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 "use strict";
  28
  29 var DygraphCanvasRenderer = function(dygraph, element, elementContext, layout) {
  30   this.dygraph_ = dygraph;
  31
  32   this.layout = layout;
  33   this.element = element;
  34   this.elementContext = elementContext;
  35   this.container = this.element.parentNode;
  36
  37   this.height = this.element.height;
  38   this.width = this.element.width;
  39
  40   // --- check whether everything is ok before we return
  41   if (!this.isIE && !(DygraphCanvasRenderer.isSupported(this.element)))
  42       throw "Canvas is not supported.";
  43
  44   // internal state
  45   this.xlabels = new Array();
  46   this.ylabels = new Array();
  47   this.annotations = new Array();
  48   this.chartLabels = {};
  49
  50   this.area = layout.getPlotArea();
  51   this.container.style.position = "relative";
  52   this.container.style.width = this.width + "px";
  53
  54   // Set up a clipping area for the canvas (and the interaction canvas).
  55   // This ensures that we don't overdraw.
  56   if (this.dygraph_.isUsingExcanvas_) {
  57     this._createIEClipArea();
  58   } else {
  59     // on Android 3 and 4, setting a clipping area on a canvas prevents it from
  60     // displaying anything.
  61     if (!Dygraph.isAndroid()) {
  62       var ctx = this.dygraph_.canvas_ctx_;
  63       ctx.beginPath();
  64       ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
  65       ctx.clip();
  66
  67       ctx = this.dygraph_.hidden_ctx_;
  68       ctx.beginPath();
  69       ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
  70       ctx.clip();
  71     }
  72   }
  73 };
  74
  75 DygraphCanvasRenderer.prototype.attr_ = function(x) {
  76   return this.dygraph_.attr_(x);
  77 };
  78
  79 DygraphCanvasRenderer.prototype.clear = function() {
  80   if (this.isIE) {
  81     // VML takes a while to start up, so we just poll every this.IEDelay
  82     try {
  83       if (this.clearDelay) {
  84         this.clearDelay.cancel();
  85         this.clearDelay = null;
  86       }
  87       var context = this.elementContext;
  88     }
  89     catch (e) {
  90       // TODO(danvk): this is broken, since MochiKit.Async is gone.
  91       this.clearDelay = MochiKit.Async.wait(this.IEDelay);
  92       this.clearDelay.addCallback(bind(this.clear, this));
  93       return;
  94     }
  95   }
  96
  97   var context = this.elementContext;
  98   context.clearRect(0, 0, this.width, this.height);
  99
 100   for (var i = 0; i < this.xlabels.length; i++) {
 101     var el = this.xlabels[i];
 102     if (el.parentNode) el.parentNode.removeChild(el);
 103   }
 104   for (var i = 0; i < this.ylabels.length; i++) {
 105     var el = this.ylabels[i];
 106     if (el.parentNode) el.parentNode.removeChild(el);
 107   }
 108   for (var i = 0; i < this.annotations.length; i++) {
 109     var el = this.annotations[i];
 110     if (el.parentNode) el.parentNode.removeChild(el);
 111   }
 112   for (var k in this.chartLabels) {
 113     if (!this.chartLabels.hasOwnProperty(k)) continue;
 114     var el = this.chartLabels[k];
 115     if (el.parentNode) el.parentNode.removeChild(el);
 116   }
 117   this.xlabels = new Array();
 118   this.ylabels = new Array();
 119   this.annotations = new Array();
 120   this.chartLabels = {};
 121 };
 122
 123
 124 DygraphCanvasRenderer.isSupported = function(canvasName) {
 125   var canvas = null;
 126   try {
 127     if (typeof(canvasName) == 'undefined' || canvasName == null)
 128       canvas = document.createElement("canvas");
 129     else
 130       canvas = canvasName;
 131     var context = canvas.getContext("2d");
 132   }
 133   catch (e) {
 134     var ie = navigator.appVersion.match(/MSIE (\d\.\d)/);
 135     var opera = (navigator.userAgent.toLowerCase().indexOf("opera") != -1);
 136     if ((!ie) || (ie[1] < 6) || (opera))
 137       return false;
 138     return true;
 139   }
 140   return true;
 141 };
 142
 143 /**
 144  * @param { [String] } colors Array of color strings. Should have one entry for
 145  * each series to be rendered.
 146  */
 147 DygraphCanvasRenderer.prototype.setColors = function(colors) {
 148   this.colorScheme_ = colors;
 149 };
 150
 151 /**
 152  * Draw an X/Y grid on top of the existing plot
 153  */
 154 DygraphCanvasRenderer.prototype.render = function() {
 155   // Draw the new X/Y grid. Lines appear crisper when pixels are rounded to
 156   // half-integers. This prevents them from drawing in two rows/cols.
 157   var ctx = this.elementContext;
 158   function halfUp(x){return Math.round(x)+0.5};
 159   function halfDown(y){return Math.round(y)-0.5};
 160
 161   if (this.attr_('underlayCallback')) {
 162     // NOTE: we pass the dygraph object to this callback twice to avoid breaking
 163     // users who expect a deprecated form of this callback.
 164     this.attr_('underlayCallback')(ctx, this.area, this.dygraph_, this.dygraph_);
 165   }
 166
 167   if (this.attr_('drawYGrid')) {
 168     var ticks = this.layout.yticks;
 169     // TODO(konigsberg): I don't think these calls to save() have a corresponding restore().
 170     ctx.save();
 171     ctx.strokeStyle = this.attr_('gridLineColor');
 172     ctx.lineWidth = this.attr_('gridLineWidth');
 173     for (var i = 0; i < ticks.length; i++) {
 174       // TODO(danvk): allow secondary axes to draw a grid, too.
 175       if (ticks[i][0] != 0) continue;
 176       var x = halfUp(this.area.x);
 177       var y = halfDown(this.area.y + ticks[i][1] * this.area.h);
 178       ctx.beginPath();
 179       ctx.moveTo(x, y);
 180       ctx.lineTo(x + this.area.w, y);
 181       ctx.closePath();
 182       ctx.stroke();
 183     }
 184   }
 185
 186   if (this.attr_('drawXGrid')) {
 187     var ticks = this.layout.xticks;
 188     ctx.save();
 189     ctx.strokeStyle = this.attr_('gridLineColor');
 190     ctx.lineWidth = this.attr_('gridLineWidth');
 191     for (var i=0; i<ticks.length; i++) {
 192       var x = halfUp(this.area.x + ticks[i][0] * this.area.w);
 193       var y = halfDown(this.area.y + this.area.h);
 194       ctx.beginPath();
 195       ctx.moveTo(x, y);
 196       ctx.lineTo(x, this.area.y);
 197       ctx.closePath();
 198       ctx.stroke();
 199     }
 200   }
 201
 202   // Do the ordinary rendering, as before
 203   this._renderLineChart();
 204   this._renderAxis();
 205   this._renderChartLabels();
 206   this._renderAnnotations();
 207 };
 208
 209 DygraphCanvasRenderer.prototype._createIEClipArea = function() {
 210   var className = 'dygraph-clip-div';
 211   var graphDiv = this.dygraph_.graphDiv;
 212
 213   // Remove old clip divs.
 214   for (var i = graphDiv.childNodes.length-1; i >= 0; i--) {
 215     if (graphDiv.childNodes[i].className == className) {
 216       graphDiv.removeChild(graphDiv.childNodes[i]);
 217     }
 218   }
 219
 220   // Determine background color to give clip divs.
 221   var backgroundColor = document.bgColor;
 222   var element = this.dygraph_.graphDiv;
 223   while (element != document) {
 224     var bgcolor = element.currentStyle.backgroundColor;
 225     if (bgcolor && bgcolor != 'transparent') {
 226       backgroundColor = bgcolor;
 227       break;
 228     }
 229     element = element.parentNode;
 230   }
 231
 232   function createClipDiv(area) {
 233     if (area.w == 0 || area.h == 0) {
 234       return;
 235     }
 236     var elem = document.createElement('div');
 237     elem.className = className;
 238     elem.style.backgroundColor = backgroundColor;
 239     elem.style.position = 'absolute';
 240     elem.style.left = area.x + 'px';
 241     elem.style.top = area.y + 'px';
 242     elem.style.width = area.w + 'px';
 243     elem.style.height = area.h + 'px';
 244     graphDiv.appendChild(elem);
 245   }
 246
 247   var plotArea = this.area;
 248   // Left side
 249   createClipDiv({x:0, y:0, w:plotArea.x, h:this.height});
 250   // Top
 251   createClipDiv({x:plotArea.x, y:0, w:this.width-plotArea.x, h:plotArea.y});
 252   // Right side
 253   createClipDiv({x:plotArea.x+plotArea.w, y:0, w:this.width-plotArea.x-plotArea.w, h:this.height});
 254   // Bottom
 255   createClipDiv({x:plotArea.x, y:plotArea.y+plotArea.h, w:this.width-plotArea.x, h:this.height-plotArea.h-plotArea.y});
 256 }
 257
 258 DygraphCanvasRenderer.prototype._renderAxis = function() {
 259   if (!this.attr_('drawXAxis') && !this.attr_('drawYAxis')) return;
 260
 261   // Round pixels to half-integer boundaries for crisper drawing.
 262   function halfUp(x){return Math.round(x)+0.5};
 263   function halfDown(y){return Math.round(y)-0.5};
 264
 265   var context = this.elementContext;
 266
 267   var labelStyle = {
 268     position: "absolute",
 269     fontSize: this.attr_('axisLabelFontSize') + "px",
 270     zIndex: 10,
 271     color: this.attr_('axisLabelColor'),
 272     width: this.attr_('axisLabelWidth') + "px",
 273     // height: this.attr_('axisLabelFontSize') + 2 + "px",
 274     lineHeight: "normal", // Something other than "normal" line-height screws up label positioning.
 275     overflow: "hidden"
 276   };
 277   var makeDiv = function(txt, axis, prec_axis) {
 278     var div = document.createElement("div");
 279     for (var name in labelStyle) {
 280       if (labelStyle.hasOwnProperty(name)) {
 281         div.style[name] = labelStyle[name];
 282       }
 283     }
 284     var inner_div = document.createElement("div");
 285     inner_div.className = 'dygraph-axis-label' +
 286                           ' dygraph-axis-label-' + axis +
 287                           (prec_axis ? ' dygraph-axis-label-' + prec_axis : '');
 288     inner_div.appendChild(document.createTextNode(txt));
 289     div.appendChild(inner_div);
 290     return div;
 291   };
 292
 293   // axis lines
 294   context.save();
 295   context.strokeStyle = this.attr_('axisLineColor');
 296   context.lineWidth = this.attr_('axisLineWidth');
 297
 298   if (this.attr_('drawYAxis')) {
 299     if (this.layout.yticks && this.layout.yticks.length > 0) {
 300       var num_axes = this.dygraph_.numAxes();
 301       for (var i = 0; i < this.layout.yticks.length; i++) {
 302         var tick = this.layout.yticks[i];
 303         if (typeof(tick) == "function") return;
 304         var x = this.area.x;
 305         var sgn = 1;
 306         var prec_axis = 'y1';
 307         if (tick[0] == 1) {  // right-side y-axis
 308           x = this.area.x + this.area.w;
 309           sgn = -1;
 310           prec_axis = 'y2';
 311         }
 312         var y = this.area.y + tick[1] * this.area.h;
 313
 314         /* Tick marks are currently clipped, so don't bother drawing them.
 315         context.beginPath();
 316         context.moveTo(halfUp(x), halfDown(y));
 317         context.lineTo(halfUp(x - sgn * this.attr_('axisTickSize')), halfDown(y));
 318         context.closePath();
 319         context.stroke();
 320         */
 321
 322         var label = makeDiv(tick[2], 'y', num_axes == 2 ? prec_axis : null);
 323         var top = (y - this.attr_('axisLabelFontSize') / 2);
 324         if (top < 0) top = 0;
 325
 326         if (top + this.attr_('axisLabelFontSize') + 3 > this.height) {
 327           label.style.bottom = "0px";
 328         } else {
 329           label.style.top = top + "px";
 330         }
 331         if (tick[0] == 0) {
 332           label.style.left = (this.area.x - this.attr_('yAxisLabelWidth') - this.attr_('axisTickSize')) + "px";
 333           label.style.textAlign = "right";
 334         } else if (tick[0] == 1) {
 335           label.style.left = (this.area.x + this.area.w +
 336                               this.attr_('axisTickSize')) + "px";
 337           label.style.textAlign = "left";
 338         }
 339         label.style.width = this.attr_('yAxisLabelWidth') + "px";
 340         this.container.appendChild(label);
 341         this.ylabels.push(label);
 342       }
 343
 344       // The lowest tick on the y-axis often overlaps with the leftmost
 345       // tick on the x-axis. Shift the bottom tick up a little bit to
 346       // compensate if necessary.
 347       var bottomTick = this.ylabels[0];
 348       var fontSize = this.attr_('axisLabelFontSize');
 349       var bottom = parseInt(bottomTick.style.top) + fontSize;
 350       if (bottom > this.height - fontSize) {
 351         bottomTick.style.top = (parseInt(bottomTick.style.top) -
 352             fontSize / 2) + "px";
 353       }
 354     }
 355
 356     // draw a vertical line on the left to separate the chart from the labels.
 357     context.beginPath();
 358     context.moveTo(halfUp(this.area.x), halfDown(this.area.y));
 359     context.lineTo(halfUp(this.area.x), halfDown(this.area.y + this.area.h));
 360     context.closePath();
 361     context.stroke();
 362
 363     // if there's a secondary y-axis, draw a vertical line for that, too.
 364     if (this.dygraph_.numAxes() == 2) {
 365       context.beginPath();
 366       context.moveTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y));
 367       context.lineTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
 368       context.closePath();
 369       context.stroke();
 370     }
 371   }
 372
 373   if (this.attr_('drawXAxis')) {
 374     if (this.layout.xticks) {
 375       for (var i = 0; i < this.layout.xticks.length; i++) {
 376         var tick = this.layout.xticks[i];
 377         if (typeof(dataset) == "function") return;
 378
 379         var x = this.area.x + tick[0] * this.area.w;
 380         var y = this.area.y + this.area.h;
 381
 382         /* Tick marks are currently clipped, so don't bother drawing them.
 383         context.beginPath();
 384         context.moveTo(halfUp(x), halfDown(y));
 385         context.lineTo(halfUp(x), halfDown(y + this.attr_('axisTickSize')));
 386         context.closePath();
 387         context.stroke();
 388         */
 389
 390         var label = makeDiv(tick[1], 'x');
 391         label.style.textAlign = "center";
 392         label.style.top = (y + this.attr_('axisTickSize')) + 'px';
 393
 394         var left = (x - this.attr_('axisLabelWidth')/2);
 395         if (left + this.attr_('axisLabelWidth') > this.width) {
 396           left = this.width - this.attr_('xAxisLabelWidth');
 397           label.style.textAlign = "right";
 398         }
 399         if (left < 0) {
 400           left = 0;
 401           label.style.textAlign = "left";
 402         }
 403
 404         label.style.left = left + "px";
 405         label.style.width = this.attr_('xAxisLabelWidth') + "px";
 406         this.container.appendChild(label);
 407         this.xlabels.push(label);
 408       }
 409     }
 410
 411     context.beginPath();
 412     context.moveTo(halfUp(this.area.x), halfDown(this.area.y + this.area.h));
 413     context.lineTo(halfUp(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
 414     context.closePath();
 415     context.stroke();
 416   }
 417
 418   context.restore();
 419 };
 420
 421
 422 DygraphCanvasRenderer.prototype._renderChartLabels = function() {
 423   // Generate divs for the chart title, xlabel and ylabel.
 424   // Space for these divs has already been taken away from the charting area in
 425   // the DygraphCanvasRenderer constructor.
 426   if (this.attr_('title')) {
 427     var div = document.createElement("div");
 428     div.style.position = 'absolute';
 429     div.style.top = '0px';
 430     div.style.left = this.area.x + 'px';
 431     div.style.width = this.area.w + 'px';
 432     div.style.height = this.attr_('titleHeight') + 'px';
 433     div.style.textAlign = 'center';
 434     div.style.fontSize = (this.attr_('titleHeight') - 8) + 'px';
 435     div.style.fontWeight = 'bold';
 436     var class_div = document.createElement("div");
 437     class_div.className = 'dygraph-label dygraph-title';
 438     class_div.innerHTML = this.attr_('title');
 439     div.appendChild(class_div);
 440     this.container.appendChild(div);
 441     this.chartLabels.title = div;
 442   }
 443
 444   if (this.attr_('xlabel')) {
 445     var div = document.createElement("div");
 446     div.style.position = 'absolute';
 447     div.style.bottom = 0;  // TODO(danvk): this is lazy. Calculate style.top.
 448     div.style.left = this.area.x + 'px';
 449     div.style.width = this.area.w + 'px';
 450     div.style.height = this.attr_('xLabelHeight') + 'px';
 451     div.style.textAlign = 'center';
 452     div.style.fontSize = (this.attr_('xLabelHeight') - 2) + 'px';
 453
 454     var class_div = document.createElement("div");
 455     class_div.className = 'dygraph-label dygraph-xlabel';
 456     class_div.innerHTML = this.attr_('xlabel');
 457     div.appendChild(class_div);
 458     this.container.appendChild(div);
 459     this.chartLabels.xlabel = div;
 460   }
 461
 462   if (this.attr_('ylabel')) {
 463     var box = {
 464       left: 0,
 465       top: this.area.y,
 466       width: this.attr_('yLabelWidth'),
 467       height: this.area.h
 468     };
 469     // TODO(danvk): is this outer div actually necessary?
 470     var div = document.createElement("div");
 471     div.style.position = 'absolute';
 472     div.style.left = box.left;
 473     div.style.top = box.top + 'px';
 474     div.style.width = box.width + 'px';
 475     div.style.height = box.height + 'px';
 476     div.style.fontSize = (this.attr_('yLabelWidth') - 2) + 'px';
 477
 478     var inner_div = document.createElement("div");
 479     inner_div.style.position = 'absolute';
 480     inner_div.style.width = box.height + 'px';
 481     inner_div.style.height = box.width + 'px';
 482     inner_div.style.top = (box.height / 2 - box.width / 2) + 'px';
 483     inner_div.style.left = (box.width / 2 - box.height / 2) + 'px';
 484     inner_div.style.textAlign = 'center';
 485
 486     // CSS rotation is an HTML5 feature which is not standardized. Hence every
 487     // browser has its own name for the CSS style.
 488     inner_div.style.transform = 'rotate(-90deg)';        // HTML5
 489     inner_div.style.WebkitTransform = 'rotate(-90deg)';  // Safari/Chrome
 490     inner_div.style.MozTransform = 'rotate(-90deg)';     // Firefox
 491     inner_div.style.OTransform = 'rotate(-90deg)';       // Opera
 492     inner_div.style.msTransform = 'rotate(-90deg)';      // IE9
 493
 494     if (typeof(document.documentMode) !== 'undefined' &&
 495         document.documentMode < 9) {
 496       // We're dealing w/ an old version of IE, so we have to rotate the text
 497       // using a BasicImage transform. This uses a different origin of rotation
 498       // than HTML5 rotation (top left of div vs. its center).
 499       inner_div.style.filter =
 500        'progid:DXImageTransform.Microsoft.BasicImage(rotation=3)';
 501       inner_div.style.left = '0px';
 502       inner_div.style.top = '0px';
 503     }
 504
 505     var class_div = document.createElement("div");
 506     class_div.className = 'dygraph-label dygraph-ylabel';
 507     class_div.innerHTML = this.attr_('ylabel');
 508
 509     inner_div.appendChild(class_div);
 510     div.appendChild(inner_div);
 511     this.container.appendChild(div);
 512     this.chartLabels.ylabel = div;
 513   }
 514 };
 515
 516
 517 DygraphCanvasRenderer.prototype._renderAnnotations = function() {
 518   var annotationStyle = {
 519     "position": "absolute",
 520     "fontSize": this.attr_('axisLabelFontSize') + "px",
 521     "zIndex": 10,
 522     "overflow": "hidden"
 523   };
 524
 525   var bindEvt = function(eventName, classEventName, p, self) {
 526     return function(e) {
 527       var a = p.annotation;
 528       if (a.hasOwnProperty(eventName)) {
 529         a[eventName](a, p, self.dygraph_, e);
 530       } else if (self.dygraph_.attr_(classEventName)) {
 531         self.dygraph_.attr_(classEventName)(a, p, self.dygraph_,e );
 532       }
 533     };
 534   }
 535
 536   // Get a list of point with annotations.
 537   var points = this.layout.annotated_points;
 538   for (var i = 0; i < points.length; i++) {
 539     var p = points[i];
 540     if (p.canvasx < this.area.x || p.canvasx > this.area.x + this.area.w) {
 541       continue;
 542     }
 543
 544     var a = p.annotation;
 545     var tick_height = 6;
 546     if (a.hasOwnProperty("tickHeight")) {
 547       tick_height = a.tickHeight;
 548     }
 549
 550     var div = document.createElement("div");
 551     for (var name in annotationStyle) {
 552       if (annotationStyle.hasOwnProperty(name)) {
 553         div.style[name] = annotationStyle[name];
 554       }
 555     }
 556     if (!a.hasOwnProperty('icon')) {
 557       div.className = "dygraphDefaultAnnotation";
 558     }
 559     if (a.hasOwnProperty('cssClass')) {
 560       div.className += " " + a.cssClass;
 561     }
 562
 563     var width = a.hasOwnProperty('width') ? a.width : 16;
 564     var height = a.hasOwnProperty('height') ? a.height : 16;
 565     if (a.hasOwnProperty('icon')) {
 566       var img = document.createElement("img");
 567       img.src = a.icon;
 568       img.width = width;
 569       img.height = height;
 570       div.appendChild(img);
 571     } else if (p.annotation.hasOwnProperty('shortText')) {
 572       div.appendChild(document.createTextNode(p.annotation.shortText));
 573     }
 574     div.style.left = (p.canvasx - width / 2) + "px";
 575     if (a.attachAtBottom) {
 576       div.style.top = (this.area.h - height - tick_height) + "px";
 577     } else {
 578       div.style.top = (p.canvasy - height - tick_height) + "px";
 579     }
 580     div.style.width = width + "px";
 581     div.style.height = height + "px";
 582     div.title = p.annotation.text;
 583     div.style.color = this.colors[p.name];
 584     div.style.borderColor = this.colors[p.name];
 585     a.div = div;
 586
 587     Dygraph.addEvent(div, 'click',
 588         bindEvt('clickHandler', 'annotationClickHandler', p, this));
 589     Dygraph.addEvent(div, 'mouseover',
 590         bindEvt('mouseOverHandler', 'annotationMouseOverHandler', p, this));
 591     Dygraph.addEvent(div, 'mouseout',
 592         bindEvt('mouseOutHandler', 'annotationMouseOutHandler', p, this));
 593     Dygraph.addEvent(div, 'dblclick',
 594         bindEvt('dblClickHandler', 'annotationDblClickHandler', p, this));
 595
 596     this.container.appendChild(div);
 597     this.annotations.push(div);
 598
 599     var ctx = this.elementContext;
 600     ctx.strokeStyle = this.colors[p.name];
 601     ctx.beginPath();
 602     if (!a.attachAtBottom) {
 603       ctx.moveTo(p.canvasx, p.canvasy);
 604       ctx.lineTo(p.canvasx, p.canvasy - 2 - tick_height);
 605     } else {
 606       ctx.moveTo(p.canvasx, this.area.h);
 607       ctx.lineTo(p.canvasx, this.area.h - 2 - tick_height);
 608     }
 609     ctx.closePath();
 610     ctx.stroke();
 611   }
 612 };
 613
 614
 615 /**
 616  * Overrides the CanvasRenderer method to draw error bars
 617  */
 618 DygraphCanvasRenderer.prototype._renderLineChart = function() {
 619   var isNullOrNaN = function(x) {
 620     return (x === null || isNaN(x));
 621   };
 622
 623   // TODO(danvk): use this.attr_ for many of these.
 624   var context = this.elementContext;
 625   var fillAlpha = this.attr_('fillAlpha');
 626   var errorBars = this.attr_("errorBars") || this.attr_("customBars");
 627   var fillGraph = this.attr_("fillGraph");
 628   var stackedGraph = this.attr_("stackedGraph");
 629   var stepPlot = this.attr_("stepPlot");
 630   var points = this.layout.points;
 631   var pointsLength = points.length;
 632
 633   var setNames = [];
 634   for (var name in this.layout.datasets) {
 635     if (this.layout.datasets.hasOwnProperty(name)) {
 636       setNames.push(name);
 637     }
 638   }
 639   var setCount = setNames.length;
 640
 641   // TODO(danvk): Move this mapping into Dygraph and get it out of here.
 642   this.colors = {}
 643   for (var i = 0; i < setCount; i++) {
 644     this.colors[setNames[i]] = this.colorScheme_[i % this.colorScheme_.length];
 645   }
 646
 647   // Update Points
 648   // TODO(danvk): here
 649   for (var i = pointsLength; i--;) {
 650     var point = points[i];
 651     point.canvasx = this.area.w * point.x + this.area.x;
 652     point.canvasy = this.area.h * point.y + this.area.y;
 653   }
 654
 655   // create paths
 656   var ctx = context;
 657   if (errorBars) {
 658     if (fillGraph) {
 659       this.dygraph_.warn("Can't use fillGraph option with error bars");
 660     }
 661
 662     for (var i = 0; i < setCount; i++) {
 663       var setName = setNames[i];
 664       var axis = this.dygraph_.axisPropertiesForSeries(setName);
 665       var color = this.colors[setName];
 666
 667       // setup graphics context
 668       ctx.save();
 669       var prevX = NaN;
 670       var prevY = NaN;
 671       var prevYs = [-1, -1];
 672       var yscale = axis.yscale;
 673       // should be same color as the lines but only 15% opaque.
 674       var rgb = new RGBColor(color);
 675       var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 676                             fillAlpha + ')';
 677       ctx.fillStyle = err_color;
 678       ctx.beginPath();
 679       for (var j = 0; j < pointsLength; j++) {
 680         var point = points[j];
 681         if (point.name == setName) {
 682           if (!Dygraph.isOK(point.y)) {
 683             prevX = NaN;
 684             continue;
 685           }
 686
 687           // TODO(danvk): here
 688           if (stepPlot) {
 689             var newYs = [ point.y_bottom, point.y_top ];
 690             prevY = point.y;
 691           } else {
 692             var newYs = [ point.y_bottom, point.y_top ];
 693           }
 694           newYs[0] = this.area.h * newYs[0] + this.area.y;
 695           newYs[1] = this.area.h * newYs[1] + this.area.y;
 696           if (!isNaN(prevX)) {
 697             if (stepPlot) {
 698               ctx.moveTo(prevX, newYs[0]);
 699             } else {
 700               ctx.moveTo(prevX, prevYs[0]);
 701             }
 702             ctx.lineTo(point.canvasx, newYs[0]);
 703             ctx.lineTo(point.canvasx, newYs[1]);
 704             if (stepPlot) {
 705               ctx.lineTo(prevX, newYs[1]);
 706             } else {
 707               ctx.lineTo(prevX, prevYs[1]);
 708             }
 709             ctx.closePath();
 710           }
 711           prevYs = newYs;
 712           prevX = point.canvasx;
 713         }
 714       }
 715       ctx.fill();
 716     }
 717   } else if (fillGraph) {
 718     var baseline = []  // for stacked graphs: baseline for filling
 719
 720     // process sets in reverse order (needed for stacked graphs)
 721     for (var i = setCount - 1; i >= 0; i--) {
 722       var setName = setNames[i];
 723       var color = this.colors[setName];
 724       var axis = this.dygraph_.axisPropertiesForSeries(setName);
 725       var axisY = 1.0 + axis.minyval * axis.yscale;
 726       if (axisY < 0.0) axisY = 0.0;
 727       else if (axisY > 1.0) axisY = 1.0;
 728       axisY = this.area.h * axisY + this.area.y;
 729
 730       // setup graphics context
 731       ctx.save();
 732       var prevX = NaN;
 733       var prevYs = [-1, -1];
 734       var yscale = axis.yscale;
 735       // should be same color as the lines but only 15% opaque.
 736       var rgb = new RGBColor(color);
 737       var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 738                             fillAlpha + ')';
 739       ctx.fillStyle = err_color;
 740       ctx.beginPath();
 741       for (var j = 0; j < pointsLength; j++) {
 742         var point = points[j];
 743         if (point.name == setName) {
 744           if (!Dygraph.isOK(point.y)) {
 745             prevX = NaN;
 746             continue;
 747           }
 748           var newYs;
 749           if (stackedGraph) {
 750             var lastY = baseline[point.canvasx];
 751             if (lastY === undefined) lastY = axisY;
 752             baseline[point.canvasx] = point.canvasy;
 753             newYs = [ point.canvasy, lastY ];
 754           } else {
 755             newYs = [ point.canvasy, axisY ];
 756           }
 757           if (!isNaN(prevX)) {
 758             ctx.moveTo(prevX, prevYs[0]);
 759             if (stepPlot) {
 760               ctx.lineTo(point.canvasx, prevYs[0]);
 761             } else {
 762               ctx.lineTo(point.canvasx, newYs[0]);
 763             }
 764             ctx.lineTo(point.canvasx, newYs[1]);
 765             ctx.lineTo(prevX, prevYs[1]);
 766             ctx.closePath();
 767           }
 768           prevYs = newYs;
 769           prevX = point.canvasx;
 770         }
 771       }
 772       ctx.fill();
 773     }
 774   }
 775
 776   // Drawing the lines.
 777   var firstIndexInSet = 0;
 778   var afterLastIndexInSet = 0;
 779   var setLength = 0;
 780   for (var i = 0; i < setCount; i += 1) {
 781     setLength = this.layout.setPointsLengths[i];
 782     afterLastIndexInSet += setLength;
 783     var setName = setNames[i];
 784     var color = this.colors[setName];
 785     var strokeWidth = this.dygraph_.attr_("strokeWidth", setName);
 786
 787     // setup graphics context
 788     context.save();
 789     var pointSize = this.dygraph_.attr_("pointSize", setName);
 790     var prevX = null, prevY = null;
 791     var drawPoints = this.dygraph_.attr_("drawPoints", setName);
 792     for (var j = firstIndexInSet; j < afterLastIndexInSet; j++) {
 793       var point = points[j];
 794       if (isNullOrNaN(point.canvasy)) {
 795         if (stepPlot && prevX != null) {
 796           // Draw a horizontal line to the start of the missing data
 797           ctx.beginPath();
 798           ctx.strokeStyle = color;
 799           ctx.lineWidth = this.attr_('strokeWidth');
 800           ctx.moveTo(prevX, prevY);
 801           ctx.lineTo(point.canvasx, prevY);
 802           ctx.stroke();
 803         }
 804         // this will make us move to the next point, not draw a line to it.
 805         prevX = prevY = null;
 806       } else {
 807         // A point is "isolated" if it is non-null but both the previous
 808         // and next points are null.
 809         var isIsolated = (!prevX && (j == points.length - 1 ||
 810                                      isNullOrNaN(points[j+1].canvasy)));
 811         if (prevX === null) {
 812           prevX = point.canvasx;
 813           prevY = point.canvasy;
 814         } else {
 815           // Skip over points that will be drawn in the same pixel.
 816           if (Math.round(prevX) == Math.round(point.canvasx) &&
 817               Math.round(prevY) == Math.round(point.canvasy)) {
 818             continue;
 819           }
 820           // TODO(antrob): skip over points that lie on a line that is already
 821           // going to be drawn. There is no need to have more than 2
 822           // consecutive points that are collinear.
 823           if (strokeWidth) {
 824             ctx.beginPath();
 825             ctx.strokeStyle = color;
 826             ctx.lineWidth = strokeWidth;
 827             ctx.moveTo(prevX, prevY);
 828             if (stepPlot) {
 829               ctx.lineTo(point.canvasx, prevY);
 830             }
 831             prevX = point.canvasx;
 832             prevY = point.canvasy;
 833             ctx.lineTo(prevX, prevY);
 834             ctx.stroke();
 835           }
 836         }
 837
 838         if (drawPoints || isIsolated) {
 839           ctx.beginPath();
 840           ctx.fillStyle = color;
 841           ctx.arc(point.canvasx, point.canvasy, pointSize,
 842                   0, 2 * Math.PI, false);
 843           ctx.fill();
 844         }
 845       }
 846     }
 847     firstIndexInSet = afterLastIndexInSet;
 848   }
 849
 850   context.restore();
 851 };