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   Dygraph.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   Dygraph.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   Dygraph.update(this.options, options);
 183
 184   this.layout = layout;
 185   this.element = element;
 186   this.container = this.element.parentNode;
 187
 188   this.height = this.element.height;
 189   this.width = this.element.width;
 190
 191   // --- check whether everything is ok before we return
 192   if (!this.isIE && !(DygraphCanvasRenderer.isSupported(this.element)))
 193       throw "Canvas is not supported.";
 194
 195   // internal state
 196   this.xlabels = new Array();
 197   this.ylabels = new Array();
 198
 199   this.area = {
 200     x: this.options.yAxisLabelWidth + 2 * this.options.axisTickSize,
 201     y: 0
 202   };
 203   this.area.w = this.width - this.area.x - this.options.rightGap;
 204   this.area.h = this.height - this.options.axisLabelFontSize -
 205                 2 * this.options.axisTickSize;
 206
 207   this.container.style.position = "relative";
 208   this.container.style.width = this.width + "px";
 209 };
 210
 211 DygraphCanvasRenderer.prototype.clear = function() {
 212   if (this.isIE) {
 213     // VML takes a while to start up, so we just poll every this.IEDelay
 214     try {
 215       if (this.clearDelay) {
 216         this.clearDelay.cancel();
 217         this.clearDelay = null;
 218       }
 219       var context = this.element.getContext("2d");
 220     }
 221     catch (e) {
 222       // TODO(danvk): this is broken, since MochiKit.Async is gone.
 223       this.clearDelay = MochiKit.Async.wait(this.IEDelay);
 224       this.clearDelay.addCallback(bind(this.clear, this));
 225       return;
 226     }
 227   }
 228
 229   var context = this.element.getContext("2d");
 230   context.clearRect(0, 0, this.width, this.height);
 231
 232   for (var i = 0; i < this.xlabels.length; i++) {
 233     var el = this.xlabels[i];
 234     el.parentNode.removeChild(el);
 235   }
 236   for (var i = 0; i < this.ylabels.length; i++) {
 237     var el = this.ylabels[i];
 238     el.parentNode.removeChild(el);
 239   }
 240   this.xlabels = new Array();
 241   this.ylabels = new Array();
 242 };
 243
 244
 245 DygraphCanvasRenderer.isSupported = function(canvasName) {
 246   var canvas = null;
 247   try {
 248     if (typeof(canvasName) == 'undefined' || canvasName == null)
 249       canvas = document.createElement("canvas");
 250     else
 251       canvas = canvasName;
 252     var context = canvas.getContext("2d");
 253   }
 254   catch (e) {
 255     var ie = navigator.appVersion.match(/MSIE (\d\.\d)/);
 256     var opera = (navigator.userAgent.toLowerCase().indexOf("opera") != -1);
 257     if ((!ie) || (ie[1] < 6) || (opera))
 258       return false;
 259     return true;
 260   }
 261   return true;
 262 };
 263
 264 /**
 265  * Draw an X/Y grid on top of the existing plot
 266  */
 267 DygraphCanvasRenderer.prototype.render = function() {
 268   // Draw the new X/Y grid
 269   var ctx = this.element.getContext("2d");
 270   if (this.options.drawYGrid) {
 271     var ticks = this.layout.yticks;
 272     ctx.save();
 273     ctx.strokeStyle = this.options.gridLineColor;
 274     ctx.lineWidth = this.options.axisLineWidth;
 275     for (var i = 0; i < ticks.length; i++) {
 276       var x = this.area.x;
 277       var y = this.area.y + ticks[i][0] * this.area.h;
 278       ctx.beginPath();
 279       ctx.moveTo(x, y);
 280       ctx.lineTo(x + this.area.w, y);
 281       ctx.closePath();
 282       ctx.stroke();
 283     }
 284   }
 285
 286   if (this.options.drawXGrid) {
 287     var ticks = this.layout.xticks;
 288     ctx.save();
 289     ctx.strokeStyle = this.options.gridLineColor;
 290     ctx.lineWidth = this.options.axisLineWidth;
 291     for (var i=0; i<ticks.length; i++) {
 292       var x = this.area.x + ticks[i][0] * this.area.w;
 293       var y = this.area.y + this.area.h;
 294       ctx.beginPath();
 295       ctx.moveTo(x, y);
 296       ctx.lineTo(x, this.area.y);
 297       ctx.closePath();
 298       ctx.stroke();
 299     }
 300   }
 301
 302   // Do the ordinary rendering, as before
 303   this._renderLineChart();
 304   this._renderAxis();
 305 };
 306
 307
 308 DygraphCanvasRenderer.prototype._renderAxis = function() {
 309   if (!this.options.drawXAxis && !this.options.drawYAxis)
 310     return;
 311
 312   var context = this.element.getContext("2d");
 313
 314   var labelStyle = {
 315     "position": "absolute",
 316     "fontSize": this.options.axisLabelFontSize + "px",
 317     "zIndex": 10,
 318     "color": this.options.axisLabelColor,
 319     "width": this.options.axisLabelWidth + "px",
 320     "overflow": "hidden"
 321   };
 322   var makeDiv = function(txt) {
 323     var div = document.createElement("div");
 324     for (var name in labelStyle) {
 325       div.style[name] = labelStyle[name];
 326     }
 327     div.appendChild(document.createTextNode(txt));
 328     return div;
 329   };
 330
 331   // axis lines
 332   context.save();
 333   context.strokeStyle = this.options.axisLineColor;
 334   context.lineWidth = this.options.axisLineWidth;
 335
 336   if (this.options.drawYAxis) {
 337     if (this.layout.yticks) {
 338       for (var i = 0; i < this.layout.yticks.length; i++) {
 339         var tick = this.layout.yticks[i];
 340         if (typeof(tick) == "function") return;
 341         var x = this.area.x;
 342         var y = this.area.y + tick[0] * this.area.h;
 343         context.beginPath();
 344         context.moveTo(x, y);
 345         context.lineTo(x - this.options.axisTickSize, y);
 346         context.closePath();
 347         context.stroke();
 348
 349         var label = makeDiv(tick[1]);
 350         var top = (y - this.options.axisLabelFontSize / 2);
 351         if (top < 0) top = 0;
 352
 353         if (top + this.options.axisLabelFontSize + 3 > this.height) {
 354           label.style.bottom = "0px";
 355         } else {
 356           label.style.top = top + "px";
 357         }
 358         label.style.left = "0px";
 359         label.style.textAlign = "right";
 360         label.style.width = this.options.yAxisLabelWidth + "px";
 361         this.container.appendChild(label);
 362         this.ylabels.push(label);
 363       }
 364
 365       // The lowest tick on the y-axis often overlaps with the leftmost
 366       // tick on the x-axis. Shift the bottom tick up a little bit to
 367       // compensate if necessary.
 368       var bottomTick = this.ylabels[0];
 369       var fontSize = this.options.axisLabelFontSize;
 370       var bottom = parseInt(bottomTick.style.top) + fontSize;
 371       if (bottom > this.height - fontSize) {
 372         bottomTick.style.top = (parseInt(bottomTick.style.top) -
 373             fontSize / 2) + "px";
 374       }
 375     }
 376
 377     context.beginPath();
 378     context.moveTo(this.area.x, this.area.y);
 379     context.lineTo(this.area.x, this.area.y + this.area.h);
 380     context.closePath();
 381     context.stroke();
 382   }
 383
 384   if (this.options.drawXAxis) {
 385     if (this.layout.xticks) {
 386       for (var i = 0; i < this.layout.xticks.length; i++) {
 387         var tick = this.layout.xticks[i];
 388         if (typeof(dataset) == "function") return;
 389
 390         var x = this.area.x + tick[0] * this.area.w;
 391         var y = this.area.y + this.area.h;
 392         context.beginPath();
 393         context.moveTo(x, y);
 394         context.lineTo(x, y + this.options.axisTickSize);
 395         context.closePath();
 396         context.stroke();
 397
 398         var label = makeDiv(tick[1]);
 399         label.style.textAlign = "center";
 400         label.style.bottom = "0px";
 401
 402         var left = (x - this.options.axisLabelWidth/2);
 403         if (left + this.options.axisLabelWidth > this.width) {
 404           left = this.width - this.options.xAxisLabelWidth;
 405           label.style.textAlign = "right";
 406         }
 407         if (left < 0) {
 408           left = 0;
 409           label.style.textAlign = "left";
 410         }
 411
 412         label.style.left = left + "px";
 413         label.style.width = this.options.xAxisLabelWidth + "px";
 414         this.container.appendChild(label);
 415         this.xlabels.push(label);
 416       }
 417     }
 418
 419     context.beginPath();
 420     context.moveTo(this.area.x, this.area.y + this.area.h);
 421     context.lineTo(this.area.x + this.area.w, this.area.y + this.area.h);
 422     context.closePath();
 423     context.stroke();
 424   }
 425
 426   context.restore();
 427 };
 428
 429
 430 /**
 431  * Overrides the CanvasRenderer method to draw error bars
 432  */
 433 DygraphCanvasRenderer.prototype._renderLineChart = function() {
 434   var context = this.element.getContext("2d");
 435   var colorCount = this.options.colorScheme.length;
 436   var colorScheme = this.options.colorScheme;
 437   var errorBars = this.layout.options.errorBars;
 438
 439   var setNames = [];
 440   for (var name in this.layout.datasets) setNames.push(name);
 441   var setCount = setNames.length;
 442
 443   //Update Points
 444   for (var i = 0; i < this.layout.points.length; i++) {
 445     var point = this.layout.points[i];
 446     point.canvasx = this.area.w * point.x + this.area.x;
 447     point.canvasy = this.area.h * point.y + this.area.y;
 448   }
 449
 450   // create paths
 451   var isOK = function(x) { return x && !isNaN(x); };
 452
 453   var ctx = context;
 454   if (errorBars) {
 455     for (var i = 0; i < setCount; i++) {
 456       var setName = setNames[i];
 457       var color = colorScheme[i % colorCount];
 458
 459       // setup graphics context
 460       ctx.save();
 461       ctx.strokeStyle = color;
 462       ctx.lineWidth = this.options.strokeWidth;
 463       var prevX = -1;
 464       var prevYs = [-1, -1];
 465       var count = 0;
 466       var yscale = this.layout.yscale;
 467       // should be same color as the lines but only 15% opaque.
 468       var rgb = new RGBColor(color);
 469       var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',0.15)';
 470       ctx.fillStyle = err_color;
 471       ctx.beginPath();
 472       for (var j = 0; j < this.layout.points.length; j++) {
 473         var point = this.layout.points[j];
 474         count++;
 475         if (point.name == setName) {
 476           if (!point.y || isNaN(point.y)) {
 477             prevX = -1;
 478             continue;
 479           }
 480           var newYs = [ point.y - point.errorPlus * yscale,
 481                         point.y + point.errorMinus * yscale ];
 482           newYs[0] = this.area.h * newYs[0] + this.area.y;
 483           newYs[1] = this.area.h * newYs[1] + this.area.y;
 484           if (prevX >= 0) {
 485             ctx.moveTo(prevX, prevYs[0]);
 486             ctx.lineTo(point.canvasx, newYs[0]);
 487             ctx.lineTo(point.canvasx, newYs[1]);
 488             ctx.lineTo(prevX, prevYs[1]);
 489             ctx.closePath();
 490           }
 491           prevYs[0] = newYs[0];
 492           prevYs[1] = newYs[1];
 493           prevX = point.canvasx;
 494         }
 495       }
 496       ctx.fill();
 497     }
 498   }
 499
 500   for (var i = 0; i < setCount; i++) {
 501     var setName = setNames[i];
 502     var color = colorScheme[i%colorCount];
 503
 504     // setup graphics context
 505     context.save();
 506     var point = this.layout.points[0];
 507     var pointSize = this.dygraph_.attr_("pointSize");
 508     var prevX = null, prevY = null;
 509     var drawPoints = this.dygraph_.attr_("drawPoints");
 510     var points = this.layout.points;
 511     for (var j = 0; j < points.length; j++) {
 512       var point = points[j];
 513       if (point.name == setName) {
 514         if (!isOK(point.canvasy)) {
 515           // this will make us move to the next point, not draw a line to it.
 516           prevX = prevY = null;
 517         } else {
 518           // A point is "isolated" if it is non-null but both the previous
 519           // and next points are null.
 520           var isIsolated = (!prevX && (j == points.length - 1 ||
 521                                        !isOK(points[j+1].canvasy)));
 522
 523           if (!prevX) {
 524             prevX = point.canvasx;
 525             prevY = point.canvasy;
 526           } else {
 527             ctx.beginPath();
 528             ctx.strokeStyle = color;
 529             ctx.lineWidth = this.options.strokeWidth;
 530             ctx.moveTo(prevX, prevY);
 531             prevX = point.canvasx;
 532             prevY = point.canvasy;
 533             ctx.lineTo(prevX, prevY);
 534             ctx.stroke();
 535           }
 536
 537           if (drawPoints || isIsolated) {
 538            ctx.beginPath();
 539            ctx.fillStyle = color;
 540            ctx.arc(point.canvasx, point.canvasy, pointSize,
 541                    0, 2 * Math.PI, false);
 542            ctx.fill();
 543           }
 544         }
 545       }
 546     }
 547   }
 548
 549   context.restore();
 550 };