + setLength;
 835
 836       var next = DygraphCanvasRenderer.makeNextPointStep_(
 837         this.attr_('connectSeparatedPoints'), points,
 838         afterLastIndexInSet);
 839
 840       // setup graphics context
 841       prevX = NaN;
 842       prevY = NaN;
 843       prevYs = [-1, -1];
 844       yscale = axis.yscale;
 845       // should be same color as the lines but only 15% opaque.
 846       rgb = new RGBColor(color);
 847       err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 848                             fillAlpha + ')';
 849       ctx.fillStyle = err_color;
 850       ctx.beginPath();
 851       for (j = firstIndexInSet; j < afterLastIndexInSet; j = next(j)) {
 852         point = points[j];
 853         if (point.name == setName) { // TODO(klausw): this is always true
 854           if (!Dygraph.isOK(point.y)) {
 855             prevX = NaN;
 856             continue;
 857           }
 858
 859           // TODO(danvk): here
 860           if (stepPlot) {
 861             newYs = [ point.y_bottom, point.y_top ];
 862             prevY = point.y;
 863           } else {
 864             newYs = [ point.y_bottom, point.y_top ];
 865           }
 866           newYs[0] = this.area.h * newYs[0] + this.area.y;
 867           newYs[1] = this.area.h * newYs[1] + this.area.y;
 868           if (!isNaN(prevX)) {
 869             if (stepPlot) {
 870               ctx.moveTo(prevX, newYs[0]);
 871             } else {
 872               ctx.moveTo(prevX, prevYs[0]);
 873             }
 874             ctx.lineTo(point.canvasx, newYs[0]);
 875             ctx.lineTo(point.canvasx, newYs[1]);
 876             if (stepPlot) {
 877               ctx.lineTo(prevX, newYs[1]);
 878             } else {
 879               ctx.lineTo(prevX, prevYs[1]);
 880             }
 881             ctx.closePath();
 882           }
 883           prevYs = newYs;
 884           prevX = point.canvasx;
 885         }
 886       }
 887       ctx.fill();
 888     }
 889     ctx.restore();
 890   } else if (fillGraph) {
 891     ctx.save();
 892     var baseline = [];  // for stacked graphs: baseline for filling
 893
 894     // process sets in reverse order (needed for stacked graphs)
 895     for (i = setCount - 1; i >= 0; i--) {
 896       setName = setNames[i];
 897       color = this.colors[setName];
 898       axis = this.dygraph_.axisPropertiesForSeries(setName);
 899       var axisY = 1.0 + axis.minyval * axis.yscale;
 900       if (axisY < 0.0) axisY = 0.0;
 901       else if (axisY > 1.0) axisY = 1.0;
 902       axisY = this.area.h * axisY + this.area.y;
 903       var firstIndexInSet = this.layout.setPointsOffsets[i];
 904       var setLength = this.layout.setPointsLengths[i];
 905       var afterLastIndexInSet = firstIndexInSet + setLength;
 906
 907       var next = DygraphCanvasRenderer.makeNextPointStep_(
 908         this.attr_('connectSeparatedPoints'), points,
 909         afterLastIndexInSet);
 910
 911       // setup graphics context
 912       prevX = NaN;
 913       prevYs = [-1, -1];
 914       yscale = axis.yscale;
 915       // should be same color as the lines but only 15% opaque.
 916       rgb = new RGBColor(color);
 917       err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 918                             fillAlpha + ')';
 919       ctx.fillStyle = err_color;
 920       ctx.beginPath();
 921       for (j = firstIndexInSet; j < afterLastIndexInSet; j = next(j)) {
 922         point = points[j];
 923         if (point.name == setName) { // TODO(klausw): this is always true
 924           if (!Dygraph.isOK(point.y)) {
 925             prevX = NaN;
 926             continue;
 927           }
 928           if (stackedGraph) {
 929             var lastY = baseline[point.canvasx];
 930             if (lastY === undefined) lastY = axisY;
 931             baseline[point.canvasx] = point.canvasy;
 932             newYs = [ point.canvasy, lastY ];
 933           } else {
 934             newYs = [ point.canvasy, axisY ];
 935           }
 936           if (!isNaN(prevX)) {
 937             ctx.moveTo(prevX, prevYs[0]);
 938             if (stepPlot) {
 939               ctx.lineTo(point.canvasx, prevYs[0]);
 940             } else {
 941               ctx.lineTo(point.canvasx, newYs[0]);
 942             }
 943             ctx.lineTo(point.canvasx, newYs[1]);
 944             ctx.lineTo(prevX, prevYs[1]);
 945             ctx.closePath();
 946           }
 947           prevYs = newYs;
 948           prevX = point.canvasx;
 949         }
 950       }
 951       ctx.fill();
 952     }
 953     ctx.restore();
 954   }
 955
 956   // Drawing the lines.
 957   for (i = 0; i < setCount; i += 1) {
 958     this._drawLine(ctx, i);
 959   }
 960 };
 961
 962 /**
 963  * This does dashed lines onto a canvas for a given pattern. You must call
 964  * ctx.stroke() after to actually draw it, much line ctx.lineTo(). It remembers
 965  * the state of the line in regards to where we left off on drawing the pattern.
 966  * You can draw a dashed line in several function calls and the pattern will be
 967  * continous as long as you didn't call this function with a different pattern
 968  * in between.
 969  * @param ctx The canvas 2d context to draw on.
 970  * @param x The start of the line's x coordinate.
 971  * @param y The start of the line's y coordinate.
 972  * @param x2 The end of the line's x coordinate.
 973  * @param y2 The end of the line's y coordinate.
 974  * @param pattern The dash pattern to draw, an array of integers where even
 975  * index is drawn and odd index is not drawn (Ex. [10, 2, 5, 2], 10 is drawn 5
 976  * is drawn, 2 is the space between.). A null pattern, array of length one, or
 977  * empty array will do just a solid line.
 978  * @private
 979  */
 980 DygraphCanvasRenderer.prototype._dashedLine = function(ctx, x, y, x2, y2, pattern) {
 981   // Original version http://stackoverflow.com/questions/4576724/dotted-stroke-in-canvas
 982   // Modified by Russell Valentine to keep line history and continue the pattern
 983   // where it left off.
 984   var dx, dy, len, rot, patternIndex, segment;
 985
 986   // If we don't have a pattern or it is an empty array or of size one just
 987   // do a solid line.
 988   if (!pattern || pattern.length <= 1) {
 989     ctx.moveTo(x, y);
 990     ctx.lineTo(x2, y2);
 991     return;
 992   }
 993
 994   // If we have a different dash pattern than the last time this was called we
 995   // reset our dash history and start the pattern from the begging
 996   // regardless of state of the last pattern.
 997   if (!Dygraph.compareArrays(pattern, this._dashedLineToHistoryPattern)) {
 998     this._dashedLineToHistoryPattern = pattern;
 999     this._dashedLineToHistory = [0, 0];
1000   }
1001   ctx.save();
1002
1003   // Calculate transformation parameters
1004   dx = (x2-x);
1005   dy = (y2-y);
1006   len = Math.sqrt(dx*dx + dy*dy);
1007   rot = Math.atan2(dy, dx);
1008
1009   // Set transformation
1010   ctx.translate(x, y);
1011   ctx.moveTo(0, 0);
1012   ctx.rotate(rot);
1013
1014   // Set last pattern index we used for this pattern.
1015   patternIndex = this._dashedLineToHistory[0];
1016   x = 0;
1017   while (len > x) {
1018     // Get the length of the pattern segment we are dealing with.
1019     segment = pattern[patternIndex];
1020     // If our last draw didn't complete the pattern segment all the way we
1021     // will try to finish it. Otherwise we will try to do the whole segment.
1022     if (this._dashedLineToHistory[1]) {
1023       x += this._dashedLineToHistory[1];
1024     } else {
1025       x += segment;
1026     }
1027     if (x > len) {
1028       // We were unable to complete this pattern index all the way, keep
1029       // where we are the history so our next draw continues where we left off
1030       // in the pattern.
1031       this._dashedLineToHistory = [patternIndex, x-len];
1032       x = len;
1033     } else {
1034       // We completed this patternIndex, we put in the history that we are on
1035       // the beginning of the next segment.
1036       this._dashedLineToHistory = [(patternIndex+1)%pattern.length, 0];
1037     }
1038
1039     // We do a line on a even pattern index and just move on a odd pattern index.
1040     // The move is the empty space in the dash.
1041     if(patternIndex % 2 === 0) {
1042       ctx.lineTo(x, 0);
1043     } else {
1044       ctx.moveTo(x, 0);
1045     }
1046     // If we are not done, next loop process the next pattern segment, or the
1047     // first segment again if we are at the end of the pattern.
1048     patternIndex = (patternIndex+1) % pattern.length;
1049   }
1050   ctx.restore();
1051 };