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     var axisX;
 387     if (this.attr_('drawAxesAtZero')) {
 388       var r = this.dygraph_.toPercentXCoord(0);
 389       if (r > 1 || r < 0) r = 0;
 390       axisX = halfUp(this.area.x + r * this.area.w);
 391     } else {
 392       axisX = halfUp(this.area.x);
 393     }
 394     context.beginPath();
 395     context.moveTo(axisX, halfDown(this.area.y));
 396     context.lineTo(axisX, halfDown(this.area.y + this.area.h));
 397     context.closePath();
 398     context.stroke();
 399
 400     // if there's a secondary y-axis, draw a vertical line for that, too.
 401     if (this.dygraph_.numAxes() == 2) {
 402       context.beginPath();
 403       context.moveTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y));
 404       context.lineTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
 405       context.closePath();
 406       context.stroke();
 407     }
 408   }
 409
 410   if (this.attr_('drawXAxis')) {
 411     if (this.layout.xticks) {
 412       for (i = 0; i < this.layout.xticks.length; i++) {
 413         tick = this.layout.xticks[i];
 414         x = this.area.x + tick[0] * this.area.w;
 415         y = this.area.y + this.area.h;
 416
 417         /* Tick marks are currently clipped, so don't bother drawing them.
 418         context.beginPath();
 419         context.moveTo(halfUp(x), halfDown(y));
 420         context.lineTo(halfUp(x), halfDown(y + this.attr_('axisTickSize')));
 421         context.closePath();
 422         context.stroke();
 423         */
 424
 425         label = makeDiv(tick[1], 'x');
 426         label.style.textAlign = "center";
 427         label.style.top = (y + this.attr_('axisTickSize')) + 'px';
 428
 429         var left = (x - this.attr_('axisLabelWidth')/2);
 430         if (left + this.attr_('axisLabelWidth') > this.width) {
 431           left = this.width - this.attr_('xAxisLabelWidth');
 432           label.style.textAlign = "right";
 433         }
 434         if (left < 0) {
 435           left = 0;
 436           label.style.textAlign = "left";
 437         }
 438
 439         label.style.left = left + "px";
 440         label.style.width = this.attr_('xAxisLabelWidth') + "px";
 441         this.container.appendChild(label);
 442         this.xlabels.push(label);
 443       }
 444     }
 445
 446     context.beginPath();
 447     var axisY;
 448     if (this.attr_('drawAxesAtZero')) {
 449       var r = this.dygraph_.toPercentYCoord(0, 0);
 450       if (r > 1 || r < 0) r = 1;
 451       axisY = halfDown(this.area.y + r * this.area.h);
 452     } else {
 453       axisY = halfDown(this.area.y + this.area.h);
 454     }
 455     context.moveTo(halfUp(this.area.x), axisY);
 456     context.lineTo(halfUp(this.area.x + this.area.w), axisY);
 457     context.closePath();
 458     context.stroke();
 459   }
 460
 461   context.restore();
 462 };
 463
 464
 465 DygraphCanvasRenderer.prototype._renderChartLabels = function() {
 466   var div, class_div;
 467
 468   // Generate divs for the chart title, xlabel and ylabel.
 469   // Space for these divs has already been taken away from the charting area in
 470   // the DygraphCanvasRenderer constructor.
 471   if (this.attr_('title')) {
 472     div = document.createElement("div");
 473     div.style.position = 'absolute';
 474     div.style.top = '0px';
 475     div.style.left = this.area.x + 'px';
 476     div.style.width = this.area.w + 'px';
 477     div.style.height = this.attr_('titleHeight') + 'px';
 478     div.style.textAlign = 'center';
 479     div.style.fontSize = (this.attr_('titleHeight') - 8) + 'px';
 480     div.style.fontWeight = 'bold';
 481     class_div = document.createElement("div");
 482     class_div.className = 'dygraph-label dygraph-title';
 483     class_div.innerHTML = this.attr_('title');
 484     div.appendChild(class_div);
 485     this.container.appendChild(div);
 486     this.chartLabels.title = div;
 487   }
 488
 489   if (this.attr_('xlabel')) {
 490     div = document.createElement("div");
 491     div.style.position = 'absolute';
 492     div.style.bottom = 0;  // TODO(danvk): this is lazy. Calculate style.top.
 493     div.style.left = this.area.x + 'px';
 494     div.style.width = this.area.w + 'px';
 495     div.style.height = this.attr_('xLabelHeight') + 'px';
 496     div.style.textAlign = 'center';
 497     div.style.fontSize = (this.attr_('xLabelHeight') - 2) + 'px';
 498
 499     class_div = document.createElement("div");
 500     class_div.className = 'dygraph-label dygraph-xlabel';
 501     class_div.innerHTML = this.attr_('xlabel');
 502     div.appendChild(class_div);
 503     this.container.appendChild(div);
 504     this.chartLabels.xlabel = div;
 505   }
 506
 507   var that = this;
 508   function createRotatedDiv(axis, classes, html) {
 509     var box = {
 510       left: 0,
 511       top: that.area.y,
 512       width: that.attr_('yLabelWidth'),
 513       height: that.area.h
 514     };
 515     // TODO(danvk): is this outer div actually necessary?
 516     div = document.createElement("div");
 517     div.style.position = 'absolute';
 518     if (axis == 1) {
 519       div.style.left = box.left;
 520     } else {
 521       div.style.right = box.left;
 522     }
 523     div.style.top = box.top + 'px';
 524     div.style.width = box.width + 'px';
 525     div.style.height = box.height + 'px';
 526     div.style.fontSize = (that.attr_('yLabelWidth') - 2) + 'px';
 527
 528     var inner_div = document.createElement("div");
 529     inner_div.style.position = 'absolute';
 530     inner_div.style.width = box.height + 'px';
 531     inner_div.style.height = box.width + 'px';
 532     inner_div.style.top = (box.height / 2 - box.width / 2) + 'px';
 533     inner_div.style.left = (box.width / 2 - box.height / 2) + 'px';
 534     inner_div.style.textAlign = 'center';
 535
 536     // CSS rotation is an HTML5 feature which is not standardized. Hence every
 537     // browser has its own name for the CSS style.
 538     var val = 'rotate(' + (axis == 1 ? '-' : '') + '90deg)';
 539     inner_div.style.transform = val;        // HTML5
 540     inner_div.style.WebkitTransform = val;  // Safari/Chrome
 541     inner_div.style.MozTransform = val;     // Firefox
 542     inner_div.style.OTransform = val;       // Opera
 543     inner_div.style.msTransform = val;      // IE9
 544
 545     if (typeof(document.documentMode) !== 'undefined' &&
 546         document.documentMode < 9) {
 547       // We're dealing w/ an old version of IE, so we have to rotate the text
 548       // using a BasicImage transform. This uses a different origin of rotation
 549       // than HTML5 rotation (top left of div vs. its center).
 550       inner_div.style.filter =
 551           'progid:DXImageTransform.Microsoft.BasicImage(rotation=' +
 552           (axis == 1 ? '3' : '1') + ')';
 553       inner_div.style.left = '0px';
 554       inner_div.style.top = '0px';
 555     }
 556
 557     class_div = document.createElement("div");
 558     class_div.className = classes;
 559     class_div.innerHTML = html;
 560
 561     inner_div.appendChild(class_div);
 562     div.appendChild(inner_div);
 563     return div;
 564   }
 565
 566   var div;
 567   if (this.attr_('ylabel')) {
 568     div = createRotatedDiv(1, 'dygraph-label dygraph-ylabel',
 569                            this.attr_('ylabel'));
 570     this.container.appendChild(div);
 571     this.chartLabels.ylabel = div;
 572   }
 573   if (this.attr_('y2label') && this.dygraph_.numAxes() == 2) {
 574     div = createRotatedDiv(2, 'dygraph-label dygraph-y2label',
 575                            this.attr_('y2label'));
 576     this.container.appendChild(div);
 577     this.chartLabels.y2label = div;
 578   }
 579 };
 580
 581
 582 DygraphCanvasRenderer.prototype._renderAnnotations = function() {
 583   var annotationStyle = {
 584     "position": "absolute",
 585     "fontSize": this.attr_('axisLabelFontSize') + "px",
 586     "zIndex": 10,
 587     "overflow": "hidden"
 588   };
 589
 590   var bindEvt = function(eventName, classEventName, p, self) {
 591     return function(e) {
 592       var a = p.annotation;
 593       if (a.hasOwnProperty(eventName)) {
 594         a[eventName](a, p, self.dygraph_, e);
 595       } else if (self.dygraph_.attr_(classEventName)) {
 596         self.dygraph_.attr_(classEventName)(a, p, self.dygraph_,e );
 597       }
 598     };
 599   };
 600
 601   // Get a list of point with annotations.
 602   var points = this.layout.annotated_points;
 603   for (var i = 0; i < points.length; i++) {
 604     var p = points[i];
 605     if (p.canvasx < this.area.x || p.canvasx > this.area.x + this.area.w ||
 606         p.canvasy < this.area.y || p.canvasy > this.area.y + this.area.h) {
 607       continue;
 608     }
 609
 610     var a = p.annotation;
 611     var tick_height = 6;
 612     if (a.hasOwnProperty("tickHeight")) {
 613       tick_height = a.tickHeight;
 614     }
 615
 616     var div = document.createElement("div");
 617     for (var name in annotationStyle) {
 618       if (annotationStyle.hasOwnProperty(name)) {
 619         div.style[name] = annotationStyle[name];
 620       }
 621     }
 622     if (!a.hasOwnProperty('icon')) {
 623       div.className = "dygraphDefaultAnnotation";
 624     }
 625     if (a.hasOwnProperty('cssClass')) {
 626       div.className += " " + a.cssClass;
 627     }
 628
 629     var width = a.hasOwnProperty('width') ? a.width : 16;
 630     var height = a.hasOwnProperty('height') ? a.height : 16;
 631     if (a.hasOwnProperty('icon')) {
 632       var img = document.createElement("img");
 633       img.src = a.icon;
 634       img.width = width;
 635       img.height = height;
 636       div.appendChild(img);
 637     } else if (p.annotation.hasOwnProperty('shortText')) {
 638       div.appendChild(document.createTextNode(p.annotation.shortText));
 639     }
 640     div.style.left = (p.canvasx - width / 2) + "px";
 641     if (a.attachAtBottom) {
 642       div.style.top = (this.area.h - height - tick_height) + "px";
 643     } else {
 644       div.style.top = (p.canvasy - height - tick_height) + "px";
 645     }
 646     div.style.width = width + "px";
 647     div.style.height = height + "px";
 648     div.title = p.annotation.text;
 649     div.style.color = this.colors[p.name];
 650     div.style.borderColor = this.colors[p.name];
 651     a.div = div;
 652
 653     this.dygraph_.addEvent(div, 'click',
 654         bindEvt('clickHandler', 'annotationClickHandler', p, this));
 655     this.dygraph_.addEvent(div, 'mouseover',
 656         bindEvt('mouseOverHandler', 'annotationMouseOverHandler', p, this));
 657     this.dygraph_.addEvent(div, 'mouseout',
 658         bindEvt('mouseOutHandler', 'annotationMouseOutHandler', p, this));
 659     this.dygraph_.addEvent(div, 'dblclick',
 660         bindEvt('dblClickHandler', 'annotationDblClickHandler', p, this));
 661
 662     this.container.appendChild(div);
 663     this.annotations.push(div);
 664
 665     var ctx = this.elementContext;
 666     ctx.strokeStyle = this.colors[p.name];
 667     ctx.beginPath();
 668     if (!a.attachAtBottom) {
 669       ctx.moveTo(p.canvasx, p.canvasy);
 670       ctx.lineTo(p.canvasx, p.canvasy - 2 - tick_height);
 671     } else {
 672       ctx.moveTo(p.canvasx, this.area.h);
 673       ctx.lineTo(p.canvasx, this.area.h - 2 - tick_height);
 674     }
 675     ctx.closePath();
 676     ctx.stroke();
 677   }
 678 };
 679
 680 DygraphCanvasRenderer.makeNextPointStep_ = function(
 681     connect, points, start, end) {
 682   if (connect) {
 683     return function(j) {
 684       while (++j + start < end) {
 685         if (!(points[start + j].yval === null)) break;
 686       }
 687       return j;
 688     }
 689   } else {
 690     return function(j) { return j + 1 };
 691   }
 692 };
 693
 694 DygraphCanvasRenderer.isNullOrNaN_ = function(x) {
 695   return (x === null || isNaN(x));
 696 };
 697
 698 DygraphCanvasRenderer.prototype._drawStyledLine = function(
 699     ctx, i, setName, color, strokeWidth, strokePattern, drawPoints,
 700     drawPointCallback, pointSize) {
 701   // TODO(konigsberg): Compute attributes outside this method call.
 702   var stepPlot = this.attr_("stepPlot");
 703   var firstIndexInSet = this.layout.setPointsOffsets[i];
 704   var setLength = this.layout.setPointsLengths[i];
 705   var points = this.layout.points;
 706   if (!Dygraph.isArrayLike(strokePattern)) {
 707     strokePattern = null;
 708   }
 709   var drawGapPoints = this.dygraph_.attr_('drawGapEdgePoints', setName);
 710
 711   ctx.save();
 712   if (strokeWidth && !stepPlot && (!strokePattern || strokePattern.length <= 1)) {
 713     this._drawTrivialLine(ctx, points, setLength, firstIndexInSet, setName, color, strokeWidth, drawPointCallback, pointSize, drawPoints, drawGapPoints);
 714   } else {
 715     this._drawNonTrivialLine(ctx, points, setLength, firstIndexInSet, setName, color, strokeWidth, strokePattern, drawPointCallback, pointSize, drawPoints, drawGapPoints, stepPlot);
 716   }
 717   ctx.restore();
 718 };
 719
 720 DygraphCanvasRenderer.prototype._drawNonTrivialLine = function(
 721     ctx, points, setLength, firstIndexInSet, setName, color, strokeWidth, strokePattern, drawPointCallback, pointSize, drawPoints, drawGapPoints, stepPlot) {
 722   var prevX = null;
 723   var prevY = null;
 724   var nextY = null;
 725   var point, nextPoint;
 726   var pointsOnLine = []; // Array of [canvasx, canvasy] pairs.
 727   var next = DygraphCanvasRenderer.makeNextPointStep_(
 728       this.attr_('connectSeparatedPoints'), points, firstIndexInSet,
 729       firstIndexInSet + setLength);
 730   for (var j = 0; j < setLength; j = next(j)) {
 731     point = points[firstIndexInSet + j];
 732     nextY = (next(j) < setLength) ?
 733         points[firstIndexInSet + next(j)].canvasy : null;
 734     if (DygraphCanvasRenderer.isNullOrNaN_(point.canvasy)) {
 735       if (stepPlot && prevX !== null) {
 736         // Draw a horizontal line to the start of the missing data
 737         ctx.beginPath();
 738         ctx.strokeStyle = color;
 739         ctx.lineWidth = this.attr_('strokeWidth');
 740         this._dashedLine(ctx, prevX, prevY, point.canvasx, prevY, strokePattern);
 741         ctx.stroke();
 742       }
 743       // this will make us move to the next point, not draw a line to it.
 744       prevX = prevY = null;
 745     } else {
 746       // A point is "isolated" if it is non-null but both the previous
 747       // and next points are null.
 748       var isIsolated = (!prevX && DygraphCanvasRenderer.isNullOrNaN_(nextY));
 749       if (drawGapPoints) {
 750         // Also consider a point to be is "isolated" if it's adjacent to a
 751         // null point, excluding the graph edges.
 752         if ((j > 0 && !prevX) ||
 753             (next(j) < setLength && DygraphCanvasRenderer.isNullOrNaN_(nextY))) {
 754           isIsolated = true;
 755         }
 756       }
 757       if (prevX === null) {
 758         prevX = point.canvasx;
 759         prevY = point.canvasy;
 760       } else {
 761         // Skip over points that will be drawn in the same pixel.
 762         if (Math.round(prevX) == Math.round(point.canvasx) &&
 763             Math.round(prevY) == Math.round(point.canvasy)) {
 764           continue;
 765         }
 766         // TODO(antrob): skip over points that lie on a line that is already
 767         // going to be drawn. There is no need to have more than 2
 768         // consecutive points that are collinear.
 769         if (strokeWidth) {
 770           ctx.beginPath();
 771           ctx.strokeStyle = color;
 772           ctx.lineWidth = strokeWidth;
 773           if (stepPlot) {
 774             this._dashedLine(ctx, prevX, prevY, point.canvasx, prevY, strokePattern);
 775             prevX = point.canvasx;
 776           }
 777           this._dashedLine(ctx, prevX, prevY, point.canvasx, point.canvasy, strokePattern);
 778           prevX = point.canvasx;
 779           prevY = point.canvasy;
 780           ctx.stroke();
 781         }
 782       }
 783
 784       if (drawPoints || isIsolated) {
 785         pointsOnLine.push([point.canvasx, point.canvasy]);
 786       }
 787     }
 788   }
 789   for (var idx = 0; idx < pointsOnLine.length; idx++) {
 790     var cb = pointsOnLine[idx];
 791     ctx.save();
 792     drawPointCallback(
 793         this.dygraph_, setName, ctx, cb[0], cb[1], color, pointSize);
 794     ctx.restore();
 795   }
 796 };
 797
 798 DygraphCanvasRenderer.prototype._drawTrivialLine = function(
 799     ctx, points, setLength, firstIndexInSet, setName, color, strokeWidth, drawPointCallback, pointSize, drawPoints, drawGapPoints) {
 800   var prevX = null;
 801   var prevY = null;
 802   var nextY = null;
 803   var pointsOnLine = []; // Array of [canvasx, canvasy] pairs.
 804   ctx.beginPath();
 805   ctx.strokeStyle = color;
 806   ctx.lineWidth = strokeWidth;
 807   for (var j = firstIndexInSet; j < firstIndexInSet + setLength; ++j) {
 808     var point = points[j];
 809     nextY = (j + 1 < firstIndexInSet + setLength) ? points[j + 1].canvasy : null;
 810     if (DygraphCanvasRenderer.isNullOrNaN_(point.canvasy)) {
 811       prevX = prevY = null;
 812     } else {
 813       var isIsolated = (!prevX && DygraphCanvasRenderer.isNullOrNaN_(nextY));
 814       if (drawGapPoints) {
 815         // Also consider a point to be is "isolated" if it's adjacent to a
 816         // null point, excluding the graph edges.
 817         if ((j > firstIndexInSet && !prevX) ||
 818             ((j + 1 < firstIndexInSet + setLength) && DygraphCanvasRenderer.isNullOrNaN_(nextY))) {
 819           isIsolated = true;
 820         }
 821       }
 822       if (prevX === null) {
 823         prevX = point.canvasx;
 824         prevY = point.canvasy;
 825         if (j === firstIndexInSet) {
 826           ctx.moveTo(point.canvasx, point.canvasy);
 827         }
 828       } else {
 829         ctx.lineTo(point.canvasx, point.canvasy);
 830       }
 831       if (drawPoints || isIsolated) {
 832         pointsOnLine.push([point.canvasx, point.canvasy]);
 833       }
 834     }
 835   }
 836   ctx.stroke();
 837   for (var idx = 0; idx < pointsOnLine.length; idx++) {
 838     var cb = pointsOnLine[idx];
 839     ctx.save();
 840     drawPointCallback(
 841         this.dygraph_, setName, ctx, cb[0], cb[1], color, pointSize);
 842     ctx.restore();
 843   }
 844 };
 845
 846 DygraphCanvasRenderer.prototype._drawLine = function(ctx, i) {
 847   var setNames = this.layout.setNames;
 848   var setName = setNames[i];
 849
 850   var strokeWidth = this.dygraph_.attr_("strokeWidth", setName);
 851   var borderWidth = this.dygraph_.attr_("strokeBorderWidth", setName);
 852   var drawPointCallback = this.dygraph_.attr_("drawPointCallback", setName) ||
 853       Dygraph.Circles.DEFAULT;
 854
 855   // TODO(konigsberg): Turn this into one call, and then consider inlining drawStyledLine.
 856   if (borderWidth && strokeWidth) {
 857     this._drawStyledLine(ctx, i, setName,
 858         this.dygraph_.attr_("strokeBorderColor", setName),
 859         strokeWidth + 2 * borderWidth,
 860         this.dygraph_.attr_("strokePattern", setName),
 861         this.dygraph_.attr_("drawPoints", setName),
 862         drawPointCallback,
 863         this.dygraph_.attr_("pointSize", setName));
 864   }
 865
 866   this._drawStyledLine(ctx, i, setName,
 867       this.colors[setName],
 868       strokeWidth,
 869       this.dygraph_.attr_("strokePattern", setName),
 870       this.dygraph_.attr_("drawPoints", setName),
 871       drawPointCallback,
 872       this.dygraph_.attr_("pointSize", setName));
 873 };
 874
 875 /**
 876  * Actually draw the lines chart, including error bars.
 877  * TODO(danvk): split this into several smaller functions.
 878  * @private
 879  */
 880 DygraphCanvasRenderer.prototype._renderLineChart = function() {
 881   // TODO(danvk): use this.attr_ for many of these.
 882   var ctx = this.elementContext;
 883   var fillAlpha = this.attr_('fillAlpha');
 884   var errorBars = this.attr_("errorBars") || this.attr_("customBars");
 885   var fillGraph = this.attr_("fillGraph");
 886   var stackedGraph = this.attr_("stackedGraph");
 887   var stepPlot = this.attr_("stepPlot");
 888   var points = this.layout.points;
 889   var pointsLength = points.length;
 890   var point, i, j, prevX, prevY, prevYs, color, setName, newYs, err_color, rgb, yscale, axis;
 891
 892   var setNames = this.layout.setNames;
 893   var setCount = setNames.length;
 894
 895   // TODO(danvk): Move this mapping into Dygraph and get it out of here.
 896   this.colors = {};
 897   for (i = 0; i < setCount; i++) {
 898     this.colors[setNames[i]] = this.colorScheme_[i % this.colorScheme_.length];
 899   }
 900
 901   // Update Points
 902   // TODO(danvk): here
 903   //
 904   // TODO(bhs): this loop is a hot-spot for high-point-count charts. These
 905   // transformations can be pushed into the canvas via linear transformation
 906   // matrices.
 907   for (i = pointsLength; i--;) {
 908     point = points[i];
 909     point.canvasx = this.area.w * point.x + this.area.x;
 910     point.canvasy = this.area.h * point.y + this.area.y;
 911   }
 912
 913   // create paths
 914   if (errorBars) {
 915     ctx.save();
 916     if (fillGraph) {
 917       this.dygraph_.warn("Can't use fillGraph option with error bars");
 918     }
 919
 920     for (i = 0; i < setCount; i++) {
 921       setName = setNames[i];
 922       axis = this.dygraph_.axisPropertiesForSeries(setName);
 923       color = this.colors[setName];
 924
 925       var firstIndexInSet = this.layout.setPointsOffsets[i];
 926       var setLength = this.layout.setPointsLengths[i];
 927       var afterLastIndexInSet = firstIndexInSet + setLength;
 928
 929       var next = DygraphCanvasRenderer.makeNextPointStep_(
 930         this.attr_('connectSeparatedPoints'), points,
 931         afterLastIndexInSet);
 932
 933       // setup graphics context
 934       prevX = NaN;
 935       prevY = NaN;
 936       prevYs = [-1, -1];
 937       yscale = axis.yscale;
 938       // should be same color as the lines but only 15% opaque.
 939       rgb = new RGBColor(color);
 940       err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 941                             fillAlpha + ')';
 942       ctx.fillStyle = err_color;
 943       ctx.beginPath();
 944       for (j = firstIndexInSet; j < afterLastIndexInSet; j = next(j)) {
 945         point = points[j];
 946         if (point.name == setName) { // TODO(klausw): this is always true
 947           if (!Dygraph.isOK(point.y)) {
 948             prevX = NaN;
 949             continue;
 950           }
 951
 952           // TODO(danvk): here
 953           if (stepPlot) {
 954             newYs = [ point.y_bottom, point.y_top ];
 955             prevY = point.y;
 956           } else {
 957             newYs = [ point.y_bottom, point.y_top ];
 958           }
 959           newYs[0] = this.area.h * newYs[0] + this.area.y;
 960           newYs[1] = this.area.h * newYs[1] + this.area.y;
 961           if (!isNaN(prevX)) {
 962             if (stepPlot) {
 963               ctx.moveTo(prevX, newYs[0]);
 964             } else {
 965               ctx.moveTo(prevX, prevYs[0]);
 966             }
 967             ctx.lineTo(point.canvasx, newYs[0]);
 968             ctx.lineTo(point.canvasx, newYs[1]);
 969             if (stepPlot) {
 970               ctx.lineTo(prevX, newYs[1]);
 971             } else {
 972               ctx.lineTo(prevX, prevYs[1]);
 973             }
 974             ctx.closePath();
 975           }
 976           prevYs = newYs;
 977           prevX = point.canvasx;
 978         }
 979       }
 980       ctx.fill();
 981     }
 982     ctx.restore();
 983   } else if (fillGraph) {
 984     ctx.save();
 985     var baseline = {};  // for stacked graphs: baseline for filling
 986     var currBaseline;
 987
 988     // process sets in reverse order (needed for stacked graphs)
 989     for (i = setCount - 1; i >= 0; i--) {
 990       setName = setNames[i];
 991       color = this.colors[setName];
 992       axis = this.dygraph_.axisPropertiesForSeries(setName);
 993       var axisY = 1.0 + axis.minyval * axis.yscale;
 994       if (axisY < 0.0) axisY = 0.0;
 995       else if (axisY > 1.0) axisY = 1.0;
 996       axisY = this.area.h * axisY + this.area.y;
 997       var firstIndexInSet = this.layout.setPointsOffsets[i];
 998       var setLength = this.layout.setPointsLengths[i];
 999       var afterLastIndexInSet = firstIndexInSet + setLength;
1000
1001       var next = DygraphCanvasRenderer.makeNextPointStep_(
1002         this.attr_('connectSeparatedPoints'), points,
1003         afterLastIndexInSet);
1004
1005       // setup graphics context
1006       prevX = NaN;
1007       prevYs = [-1, -1];
1008       yscale = axis.yscale;
1009       // should be same color as the lines but only 15% opaque.
1010       rgb = new RGBColor(color);
1011       err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
1012                             fillAlpha + ')';
1013       ctx.fillStyle = err_color;
1014       ctx.beginPath();
1015       for (j = firstIndexInSet; j < afterLastIndexInSet; j = next(j)) {
1016         point = points[j];
1017         if (point.name == setName) { // TODO(klausw): this is always true
1018           if (!Dygraph.isOK(point.y)) {
1019             prevX = NaN;
1020             continue;
1021           }
1022           if (stackedGraph) {
1023             currBaseline = baseline[point.canvasx];
1024             var lastY;
1025             if (currBaseline === undefined) {
1026               lastY = axisY;
1027             } else {
1028               if(stepPlot) {
1029                 lastY = currBaseline[0];
1030               } else {
1031                 lastY = currBaseline;
1032               }
1033             }
1034             newYs = [ point.canvasy, lastY ];
1035
1036             if(stepPlot) {
1037               // Step plots must keep track of the top and bottom of
1038               // the baseline at each point.
1039               if(prevYs[0] === -1) {
1040                 baseline[point.canvasx] = [ point.canvasy, axisY ];
1041               } else {
1042                 baseline[point.canvasx] = [ point.canvasy, prevYs[0] ];
1043               }
1044             } else {
1045               baseline[point.canvasx] = point.canvasy;
1046             }
1047
1048           } else {
1049             newYs = [ point.canvasy, axisY ];
1050           }
1051           if (!isNaN(prevX)) {
1052             ctx.moveTo(prevX, prevYs[0]);
1053
1054             if (stepPlot) {
1055               ctx.lineTo(point.canvasx, prevYs[0]);
1056               if(currBaseline) {
1057                 // Draw to the bottom of the baseline
1058                 ctx.lineTo(point.canvasx, currBaseline[1]);
1059               } else {
1060                 ctx.lineTo(point.canvasx, newYs[1]);
1061               }
1062             } else {
1063               ctx.lineTo(point.canvasx, newYs[0]);
1064               ctx.lineTo(point.canvasx, newYs[1]);
1065             }
1066
1067             ctx.lineTo(prevX, prevYs[1]);
1068             ctx.closePath();
1069           }
1070           prevYs = newYs;
1071           prevX = point.canvasx;
1072         }
1073       }
1074       ctx.fill();
1075     }
1076     ctx.restore();
1077   }
1078
1079   // Drawing the lines.
1080   for (i = 0; i < setCount; i += 1) {
1081     this._drawLine(ctx, i);
1082   }
1083 };
1084
1085 /**
1086  * This does dashed lines onto a canvas for a given pattern. You must call
1087  * ctx.stroke() after to actually draw it, much line ctx.lineTo(). It remembers
1088  * the state of the line in regards to where we left off on drawing the pattern.
1089  * You can draw a dashed line in several function calls and the pattern will be
1090  * continous as long as you didn't call this function with a different pattern
1091  * in between.
1092  * @param ctx The canvas 2d context to draw on.
1093  * @param x The start of the line's x coordinate.
1094  * @param y The start of the line's y coordinate.
1095  * @param x2 The end of the line's x coordinate.
1096  * @param y2 The end of the line's y coordinate.
1097  * @param pattern The dash pattern to draw, an array of integers where even
1098  * index is drawn and odd index is not drawn (Ex. [10, 2, 5, 2], 10 is drawn 5
1099  * is drawn, 2 is the space between.). A null pattern, array of length one, or
1100  * empty array will do just a solid line.
1101  * @private
1102  */
1103 DygraphCanvasRenderer.prototype._dashedLine = function(ctx, x, y, x2, y2, pattern) {
1104   // Original version http://stackoverflow.com/questions/4576724/dotted-stroke-in-canvas
1105   // Modified by Russell Valentine to keep line history and continue the pattern
1106   // where it left off.
1107   var dx, dy, len, rot, patternIndex, segment;
1108
1109   // If we don't have a pattern or it is an empty array or of size one just
1110   // do a solid line.
1111   if (!pattern || pattern.length <= 1) {
1112     ctx.moveTo(x, y);
1113     ctx.lineTo(x2, y2);
1114     return;
1115   }
1116
1117   // If we have a different dash pattern than the last time this was called we
1118   // reset our dash history and start the pattern from the begging
1119   // regardless of state of the last pattern.
1120   if (!Dygraph.compareArrays(pattern, this._dashedLineToHistoryPattern)) {
1121     this._dashedLineToHistoryPattern = pattern;
1122     this._dashedLineToHistory = [0, 0];
1123   }
1124   ctx.save();
1125
1126   // Calculate transformation parameters
1127   dx = (x2-x);
1128   dy = (y2-y);
1129   len = Math.sqrt(dx*dx + dy*dy);
1130   rot = Math.atan2(dy, dx);
1131
1132   // Set transformation
1133   ctx.translate(x, y);
1134   ctx.moveTo(0, 0);
1135   ctx.rotate(rot);
1136
1137   // Set last pattern index we used for this pattern.
1138   patternIndex = this._dashedLineToHistory[0];
1139   x = 0;
1140   while (len > x) {
1141     // Get the length of the pattern segment we are dealing with.
1142     segment = pattern[patternIndex];
1143     // If our last draw didn't complete the pattern segment all the way we
1144     // will try to finish it. Otherwise we will try to do the whole segment.
1145     if (this._dashedLineToHistory[1]) {
1146       x += this._dashedLineToHistory[1];
1147     } else {
1148       x += segment;
1149     }
1150     if (x > len) {
1151       // We were unable to complete this pattern index all the way, keep
1152       // where we are the history so our next draw continues where we left off
1153       // in the pattern.
1154       this._dashedLineToHistory = [patternIndex, x-len];
1155       x = len;
1156     } else {
1157       // We completed this patternIndex, we put in the history that we are on
1158       // the beginning of the next segment.
1159       this._dashedLineToHistory = [(patternIndex+1)%pattern.length, 0];
1160     }
1161
1162     // We do a line on a even pattern index and just move on a odd pattern index.
1163     // The move is the empty space in the dash.
1164     if(patternIndex % 2 === 0) {
1165       ctx.lineTo(x, 0);
1166     } else {
1167       ctx.moveTo(x, 0);
1168     }
1169     // If we are not done, next loop process the next pattern segment, or the
1170     // first segment again if we are at the end of the pattern.
1171     patternIndex = (patternIndex+1) % pattern.length;
1172   }
1173   ctx.restore();
1174 };