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   }
 190
 191   if (this.attr_('drawXGrid')) {
 192     ticks = this.layout.xticks;
 193     ctx.save();
 194     ctx.strokeStyle = this.attr_('gridLineColor');
 195     ctx.lineWidth = this.attr_('gridLineWidth');
 196     for (i=0; i<ticks.length; i++) {
 197       x = halfUp(this.area.x + ticks[i][0] * this.area.w);
 198       y = halfDown(this.area.y + this.area.h);
 199       ctx.beginPath();
 200       ctx.moveTo(x, y);
 201       ctx.lineTo(x, this.area.y);
 202       ctx.closePath();
 203       ctx.stroke();
 204     }
 205   }
 206
 207   // Do the ordinary rendering, as before
 208   this._renderLineChart();
 209   this._renderAxis();
 210   this._renderChartLabels();
 211   this._renderAnnotations();
 212 };
 213
 214 DygraphCanvasRenderer.prototype._createIEClipArea = function() {
 215   var className = 'dygraph-clip-div';
 216   var graphDiv = this.dygraph_.graphDiv;
 217
 218   // Remove old clip divs.
 219   for (var i = graphDiv.childNodes.length-1; i >= 0; i--) {
 220     if (graphDiv.childNodes[i].className == className) {
 221       graphDiv.removeChild(graphDiv.childNodes[i]);
 222     }
 223   }
 224
 225   // Determine background color to give clip divs.
 226   var backgroundColor = document.bgColor;
 227   var element = this.dygraph_.graphDiv;
 228   while (element != document) {
 229     var bgcolor = element.currentStyle.backgroundColor;
 230     if (bgcolor && bgcolor != 'transparent') {
 231       backgroundColor = bgcolor;
 232       break;
 233     }
 234     element = element.parentNode;
 235   }
 236
 237   function createClipDiv(area) {
 238     if (area.w === 0 || area.h === 0) {
 239       return;
 240     }
 241     var elem = document.createElement('div');
 242     elem.className = className;
 243     elem.style.backgroundColor = backgroundColor;
 244     elem.style.position = 'absolute';
 245     elem.style.left = area.x + 'px';
 246     elem.style.top = area.y + 'px';
 247     elem.style.width = area.w + 'px';
 248     elem.style.height = area.h + 'px';
 249     graphDiv.appendChild(elem);
 250   }
 251
 252   var plotArea = this.area;
 253   // Left side
 254   createClipDiv({
 255     x:0, y:0,
 256     w:plotArea.x,
 257     h:this.height
 258   });
 259
 260   // Top
 261   createClipDiv({
 262     x: plotArea.x, y: 0,
 263     w: this.width - plotArea.x,
 264     h: plotArea.y
 265   });
 266
 267   // Right side
 268   createClipDiv({
 269     x: plotArea.x + plotArea.w, y: 0,
 270     w: this.width-plotArea.x - plotArea.w,
 271     h: this.height
 272   });
 273
 274   // Bottom
 275   createClipDiv({
 276     x: plotArea.x,
 277     y: plotArea.y + plotArea.h,
 278     w: this.width - plotArea.x,
 279     h: this.height - plotArea.h - plotArea.y
 280   });
 281 };
 282
 283 DygraphCanvasRenderer.prototype._renderAxis = function() {
 284   if (!this.attr_('drawXAxis') && !this.attr_('drawYAxis')) return;
 285
 286   // Round pixels to half-integer boundaries for crisper drawing.
 287   function halfUp(x)  { return Math.round(x) + 0.5; }
 288   function halfDown(y){ return Math.round(y) - 0.5; }
 289
 290   var context = this.elementContext;
 291
 292   var label, x, y, tick, i;
 293
 294   var labelStyle = {
 295     position: "absolute",
 296     fontSize: this.attr_('axisLabelFontSize') + "px",
 297     zIndex: 10,
 298     color: this.attr_('axisLabelColor'),
 299     width: this.attr_('axisLabelWidth') + "px",
 300     // height: this.attr_('axisLabelFontSize') + 2 + "px",
 301     lineHeight: "normal",  // Something other than "normal" line-height screws up label positioning.
 302     overflow: "hidden"
 303   };
 304   var makeDiv = function(txt, axis, prec_axis) {
 305     var div = document.createElement("div");
 306     for (var name in labelStyle) {
 307       if (labelStyle.hasOwnProperty(name)) {
 308         div.style[name] = labelStyle[name];
 309       }
 310     }
 311     var inner_div = document.createElement("div");
 312     inner_div.className = 'dygraph-axis-label' +
 313                           ' dygraph-axis-label-' + axis +
 314                           (prec_axis ? ' dygraph-axis-label-' + prec_axis : '');
 315     inner_div.innerHTML=txt;
 316     div.appendChild(inner_div);
 317     return div;
 318   };
 319
 320   // axis lines
 321   context.save();
 322   context.strokeStyle = this.attr_('axisLineColor');
 323   context.lineWidth = this.attr_('axisLineWidth');
 324
 325   if (this.attr_('drawYAxis')) {
 326     if (this.layout.yticks && this.layout.yticks.length > 0) {
 327       var num_axes = this.dygraph_.numAxes();
 328       for (i = 0; i < this.layout.yticks.length; i++) {
 329         tick = this.layout.yticks[i];
 330         if (typeof(tick) == "function") return;
 331         x = this.area.x;
 332         var sgn = 1;
 333         var prec_axis = 'y1';
 334         if (tick[0] == 1) {  // right-side y-axis
 335           x = this.area.x + this.area.w;
 336           sgn = -1;
 337           prec_axis = 'y2';
 338         }
 339         y = this.area.y + tick[1] * this.area.h;
 340
 341         /* Tick marks are currently clipped, so don't bother drawing them.
 342         context.beginPath();
 343         context.moveTo(halfUp(x), halfDown(y));
 344         context.lineTo(halfUp(x - sgn * this.attr_('axisTickSize')), halfDown(y));
 345         context.closePath();
 346         context.stroke();
 347         */
 348
 349         label = makeDiv(tick[2], 'y', num_axes == 2 ? prec_axis : null);
 350         var top = (y - this.attr_('axisLabelFontSize') / 2);
 351         if (top < 0) top = 0;
 352
 353         if (top + this.attr_('axisLabelFontSize') + 3 > this.height) {
 354           label.style.bottom = "0px";
 355         } else {
 356           label.style.top = top + "px";
 357         }
 358         if (tick[0] === 0) {
 359           label.style.left = (this.area.x - this.attr_('yAxisLabelWidth') - this.attr_('axisTickSize')) + "px";
 360           label.style.textAlign = "right";
 361         } else if (tick[0] == 1) {
 362           label.style.left = (this.area.x + this.area.w +
 363                               this.attr_('axisTickSize')) + "px";
 364           label.style.textAlign = "left";
 365         }
 366         label.style.width = this.attr_('yAxisLabelWidth') + "px";
 367         this.container.appendChild(label);
 368         this.ylabels.push(label);
 369       }
 370
 371       // The lowest tick on the y-axis often overlaps with the leftmost
 372       // tick on the x-axis. Shift the bottom tick up a little bit to
 373       // compensate if necessary.
 374       var bottomTick = this.ylabels[0];
 375       var fontSize = this.attr_('axisLabelFontSize');
 376       var bottom = parseInt(bottomTick.style.top, 10) + fontSize;
 377       if (bottom > this.height - fontSize) {
 378         bottomTick.style.top = (parseInt(bottomTick.style.top, 10) -
 379             fontSize / 2) + "px";
 380       }
 381     }
 382
 383     // draw a vertical line on the left to separate the chart from the labels.
 384     context.beginPath();
 385     context.moveTo(halfUp(this.area.x), halfDown(this.area.y));
 386     context.lineTo(halfUp(this.area.x), halfDown(this.area.y + this.area.h));
 387     context.closePath();
 388     context.stroke();
 389
 390     // if there's a secondary y-axis, draw a vertical line for that, too.
 391     if (this.dygraph_.numAxes() == 2) {
 392       context.beginPath();
 393       context.moveTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y));
 394       context.lineTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
 395       context.closePath();
 396       context.stroke();
 397     }
 398   }
 399
 400   if (this.attr_('drawXAxis')) {
 401     if (this.layout.xticks) {
 402       for (i = 0; i < this.layout.xticks.length; i++) {
 403         tick = this.layout.xticks[i];
 404         x = this.area.x + tick[0] * this.area.w;
 405         y = this.area.y + this.area.h;
 406
 407         /* Tick marks are currently clipped, so don't bother drawing them.
 408         context.beginPath();
 409         context.moveTo(halfUp(x), halfDown(y));
 410         context.lineTo(halfUp(x), halfDown(y + this.attr_('axisTickSize')));
 411         context.closePath();
 412         context.stroke();
 413         */
 414
 415         label = makeDiv(tick[1], 'x');
 416         label.style.textAlign = "center";
 417         label.style.top = (y + this.attr_('axisTickSize')) + 'px';
 418
 419         var left = (x - this.attr_('axisLabelWidth')/2);
 420         if (left + this.attr_('axisLabelWidth') > this.width) {
 421           left = this.width - this.attr_('xAxisLabelWidth');
 422           label.style.textAlign = "right";
 423         }
 424         if (left < 0) {
 425           left = 0;
 426           label.style.textAlign = "left";
 427         }
 428
 429         label.style.left = left + "px";
 430         label.style.width = this.attr_('xAxisLabelWidth') + "px";
 431         this.container.appendChild(label);
 432         this.xlabels.push(label);
 433       }
 434     }
 435
 436     context.beginPath();
 437     context.moveTo(halfUp(this.area.x), halfDown(this.area.y + this.area.h));
 438     context.lineTo(halfUp(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
 439     context.closePath();
 440     context.stroke();
 441   }
 442
 443   context.restore();
 444 };
 445
 446
 447 DygraphCanvasRenderer.prototype._renderChartLabels = function() {
 448   var div, class_div;
 449
 450   // Generate divs for the chart title, xlabel and ylabel.
 451   // Space for these divs has already been taken away from the charting area in
 452   // the DygraphCanvasRenderer constructor.
 453   if (this.attr_('title')) {
 454     div = document.createElement("div");
 455     div.style.position = 'absolute';
 456     div.style.top = '0px';
 457     div.style.left = this.area.x + 'px';
 458     div.style.width = this.area.w + 'px';
 459     div.style.height = this.attr_('titleHeight') + 'px';
 460     div.style.textAlign = 'center';
 461     div.style.fontSize = (this.attr_('titleHeight') - 8) + 'px';
 462     div.style.fontWeight = 'bold';
 463     class_div = document.createElement("div");
 464     class_div.className = 'dygraph-label dygraph-title';
 465     class_div.innerHTML = this.attr_('title');
 466     div.appendChild(class_div);
 467     this.container.appendChild(div);
 468     this.chartLabels.title = div;
 469   }
 470
 471   if (this.attr_('xlabel')) {
 472     div = document.createElement("div");
 473     div.style.position = 'absolute';
 474     div.style.bottom = 0;  // TODO(danvk): this is lazy. Calculate style.top.
 475     div.style.left = this.area.x + 'px';
 476     div.style.width = this.area.w + 'px';
 477     div.style.height = this.attr_('xLabelHeight') + 'px';
 478     div.style.textAlign = 'center';
 479     div.style.fontSize = (this.attr_('xLabelHeight') - 2) + 'px';
 480
 481     class_div = document.createElement("div");
 482     class_div.className = 'dygraph-label dygraph-xlabel';
 483     class_div.innerHTML = this.attr_('xlabel');
 484     div.appendChild(class_div);
 485     this.container.appendChild(div);
 486     this.chartLabels.xlabel = div;
 487   }
 488
 489   var that = this;
 490   function createRotatedDiv(axis, classes, html) {
 491     var box = {
 492       left: 0,
 493       top: that.area.y,
 494       width: that.attr_('yLabelWidth'),
 495       height: that.area.h
 496     };
 497     // TODO(danvk): is this outer div actually necessary?
 498     div = document.createElement("div");
 499     div.style.position = 'absolute';
 500     if (axis == 1) {
 501       div.style.left = box.left;
 502     } else {
 503       div.style.right = box.left;
 504     }
 505     div.style.top = box.top + 'px';
 506     div.style.width = box.width + 'px';
 507     div.style.height = box.height + 'px';
 508     div.style.fontSize = (that.attr_('yLabelWidth') - 2) + 'px';
 509
 510     var inner_div = document.createElement("div");
 511     inner_div.style.position = 'absolute';
 512     inner_div.style.width = box.height + 'px';
 513     inner_div.style.height = box.width + 'px';
 514     inner_div.style.top = (box.height / 2 - box.width / 2) + 'px';
 515     inner_div.style.left = (box.width / 2 - box.height / 2) + 'px';
 516     inner_div.style.textAlign = 'center';
 517
 518     // CSS rotation is an HTML5 feature which is not standardized. Hence every
 519     // browser has its own name for the CSS style.
 520     var val = 'rotate(' + (axis == 1 ? '-' : '') + '90deg)';
 521     inner_div.style.transform = val;        // HTML5
 522     inner_div.style.WebkitTransform = val;  // Safari/Chrome
 523     inner_div.style.MozTransform = val;     // Firefox
 524     inner_div.style.OTransform = val;       // Opera
 525     inner_div.style.msTransform = val;      // IE9
 526
 527     if (typeof(document.documentMode) !== 'undefined' &&
 528         document.documentMode < 9) {
 529       // We're dealing w/ an old version of IE, so we have to rotate the text
 530       // using a BasicImage transform. This uses a different origin of rotation
 531       // than HTML5 rotation (top left of div vs. its center).
 532       inner_div.style.filter =
 533           'progid:DXImageTransform.Microsoft.BasicImage(rotation=' +
 534           (axis == 1 ? '3' : '1') + ')';
 535       inner_div.style.left = '0px';
 536       inner_div.style.top = '0px';
 537     }
 538
 539     class_div = document.createElement("div");
 540     class_div.className = classes;
 541     class_div.innerHTML = html;
 542
 543     inner_div.appendChild(class_div);
 544     div.appendChild(inner_div);
 545     return div;
 546   }
 547
 548   var div;
 549   if (this.attr_('ylabel')) {
 550     div = createRotatedDiv(1, 'dygraph-label dygraph-ylabel',
 551                            this.attr_('ylabel'));
 552     this.container.appendChild(div);
 553     this.chartLabels.ylabel = div;
 554   }
 555   if (this.attr_('y2label') && this.dygraph_.numAxes() == 2) {
 556     div = createRotatedDiv(2, 'dygraph-label dygraph-y2label',
 557                            this.attr_('y2label'));
 558     this.container.appendChild(div);
 559     this.chartLabels.y2label = div;
 560   }
 561 };
 562
 563
 564 DygraphCanvasRenderer.prototype._renderAnnotations = function() {
 565   var annotationStyle = {
 566     "position": "absolute",
 567     "fontSize": this.attr_('axisLabelFontSize') + "px",
 568     "zIndex": 10,
 569     "overflow": "hidden"
 570   };
 571
 572   var bindEvt = function(eventName, classEventName, p, self) {
 573     return function(e) {
 574       var a = p.annotation;
 575       if (a.hasOwnProperty(eventName)) {
 576         a[eventName](a, p, self.dygraph_, e);
 577       } else if (self.dygraph_.attr_(classEventName)) {
 578         self.dygraph_.attr_(classEventName)(a, p, self.dygraph_,e );
 579       }
 580     };
 581   };
 582
 583   // Get a list of point with annotations.
 584   var points = this.layout.annotated_points;
 585   for (var i = 0; i < points.length; i++) {
 586     var p = points[i];
 587     if (p.canvasx < this.area.x || p.canvasx > this.area.x + this.area.w) {
 588       continue;
 589     }
 590
 591     var a = p.annotation;
 592     var tick_height = 6;
 593     if (a.hasOwnProperty("tickHeight")) {
 594       tick_height = a.tickHeight;
 595     }
 596
 597     var div = document.createElement("div");
 598     for (var name in annotationStyle) {
 599       if (annotationStyle.hasOwnProperty(name)) {
 600         div.style[name] = annotationStyle[name];
 601       }
 602     }
 603     if (!a.hasOwnProperty('icon')) {
 604       div.className = "dygraphDefaultAnnotation";
 605     }
 606     if (a.hasOwnProperty('cssClass')) {
 607       div.className += " " + a.cssClass;
 608     }
 609
 610     var width = a.hasOwnProperty('width') ? a.width : 16;
 611     var height = a.hasOwnProperty('height') ? a.height : 16;
 612     if (a.hasOwnProperty('icon')) {
 613       var img = document.createElement("img");
 614       img.src = a.icon;
 615       img.width = width;
 616       img.height = height;
 617       div.appendChild(img);
 618     } else if (p.annotation.hasOwnProperty('shortText')) {
 619       div.appendChild(document.createTextNode(p.annotation.shortText));
 620     }
 621     div.style.left = (p.canvasx - width / 2) + "px";
 622     if (a.attachAtBottom) {
 623       div.style.top = (this.area.h - height - tick_height) + "px";
 624     } else {
 625       div.style.top = (p.canvasy - height - tick_height) + "px";
 626     }
 627     div.style.width = width + "px";
 628     div.style.height = height + "px";
 629     div.title = p.annotation.text;
 630     div.style.color = this.colors[p.name];
 631     div.style.borderColor = this.colors[p.name];
 632     a.div = div;
 633
 634     Dygraph.addEvent(div, 'click',
 635         bindEvt('clickHandler', 'annotationClickHandler', p, this));
 636     Dygraph.addEvent(div, 'mouseover',
 637         bindEvt('mouseOverHandler', 'annotationMouseOverHandler', p, this));
 638     Dygraph.addEvent(div, 'mouseout',
 639         bindEvt('mouseOutHandler', 'annotationMouseOutHandler', p, this));
 640     Dygraph.addEvent(div, 'dblclick',
 641         bindEvt('dblClickHandler', 'annotationDblClickHandler', p, this));
 642
 643     this.container.appendChild(div);
 644     this.annotations.push(div);
 645
 646     var ctx = this.elementContext;
 647     ctx.strokeStyle = this.colors[p.name];
 648     ctx.beginPath();
 649     if (!a.attachAtBottom) {
 650       ctx.moveTo(p.canvasx, p.canvasy);
 651       ctx.lineTo(p.canvasx, p.canvasy - 2 - tick_height);
 652     } else {
 653       ctx.moveTo(p.canvasx, this.area.h);
 654       ctx.lineTo(p.canvasx, this.area.h - 2 - tick_height);
 655     }
 656     ctx.closePath();
 657     ctx.stroke();
 658   }
 659 };
 660
 661
 662 /**
 663  * Actually draw the lines chart, including error bars.
 664  * TODO(danvk): split this into several smaller functions.
 665  * @private
 666  */
 667 DygraphCanvasRenderer.prototype._renderLineChart = function() {
 668   var isNullOrNaN = function(x) {
 669     return (x === null || isNaN(x));
 670   };
 671
 672   // TODO(danvk): use this.attr_ for many of these.
 673   var context = this.elementContext;
 674   var fillAlpha = this.attr_('fillAlpha');
 675   var errorBars = this.attr_("errorBars") || this.attr_("customBars");
 676   var fillGraph = this.attr_("fillGraph");
 677   var stackedGraph = this.attr_("stackedGraph");
 678   var stepPlot = this.attr_("stepPlot");
 679   var points = this.layout.points;
 680   var pointsLength = points.length;
 681   var point, i, j, prevX, prevY, prevYs, color, setName, newYs, err_color, rgb, yscale, axis;
 682
 683   var setNames = this.layout.setNames;
 684   var setCount = setNames.length;
 685
 686   // TODO(danvk): Move this mapping into Dygraph and get it out of here.
 687   this.colors = {};
 688   for (i = 0; i < setCount; i++) {
 689     this.colors[setNames[i]] = this.colorScheme_[i % this.colorScheme_.length];
 690   }
 691
 692   // Update Points
 693   // TODO(danvk): here
 694   for (i = pointsLength; i--;) {
 695     point = points[i];
 696     point.canvasx = this.area.w * point.x + this.area.x;
 697     point.canvasy = this.area.h * point.y + this.area.y;
 698   }
 699
 700   // create paths
 701   var ctx = context;
 702   if (errorBars) {
 703     if (fillGraph) {
 704       this.dygraph_.warn("Can't use fillGraph option with error bars");
 705     }
 706
 707     for (i = 0; i < setCount; i++) {
 708       setName = setNames[i];
 709       axis = this.dygraph_.axisPropertiesForSeries(setName);
 710       color = this.colors[setName];
 711
 712       // setup graphics context
 713       ctx.save();
 714       prevX = NaN;
 715       prevY = NaN;
 716       prevYs = [-1, -1];
 717       yscale = axis.yscale;
 718       // should be same color as the lines but only 15% opaque.
 719       rgb = new RGBColor(color);
 720       err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 721                             fillAlpha + ')';
 722       ctx.fillStyle = err_color;
 723       ctx.beginPath();
 724       for (j = 0; j < pointsLength; j++) {
 725         point = points[j];
 726         if (point.name == setName) {
 727           if (!Dygraph.isOK(point.y)) {
 728             prevX = NaN;
 729             continue;
 730           }
 731
 732           // TODO(danvk): here
 733           if (stepPlot) {
 734             newYs = [ point.y_bottom, point.y_top ];
 735             prevY = point.y;
 736           } else {
 737             newYs = [ point.y_bottom, point.y_top ];
 738           }
 739           newYs[0] = this.area.h * newYs[0] + this.area.y;
 740           newYs[1] = this.area.h * newYs[1] + this.area.y;
 741           if (!isNaN(prevX)) {
 742             if (stepPlot) {
 743               ctx.moveTo(prevX, newYs[0]);
 744             } else {
 745               ctx.moveTo(prevX, prevYs[0]);
 746             }
 747             ctx.lineTo(point.canvasx, newYs[0]);
 748             ctx.lineTo(point.canvasx, newYs[1]);
 749             if (stepPlot) {
 750               ctx.lineTo(prevX, newYs[1]);
 751             } else {
 752               ctx.lineTo(prevX, prevYs[1]);
 753             }
 754             ctx.closePath();
 755           }
 756           prevYs = newYs;
 757           prevX = point.canvasx;
 758         }
 759       }
 760       ctx.fill();
 761     }
 762   } else if (fillGraph) {
 763     var baseline = [];  // for stacked graphs: baseline for filling
 764
 765     // process sets in reverse order (needed for stacked graphs)
 766     for (i = setCount - 1; i >= 0; i--) {
 767       setName = setNames[i];
 768       color = this.colors[setName];
 769       axis = this.dygraph_.axisPropertiesForSeries(setName);
 770       var axisY = 1.0 + axis.minyval * axis.yscale;
 771       if (axisY < 0.0) axisY = 0.0;
 772       else if (axisY > 1.0) axisY = 1.0;
 773       axisY = this.area.h * axisY + this.area.y;
 774
 775       // setup graphics context
 776       ctx.save();
 777       prevX = NaN;
 778       prevYs = [-1, -1];
 779       yscale = axis.yscale;
 780       // should be same color as the lines but only 15% opaque.
 781       rgb = new RGBColor(color);
 782       err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 783                             fillAlpha + ')';
 784       ctx.fillStyle = err_color;
 785       ctx.beginPath();
 786       for (j = 0; j < pointsLength; j++) {
 787         point = points[j];
 788         if (point.name == setName) {
 789           if (!Dygraph.isOK(point.y)) {
 790             prevX = NaN;
 791             continue;
 792           }
 793           if (stackedGraph) {
 794             var lastY = baseline[point.canvasx];
 795             if (lastY === undefined) lastY = axisY;
 796             baseline[point.canvasx] = point.canvasy;
 797             newYs = [ point.canvasy, lastY ];
 798           } else {
 799             newYs = [ point.canvasy, axisY ];
 800           }
 801           if (!isNaN(prevX)) {
 802             ctx.moveTo(prevX, prevYs[0]);
 803             if (stepPlot) {
 804               ctx.lineTo(point.canvasx, prevYs[0]);
 805             } else {
 806               ctx.lineTo(point.canvasx, newYs[0]);
 807             }
 808             ctx.lineTo(point.canvasx, newYs[1]);
 809             ctx.lineTo(prevX, prevYs[1]);
 810             ctx.closePath();
 811           }
 812           prevYs = newYs;
 813           prevX = point.canvasx;
 814         }
 815       }
 816       ctx.fill();
 817     }
 818   }
 819
 820   // Drawing the lines.
 821   var firstIndexInSet = 0;
 822   var afterLastIndexInSet = 0;
 823   var setLength = 0;
 824   for (i = 0; i < setCount; i += 1) {
 825     firstIndexInSet = this.layout.setPointsOffsets[i];
 826     setLength = this.layout.setPointsLengths[i];
 827     afterLastIndexInSet = firstIndexInSet + setLength;
 828     setName = setNames[i];
 829     color = this.colors[setName];
 830     var strokeWidth = this.dygraph_.attr_("strokeWidth", setName);
 831
 832     // setup graphics context
 833     // TODO(konigsberg): This function has ctx and context. Clarify the difference.
 834     context.save();
 835     var pointSize = this.dygraph_.attr_("pointSize", setName);
 836     prevX = null;
 837     prevY = null;
 838     var drawPoints = this.dygraph_.attr_("drawPoints", setName);
 839     var drawPointCallback = this.dygraph_.attr_("drawPointCallback", setName);
 840     if (!drawPointCallback) {
 841       drawPointCallback = Dygraph.Circles.DEFAULT;
 842     }
 843     var pointsOnLine = []; // Array of [canvasx, canvasy] pairs.
 844     var strokePattern = this.dygraph_.attr_("strokePattern", setName);
 845     if (!Dygraph.isArrayLike(strokePattern)) {
 846       strokePattern = null;
 847     }
 848     for (j = firstIndexInSet; j < afterLastIndexInSet; j++) {
 849       point = points[j];
 850       if (isNullOrNaN(point.canvasy)) {
 851         if (stepPlot && prevX !== null) {
 852           // Draw a horizontal line to the start of the missing data
 853           ctx.beginPath();
 854           ctx.strokeStyle = color;
 855           ctx.lineWidth = this.attr_('strokeWidth');
 856           this._dashedLine(ctx, prevX, prevY, point.canvasx, prevY, strokePattern);
 857           ctx.stroke();
 858         }
 859         // this will make us move to the next point, not draw a line to it.
 860         prevX = prevY = null;
 861       } else {
 862         // A point is "isolated" if it is non-null but both the previous
 863         // and next points are null.
 864         var isIsolated = (!prevX && (j == points.length - 1 ||
 865                                      isNullOrNaN(points[j+1].canvasy)));
 866         if (prevX === null) {
 867           prevX = point.canvasx;
 868           prevY = point.canvasy;
 869         } else {
 870           // Skip over points that will be drawn in the same pixel.
 871           if (Math.round(prevX) == Math.round(point.canvasx) &&
 872               Math.round(prevY) == Math.round(point.canvasy)) {
 873             continue;
 874           }
 875           // TODO(antrob): skip over points that lie on a line that is already
 876           // going to be drawn. There is no need to have more than 2
 877           // consecutive points that are collinear.
 878           if (strokeWidth) {
 879             ctx.beginPath();
 880             ctx.strokeStyle = color;
 881             ctx.lineWidth = strokeWidth;
 882             if (stepPlot) {
 883               this._dashedLine(ctx, prevX, prevY, point.canvasx, prevY, strokePattern);
 884             }
 885             this._dashedLine(ctx, prevX, prevY, point.canvasx, point.canvasy, strokePattern);
 886             prevX = point.canvasx;
 887             prevY = point.canvasy;
 888             ctx.stroke();
 889           }
 890         }
 891
 892         if (drawPoints || isIsolated) {
 893           pointsOnLine.push([point.canvasx, point.canvasy]);
 894         }
 895       }
 896     }
 897     for (var idx = 0; idx < pointsOnLine.length; idx++) {
 898       var cb = pointsOnLine[idx];
 899       ctx.save();
 900       drawPointCallback(
 901           this.dygraph_, setName, ctx, cb[0], cb[1], color, pointSize);
 902       ctx.restore();
 903
 904     }
 905     firstIndexInSet = afterLastIndexInSet;
 906   }
 907
 908   context.restore();
 909 };
 910
 911 /**
 912  * This does dashed lines onto a canvas for a given pattern. You must call
 913  * ctx.stroke() after to actually draw it, much line ctx.lineTo(). It remembers
 914  * the state of the line in regards to where we left off on drawing the pattern.
 915  * You can draw a dashed line in several function calls and the pattern will be
 916  * continous as long as you didn't call this function with a different pattern
 917  * in between.
 918  * @param ctx The canvas 2d context to draw on.
 919  * @param x The start of the line's x coordinate.
 920  * @param y The start of the line's y coordinate.
 921  * @param x2 The end of the line's x coordinate.
 922  * @param y2 The end of the line's y coordinate.
 923  * @param pattern The dash pattern to draw, an array of integers where even
 924  * index is drawn and odd index is not drawn (Ex. [10, 2, 5, 2], 10 is drawn 5
 925  * is drawn, 2 is the space between.). A null pattern, array of length one, or
 926  * empty array will do just a solid line.
 927  * @private
 928  */
 929 DygraphCanvasRenderer.prototype._dashedLine = function(ctx, x, y, x2, y2, pattern) {
 930   // Original version http://stackoverflow.com/questions/4576724/dotted-stroke-in-canvas
 931   // Modified by Russell Valentine to keep line history and continue the pattern
 932   // where it left off.
 933   var dx, dy, len, rot, patternIndex, segment;
 934
 935   // If we don't have a pattern or it is an empty array or of size one just
 936   // do a solid line.
 937   if (!pattern || pattern.length <= 1) {
 938     ctx.moveTo(x, y);
 939     ctx.lineTo(x2, y2);
 940     return;
 941   }
 942
 943   // If we have a different dash pattern than the last time this was called we
 944   // reset our dash history and start the pattern from the begging
 945   // regardless of state of the last pattern.
 946   if (!Dygraph.compareArrays(pattern, this._dashedLineToHistoryPattern)) {
 947     this._dashedLineToHistoryPattern = pattern;
 948     this._dashedLineToHistory = [0, 0];
 949   }
 950   ctx.save();
 951
 952   // Calculate transformation parameters
 953   dx = (x2-x);
 954   dy = (y2-y);
 955   len = Math.sqrt(dx*dx + dy*dy);
 956   rot = Math.atan2(dy, dx);
 957
 958   // Set transformation
 959   ctx.translate(x, y);
 960   ctx.moveTo(0, 0);
 961   ctx.rotate(rot);
 962
 963   // Set last pattern index we used for this pattern.
 964   patternIndex = this._dashedLineToHistory[0];
 965   x = 0;
 966   while (len > x) {
 967     // Get the length of the pattern segment we are dealing with.
 968     segment = pattern[patternIndex];
 969     // If our last draw didn't complete the pattern segment all the way we
 970     // will try to finish it. Otherwise we will try to do the whole segment.
 971     if (this._dashedLineToHistory[1]) {
 972       x += this._dashedLineToHistory[1];
 973     } else {
 974       x += segment;
 975     }
 976     if (x > len) {
 977       // We were unable to complete this pattern index all the way, keep
 978       // where we are the history so our next draw continues where we left off
 979       // in the pattern.
 980       this._dashedLineToHistory = [patternIndex, x-len];
 981       x = len;
 982     } else {
 983       // We completed this patternIndex, we put in the history that we are on
 984       // the beginning of the next segment.
 985       this._dashedLineToHistory = [(patternIndex+1)%pattern.length, 0];
 986     }
 987
 988     // We do a line on a even pattern index and just move on a odd pattern index.
 989     // The move is the empty space in the dash.
 990     if(patternIndex % 2 === 0) {
 991       ctx.lineTo(x, 0);
 992     } else {
 993       ctx.moveTo(x, 0);
 994     }
 995     // If we are not done, next loop process the next pattern segment, or the
 996     // first segment again if we are at the end of the pattern.
 997     patternIndex = (patternIndex+1) % pattern.length;
 998   }
 999   ctx.restore();
1000 };