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   };
 192   Dygraph.update(this.options, options);
 193
 194   this.layout = layout;
 195   this.element = element;
 196   this.container = this.element.parentNode;
 197
 198   this.height = this.element.height;
 199   this.width = this.element.width;
 200
 201   // --- check whether everything is ok before we return
 202   if (!this.isIE && !(DygraphCanvasRenderer.isSupported(this.element)))
 203       throw "Canvas is not supported.";
 204
 205   // internal state
 206   this.xlabels = new Array();
 207   this.ylabels = new Array();
 208
 209   this.area = {
 210     x: this.options.yAxisLabelWidth + 2 * this.options.axisTickSize,
 211     y: 0
 212   };
 213   this.area.w = this.width - this.area.x - this.options.rightGap;
 214   this.area.h = this.height - this.options.axisLabelFontSize -
 215                 2 * this.options.axisTickSize;
 216
 217   this.container.style.position = "relative";
 218   this.container.style.width = this.width + "px";
 219 };
 220
 221 DygraphCanvasRenderer.prototype.clear = function() {
 222   if (this.isIE) {
 223     // VML takes a while to start up, so we just poll every this.IEDelay
 224     try {
 225       if (this.clearDelay) {
 226         this.clearDelay.cancel();
 227         this.clearDelay = null;
 228       }
 229       var context = this.element.getContext("2d");
 230     }
 231     catch (e) {
 232       // TODO(danvk): this is broken, since MochiKit.Async is gone.
 233       this.clearDelay = MochiKit.Async.wait(this.IEDelay);
 234       this.clearDelay.addCallback(bind(this.clear, this));
 235       return;
 236     }
 237   }
 238
 239   var context = this.element.getContext("2d");
 240   context.clearRect(0, 0, this.width, this.height);
 241
 242   for (var i = 0; i < this.xlabels.length; i++) {
 243     var el = this.xlabels[i];
 244     el.parentNode.removeChild(el);
 245   }
 246   for (var i = 0; i < this.ylabels.length; i++) {
 247     var el = this.ylabels[i];
 248     el.parentNode.removeChild(el);
 249   }
 250   this.xlabels = new Array();
 251   this.ylabels = new Array();
 252 };
 253
 254
 255 DygraphCanvasRenderer.isSupported = function(canvasName) {
 256   var canvas = null;
 257   try {
 258     if (typeof(canvasName) == 'undefined' || canvasName == null)
 259       canvas = document.createElement("canvas");
 260     else
 261       canvas = canvasName;
 262     var context = canvas.getContext("2d");
 263   }
 264   catch (e) {
 265     var ie = navigator.appVersion.match(/MSIE (\d\.\d)/);
 266     var opera = (navigator.userAgent.toLowerCase().indexOf("opera") != -1);
 267     if ((!ie) || (ie[1] < 6) || (opera))
 268       return false;
 269     return true;
 270   }
 271   return true;
 272 };
 273
 274 /**
 275  * Draw an X/Y grid on top of the existing plot
 276  */
 277 DygraphCanvasRenderer.prototype.render = function() {
 278   // Draw the new X/Y grid
 279   var ctx = this.element.getContext("2d");
 280   if (this.options.drawYGrid) {
 281     var ticks = this.layout.yticks;
 282     ctx.save();
 283     ctx.strokeStyle = this.options.gridLineColor;
 284     ctx.lineWidth = this.options.axisLineWidth;
 285     for (var i = 0; i < ticks.length; i++) {
 286       var x = this.area.x;
 287       var y = this.area.y + ticks[i][0] * this.area.h;
 288       ctx.beginPath();
 289       ctx.moveTo(x, y);
 290       ctx.lineTo(x + this.area.w, y);
 291       ctx.closePath();
 292       ctx.stroke();
 293     }
 294   }
 295
 296   if (this.options.drawXGrid) {
 297     var ticks = this.layout.xticks;
 298     ctx.save();
 299     ctx.strokeStyle = this.options.gridLineColor;
 300     ctx.lineWidth = this.options.axisLineWidth;
 301     for (var i=0; i<ticks.length; i++) {
 302       var x = this.area.x + ticks[i][0] * this.area.w;
 303       var y = this.area.y + this.area.h;
 304       ctx.beginPath();
 305       ctx.moveTo(x, y);
 306       ctx.lineTo(x, this.area.y);
 307       ctx.closePath();
 308       ctx.stroke();
 309     }
 310   }
 311
 312   // Do the ordinary rendering, as before
 313   this._renderLineChart();
 314   this._renderAxis();
 315 };
 316
 317
 318 DygraphCanvasRenderer.prototype._renderAxis = function() {
 319   if (!this.options.drawXAxis && !this.options.drawYAxis)
 320     return;
 321
 322   var context = this.element.getContext("2d");
 323
 324   var labelStyle = {
 325     "position": "absolute",
 326     "fontSize": this.options.axisLabelFontSize + "px",
 327     "zIndex": 10,
 328     "color": this.options.axisLabelColor,
 329     "width": this.options.axisLabelWidth + "px",
 330     "overflow": "hidden"
 331   };
 332   var makeDiv = function(txt) {
 333     var div = document.createElement("div");
 334     for (var name in labelStyle) {
 335       if (labelStyle.hasOwnProperty(name)) {
 336         div.style[name] = labelStyle[name];
 337       }
 338     }
 339     div.appendChild(document.createTextNode(txt));
 340     return div;
 341   };
 342
 343   // axis lines
 344   context.save();
 345   context.strokeStyle = this.options.axisLineColor;
 346   context.lineWidth = this.options.axisLineWidth;
 347
 348   if (this.options.drawYAxis) {
 349     if (this.layout.yticks && this.layout.yticks.length > 0) {
 350       for (var i = 0; i < this.layout.yticks.length; i++) {
 351         var tick = this.layout.yticks[i];
 352         if (typeof(tick) == "function") return;
 353         var x = this.area.x;
 354         var y = this.area.y + tick[0] * this.area.h;
 355         context.beginPath();
 356         context.moveTo(x, y);
 357         context.lineTo(x - this.options.axisTickSize, y);
 358         context.closePath();
 359         context.stroke();
 360
 361         var label = makeDiv(tick[1]);
 362         var top = (y - this.options.axisLabelFontSize / 2);
 363         if (top < 0) top = 0;
 364
 365         if (top + this.options.axisLabelFontSize + 3 > this.height) {
 366           label.style.bottom = "0px";
 367         } else {
 368           label.style.top = top + "px";
 369         }
 370         label.style.left = "0px";
 371         label.style.textAlign = "right";
 372         label.style.width = this.options.yAxisLabelWidth + "px";
 373         this.container.appendChild(label);
 374         this.ylabels.push(label);
 375       }
 376
 377       // The lowest tick on the y-axis often overlaps with the leftmost
 378       // tick on the x-axis. Shift the bottom tick up a little bit to
 379       // compensate if necessary.
 380       var bottomTick = this.ylabels[0];
 381       var fontSize = this.options.axisLabelFontSize;
 382       var bottom = parseInt(bottomTick.style.top) + fontSize;
 383       if (bottom > this.height - fontSize) {
 384         bottomTick.style.top = (parseInt(bottomTick.style.top) -
 385             fontSize / 2) + "px";
 386       }
 387     }
 388
 389     context.beginPath();
 390     context.moveTo(this.area.x, this.area.y);
 391     context.lineTo(this.area.x, this.area.y + this.area.h);
 392     context.closePath();
 393     context.stroke();
 394   }
 395
 396   if (this.options.drawXAxis) {
 397     if (this.layout.xticks) {
 398       for (var i = 0; i < this.layout.xticks.length; i++) {
 399         var tick = this.layout.xticks[i];
 400         if (typeof(dataset) == "function") return;
 401
 402         var x = this.area.x + tick[0] * this.area.w;
 403         var y = this.area.y + this.area.h;
 404         context.beginPath();
 405         context.moveTo(x, y);
 406         context.lineTo(x, y + this.options.axisTickSize);
 407         context.closePath();
 408         context.stroke();
 409
 410         var label = makeDiv(tick[1]);
 411         label.style.textAlign = "center";
 412         label.style.bottom = "0px";
 413
 414         var left = (x - this.options.axisLabelWidth/2);
 415         if (left + this.options.axisLabelWidth > this.width) {
 416           left = this.width - this.options.xAxisLabelWidth;
 417           label.style.textAlign = "right";
 418         }
 419         if (left < 0) {
 420           left = 0;
 421           label.style.textAlign = "left";
 422         }
 423
 424         label.style.left = left + "px";
 425         label.style.width = this.options.xAxisLabelWidth + "px";
 426         this.container.appendChild(label);
 427         this.xlabels.push(label);
 428       }
 429     }
 430
 431     context.beginPath();
 432     context.moveTo(this.area.x, this.area.y + this.area.h);
 433     context.lineTo(this.area.x + this.area.w, this.area.y + this.area.h);
 434     context.closePath();
 435     context.stroke();
 436   }
 437
 438   context.restore();
 439 };
 440
 441
 442 /**
 443  * Overrides the CanvasRenderer method to draw error bars
 444  */
 445 DygraphCanvasRenderer.prototype._renderLineChart = function() {
 446   var context = this.element.getContext("2d");
 447   var colorCount = this.options.colorScheme.length;
 448   var colorScheme = this.options.colorScheme;
 449   var errorBars = this.layout.options.errorBars;
 450   var fillGraph = this.layout.options.fillGraph;
 451
 452   var setNames = [];
 453   for (var name in this.layout.datasets) {
 454     if (this.layout.datasets.hasOwnProperty(name)) {
 455       setNames.push(name);
 456     }
 457   }
 458   var setCount = setNames.length;
 459
 460   // Update Points
 461   // TODO(danvk): here
 462   for (var i = 0; i < this.layout.points.length; i++) {
 463     var point = this.layout.points[i];
 464     point.canvasx = this.area.w * point.x + this.area.x;
 465     point.canvasy = this.area.h * point.y + this.area.y;
 466   }
 467
 468   // create paths
 469   var isOK = function(x) { return x && !isNaN(x); };
 470
 471   var ctx = context;
 472   if (errorBars) {
 473     if (fillGraph) {
 474       this.dygraph_.warn("Can't use fillGraph option with error bars");
 475     }
 476
 477     for (var i = 0; i < setCount; i++) {
 478       var setName = setNames[i];
 479       var color = colorScheme[i % colorCount];
 480
 481       // setup graphics context
 482       ctx.save();
 483       ctx.strokeStyle = color;
 484       ctx.lineWidth = this.options.strokeWidth;
 485       var prevX = -1;
 486       var prevYs = [-1, -1];
 487       var count = 0;
 488       var yscale = this.layout.yscale;
 489       // should be same color as the lines but only 15% opaque.
 490       var rgb = new RGBColor(color);
 491       var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',0.15)';
 492       ctx.fillStyle = err_color;
 493       ctx.beginPath();
 494       for (var j = 0; j < this.layout.points.length; j++) {
 495         var point = this.layout.points[j];
 496         count++;
 497         if (point.name == setName) {
 498           if (!isOK(point.y)) {
 499             prevX = -1;
 500             continue;
 501           }
 502           // TODO(danvk): here
 503           var newYs = [ point.y - point.errorPlus * yscale,
 504                         point.y + point.errorMinus * yscale ];
 505           newYs[0] = this.area.h * newYs[0] + this.area.y;
 506           newYs[1] = this.area.h * newYs[1] + this.area.y;
 507           if (prevX >= 0) {
 508             ctx.moveTo(prevX, prevYs[0]);
 509             ctx.lineTo(point.canvasx, newYs[0]);
 510             ctx.lineTo(point.canvasx, newYs[1]);
 511             ctx.lineTo(prevX, prevYs[1]);
 512             ctx.closePath();
 513           }
 514           prevYs[0] = newYs[0];
 515           prevYs[1] = newYs[1];
 516           prevX = point.canvasx;
 517         }
 518       }
 519       ctx.fill();
 520     }
 521   } else if (fillGraph) {
 522     // TODO(danvk): merge this code with the logic above; they're very similar.
 523     for (var i = 0; i < setCount; i++) {
 524       var setName = setNames[i];
 525       var setNameLast;
 526       if (i>0) setNameLast = setNames[i-1];
 527       var color = colorScheme[i % colorCount];
 528
 529       // setup graphics context
 530       ctx.save();
 531       ctx.strokeStyle = color;
 532       ctx.lineWidth = this.options.strokeWidth;
 533       var prevX = -1;
 534       var prevYs = [-1, -1];
 535       var count = 0;
 536       var yscale = this.layout.yscale;
 537       // should be same color as the lines but only 15% opaque.
 538       var rgb = new RGBColor(color);
 539       var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',0.15)';
 540       ctx.fillStyle = err_color;
 541       ctx.beginPath();
 542       for (var j = 0; j < this.layout.points.length; j++) {
 543         var point = this.layout.points[j];
 544         count++;
 545         if (point.name == setName) {
 546           if (!isOK(point.y)) {
 547             prevX = -1;
 548             continue;
 549           }
 550           var pX = 1.0 + this.layout.minyval * this.layout.yscale;
 551           if (pX < 0.0) pX = 0.0;
 552           else if (pX > 1.0) pX = 1.0;
 553           var newYs = [ point.y, pX ];
 554           newYs[0] = this.area.h * newYs[0] + this.area.y;
 555           newYs[1] = this.area.h * newYs[1] + this.area.y;
 556           if (prevX >= 0) {
 557             ctx.moveTo(prevX, prevYs[0]);
 558             ctx.lineTo(point.canvasx, newYs[0]);
 559             ctx.lineTo(point.canvasx, newYs[1]);
 560             ctx.lineTo(prevX, prevYs[1]);
 561             ctx.closePath();
 562           }
 563           prevYs[0] = newYs[0];
 564           prevYs[1] = newYs[1];
 565           prevX = point.canvasx;
 566         }
 567       }
 568       ctx.fill();
 569     }
 570   }
 571
 572   for (var i = 0; i < setCount; i++) {
 573     var setName = setNames[i];
 574     var color = colorScheme[i%colorCount];
 575
 576     // setup graphics context
 577     context.save();
 578     var point = this.layout.points[0];
 579     var pointSize = this.dygraph_.attr_("pointSize");
 580     var prevX = null, prevY = null;
 581     var drawPoints = this.dygraph_.attr_("drawPoints");
 582     var points = this.layout.points;
 583     for (var j = 0; j < points.length; j++) {
 584       var point = points[j];
 585       if (point.name == setName) {
 586         if (!isOK(point.canvasy)) {
 587           // this will make us move to the next point, not draw a line to it.
 588           prevX = prevY = null;
 589         } else {
 590           // A point is "isolated" if it is non-null but both the previous
 591           // and next points are null.
 592           var isIsolated = (!prevX && (j == points.length - 1 ||
 593                                        !isOK(points[j+1].canvasy)));
 594
 595           if (!prevX) {
 596             prevX = point.canvasx;
 597             prevY = point.canvasy;
 598           } else {
 599             ctx.beginPath();
 600             ctx.strokeStyle = color;
 601             ctx.lineWidth = this.options.strokeWidth;
 602             ctx.moveTo(prevX, prevY);
 603             prevX = point.canvasx;
 604             prevY = point.canvasy;
 605             ctx.lineTo(prevX, prevY);
 606             ctx.stroke();
 607           }
 608
 609           if (drawPoints || isIsolated) {
 610            ctx.beginPath();
 611            ctx.fillStyle = color;
 612            ctx.arc(point.canvasx, point.canvasy, pointSize,
 613                    0, 2 * Math.PI, false);
 614            ctx.fill();
 615           }
 616         }
 617       }
 618     }
 619   }
 620
 621   context.restore();
 622 };