plugins/range-selector.js

   1 /**
   2  * @license
   3  * Copyright 2011 Paul Felix (paul.eric.felix@gmail.com)
   4  * MIT-licensed (http://opensource.org/licenses/MIT)
   5  */
   6 /*global Dygraph:false,TouchEvent:false */
   7
   8 /**
   9  * @fileoverview This file contains the RangeSelector plugin used to provide
  10  * a timeline range selector widget for dygraphs.
  11  */
  12
  13 Dygraph.Plugins.RangeSelector = (function() {
  14
  15 /*global Dygraph:false */
  16 "use strict";
  17
  18 var rangeSelector = function() {
  19   this.isIE_ = /MSIE/.test(navigator.userAgent) && !window.opera;
  20   this.hasTouchInterface_ = typeof(TouchEvent) != 'undefined';
  21   this.isMobileDevice_ = /mobile|android/gi.test(navigator.appVersion);
  22   this.interfaceCreated_ = false;
  23 };
  24
  25 rangeSelector.prototype.toString = function() {
  26   return "RangeSelector Plugin";
  27 };
  28
  29 rangeSelector.prototype.activate = function(dygraph) {
  30   this.dygraph_ = dygraph;
  31   this.isUsingExcanvas_ = dygraph.isUsingExcanvas_;
  32   if (this.getOption_('showRangeSelector')) {
  33     this.createInterface_();
  34   }
  35   return {
  36     layout: this.reserveSpace_,
  37     predraw: this.renderStaticLayer_,
  38     didDrawChart: this.renderInteractiveLayer_
  39   };
  40 };
  41
  42 rangeSelector.prototype.destroy = function() {
  43   this.bgcanvas_ = null;
  44   this.fgcanvas_ = null;
  45   this.leftZoomHandle_ = null;
  46   this.rightZoomHandle_ = null;
  47   this.iePanOverlay_ = null;
  48 };
  49
  50 //------------------------------------------------------------------
  51 // Private methods
  52 //------------------------------------------------------------------
  53
  54 rangeSelector.prototype.getOption_ = function(name, opt_series) {
  55   return this.dygraph_.getOption(name, opt_series);
  56 };
  57
  58 rangeSelector.prototype.setDefaultOption_ = function(name, value) {
  59   this.dygraph_.attrs_[name] = value;
  60 };
  61
  62 /**
  63  * @private
  64  * Creates the range selector elements and adds them to the graph.
  65  */
  66 rangeSelector.prototype.createInterface_ = function() {
  67   this.createCanvases_();
  68   if (this.isUsingExcanvas_) {
  69     this.createIEPanOverlay_();
  70   }
  71   this.createZoomHandles_();
  72   this.initInteraction_();
  73
  74   // Range selector and animatedZooms have a bad interaction. See issue 359.
  75   if (this.getOption_('animatedZooms')) {
  76     console.warn('Animated zooms and range selector are not compatible; disabling animatedZooms.');
  77     this.dygraph_.updateOptions({animatedZooms: false}, true);
  78   }
  79
  80   this.interfaceCreated_ = true;
  81   this.addToGraph_();
  82 };
  83
  84 /**
  85  * @private
  86  * Adds the range selector to the graph.
  87  */
  88 rangeSelector.prototype.addToGraph_ = function() {
  89   var graphDiv = this.graphDiv_ = this.dygraph_.graphDiv;
  90   graphDiv.appendChild(this.bgcanvas_);
  91   graphDiv.appendChild(this.fgcanvas_);
  92   graphDiv.appendChild(this.leftZoomHandle_);
  93   graphDiv.appendChild(this.rightZoomHandle_);
  94 };
  95
  96 /**
  97  * @private
  98  * Removes the range selector from the graph.
  99  */
 100 rangeSelector.prototype.removeFromGraph_ = function() {
 101   var graphDiv = this.graphDiv_;
 102   graphDiv.removeChild(this.bgcanvas_);
 103   graphDiv.removeChild(this.fgcanvas_);
 104   graphDiv.removeChild(this.leftZoomHandle_);
 105   graphDiv.removeChild(this.rightZoomHandle_);
 106   this.graphDiv_ = null;
 107 };
 108
 109 /**
 110  * @private
 111  * Called by Layout to allow range selector to reserve its space.
 112  */
 113 rangeSelector.prototype.reserveSpace_ = function(e) {
 114   if (this.getOption_('showRangeSelector')) {
 115     e.reserveSpaceBottom(this.getOption_('rangeSelectorHeight') + 4);
 116   }
 117 };
 118
 119 /**
 120  * @private
 121  * Renders the static portion of the range selector at the predraw stage.
 122  */
 123 rangeSelector.prototype.renderStaticLayer_ = function() {
 124   if (!this.updateVisibility_()) {
 125     return;
 126   }
 127   this.resize_();
 128   this.drawStaticLayer_();
 129 };
 130
 131 /**
 132  * @private
 133  * Renders the interactive portion of the range selector after the chart has been drawn.
 134  */
 135 rangeSelector.prototype.renderInteractiveLayer_ = function() {
 136   if (!this.updateVisibility_() || this.isChangingRange_) {
 137     return;
 138   }
 139   this.placeZoomHandles_();
 140   this.drawInteractiveLayer_();
 141 };
 142
 143 /**
 144  * @private
 145  * Check to see if the range selector is enabled/disabled and update visibility accordingly.
 146  */
 147 rangeSelector.prototype.updateVisibility_ = function() {
 148   var enabled = this.getOption_('showRangeSelector');
 149   if (enabled) {
 150     if (!this.interfaceCreated_) {
 151       this.createInterface_();
 152     } else if (!this.graphDiv_ || !this.graphDiv_.parentNode) {
 153       this.addToGraph_();
 154     }
 155   } else if (this.graphDiv_) {
 156     this.removeFromGraph_();
 157     var dygraph = this.dygraph_;
 158     setTimeout(function() { dygraph.width_ = 0; dygraph.resize(); }, 1);
 159   }
 160   return enabled;
 161 };
 162
 163 /**
 164  * @private
 165  * Resizes the range selector.
 166  */
 167 rangeSelector.prototype.resize_ = function() {
 168   function setElementRect(canvas, context, rect) {
 169     var canvasScale = Dygraph.getContextPixelRatio(context);
 170
 171     canvas.style.top = rect.y + 'px';
 172     canvas.style.left = rect.x + 'px';
 173     canvas.width = rect.w * canvasScale;
 174     canvas.height = rect.h * canvasScale;
 175     canvas.style.width = rect.w + 'px';
 176     canvas.style.height = rect.h + 'px';
 177
 178     if(canvasScale != 1) {
 179       context.scale(canvasScale, canvasScale);
 180     }
 181   }
 182
 183   var plotArea = this.dygraph_.layout_.getPlotArea();
 184
 185   var xAxisLabelHeight = 0;
 186   if (this.dygraph_.getOptionForAxis('drawAxis', 'x')) {
 187     xAxisLabelHeight = this.getOption_('xAxisHeight') || (this.getOption_('axisLabelFontSize') + 2 * this.getOption_('axisTickSize'));
 188   }
 189   this.canvasRect_ = {
 190     x: plotArea.x,
 191     y: plotArea.y + plotArea.h + xAxisLabelHeight + 4,
 192     w: plotArea.w,
 193     h: this.getOption_('rangeSelectorHeight')
 194   };
 195
 196   setElementRect(this.bgcanvas_, this.bgcanvas_ctx_, this.canvasRect_);
 197   setElementRect(this.fgcanvas_, this.fgcanvas_ctx_, this.canvasRect_);
 198 };
 199
 200 /**
 201  * @private
 202  * Creates the background and foreground canvases.
 203  */
 204 rangeSelector.prototype.createCanvases_ = function() {
 205   this.bgcanvas_ = Dygraph.createCanvas();
 206   this.bgcanvas_.className = 'dygraph-rangesel-bgcanvas';
 207   this.bgcanvas_.style.position = 'absolute';
 208   this.bgcanvas_.style.zIndex = 9;
 209   this.bgcanvas_ctx_ = Dygraph.getContext(this.bgcanvas_);
 210
 211   this.fgcanvas_ = Dygraph.createCanvas();
 212   this.fgcanvas_.className = 'dygraph-rangesel-fgcanvas';
 213   this.fgcanvas_.style.position = 'absolute';
 214   this.fgcanvas_.style.zIndex = 9;
 215   this.fgcanvas_.style.cursor = 'default';
 216   this.fgcanvas_ctx_ = Dygraph.getContext(this.fgcanvas_);
 217 };
 218
 219 /**
 220  * @private
 221  * Creates overlay divs for IE/Excanvas so that mouse events are handled properly.
 222  */
 223 rangeSelector.prototype.createIEPanOverlay_ = function() {
 224   this.iePanOverlay_ = document.createElement("div");
 225   this.iePanOverlay_.style.position = 'absolute';
 226   this.iePanOverlay_.style.backgroundColor = 'white';
 227   this.iePanOverlay_.style.filter = 'alpha(opacity=0)';
 228   this.iePanOverlay_.style.display = 'none';
 229   this.iePanOverlay_.style.cursor = 'move';
 230   this.fgcanvas_.appendChild(this.iePanOverlay_);
 231 };
 232
 233 /**
 234  * @private
 235  * Creates the zoom handle elements.
 236  */
 237 rangeSelector.prototype.createZoomHandles_ = function() {
 238   var img = new Image();
 239   img.className = 'dygraph-rangesel-zoomhandle';
 240   img.style.position = 'absolute';
 241   img.style.zIndex = 10;
 242   img.style.visibility = 'hidden'; // Initially hidden so they don't show up in the wrong place.
 243   img.style.cursor = 'col-resize';
 244
 245   if (/MSIE 7/.test(navigator.userAgent)) { // IE7 doesn't support embedded src data.
 246     img.width = 7;
 247     img.height = 14;
 248     img.style.backgroundColor = 'white';
 249     img.style.border = '1px solid #333333'; // Just show box in IE7.
 250   } else {
 251     img.width = 9;
 252     img.height = 16;
 253     img.src = 'data:image/png;base64,' +
 254 'iVBORw0KGgoAAAANSUhEUgAAAAkAAAAQCAYAAADESFVDAAAAAXNSR0IArs4c6QAAAAZiS0dEANAA' +
 255 'zwDP4Z7KegAAAAlwSFlzAAAOxAAADsQBlSsOGwAAAAd0SU1FB9sHGw0cMqdt1UwAAAAZdEVYdENv' +
 256 'bW1lbnQAQ3JlYXRlZCB3aXRoIEdJTVBXgQ4XAAAAaElEQVQoz+3SsRFAQBCF4Z9WJM8KCDVwownl' +
 257 '6YXsTmCUsyKGkZzcl7zkz3YLkypgAnreFmDEpHkIwVOMfpdi9CEEN2nGpFdwD03yEqDtOgCaun7s' +
 258 'qSTDH32I1pQA2Pb9sZecAxc5r3IAb21d6878xsAAAAAASUVORK5CYII=';
 259   }
 260
 261   if (this.isMobileDevice_) {
 262     img.width *= 2;
 263     img.height *= 2;
 264   }
 265
 266   this.leftZoomHandle_ = img;
 267   this.rightZoomHandle_ = img.cloneNode(false);
 268 };
 269
 270 /**
 271  * @private
 272  * Sets up the interaction for the range selector.
 273  */
 274 rangeSelector.prototype.initInteraction_ = function() {
 275   var self = this;
 276   var topElem = document;
 277   var clientXLast = 0;
 278   var handle = null;
 279   var isZooming = false;
 280   var isPanning = false;
 281   var dynamic = !this.isMobileDevice_ && !this.isUsingExcanvas_;
 282
 283   // We cover iframes during mouse interactions. See comments in
 284   // dygraph-utils.js for more info on why this is a good idea.
 285   var tarp = new Dygraph.IFrameTarp();
 286
 287   // functions, defined below.  Defining them this way (rather than with
 288   // "function foo() {...}" makes JSHint happy.
 289   var toXDataWindow, onZoomStart, onZoom, onZoomEnd, doZoom, isMouseInPanZone,
 290       onPanStart, onPan, onPanEnd, doPan, onCanvasHover;
 291
 292   // Touch event functions
 293   var onZoomHandleTouchEvent, onCanvasTouchEvent, addTouchEvents;
 294
 295   toXDataWindow = function(zoomHandleStatus) {
 296     var xDataLimits = self.dygraph_.xAxisExtremes();
 297     var fact = (xDataLimits[1] - xDataLimits[0])/self.canvasRect_.w;
 298     var xDataMin = xDataLimits[0] + (zoomHandleStatus.leftHandlePos - self.canvasRect_.x)*fact;
 299     var xDataMax = xDataLimits[0] + (zoomHandleStatus.rightHandlePos - self.canvasRect_.x)*fact;
 300     return [xDataMin, xDataMax];
 301   };
 302
 303   onZoomStart = function(e) {
 304     Dygraph.cancelEvent(e);
 305     isZooming = true;
 306     clientXLast = e.clientX;
 307     handle = e.target ? e.target : e.srcElement;
 308     if (e.type === 'mousedown' || e.type === 'dragstart') {
 309       // These events are removed manually.
 310       Dygraph.addEvent(topElem, 'mousemove', onZoom);
 311       Dygraph.addEvent(topElem, 'mouseup', onZoomEnd);
 312     }
 313     self.fgcanvas_.style.cursor = 'col-resize';
 314     tarp.cover();
 315     return true;
 316   };
 317
 318   onZoom = function(e) {
 319     if (!isZooming) {
 320       return false;
 321     }
 322     Dygraph.cancelEvent(e);
 323
 324     var delX = e.clientX - clientXLast;
 325     if (Math.abs(delX) < 4) {
 326       return true;
 327     }
 328     clientXLast = e.clientX;
 329
 330     // Move handle.
 331     var zoomHandleStatus = self.getZoomHandleStatus_();
 332     var newPos;
 333     if (handle == self.leftZoomHandle_) {
 334       newPos = zoomHandleStatus.leftHandlePos + delX;
 335       newPos = Math.min(newPos, zoomHandleStatus.rightHandlePos - handle.width - 3);
 336       newPos = Math.max(newPos, self.canvasRect_.x);
 337     } else {
 338       newPos = zoomHandleStatus.rightHandlePos + delX;
 339       newPos = Math.min(newPos, self.canvasRect_.x + self.canvasRect_.w);
 340       newPos = Math.max(newPos, zoomHandleStatus.leftHandlePos + handle.width + 3);
 341     }
 342     var halfHandleWidth = handle.width/2;
 343     handle.style.left = (newPos - halfHandleWidth) + 'px';
 344     self.drawInteractiveLayer_();
 345
 346     // Zoom on the fly (if not using excanvas).
 347     if (dynamic) {
 348       doZoom();
 349     }
 350     return true;
 351   };
 352
 353   onZoomEnd = function(e) {
 354     if (!isZooming) {
 355       return false;
 356     }
 357     isZooming = false;
 358     tarp.uncover();
 359     Dygraph.removeEvent(topElem, 'mousemove', onZoom);
 360     Dygraph.removeEvent(topElem, 'mouseup', onZoomEnd);
 361     self.fgcanvas_.style.cursor = 'default';
 362
 363     // If using excanvas, Zoom now.
 364     if (!dynamic) {
 365       doZoom();
 366     }
 367     return true;
 368   };
 369
 370   doZoom = function() {
 371     try {
 372       var zoomHandleStatus = self.getZoomHandleStatus_();
 373       self.isChangingRange_ = true;
 374       if (!zoomHandleStatus.isZoomed) {
 375         self.dygraph_.resetZoom();
 376       } else {
 377         var xDataWindow = toXDataWindow(zoomHandleStatus);
 378         self.dygraph_.doZoomXDates_(xDataWindow[0], xDataWindow[1]);
 379       }
 380     } finally {
 381       self.isChangingRange_ = false;
 382     }
 383   };
 384
 385   isMouseInPanZone = function(e) {
 386     if (self.isUsingExcanvas_) {
 387         return e.srcElement == self.iePanOverlay_;
 388     } else {
 389       var rect = self.leftZoomHandle_.getBoundingClientRect();
 390       var leftHandleClientX = rect.left + rect.width/2;
 391       rect = self.rightZoomHandle_.getBoundingClientRect();
 392       var rightHandleClientX = rect.left + rect.width/2;
 393       return (e.clientX > leftHandleClientX && e.clientX < rightHandleClientX);
 394     }
 395   };
 396
 397   onPanStart = function(e) {
 398     if (!isPanning && isMouseInPanZone(e) && self.getZoomHandleStatus_().isZoomed) {
 399       Dygraph.cancelEvent(e);
 400       isPanning = true;
 401       clientXLast = e.clientX;
 402       if (e.type === 'mousedown') {
 403         // These events are removed manually.
 404         Dygraph.addEvent(topElem, 'mousemove', onPan);
 405         Dygraph.addEvent(topElem, 'mouseup', onPanEnd);
 406       }
 407       return true;
 408     }
 409     return false;
 410   };
 411
 412   onPan = function(e) {
 413     if (!isPanning) {
 414       return false;
 415     }
 416     Dygraph.cancelEvent(e);
 417
 418     var delX = e.clientX - clientXLast;
 419     if (Math.abs(delX) < 4) {
 420       return true;
 421     }
 422     clientXLast = e.clientX;
 423
 424     // Move range view
 425     var zoomHandleStatus = self.getZoomHandleStatus_();
 426     var leftHandlePos = zoomHandleStatus.leftHandlePos;
 427     var rightHandlePos = zoomHandleStatus.rightHandlePos;
 428     var rangeSize = rightHandlePos - leftHandlePos;
 429     if (leftHandlePos + delX <= self.canvasRect_.x) {
 430       leftHandlePos = self.canvasRect_.x;
 431       rightHandlePos = leftHandlePos + rangeSize;
 432     } else if (rightHandlePos + delX >= self.canvasRect_.x + self.canvasRect_.w) {
 433       rightHandlePos = self.canvasRect_.x + self.canvasRect_.w;
 434       leftHandlePos = rightHandlePos - rangeSize;
 435     } else {
 436       leftHandlePos += delX;
 437       rightHandlePos += delX;
 438     }
 439     var halfHandleWidth = self.leftZoomHandle_.width/2;
 440     self.leftZoomHandle_.style.left = (leftHandlePos - halfHandleWidth) + 'px';
 441     self.rightZoomHandle_.style.left = (rightHandlePos - halfHandleWidth) + 'px';
 442     self.drawInteractiveLayer_();
 443
 444     // Do pan on the fly (if not using excanvas).
 445     if (dynamic) {
 446       doPan();
 447     }
 448     return true;
 449   };
 450
 451   onPanEnd = function(e) {
 452     if (!isPanning) {
 453       return false;
 454     }
 455     isPanning = false;
 456     Dygraph.removeEvent(topElem, 'mousemove', onPan);
 457     Dygraph.removeEvent(topElem, 'mouseup', onPanEnd);
 458     // If using excanvas, do pan now.
 459     if (!dynamic) {
 460       doPan();
 461     }
 462     return true;
 463   };
 464
 465   doPan = function() {
 466     try {
 467       self.isChangingRange_ = true;
 468       self.dygraph_.dateWindow_ = toXDataWindow(self.getZoomHandleStatus_());
 469       self.dygraph_.drawGraph_(false);
 470     } finally {
 471       self.isChangingRange_ = false;
 472     }
 473   };
 474
 475   onCanvasHover = function(e) {
 476     if (isZooming || isPanning) {
 477       return;
 478     }
 479     var cursor = isMouseInPanZone(e) ? 'move' : 'default';
 480     if (cursor != self.fgcanvas_.style.cursor) {
 481       self.fgcanvas_.style.cursor = cursor;
 482     }
 483   };
 484
 485   onZoomHandleTouchEvent = function(e) {
 486     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 487       if (onZoomStart(e.targetTouches[0])) {
 488         Dygraph.cancelEvent(e);
 489       }
 490     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 491       if (onZoom(e.targetTouches[0])) {
 492         Dygraph.cancelEvent(e);
 493       }
 494     } else {
 495       onZoomEnd(e);
 496     }
 497   };
 498
 499   onCanvasTouchEvent = function(e) {
 500     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 501       if (onPanStart(e.targetTouches[0])) {
 502         Dygraph.cancelEvent(e);
 503       }
 504     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 505       if (onPan(e.targetTouches[0])) {
 506         Dygraph.cancelEvent(e);
 507       }
 508     } else {
 509       onPanEnd(e);
 510     }
 511   };
 512
 513   addTouchEvents = function(elem, fn) {
 514     var types = ['touchstart', 'touchend', 'touchmove', 'touchcancel'];
 515     for (var i = 0; i < types.length; i++) {
 516       self.dygraph_.addAndTrackEvent(elem, types[i], fn);
 517     }
 518   };
 519
 520   this.setDefaultOption_('interactionModel', Dygraph.Interaction.dragIsPanInteractionModel);
 521   this.setDefaultOption_('panEdgeFraction', 0.0001);
 522
 523   var dragStartEvent = window.opera ? 'mousedown' : 'dragstart';
 524   this.dygraph_.addAndTrackEvent(this.leftZoomHandle_, dragStartEvent, onZoomStart);
 525   this.dygraph_.addAndTrackEvent(this.rightZoomHandle_, dragStartEvent, onZoomStart);
 526
 527   if (this.isUsingExcanvas_) {
 528     this.dygraph_.addAndTrackEvent(this.iePanOverlay_, 'mousedown', onPanStart);
 529   } else {
 530     this.dygraph_.addAndTrackEvent(this.fgcanvas_, 'mousedown', onPanStart);
 531     this.dygraph_.addAndTrackEvent(this.fgcanvas_, 'mousemove', onCanvasHover);
 532   }
 533
 534   // Touch events
 535   if (this.hasTouchInterface_) {
 536     addTouchEvents(this.leftZoomHandle_, onZoomHandleTouchEvent);
 537     addTouchEvents(this.rightZoomHandle_, onZoomHandleTouchEvent);
 538     addTouchEvents(this.fgcanvas_, onCanvasTouchEvent);
 539   }
 540 };
 541
 542 /**
 543  * @private
 544  * Draws the static layer in the background canvas.
 545  */
 546 rangeSelector.prototype.drawStaticLayer_ = function() {
 547   var ctx = this.bgcanvas_ctx_;
 548   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 549   try {
 550     this.drawMiniPlot_();
 551   } catch(ex) {
 552     console.warn(ex);
 553   }
 554
 555   var margin = 0.5;
 556   this.bgcanvas_ctx_.lineWidth = 1;
 557   ctx.strokeStyle = 'gray';
 558   ctx.beginPath();
 559   ctx.moveTo(margin, margin);
 560   ctx.lineTo(margin, this.canvasRect_.h-margin);
 561   ctx.lineTo(this.canvasRect_.w-margin, this.canvasRect_.h-margin);
 562   ctx.lineTo(this.canvasRect_.w-margin, margin);
 563   ctx.stroke();
 564 };
 565
 566
 567 /**
 568  * @private
 569  * Draws the mini plot in the background canvas.
 570  */
 571 rangeSelector.prototype.drawMiniPlot_ = function() {
 572   var fillStyle = this.getOption_('rangeSelectorPlotFillColor');
 573   var strokeStyle = this.getOption_('rangeSelectorPlotStrokeColor');
 574   if (!fillStyle && !strokeStyle) {
 575     return;
 576   }
 577
 578   var stepPlot = this.getOption_('stepPlot');
 579
 580   var combinedSeriesData = this.computeCombinedSeriesAndLimits_();
 581   var yRange = combinedSeriesData.yMax - combinedSeriesData.yMin;
 582
 583   // Draw the mini plot.
 584   var ctx = this.bgcanvas_ctx_;
 585   var margin = 0.5;
 586
 587   var xExtremes = this.dygraph_.xAxisExtremes();
 588   var xRange = Math.max(xExtremes[1] - xExtremes[0], 1.e-30);
 589   var xFact = (this.canvasRect_.w - margin)/xRange;
 590   var yFact = (this.canvasRect_.h - margin)/yRange;
 591   var canvasWidth = this.canvasRect_.w - margin;
 592   var canvasHeight = this.canvasRect_.h - margin;
 593
 594   var prevX = null, prevY = null;
 595
 596   ctx.beginPath();
 597   ctx.moveTo(margin, canvasHeight);
 598   for (var i = 0; i < combinedSeriesData.data.length; i++) {
 599     var dataPoint = combinedSeriesData.data[i];
 600     var x = ((dataPoint[0] !== null) ? ((dataPoint[0] - xExtremes[0])*xFact) : NaN);
 601     var y = ((dataPoint[1] !== null) ? (canvasHeight - (dataPoint[1] - combinedSeriesData.yMin)*yFact) : NaN);
 602
 603     // Skip points that don't change the x-value. Overly fine-grained points
 604     // can cause major slowdowns with the ctx.fill() call below.
 605     if (!stepPlot && prevX !== null && Math.round(x) == Math.round(prevX)) {
 606       continue;
 607     }
 608
 609     if (isFinite(x) && isFinite(y)) {
 610       if(prevX === null) {
 611         ctx.lineTo(x, canvasHeight);
 612       }
 613       else if (stepPlot) {
 614         ctx.lineTo(x, prevY);
 615       }
 616       ctx.lineTo(x, y);
 617       prevX = x;
 618       prevY = y;
 619     }
 620     else {
 621       if(prevX !== null) {
 622         if (stepPlot) {
 623           ctx.lineTo(x, prevY);
 624           ctx.lineTo(x, canvasHeight);
 625         }
 626         else {
 627           ctx.lineTo(prevX, canvasHeight);
 628         }
 629       }
 630       prevX = prevY = null;
 631     }
 632   }
 633   ctx.lineTo(canvasWidth, canvasHeight);
 634   ctx.closePath();
 635
 636   if (fillStyle) {
 637     var lingrad = this.bgcanvas_ctx_.createLinearGradient(0, 0, 0, canvasHeight);
 638     lingrad.addColorStop(0, 'white');
 639     lingrad.addColorStop(1, fillStyle);
 640     this.bgcanvas_ctx_.fillStyle = lingrad;
 641     ctx.fill();
 642   }
 643
 644   if (strokeStyle) {
 645     this.bgcanvas_ctx_.strokeStyle = strokeStyle;
 646     this.bgcanvas_ctx_.lineWidth = 1.5;
 647     ctx.stroke();
 648   }
 649 };
 650
 651 /**
 652  * @private
 653  * Computes and returns the combined series data along with min/max for the mini plot.
 654  * The combined series consists of averaged values for all series.
 655  * When series have error bars, the error bars are ignored.
 656  * @return {Object} An object containing combined series array, ymin, ymax.
 657  */
 658 rangeSelector.prototype.computeCombinedSeriesAndLimits_ = function() {
 659   var g = this.dygraph_;
 660   var logscale = this.getOption_('logscale');
 661   var i;
 662
 663   // Select series to combine. By default, all series are combined.
 664   var numColumns = g.numColumns();
 665   var labels = g.getLabels();
 666   var includeSeries = new Array(numColumns);
 667   var anySet = false;
 668   for (i = 1; i < numColumns; i++) {
 669     var include = this.getOption_('showInRangeSelector', labels[i]);
 670     includeSeries[i] = include;
 671     if (include !== null) anySet = true;  // it's set explicitly for this series
 672   }
 673   if (!anySet) {
 674     for (i = 0; i < includeSeries.length; i++) includeSeries[i] = true;
 675   }
 676
 677   // Create a combined series (average of selected series values).
 678   // TODO(danvk): short-circuit if there's only one series.
 679   var rolledSeries = [];
 680   var dataHandler = g.dataHandler_;
 681   var options = g.attributes_;
 682   for (i = 1; i < g.numColumns(); i++) {
 683     if (!includeSeries[i]) continue;
 684     var series = dataHandler.extractSeries(g.rawData_, i, options);
 685     if (g.rollPeriod() > 1) {
 686       series = dataHandler.rollingAverage(series, g.rollPeriod(), options);
 687     }
 688
 689     rolledSeries.push(series);
 690   }
 691
 692   var combinedSeries = [];
 693   for (i = 0; i < rolledSeries[0].length; i++) {
 694     var sum = 0;
 695     var count = 0;
 696     for (var j = 0; j < rolledSeries.length; j++) {
 697       var y = rolledSeries[j][i][1];
 698       if (y === null || isNaN(y)) continue;
 699       count++;
 700       sum += y;
 701     }
 702     combinedSeries.push([rolledSeries[0][i][0], sum / count]);
 703   }
 704
 705   // Compute the y range.
 706   var yMin = Number.MAX_VALUE;
 707   var yMax = -Number.MAX_VALUE;
 708   for (i = 0; i < combinedSeries.length; i++) {
 709     var yVal = combinedSeries[i][1];
 710     if (yVal !== null && isFinite(yVal) && (!logscale || yVal > 0)) {
 711       yMin = Math.min(yMin, yVal);
 712       yMax = Math.max(yMax, yVal);
 713     }
 714   }
 715
 716   // Convert Y data to log scale if needed.
 717   // Also, expand the Y range to compress the mini plot a little.
 718   var extraPercent = 0.25;
 719   if (logscale) {
 720     yMax = Dygraph.log10(yMax);
 721     yMax += yMax*extraPercent;
 722     yMin = Dygraph.log10(yMin);
 723     for (i = 0; i < combinedSeries.length; i++) {
 724       combinedSeries[i][1] = Dygraph.log10(combinedSeries[i][1]);
 725     }
 726   } else {
 727     var yExtra;
 728     var yRange = yMax - yMin;
 729     if (yRange <= Number.MIN_VALUE) {
 730       yExtra = yMax*extraPercent;
 731     } else {
 732       yExtra = yRange*extraPercent;
 733     }
 734     yMax += yExtra;
 735     yMin -= yExtra;
 736   }
 737
 738   return {data: combinedSeries, yMin: yMin, yMax: yMax};
 739 };
 740
 741 /**
 742  * @private
 743  * Places the zoom handles in the proper position based on the current X data window.
 744  */
 745 rangeSelector.prototype.placeZoomHandles_ = function() {
 746   var xExtremes = this.dygraph_.xAxisExtremes();
 747   var xWindowLimits = this.dygraph_.xAxisRange();
 748   var xRange = xExtremes[1] - xExtremes[0];
 749   var leftPercent = Math.max(0, (xWindowLimits[0] - xExtremes[0])/xRange);
 750   var rightPercent = Math.max(0, (xExtremes[1] - xWindowLimits[1])/xRange);
 751   var leftCoord = this.canvasRect_.x + this.canvasRect_.w*leftPercent;
 752   var rightCoord = this.canvasRect_.x + this.canvasRect_.w*(1 - rightPercent);
 753   var handleTop = Math.max(this.canvasRect_.y, this.canvasRect_.y + (this.canvasRect_.h - this.leftZoomHandle_.height)/2);
 754   var halfHandleWidth = this.leftZoomHandle_.width/2;
 755   this.leftZoomHandle_.style.left = (leftCoord - halfHandleWidth) + 'px';
 756   this.leftZoomHandle_.style.top = handleTop + 'px';
 757   this.rightZoomHandle_.style.left = (rightCoord - halfHandleWidth) + 'px';
 758   this.rightZoomHandle_.style.top = this.leftZoomHandle_.style.top;
 759
 760   this.leftZoomHandle_.style.visibility = 'visible';
 761   this.rightZoomHandle_.style.visibility = 'visible';
 762 };
 763
 764 /**
 765  * @private
 766  * Draws the interactive layer in the foreground canvas.
 767  */
 768 rangeSelector.prototype.drawInteractiveLayer_ = function() {
 769   var ctx = this.fgcanvas_ctx_;
 770   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 771   var margin = 1;
 772   var width = this.canvasRect_.w - margin;
 773   var height = this.canvasRect_.h - margin;
 774   var zoomHandleStatus = this.getZoomHandleStatus_();
 775
 776   ctx.strokeStyle = 'black';
 777   if (!zoomHandleStatus.isZoomed) {
 778     ctx.beginPath();
 779     ctx.moveTo(margin, margin);
 780     ctx.lineTo(margin, height);
 781     ctx.lineTo(width, height);
 782     ctx.lineTo(width, margin);
 783     ctx.stroke();
 784     if (this.iePanOverlay_) {
 785       this.iePanOverlay_.style.display = 'none';
 786     }
 787   } else {
 788     var leftHandleCanvasPos = Math.max(margin, zoomHandleStatus.leftHandlePos - this.canvasRect_.x);
 789     var rightHandleCanvasPos = Math.min(width, zoomHandleStatus.rightHandlePos - this.canvasRect_.x);
 790
 791     ctx.fillStyle = 'rgba(240, 240, 240, 0.6)';
 792     ctx.fillRect(0, 0, leftHandleCanvasPos, this.canvasRect_.h);
 793     ctx.fillRect(rightHandleCanvasPos, 0, this.canvasRect_.w - rightHandleCanvasPos, this.canvasRect_.h);
 794
 795     ctx.beginPath();
 796     ctx.moveTo(margin, margin);
 797     ctx.lineTo(leftHandleCanvasPos, margin);
 798     ctx.lineTo(leftHandleCanvasPos, height);
 799     ctx.lineTo(rightHandleCanvasPos, height);
 800     ctx.lineTo(rightHandleCanvasPos, margin);
 801     ctx.lineTo(width, margin);
 802     ctx.stroke();
 803
 804     if (this.isUsingExcanvas_) {
 805       this.iePanOverlay_.style.width = (rightHandleCanvasPos - leftHandleCanvasPos) + 'px';
 806       this.iePanOverlay_.style.left = leftHandleCanvasPos + 'px';
 807       this.iePanOverlay_.style.height = height + 'px';
 808       this.iePanOverlay_.style.display = 'inline';
 809     }
 810   }
 811 };
 812
 813 /**
 814  * @private
 815  * Returns the current zoom handle position information.
 816  * @return {Object} The zoom handle status.
 817  */
 818 rangeSelector.prototype.getZoomHandleStatus_ = function() {
 819   var halfHandleWidth = this.leftZoomHandle_.width/2;
 820   var leftHandlePos = parseFloat(this.leftZoomHandle_.style.left) + halfHandleWidth;
 821   var rightHandlePos = parseFloat(this.rightZoomHandle_.style.left) + halfHandleWidth;
 822   return {
 823       leftHandlePos: leftHandlePos,
 824       rightHandlePos: rightHandlePos,
 825       isZoomed: (leftHandlePos - 1 > this.canvasRect_.x || rightHandlePos + 1 < this.canvasRect_.x+this.canvasRect_.w)
 826   };
 827 };
 828
 829 return rangeSelector;
 830
 831 })();