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 /**
 681  * Returns a predicate to be used with an iterator, which will
 682  * iterate over points appropriately, depending on whether
 683  * connectSeparatedPoints is true. When it's false, the predicate will
 684  * skip over points with missing yVals.
 685  */
 686 DygraphCanvasRenderer._getIteratorPredicate = function(connectSeparatedPoints) {
 687   return connectSeparatedPoints ? DygraphCanvasRenderer._predicateThatSkipsEmptyPoints : null;
 688 }
 689
 690 DygraphCanvasRenderer._predicateThatSkipsEmptyPoints =
 691   function(array, idx) { return array[idx].yval !== null; }
 692
 693 DygraphCanvasRenderer.prototype._drawStyledLine = function(
 694     ctx, i, setName, color, strokeWidth, strokePattern, drawPoints,
 695     drawPointCallback, pointSize) {
 696   // TODO(konigsberg): Compute attributes outside this method call.
 697   var stepPlot = this.attr_("stepPlot");
 698   var firstIndexInSet = this.layout.setPointsOffsets[i];
 699   var setLength = this.layout.setPointsLengths[i];
 700   var points = this.layout.points;
 701   if (!Dygraph.isArrayLike(strokePattern)) {
 702     strokePattern = null;
 703   }
 704   var drawGapPoints = this.dygraph_.attr_('drawGapEdgePoints', setName);
 705
 706   ctx.save();
 707
 708   var iter = Dygraph.createIterator(points, firstIndexInSet, setLength,
 709       DygraphCanvasRenderer._getIteratorPredicate(this.attr_("connectSeparatedPoints")));
 710
 711   var pointsOnLine;
 712   var strategy;
 713   if (!strokePattern || strokePattern.length <= 1) {
 714     strategy = trivialStrategy(ctx, color, strokeWidth);
 715   } else {
 716     strategy = nonTrivialStrategy(this, ctx, color, strokeWidth, strokePattern);
 717   }
 718   pointsOnLine = this._drawSeries(ctx, iter, strokeWidth, pointSize, drawPoints, drawGapPoints, stepPlot, strategy);
 719   this._drawPointsOnLine(ctx, pointsOnLine, drawPointCallback, setName, color, pointSize);
 720
 721   ctx.restore();
 722 };
 723
 724 var nonTrivialStrategy = function(renderer, ctx, color, strokeWidth, strokePattern) {
 725   return new function() {
 726     this.init = function() {  };
 727     this.finish = function() { };
 728     this.startSegment = function() {
 729        ctx.beginPath();
 730        ctx.strokeStyle = color;
 731        ctx.lineWidth = strokeWidth;
 732     };
 733     this.endSegment = function() {
 734       ctx.stroke(); // should this include closePath?
 735     };
 736     this.drawLine = function(x1, y1, x2, y2) {
 737       renderer._dashedLine(ctx, x1, y1, x2, y2, strokePattern);
 738     };
 739     this.skipPixel = function(prevX, prevY, curX, curY) {
 740       // TODO(konigsberg): optimize with http://jsperf.com/math-round-vs-hack/6 ?
 741       return (Math.round(prevX) == Math.round(curX) &&
 742            Math.round(prevY) == Math.round(curY));
 743     };
 744   };
 745 };
 746
 747 var trivialStrategy = function(ctx, color, strokeWidth) {
 748   return new function() {
 749     this.init = function() {
 750       ctx.beginPath();
 751       ctx.strokeStyle = color;
 752       ctx.lineWidth = strokeWidth;
 753     };
 754     this.finish = function() {
 755       ctx.stroke(); // should this include closePath?
 756     };
 757     this.startSegment = function() { };
 758     this.endSegment = function() { };
 759     this.drawLine = function(x1, y1, x2, y2) {
 760       ctx.moveTo(x1, y1);
 761       ctx.lineTo(x2, y2);
 762     };
 763     // don't skip pixels.
 764     this.skipPixel = function() {
 765       return false;
 766     };
 767   };
 768 };
 769
 770 DygraphCanvasRenderer.prototype._drawPointsOnLine = function(ctx, pointsOnLine, drawPointCallback, setName, color, pointSize) {
 771   for (var idx = 0; idx < pointsOnLine.length; idx++) {
 772     var cb = pointsOnLine[idx];
 773     ctx.save();
 774     drawPointCallback(
 775         this.dygraph_, setName, ctx, cb[0], cb[1], color, pointSize);
 776     ctx.restore();
 777   }
 778 }
 779
 780 DygraphCanvasRenderer.prototype._drawSeries = function(
 781     ctx, iter, strokeWidth, pointSize, drawPoints, drawGapPoints,
 782     stepPlot, strategy) {
 783
 784   var prevCanvasX = null;
 785   var prevCanvasY = null;
 786   var nextCanvasY = null;
 787   var isIsolated; // true if this point is isolated (no line segments)
 788   var point; // the point being processed in the while loop
 789   var pointsOnLine = []; // Array of [canvasx, canvasy] pairs.
 790   var first = true; // the first cycle through the while loop
 791
 792   strategy.init();
 793
 794   while(iter.hasNext()) {
 795     point = iter.next();
 796     if (point.canvasy === null || point.canvasy != point.canvasy) {
 797       if (stepPlot && prevCanvasX !== null) {
 798         // Draw a horizontal line to the start of the missing data
 799         strategy.startSegment();
 800         strategy.drawLine(prevX, prevY, point.canvasx, prevY);
 801         strategy.endSegment();
 802       }
 803       prevCanvasX = prevCanvasY = null;
 804     } else {
 805       nextCanvasY = iter.hasNext() ? iter.peek().canvasy : null;
 806       // TODO: we calculate isNullOrNaN for this point, and the next, and then, when
 807       // we iterate, test for isNullOrNaN again. Why bother?
 808       var isNextCanvasYNullOrNaN = nextCanvasY === null || nextCanvasY != nextCanvasY;
 809       isIsolated = (!prevCanvasX && isNextCanvasYNullOrNaN);
 810       if (drawGapPoints) {
 811         // Also consider a point to be "isolated" if it's adjacent to a
 812         // null point, excluding the graph edges.
 813         if ((!first && !prevCanvasX) ||
 814             (iter.hasNext() && isNextCanvasYNullOrNaN)) {
 815           isIsolated = true;
 816         }
 817       }
 818       if (prevCanvasX !== null) {
 819         if (strategy.skipPixel(prevCanvasX, prevCanvasY, point.canvasx, point.canvasy)) {
 820           continue;
 821         }
 822         if (strokeWidth) {
 823           strategy.startSegment();
 824           if (stepPlot) {
 825             strategy.drawLine(prevCanvasX, prevCanvasY, point.canvasx, prevCanvasY);
 826             prevCanvasX = point.canvasx;
 827           }
 828           strategy.drawLine(prevCanvasX, prevCanvasY, point.canvasx, point.canvasy);
 829           strategy.endSegment();
 830         }
 831       }
 832       if (drawPoints || isIsolated) {
 833         pointsOnLine.push([point.canvasx, point.canvasy]);
 834       }
 835       prevCanvasX = point.canvasx;
 836       prevCanvasY = point.canvasy;
 837     }
 838     first = false;
 839   }
 840   strategy.finish();
 841   return pointsOnLine;
 842 };
 843
 844 DygraphCanvasRenderer.prototype._drawLine = function(ctx, i) {
 845   var setNames = this.layout.setNames;
 846   var setName = setNames[i];
 847
 848   var strokeWidth = this.dygraph_.attr_("strokeWidth", setName);
 849   var borderWidth = this.dygraph_.attr_("strokeBorderWidth", setName);
 850   var drawPointCallback = this.dygraph_.attr_("drawPointCallback", setName) ||
 851       Dygraph.Circles.DEFAULT;
 852
 853   if (borderWidth && strokeWidth) {
 854     this._drawStyledLine(ctx, i, setName,
 855         this.dygraph_.attr_("strokeBorderColor", setName),
 856         strokeWidth + 2 * borderWidth,
 857         this.dygraph_.attr_("strokePattern", setName),
 858         this.dygraph_.attr_("drawPoints", setName),
 859         drawPointCallback,
 860         this.dygraph_.attr_("pointSize", setName));
 861   }
 862
 863   this._drawStyledLine(ctx, i, setName,
 864       this.colors[setName],
 865       strokeWidth,
 866       this.dygraph_.attr_("strokePattern", setName),
 867       this.dygraph_.attr_("drawPoints", setName),
 868       drawPointCallback,
 869       this.dygraph_.attr_("pointSize", setName));
 870 };
 871
 872 /**
 873  * Actually draw the lines chart, including error bars.
 874  * TODO(danvk): split this into several smaller functions.
 875  * @private
 876  */
 877 DygraphCanvasRenderer.prototype._renderLineChart = function() {
 878   // TODO(danvk): use this.attr_ for many of these.
 879   var ctx = this.elementContext;
 880   var fillAlpha = this.attr_('fillAlpha');
 881   var errorBars = this.attr_("errorBars") || this.attr_("customBars");
 882   var fillGraph = this.attr_("fillGraph");
 883   var stackedGraph = this.attr_("stackedGraph");
 884   var stepPlot = this.attr_("stepPlot");
 885   var points = this.layout.points;
 886   var pointsLength = points.length;
 887   var point, i, prevX, prevY, prevYs, color, setName, newYs, err_color, rgb, yscale, axis;
 888
 889   var setNames = this.layout.setNames;
 890   var setCount = setNames.length;
 891
 892   // TODO(danvk): Move this mapping into Dygraph and get it out of here.
 893   this.colors = {};
 894   for (i = 0; i < setCount; i++) {
 895     this.colors[setNames[i]] = this.colorScheme_[i % this.colorScheme_.length];
 896   }
 897
 898   // Update Points
 899   // TODO(danvk): here
 900   //
 901   // TODO(bhs): this loop is a hot-spot for high-point-count charts. These
 902   // transformations can be pushed into the canvas via linear transformation
 903   // matrices.
 904   for (i = pointsLength; i--;) {
 905     point = points[i];
 906     point.canvasx = this.area.w * point.x + this.area.x;
 907     point.canvasy = this.area.h * point.y + this.area.y;
 908   }
 909
 910   // create paths
 911   if (errorBars) {
 912     ctx.save();
 913     if (fillGraph) {
 914       this.dygraph_.warn("Can't use fillGraph option with error bars");
 915     }
 916
 917     for (i = 0; i < setCount; i++) {
 918       setName = setNames[i];
 919       axis = this.dygraph_.axisPropertiesForSeries(setName);
 920       color = this.colors[setName];
 921
 922       var firstIndexInSet = this.layout.setPointsOffsets[i];
 923       var setLength = this.layout.setPointsLengths[i];
 924
 925       var iter = Dygraph.createIterator(points, firstIndexInSet, setLength,
 926           DygraphCanvasRenderer._getIteratorPredicate(this.attr_("connectSeparatedPoints")));
 927
 928       // setup graphics context
 929       prevX = NaN;
 930       prevY = NaN;
 931       prevYs = [-1, -1];
 932       yscale = axis.yscale;
 933       // should be same color as the lines but only 15% opaque.
 934       rgb = new RGBColor(color);
 935       err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 936                             fillAlpha + ')';
 937       ctx.fillStyle = err_color;
 938       ctx.beginPath();
 939       while (iter.hasNext()) {
 940         point = iter.next();
 941         if (point.name == setName) { // TODO(klausw): this is always true
 942           if (!Dygraph.isOK(point.y)) {
 943             prevX = NaN;
 944             continue;
 945           }
 946
 947           // TODO(danvk): here
 948           if (stepPlot) {
 949             newYs = [ point.y_bottom, point.y_top ];
 950             prevY = point.y;
 951           } else {
 952             newYs = [ point.y_bottom, point.y_top ];
 953           }
 954           newYs[0] = this.area.h * newYs[0] + this.area.y;
 955           newYs[1] = this.area.h * newYs[1] + this.area.y;
 956           if (!isNaN(prevX)) {
 957             if (stepPlot) {
 958               ctx.moveTo(prevX, newYs[0]);
 959             } else {
 960               ctx.moveTo(prevX, prevYs[0]);
 961             }
 962             ctx.lineTo(point.canvasx, newYs[0]);
 963             ctx.lineTo(point.canvasx, newYs[1]);
 964             if (stepPlot) {
 965               ctx.lineTo(prevX, newYs[1]);
 966             } else {
 967               ctx.lineTo(prevX, prevYs[1]);
 968             }
 969             ctx.closePath();
 970           }
 971           prevYs = newYs;
 972           prevX = point.canvasx;
 973         }
 974       }
 975       ctx.fill();
 976     }
 977     ctx.restore();
 978   } else if (fillGraph) {
 979     ctx.save();
 980     var baseline = {};  // for stacked graphs: baseline for filling
 981     var currBaseline;
 982
 983     // process sets in reverse order (needed for stacked graphs)
 984     for (i = setCount - 1; i >= 0; i--) {
 985       setName = setNames[i];
 986       color = this.colors[setName];
 987       axis = this.dygraph_.axisPropertiesForSeries(setName);
 988       var axisY = 1.0 + axis.minyval * axis.yscale;
 989       if (axisY < 0.0) axisY = 0.0;
 990       else if (axisY > 1.0) axisY = 1.0;
 991       axisY = this.area.h * axisY + this.area.y;
 992       var firstIndexInSet = this.layout.setPointsOffsets[i];
 993       var setLength = this.layout.setPointsLengths[i];
 994
 995       var iter = Dygraph.createIterator(points, firstIndexInSet, setLength,
 996           DygraphCanvasRenderer._getIteratorPredicate(this.attr_("connectSeparatedPoints")));
 997
 998       // setup graphics context
 999       prevX = NaN;
1000       prevYs = [-1, -1];
1001       yscale = axis.yscale;
1002       // should be same color as the lines but only 15% opaque.
1003       rgb = new RGBColor(color);
1004       err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
1005                             fillAlpha + ')';
1006       ctx.fillStyle = err_color;
1007       ctx.beginPath();
1008       while(iter.hasNext()) {
1009         point = iter.next();
1010         if (point.name == setName) { // TODO(klausw): this is always true
1011           if (!Dygraph.isOK(point.y)) {
1012             prevX = NaN;
1013             continue;
1014           }
1015           if (stackedGraph) {
1016             currBaseline = baseline[point.canvasx];
1017             var lastY;
1018             if (currBaseline === undefined) {
1019               lastY = axisY;
1020             } else {
1021               if(stepPlot) {
1022                 lastY = currBaseline[0];
1023               } else {
1024                 lastY = currBaseline;
1025               }
1026             }
1027             newYs = [ point.canvasy, lastY ];
1028
1029             if(stepPlot) {
1030               // Step plots must keep track of the top and bottom of
1031               // the baseline at each point.
1032               if(prevYs[0] === -1) {
1033                 baseline[point.canvasx] = [ point.canvasy, axisY ];
1034               } else {
1035                 baseline[point.canvasx] = [ point.canvasy, prevYs[0] ];
1036               }
1037             } else {
1038               baseline[point.canvasx] = point.canvasy;
1039             }
1040
1041           } else {
1042             newYs = [ point.canvasy, axisY ];
1043           }
1044           if (!isNaN(prevX)) {
1045             ctx.moveTo(prevX, prevYs[0]);
1046
1047             if (stepPlot) {
1048               ctx.lineTo(point.canvasx, prevYs[0]);
1049               if(currBaseline) {
1050                 // Draw to the bottom of the baseline
1051                 ctx.lineTo(point.canvasx, currBaseline[1]);
1052               } else {
1053                 ctx.lineTo(point.canvasx, newYs[1]);
1054               }
1055             } else {
1056               ctx.lineTo(point.canvasx, newYs[0]);
1057               ctx.lineTo(point.canvasx, newYs[1]);
1058             }
1059
1060             ctx.lineTo(prevX, prevYs[1]);
1061             ctx.closePath();
1062           }
1063           prevYs = newYs;
1064           prevX = point.canvasx;
1065         }
1066       }
1067       ctx.fill();
1068     }
1069     ctx.restore();
1070   }
1071
1072   // Drawing the lines.
1073   for (i = 0; i < setCount; i += 1) {
1074     this._drawLine(ctx, i);
1075   }
1076 };
1077
1078 /**
1079  * This does dashed lines onto a canvas for a given pattern. You must call
1080  * ctx.stroke() after to actually draw it, much line ctx.lineTo(). It remembers
1081  * the state of the line in regards to where we left off on drawing the pattern.
1082  * You can draw a dashed line in several function calls and the pattern will be
1083  * continous as long as you didn't call this function with a different pattern
1084  * in between.
1085  * @param ctx The canvas 2d context to draw on.
1086  * @param x The start of the line's x coordinate.
1087  * @param y The start of the line's y coordinate.
1088  * @param x2 The end of the line's x coordinate.
1089  * @param y2 The end of the line's y coordinate.
1090  * @param pattern The dash pattern to draw, an array of integers where even
1091  * index is drawn and odd index is not drawn (Ex. [10, 2, 5, 2], 10 is drawn 5
1092  * is drawn, 2 is the space between.). A null pattern, array of length one, or
1093  * empty array will do just a solid line.
1094  * @private
1095  */
1096 DygraphCanvasRenderer.prototype._dashedLine = function(ctx, x, y, x2, y2, pattern) {
1097   // Original version http://stackoverflow.com/questions/4576724/dotted-stroke-in-canvas
1098   // Modified by Russell Valentine to keep line history and continue the pattern
1099   // where it left off.
1100   var dx, dy, len, rot, patternIndex, segment;
1101
1102   // If we don't have a pattern or it is an empty array or of size one just
1103   // do a solid line.
1104   if (!pattern || pattern.length <= 1) {
1105     ctx.moveTo(x, y);
1106     ctx.lineTo(x2, y2);
1107     return;
1108   }
1109
1110   // If we have a different dash pattern than the last time this was called we
1111   // reset our dash history and start the pattern from the begging
1112   // regardless of state of the last pattern.
1113   if (!Dygraph.compareArrays(pattern, this._dashedLineToHistoryPattern)) {
1114     this._dashedLineToHistoryPattern = pattern;
1115     this._dashedLineToHistory = [0, 0];
1116   }
1117   ctx.save();
1118
1119   // Calculate transformation parameters
1120   dx = (x2-x);
1121   dy = (y2-y);
1122   len = Math.sqrt(dx*dx + dy*dy);
1123   rot = Math.atan2(dy, dx);
1124
1125   // Set transformation
1126   ctx.translate(x, y);
1127   ctx.moveTo(0, 0);
1128   ctx.rotate(rot);
1129
1130   // Set last pattern index we used for this pattern.
1131   patternIndex = this._dashedLineToHistory[0];
1132   x = 0;
1133   while (len > x) {
1134     // Get the length of the pattern segment we are dealing with.
1135     segment = pattern[patternIndex];
1136     // If our last draw didn't complete the pattern segment all the way we
1137     // will try to finish it. Otherwise we will try to do the whole segment.
1138     if (this._dashedLineToHistory[1]) {
1139       x += this._dashedLineToHistory[1];
1140     } else {
1141       x += segment;
1142     }
1143     if (x > len) {
1144       // We were unable to complete this pattern index all the way, keep
1145       // where we are the history so our next draw continues where we left off
1146       // in the pattern.
1147       this._dashedLineToHistory = [patternIndex, x-len];
1148       x = len;
1149     } else {
1150       // We completed this patternIndex, we put in the history that we are on
1151       // the beginning of the next segment.
1152       this._dashedLineToHistory = [(patternIndex+1)%pattern.length, 0];
1153     }
1154
1155     // We do a line on a even pattern index and just move on a odd pattern index.
1156     // The move is the empty space in the dash.
1157     if(patternIndex % 2 === 0) {
1158       ctx.lineTo(x, 0);
1159     } else {
1160       ctx.moveTo(x, 0);
1161     }
1162     // If we are not done, next loop process the next pattern segment, or the
1163     // first segment again if we are at the end of the pattern.
1164     patternIndex = (patternIndex+1) % pattern.length;
1165   }
1166   ctx.restore();
1167 };