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   if (this.options.dateWindow) {
  41     this.minxval = this.options.dateWindow[0];
  42     this.maxxval = this.options.dateWindow[1];
  43   } else {
  44     for (var name in this.datasets) {
  45       if (!this.datasets.hasOwnProperty(name)) continue;
  46       var series = this.datasets[name];
  47       var x1 = series[0][0];
  48       if (!this.minxval || x1 < this.minxval) this.minxval = x1;
  49
  50       var x2 = series[series.length - 1][0];
  51       if (!this.maxxval || x2 > this.maxxval) this.maxxval = x2;
  52     }
  53   }
  54   this.xrange = this.maxxval - this.minxval;
  55   this.xscale = (this.xrange != 0 ? 1/this.xrange : 1.0);
  56
  57   this.minyval = this.options.yAxis[0];
  58   this.maxyval = this.options.yAxis[1];
  59   this.yrange = this.maxyval - this.minyval;
  60   this.yscale = (this.yrange != 0 ? 1/this.yrange : 1.0);
  61 };
  62
  63 DygraphLayout.prototype._evaluateLineCharts = function() {
  64   // add all the rects
  65   this.points = new Array();
  66   for (var setName in this.datasets) {
  67     if (!this.datasets.hasOwnProperty(setName)) continue;
  68
  69     var dataset = this.datasets[setName];
  70     for (var j = 0; j < dataset.length; j++) {
  71       var item = dataset[j];
  72       var point = {
  73         // TODO(danvk): here
  74         x: ((parseFloat(item[0]) - this.minxval) * this.xscale),
  75         y: 1.0 - ((parseFloat(item[1]) - this.minyval) * this.yscale),
  76         xval: parseFloat(item[0]),
  77         yval: parseFloat(item[1]),
  78         name: setName
  79       };
  80
  81       // limit the x, y values so they do not overdraw
  82       if (point.y <= 0.0) {
  83         point.y = 0.0;
  84       }
  85       if (point.y >= 1.0) {
  86         point.y = 1.0;
  87       }
  88       // if ((point.x >= 0.0) && (point.x <= 1.0)) {
  89         this.points.push(point);
  90       // }
  91     }
  92   }
  93 };
  94
  95 DygraphLayout.prototype._evaluateLineTicks = function() {
  96   this.xticks = new Array();
  97   for (var i = 0; i < this.options.xTicks.length; i++) {
  98     var tick = this.options.xTicks[i];
  99     var label = tick.label;
 100     var pos = this.xscale * (tick.v - this.minxval);
 101     if ((pos >= 0.0) && (pos <= 1.0)) {
 102       this.xticks.push([pos, label]);
 103     }
 104   }
 105
 106   this.yticks = new Array();
 107   for (var i = 0; i < this.options.yTicks.length; i++) {
 108     var tick = this.options.yTicks[i];
 109     var label = tick.label;
 110     var pos = 1.0 - (this.yscale * (tick.v - this.minyval));
 111     if ((pos >= 0.0) && (pos <= 1.0)) {
 112       this.yticks.push([pos, label]);
 113     }
 114   }
 115 };
 116
 117
 118 /**
 119  * Behaves the same way as PlotKit.Layout, but also copies the errors
 120  * @private
 121  */
 122 DygraphLayout.prototype.evaluateWithError = function() {
 123   this.evaluate();
 124   if (!this.options.errorBars) return;
 125
 126   // Copy over the error terms
 127   var i = 0; // index in this.points
 128   for (var setName in this.datasets) {
 129     if (!this.datasets.hasOwnProperty(setName)) continue;
 130     var j = 0;
 131     var dataset = this.datasets[setName];
 132     for (var j = 0; j < dataset.length; j++, i++) {
 133       var item = dataset[j];
 134       var xv = parseFloat(item[0]);
 135       var yv = parseFloat(item[1]);
 136
 137       if (xv == this.points[i].xval &&
 138           yv == this.points[i].yval) {
 139         this.points[i].errorMinus = parseFloat(item[2]);
 140         this.points[i].errorPlus = parseFloat(item[3]);
 141       }
 142     }
 143   }
 144 };
 145
 146 /**
 147  * Convenience function to remove all the data sets from a graph
 148  */
 149 DygraphLayout.prototype.removeAllDatasets = function() {
 150   delete this.datasets;
 151   this.datasets = new Array();
 152 };
 153
 154 /**
 155  * Change the values of various layout options
 156  * @param {Object} new_options an associative array of new properties
 157  */
 158 DygraphLayout.prototype.updateOptions = function(new_options) {
 159   Dygraph.update(this.options, new_options ? new_options : {});
 160 };
 161
 162 // Subclass PlotKit.CanvasRenderer to add:
 163 // 1. X/Y grid overlay
 164 // 2. Ability to draw error bars (if required)
 165
 166 /**
 167  * Sets some PlotKit.CanvasRenderer options
 168  * @param {Object} element The canvas to attach to
 169  * @param {Layout} layout The DygraphLayout object for this graph.
 170  * @param {Object} options Options to pass on to CanvasRenderer
 171  */
 172 DygraphCanvasRenderer = function(dygraph, element, layout, options) {
 173   // TODO(danvk): remove options, just use dygraph.attr_.
 174   this.dygraph_ = dygraph;
 175
 176   // default options
 177   this.options = {
 178     "strokeWidth": 0.5,
 179     "drawXAxis": true,
 180     "drawYAxis": true,
 181     "axisLineColor": "black",
 182     "axisLineWidth": 0.5,
 183     "axisTickSize": 3,
 184     "axisLabelColor": "black",
 185     "axisLabelFont": "Arial",
 186     "axisLabelFontSize": 9,
 187     "axisLabelWidth": 50,
 188     "drawYGrid": true,
 189     "drawXGrid": true,
 190     "gridLineColor": "rgb(128,128,128)",
 191     "fillAlpha": 0.15,
 192   };
 193   Dygraph.update(this.options, options);
 194
 195   this.layout = layout;
 196   this.element = element;
 197   this.container = this.element.parentNode;
 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       if (labelStyle.hasOwnProperty(name)) {
 337         div.style[name] = labelStyle[name];
 338       }
 339     }
 340     div.appendChild(document.createTextNode(txt));
 341     return div;
 342   };
 343
 344   // axis lines
 345   context.save();
 346   context.strokeStyle = this.options.axisLineColor;
 347   context.lineWidth = this.options.axisLineWidth;
 348
 349   if (this.options.drawYAxis) {
 350     if (this.layout.yticks && this.layout.yticks.length > 0) {
 351       for (var i = 0; i < this.layout.yticks.length; i++) {
 352         var tick = this.layout.yticks[i];
 353         if (typeof(tick) == "function") return;
 354         var x = this.area.x;
 355         var y = this.area.y + tick[0] * this.area.h;
 356         context.beginPath();
 357         context.moveTo(x, y);
 358         context.lineTo(x - this.options.axisTickSize, y);
 359         context.closePath();
 360         context.stroke();
 361
 362         var label = makeDiv(tick[1]);
 363         var top = (y - this.options.axisLabelFontSize / 2);
 364         if (top < 0) top = 0;
 365
 366         if (top + this.options.axisLabelFontSize + 3 > this.height) {
 367           label.style.bottom = "0px";
 368         } else {
 369           label.style.top = top + "px";
 370         }
 371         label.style.left = "0px";
 372         label.style.textAlign = "right";
 373         label.style.width = this.options.yAxisLabelWidth + "px";
 374         this.container.appendChild(label);
 375         this.ylabels.push(label);
 376       }
 377
 378       // The lowest tick on the y-axis often overlaps with the leftmost
 379       // tick on the x-axis. Shift the bottom tick up a little bit to
 380       // compensate if necessary.
 381       var bottomTick = this.ylabels[0];
 382       var fontSize = this.options.axisLabelFontSize;
 383       var bottom = parseInt(bottomTick.style.top) + fontSize;
 384       if (bottom > this.height - fontSize) {
 385         bottomTick.style.top = (parseInt(bottomTick.style.top) -
 386             fontSize / 2) + "px";
 387       }
 388     }
 389
 390     context.beginPath();
 391     context.moveTo(this.area.x, this.area.y);
 392     context.lineTo(this.area.x, this.area.y + this.area.h);
 393     context.closePath();
 394     context.stroke();
 395   }
 396
 397   if (this.options.drawXAxis) {
 398     if (this.layout.xticks) {
 399       for (var i = 0; i < this.layout.xticks.length; i++) {
 400         var tick = this.layout.xticks[i];
 401         if (typeof(dataset) == "function") return;
 402
 403         var x = this.area.x + tick[0] * this.area.w;
 404         var y = this.area.y + this.area.h;
 405         context.beginPath();
 406         context.moveTo(x, y);
 407         context.lineTo(x, y + this.options.axisTickSize);
 408         context.closePath();
 409         context.stroke();
 410
 411         var label = makeDiv(tick[1]);
 412         label.style.textAlign = "center";
 413         label.style.bottom = "0px";
 414
 415         var left = (x - this.options.axisLabelWidth/2);
 416         if (left + this.options.axisLabelWidth > this.width) {
 417           left = this.width - this.options.xAxisLabelWidth;
 418           label.style.textAlign = "right";
 419         }
 420         if (left < 0) {
 421           left = 0;
 422           label.style.textAlign = "left";
 423         }
 424
 425         label.style.left = left + "px";
 426         label.style.width = this.options.xAxisLabelWidth + "px";
 427         this.container.appendChild(label);
 428         this.xlabels.push(label);
 429       }
 430     }
 431
 432     context.beginPath();
 433     context.moveTo(this.area.x, this.area.y + this.area.h);
 434     context.lineTo(this.area.x + this.area.w, this.area.y + this.area.h);
 435     context.closePath();
 436     context.stroke();
 437   }
 438
 439   context.restore();
 440 };
 441
 442
 443 /**
 444  * Overrides the CanvasRenderer method to draw error bars
 445  */
 446 DygraphCanvasRenderer.prototype._renderLineChart = function() {
 447   var context = this.element.getContext("2d");
 448   var colorCount = this.options.colorScheme.length;
 449   var colorScheme = this.options.colorScheme;
 450   var fillAlpha = this.options.fillAlpha;
 451   var errorBars = this.layout.options.errorBars;
 452   var fillGraph = this.layout.options.fillGraph;
 453
 454   var setNames = [];
 455   for (var name in this.layout.datasets) {
 456     if (this.layout.datasets.hasOwnProperty(name)) {
 457       setNames.push(name);
 458     }
 459   }
 460   var setCount = setNames.length;
 461
 462   // Update Points
 463   // TODO(danvk): here
 464   for (var i = 0; i < this.layout.points.length; i++) {
 465     var point = this.layout.points[i];
 466     point.canvasx = this.area.w * point.x + this.area.x;
 467     point.canvasy = this.area.h * point.y + this.area.y;
 468   }
 469
 470   // create paths
 471   var isOK = function(x) { return x && !isNaN(x); };
 472
 473   var ctx = context;
 474   if (errorBars) {
 475     if (fillGraph) {
 476       this.dygraph_.warn("Can't use fillGraph option with error bars");
 477     }
 478
 479     for (var i = 0; i < setCount; i++) {
 480       var setName = setNames[i];
 481       var color = colorScheme[i % colorCount];
 482
 483       // setup graphics context
 484       ctx.save();
 485       ctx.strokeStyle = color;
 486       ctx.lineWidth = this.options.strokeWidth;
 487       var prevX = -1;
 488       var prevYs = [-1, -1];
 489       var count = 0;
 490       var yscale = this.layout.yscale;
 491       // should be same color as the lines but only 15% opaque.
 492       var rgb = new RGBColor(color);
 493       var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 494                             fillAlpha + ')';
 495       ctx.fillStyle = err_color;
 496       ctx.beginPath();
 497       for (var j = 0; j < this.layout.points.length; j++) {
 498         var point = this.layout.points[j];
 499         count++;
 500         if (point.name == setName) {
 501           if (!isOK(point.y)) {
 502             prevX = -1;
 503             continue;
 504           }
 505           // TODO(danvk): here
 506           var newYs = [ point.y - point.errorPlus * yscale,
 507                         point.y + point.errorMinus * yscale ];
 508           newYs[0] = this.area.h * newYs[0] + this.area.y;
 509           newYs[1] = this.area.h * newYs[1] + this.area.y;
 510           if (prevX >= 0) {
 511             ctx.moveTo(prevX, prevYs[0]);
 512             ctx.lineTo(point.canvasx, newYs[0]);
 513             ctx.lineTo(point.canvasx, newYs[1]);
 514             ctx.lineTo(prevX, prevYs[1]);
 515             ctx.closePath();
 516           }
 517           prevYs[0] = newYs[0];
 518           prevYs[1] = newYs[1];
 519           prevX = point.canvasx;
 520         }
 521       }
 522       ctx.fill();
 523     }
 524   } else if (fillGraph) {
 525     // TODO(danvk): merge this code with the logic above; they're very similar.
 526     for (var i = 0; i < setCount; i++) {
 527       var setName = setNames[i];
 528       var setNameLast;
 529       if (i>0) setNameLast = setNames[i-1];
 530       var color = colorScheme[i % colorCount];
 531
 532       // setup graphics context
 533       ctx.save();
 534       ctx.strokeStyle = color;
 535       ctx.lineWidth = this.options.strokeWidth;
 536       var prevX = -1;
 537       var prevYs = [-1, -1];
 538       var count = 0;
 539       var yscale = this.layout.yscale;
 540       // should be same color as the lines but only 15% opaque.
 541       var rgb = new RGBColor(color);
 542       var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
 543                             fillAlpha + ')';
 544       ctx.fillStyle = err_color;
 545       ctx.beginPath();
 546       for (var j = 0; j < this.layout.points.length; j++) {
 547         var point = this.layout.points[j];
 548         count++;
 549         if (point.name == setName) {
 550           if (!isOK(point.y)) {
 551             prevX = -1;
 552             continue;
 553           }
 554           var pX = 1.0 + this.layout.minyval * this.layout.yscale;
 555           if (pX < 0.0) pX = 0.0;
 556           else if (pX > 1.0) pX = 1.0;
 557           var newYs = [ point.y, pX ];
 558           newYs[0] = this.area.h * newYs[0] + this.area.y;
 559           newYs[1] = this.area.h * newYs[1] + this.area.y;
 560           if (prevX >= 0) {
 561             ctx.moveTo(prevX, prevYs[0]);
 562             ctx.lineTo(point.canvasx, newYs[0]);
 563             ctx.lineTo(point.canvasx, newYs[1]);
 564             ctx.lineTo(prevX, prevYs[1]);
 565             ctx.closePath();
 566           }
 567           prevYs[0] = newYs[0];
 568           prevYs[1] = newYs[1];
 569           prevX = point.canvasx;
 570         }
 571       }
 572       ctx.fill();
 573     }
 574   }
 575
 576   for (var i = 0; i < setCount; i++) {
 577     var setName = setNames[i];
 578     var color = colorScheme[i%colorCount];
 579
 580     // setup graphics context
 581     context.save();
 582     var point = this.layout.points[0];
 583     var pointSize = this.dygraph_.attr_("pointSize");
 584     var prevX = null, prevY = null;
 585     var drawPoints = this.dygraph_.attr_("drawPoints");
 586     var points = this.layout.points;
 587     for (var j = 0; j < points.length; j++) {
 588       var point = points[j];
 589       if (point.name == setName) {
 590         if (!isOK(point.canvasy)) {
 591           // this will make us move to the next point, not draw a line to it.
 592           prevX = prevY = null;
 593         } else {
 594           // A point is "isolated" if it is non-null but both the previous
 595           // and next points are null.
 596           var isIsolated = (!prevX && (j == points.length - 1 ||
 597                                        !isOK(points[j+1].canvasy)));
 598
 599           if (!prevX) {
 600             prevX = point.canvasx;
 601             prevY = point.canvasy;
 602           } else {
 603             ctx.beginPath();
 604             ctx.strokeStyle = color;
 605             ctx.lineWidth = this.options.strokeWidth;
 606             ctx.moveTo(prevX, prevY);
 607             prevX = point.canvasx;
 608             prevY = point.canvasy;
 609             ctx.lineTo(prevX, prevY);
 610             ctx.stroke();
 611           }
 612
 613           if (drawPoints || isIsolated) {
 614            ctx.beginPath();
 615            ctx.fillStyle = color;
 616            ctx.arc(point.canvasx, point.canvasy, pointSize,
 617                    0, 2 * Math.PI, false);
 618            ctx.fill();
 619           }
 620         }
 621       }
 622     }
 623   }
 624
 625   context.restore();
 626 };