dygraph-canvas.js

   1 // Copyright 2006 Dan Vanderkam (danvdk@gmail.com)
   2 // All Rights Reserved.
   3
   4 /**
   5  * @fileoverview Based on PlotKit, but modified to meet the needs of dygraphs.
   6  * In particular, support for:
   7  * - grid overlays
   8  * - error bars
   9  * - dygraphs attribute system
  10  */
  11
  12 /**
  13  * Creates a new DygraphLayout object.
  14  * @param {Object} options Options for PlotKit.Layout
  15  * @return {Object} The DygraphLayout object
  16  */
  17 DygraphLayout = function(dygraph, options) {
  18   this.dygraph_ = dygraph;
  19   this.options = {};  // TODO(danvk): remove, use attr_ instead.
  20   MochiKit.Base.update(this.options, options ? options : {});
  21   this.datasets = new Array();
  22 };
  23
  24 DygraphLayout.prototype.attr_ = function(name) {
  25   return this.dygraph_.attr_(name);
  26 };
  27
  28 DygraphLayout.prototype.addDataset = function(setname, set_xy) {
  29   this.datasets[setname] = set_xy;
  30 };
  31
  32 DygraphLayout.prototype.evaluate = function() {
  33   this._evaluateLimits();
  34   this._evaluateLineCharts();
  35   this._evaluateLineTicks();
  36 };
  37
  38 DygraphLayout.prototype._evaluateLimits = function() {
  39   this.minxval = this.maxxval = null;
  40   for (var name in this.datasets) {
  41     var series = this.datasets[name];
  42     var x1 = series[0][0];
  43     if (!this.minxval || x1 < this.minxval) this.minxval = x1;
  44
  45     var x2 = series[series.length - 1][0];
  46     if (!this.maxxval || x2 > this.maxxval) this.maxxval = x2;
  47   }
  48   this.xrange = this.maxxval - this.minxval;
  49   this.xscale = (this.xrange != 0 ? 1/this.xrange : 1.0);
  50
  51   this.minyval = this.options.yAxis[0];
  52   this.maxyval = this.options.yAxis[1];
  53   this.yrange = this.maxyval - this.minyval;
  54   this.yscale = (this.yrange != 0 ? 1/this.yrange : 1.0);
  55 };
  56
  57 DygraphLayout.prototype._evaluateLineCharts = function() {
  58   // add all the rects
  59   this.points = new Array();
  60   for (var setName in this.datasets) {
  61     var dataset = this.datasets[setName];
  62     for (var j = 0; j < dataset.length; j++) {
  63       var item = dataset[j];
  64       var point = {
  65         x: ((parseFloat(item[0]) - this.minxval) * this.xscale),
  66         y: 1.0 - ((parseFloat(item[1]) - this.minyval) * this.yscale),
  67         xval: parseFloat(item[0]),
  68         yval: parseFloat(item[1]),
  69         name: setName
  70       };
  71
  72       // limit the x, y values so they do not overdraw
  73       if (point.y <= 0.0) {
  74         point.y = 0.0;
  75       }
  76       if (point.y >= 1.0) {
  77         point.y = 1.0;
  78       }
  79       if ((point.x >= 0.0) && (point.x <= 1.0)) {
  80         this.points.push(point);
  81       }
  82     }
  83   }
  84 };
  85
  86 DygraphLayout.prototype._evaluateLineTicks = function() {
  87   this.xticks = new Array();
  88   for (var i = 0; i < this.options.xTicks.length; i++) {
  89     var tick = this.options.xTicks[i];
  90     var label = tick.label;
  91     var pos = this.xscale * (tick.v - this.minxval);
  92     if ((pos >= 0.0) && (pos <= 1.0)) {
  93       this.xticks.push([pos, label]);
  94     }
  95   }
  96
  97   this.yticks = new Array();
  98   for (var i = 0; i < this.options.yTicks.length; i++) {
  99     var tick = this.options.yTicks[i];
 100     var label = tick.label;
 101     var pos = 1.0 - (this.yscale * (tick.v - this.minyval));
 102     if ((pos >= 0.0) && (pos <= 1.0)) {
 103       this.yticks.push([pos, label]);
 104     }
 105   }
 106 };
 107
 108
 109 /**
 110  * Behaves the same way as PlotKit.Layout, but also copies the errors
 111  * @private
 112  */
 113 DygraphLayout.prototype.evaluateWithError = function() {
 114   this.evaluate();
 115   if (!this.options.errorBars) return;
 116
 117   // Copy over the error terms
 118   var i = 0; // index in this.points
 119   for (var setName in this.datasets) {
 120     var j = 0;
 121     var dataset = this.datasets[setName];
 122     for (var j = 0; j < dataset.length; j++, i++) {
 123       var item = dataset[j];
 124       var xv = parseFloat(item[0]);
 125       var yv = parseFloat(item[1]);
 126
 127       if (xv == this.points[i].xval &&
 128           yv == this.points[i].yval) {
 129         this.points[i].errorMinus = parseFloat(item[2]);
 130         this.points[i].errorPlus = parseFloat(item[3]);
 131       }
 132     }
 133   }
 134 };
 135
 136 /**
 137  * Convenience function to remove all the data sets from a graph
 138  */
 139 DygraphLayout.prototype.removeAllDatasets = function() {
 140   delete this.datasets;
 141   this.datasets = new Array();
 142 };
 143
 144 /**
 145  * Change the values of various layout options
 146  * @param {Object} new_options an associative array of new properties
 147  */
 148 DygraphLayout.prototype.updateOptions = function(new_options) {
 149   MochiKit.Base.update(this.options, new_options ? new_options : {});
 150 };
 151
 152 // Subclass PlotKit.CanvasRenderer to add:
 153 // 1. X/Y grid overlay
 154 // 2. Ability to draw error bars (if required)
 155
 156 /**
 157  * Sets some PlotKit.CanvasRenderer options
 158  * @param {Object} element The canvas to attach to
 159  * @param {Layout} layout The DygraphLayout object for this graph.
 160  * @param {Object} options Options to pass on to CanvasRenderer
 161  */
 162 DygraphCanvasRenderer = function(dygraph, element, layout, options) {
 163   // TODO(danvk): remove options, just use dygraph.attr_.
 164   this.dygraph_ = dygraph;
 165
 166   // default options
 167   this.options = {
 168     "strokeWidth": 0.5,
 169     "drawXAxis": true,
 170     "drawYAxis": true,
 171     "axisLineColor": "black",
 172     "axisLineWidth": 0.5,
 173     "axisTickSize": 3,
 174     "axisLabelColor": "black",
 175     "axisLabelFont": "Arial",
 176     "axisLabelFontSize": 9,
 177     "axisLabelWidth": 50,
 178     "drawYGrid": true,
 179     "drawXGrid": true,
 180     "gridLineColor": "rgb(128,128,128)"
 181   };
 182   MochiKit.Base.update(this.options, options);
 183
 184   this.layout = layout;
 185   this.element = element;
 186   this.container = this.element.parentNode;
 187
 188   // Stuff relating to Canvas on IE support
 189   this.isIE = (/MSIE/.test(navigator.userAgent) && !window.opera);
 190
 191   if (this.isIE && !isNil(G_vmlCanvasManager)) {
 192       this.IEDelay = 0.5;
 193       this.maxTries = 5;
 194       this.renderDelay = null;
 195       this.clearDelay = null;
 196       this.element = G_vmlCanvasManager.initElement(this.element);
 197   }
 198
 199   this.height = this.element.height;
 200   this.width = this.element.width;
 201
 202   // --- check whether everything is ok before we return
 203   if (!this.isIE && !(DygraphCanvasRenderer.isSupported(this.element)))
 204       throw "Canvas is not supported.";
 205
 206   // internal state
 207   this.xlabels = new Array();
 208   this.ylabels = new Array();
 209
 210   this.area = {
 211     x: this.options.yAxisLabelWidth + 2 * this.options.axisTickSize,
 212     y: 0
 213   };
 214   this.area.w = this.width - this.area.x - this.options.rightGap;
 215   this.area.h = this.height - this.options.axisLabelFontSize -
 216                 2 * this.options.axisTickSize;
 217
 218   this.container.style.position = "relative";
 219   this.container.style.width = this.width + "px";
 220 };
 221
 222 DygraphCanvasRenderer.prototype.clear = function() {
 223   if (this.isIE) {
 224     // VML takes a while to start up, so we just poll every this.IEDelay
 225     try {
 226       if (this.clearDelay) {
 227         this.clearDelay.cancel();
 228         this.clearDelay = null;
 229       }
 230       var context = this.element.getContext("2d");
 231     }
 232     catch (e) {
 233       // TODO(danvk): this is broken, since MochiKit.Async is gone.
 234       this.clearDelay = MochiKit.Async.wait(this.IEDelay);
 235       this.clearDelay.addCallback(bind(this.clear, this));
 236       return;
 237     }
 238   }
 239
 240   var context = this.element.getContext("2d");
 241   context.clearRect(0, 0, this.width, this.height);
 242
 243   for (var i = 0; i < this.xlabels.length; i++) {
 244     var el = this.xlabels[i];
 245     el.parentNode.removeChild(el);
 246   }
 247   for (var i = 0; i < this.ylabels.length; i++) {
 248     var el = this.ylabels[i];
 249     el.parentNode.removeChild(el);
 250   }
 251   this.xlabels = new Array();
 252   this.ylabels = new Array();
 253 };
 254
 255
 256 DygraphCanvasRenderer.isSupported = function(canvasName) {
 257   var canvas = null;
 258   try {
 259     if (typeof(canvasName) == 'undefined' || canvasName == null)
 260       canvas = document.createElement("canvas");
 261     else
 262       canvas = canvasName;
 263     var context = canvas.getContext("2d");
 264   }
 265   catch (e) {
 266     var ie = navigator.appVersion.match(/MSIE (\d\.\d)/);
 267     var opera = (navigator.userAgent.toLowerCase().indexOf("opera") != -1);
 268     if ((!ie) || (ie[1] < 6) || (opera))
 269       return false;
 270     return true;
 271   }
 272   return true;
 273 };
 274
 275 /**
 276  * Draw an X/Y grid on top of the existing plot
 277  */
 278 DygraphCanvasRenderer.prototype.render = function() {
 279   // Draw the new X/Y grid
 280   var ctx = this.element.getContext("2d");
 281   if (this.options.drawYGrid) {
 282     var ticks = this.layout.yticks;
 283     ctx.save();
 284     ctx.strokeStyle = this.options.gridLineColor;
 285     ctx.lineWidth = this.options.axisLineWidth;
 286     for (var i = 0; i < ticks.length; i++) {
 287       var x = this.area.x;
 288       var y = this.area.y + ticks[i][0] * this.area.h;
 289       ctx.beginPath();
 290       ctx.moveTo(x, y);
 291       ctx.lineTo(x + this.area.w, y);
 292       ctx.closePath();
 293       ctx.stroke();
 294     }
 295   }
 296
 297   if (this.options.drawXGrid) {
 298     var ticks = this.layout.xticks;
 299     ctx.save();
 300     ctx.strokeStyle = this.options.gridLineColor;
 301     ctx.lineWidth = this.options.axisLineWidth;
 302     for (var i=0; i<ticks.length; i++) {
 303       var x = this.area.x + ticks[i][0] * this.area.w;
 304       var y = this.area.y + this.area.h;
 305       ctx.beginPath();
 306       ctx.moveTo(x, y);
 307       ctx.lineTo(x, this.area.y);
 308       ctx.closePath();
 309       ctx.stroke();
 310     }
 311   }
 312
 313   // Do the ordinary rendering, as before
 314   this._renderLineChart();
 315   this._renderAxis();
 316 };
 317
 318
 319 DygraphCanvasRenderer.prototype._renderAxis = function() {
 320   if (!this.options.drawXAxis && !this.options.drawYAxis)
 321     return;
 322
 323   var context = this.element.getContext("2d");
 324
 325   var labelStyle = {
 326     "position": "absolute",
 327     "fontSize": this.options.axisLabelFontSize + "px",
 328     "zIndex": 10,
 329     "color": this.options.axisLabelColor,
 330     "width": this.options.axisLabelWidth + "px",
 331     "overflow": "hidden"
 332   };
 333   var makeDiv = function(txt) {
 334     var div = document.createElement("div");
 335     for (var name in labelStyle) {
 336       div.style[name] = labelStyle[name];
 337     }
 338     div.appendChild(document.createTextNode(txt));
 339     return div;
 340   };
 341
 342   // axis lines
 343   context.save();
 344   context.strokeStyle = this.options.axisLineColor;
 345   context.lineWidth = this.options.axisLineWidth;
 346
 347   if (this.options.drawYAxis) {
 348     if (this.layout.yticks) {
 349       for (var i = 0; i < this.layout.yticks.length; i++) {
 350         var tick = this.layout.yticks[i];
 351         if (typeof(tick) == "function") return;
 352         var x = this.area.x;
 353         var y = this.area.y + tick[0] * this.area.h;
 354         context.beginPath();
 355         context.moveTo(x, y);
 356         context.lineTo(x - this.options.axisTickSize, y);
 357         context.closePath();
 358         context.stroke();
 359
 360         var label = makeDiv(tick[1]);
 361         var top = (y - this.options.axisLabelFontSize / 2);
 362         if (top < 0) top = 0;
 363
 364         if (top + this.options.axisLabelFontSize + 3 > this.height) {
 365           label.style.bottom = "0px";
 366         } else {
 367           label.style.top = top + "px";
 368         }
 369         label.style.left = "0px";
 370         label.style.textAlign = "right";
 371         label.style.width = this.options.yAxisLabelWidth + "px";
 372         this.container.appendChild(label);
 373         this.ylabels.push(label);
 374       }
 375
 376       // The lowest tick on the y-axis often overlaps with the leftmost
 377       // tick on the x-axis. Shift the bottom tick up a little bit to
 378       // compensate if necessary.
 379       var bottomTick = this.ylabels[0];
 380       var fontSize = this.options.axisLabelFontSize;
 381       var bottom = parseInt(bottomTick.style.top) + fontSize;
 382       if (bottom > this.height - fontSize) {
 383         bottomTick.style.top = (parseInt(bottomTick.style.top) -
 384             fontSize / 2) + "px";
 385       }
 386     }
 387
 388     context.beginPath();
 389     context.moveTo(this.area.x, this.area.y);
 390     context.lineTo(this.area.x, this.area.y + this.area.h);
 391     context.closePath();
 392     context.stroke();
 393   }
 394
 395   if (this.options.drawXAxis) {
 396     if (this.layout.xticks) {
 397       for (var i = 0; i < this.layout.xticks.length; i++) {
 398         var tick = this.layout.xticks[i];
 399         if (typeof(dataset) == "function") return;
 400
 401         var x = this.area.x + tick[0] * this.area.w;
 402         var y = this.area.y + this.area.h;
 403         context.beginPath();
 404         context.moveTo(x, y);
 405         context.lineTo(x, y + this.options.axisTickSize);
 406         context.closePath();
 407         context.stroke();
 408
 409         var label = makeDiv(tick[1]);
 410         label.style.textAlign = "center";
 411         label.style.bottom = "0px";
 412
 413         var left = (x - this.options.axisLabelWidth/2);
 414         if (left + this.options.axisLabelWidth > this.width) {
 415           left = this.width - this.options.xAxisLabelWidth;
 416           label.style.textAlign = "right";
 417         }
 418         if (left < 0) {
 419           left = 0;
 420           label.style.textAlign = "left";
 421         }
 422
 423         label.style.left = left + "px";
 424         label.style.width = this.options.xAxisLabelWidth + "px";
 425         this.container.appendChild(label);
 426         this.xlabels.push(label);
 427       }
 428     }
 429
 430     context.beginPath();
 431     context.moveTo(this.area.x, this.area.y + this.area.h);
 432     context.lineTo(this.area.x + this.area.w, this.area.y + this.area.h);
 433     context.closePath();
 434     context.stroke();
 435   }
 436
 437   context.restore();
 438 };
 439
 440
 441 /**
 442  * Overrides the CanvasRenderer method to draw error bars
 443  */
 444 DygraphCanvasRenderer.prototype._renderLineChart = function() {
 445   var context = this.element.getContext("2d");
 446   var colorCount = this.options.colorScheme.length;
 447   var colorScheme = this.options.colorScheme;
 448   var errorBars = this.layout.options.errorBars;
 449
 450   var setNames = [];
 451   for (var name in this.layout.datasets) setNames.push(name);
 452   var setCount = setNames.length;
 453
 454   //Update Points
 455   for (var i = 0; i < this.layout.points.length; i++) {
 456     var point = this.layout.points[i];
 457     point.canvasx = this.area.w * point.x + this.area.x;
 458     point.canvasy = this.area.h * point.y + this.area.y;
 459   }
 460
 461   // create paths
 462   var isOK = function(x) { return x && !isNaN(x); };
 463
 464   var ctx = context;
 465   if (errorBars) {
 466     for (var i = 0; i < setCount; i++) {
 467       var setName = setNames[i];
 468       var color = colorScheme[i % colorCount];
 469
 470       // setup graphics context
 471       ctx.save();
 472       ctx.strokeStyle = color;
 473       ctx.lineWidth = this.options.strokeWidth;
 474       var prevX = -1;
 475       var prevYs = [-1, -1];
 476       var count = 0;
 477       var yscale = this.layout.yscale;
 478       // should be same color as the lines but only 15% opaque.
 479       var rgb = new RGBColor(color);
 480       var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',0.15)';
 481       ctx.fillStyle = err_color;
 482       ctx.beginPath();
 483       for (var j = 0; j < this.layout.points.length; j++) {
 484         var point = this.layout.points[j];
 485         count++;
 486         if (point.name == setName) {
 487           if (!point.y || isNaN(point.y)) {
 488             prevX = -1;
 489             continue;
 490           }
 491           var newYs = [ point.y - point.errorPlus * yscale,
 492                         point.y + point.errorMinus * yscale ];
 493           newYs[0] = this.area.h * newYs[0] + this.area.y;
 494           newYs[1] = this.area.h * newYs[1] + this.area.y;
 495           if (prevX >= 0) {
 496             ctx.moveTo(prevX, prevYs[0]);
 497             ctx.lineTo(point.canvasx, newYs[0]);
 498             ctx.lineTo(point.canvasx, newYs[1]);
 499             ctx.lineTo(prevX, prevYs[1]);
 500             ctx.closePath();
 501           }
 502           prevYs[0] = newYs[0];
 503           prevYs[1] = newYs[1];
 504           prevX = point.canvasx;
 505         }
 506       }
 507       ctx.fill();
 508     }
 509   }
 510
 511   for (var i = 0; i < setCount; i++) {
 512     var setName = setNames[i];
 513     var color = colorScheme[i%colorCount];
 514
 515     // setup graphics context
 516     context.save();
 517     var point = this.layout.points[0];
 518     var pointSize = this.dygraph_.attr_("pointSize");
 519     var prevX = null, prevY = null;
 520     var drawPoints = this.dygraph_.attr_("drawPoints");
 521     var points = this.layout.points;
 522     for (var j = 0; j < points.length; j++) {
 523       var point = points[j];
 524       if (point.name == setName) {
 525         if (!isOK(point.canvasy)) {
 526           // this will make us move to the next point, not draw a line to it.
 527           prevX = prevY = null;
 528         } else {
 529           // A point is "isolated" if it is non-null but both the previous
 530           // and next points are null.
 531           var isIsolated = (!prevX && (j == points.length - 1 ||
 532                                        !isOK(points[j+1].canvasy)));
 533
 534           if (!prevX) {
 535             prevX = point.canvasx;
 536             prevY = point.canvasy;
 537           } else {
 538             ctx.beginPath();
 539             ctx.strokeStyle = color;
 540             ctx.lineWidth = this.options.strokeWidth;
 541             ctx.moveTo(prevX, prevY);
 542             prevX = point.canvasx;
 543             prevY = point.canvasy;
 544             ctx.lineTo(prevX, prevY);
 545             ctx.stroke();
 546           }
 547
 548           if (drawPoints || isIsolated) {
 549            ctx.beginPath();
 550            ctx.fillStyle = color;
 551            ctx.arc(point.canvasx, point.canvasy, pointSize, 0, 360, false);
 552            ctx.fill();
 553           }
 554         }
 555       }
 556     }
 557   }
 558
 559   context.restore();
 560 };