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 /*jshint globalstrict: true */
  16 /*global Dygraph:false */
  17 "use strict";
  18
  19 var rangeSelector = function() {
  20   this.isIE_ = /MSIE/.test(navigator.userAgent) && !window.opera;
  21   this.hasTouchInterface_ = typeof(TouchEvent) != 'undefined';
  22   this.isMobileDevice_ = /mobile|android/gi.test(navigator.appVersion);
  23   this.interfaceCreated_ = false;
  24 };
  25
  26 rangeSelector.prototype.toString = function() {
  27   return "RangeSelector Plugin";
  28 };
  29
  30 rangeSelector.prototype.activate = function(dygraph) {
  31   this.dygraph_ = dygraph;
  32   this.isUsingExcanvas_ = dygraph.isUsingExcanvas_;
  33   if (this.getOption_('showRangeSelector')) {
  34     this.createInterface_();
  35   }
  36   return {
  37     layout: this.reserveSpace_,
  38     predraw: this.renderStaticLayer_,
  39     didDrawChart: this.renderInteractiveLayer_
  40   };
  41 };
  42
  43 rangeSelector.prototype.destroy = function() {
  44   this.bgcanvas_ = null;
  45   this.fgcanvas_ = null;
  46   this.leftZoomHandle_ = null;
  47   this.rightZoomHandle_ = null;
  48   this.iePanOverlay_ = null;
  49 };
  50
  51 //------------------------------------------------------------------
  52 // Private methods
  53 //------------------------------------------------------------------
  54
  55 rangeSelector.prototype.getOption_ = function(name) {
  56   return this.dygraph_.getOption(name);
  57 };
  58
  59 rangeSelector.prototype.setDefaultOption_ = function(name, value) {
  60   return this.dygraph_.attrs_[name] = value;
  61 };
  62
  63 /**
  64  * @private
  65  * Creates the range selector elements and adds them to the graph.
  66  */
  67 rangeSelector.prototype.createInterface_ = function() {
  68   this.createCanvases_();
  69   if (this.isUsingExcanvas_) {
  70     this.createIEPanOverlay_();
  71   }
  72   this.createZoomHandles_();
  73   this.initInteraction_();
  74
  75   // Range selector and animatedZooms have a bad interaction. See issue 359.
  76   if (this.getOption_('animatedZooms')) {
  77     this.dygraph_.warn('Animated zooms and range selector are not compatible; disabling animatedZooms.');
  78     this.dygraph_.updateOptions({animatedZooms: false}, true);
  79   }
  80
  81   this.interfaceCreated_ = true;
  82   this.addToGraph_();
  83 };
  84
  85 /**
  86  * @private
  87  * Adds the range selector to the graph.
  88  */
  89 rangeSelector.prototype.addToGraph_ = function() {
  90   var graphDiv = this.graphDiv_ = this.dygraph_.graphDiv;
  91   graphDiv.appendChild(this.bgcanvas_);
  92   graphDiv.appendChild(this.fgcanvas_);
  93   graphDiv.appendChild(this.leftZoomHandle_);
  94   graphDiv.appendChild(this.rightZoomHandle_);
  95 };
  96
  97 /**
  98  * @private
  99  * Removes the range selector from the graph.
 100  */
 101 rangeSelector.prototype.removeFromGraph_ = function() {
 102   var graphDiv = this.graphDiv_;
 103   graphDiv.removeChild(this.bgcanvas_);
 104   graphDiv.removeChild(this.fgcanvas_);
 105   graphDiv.removeChild(this.leftZoomHandle_);
 106   graphDiv.removeChild(this.rightZoomHandle_);
 107   this.graphDiv_ = null;
 108 };
 109
 110 /**
 111  * @private
 112  * Called by Layout to allow range selector to reserve its space.
 113  */
 114 rangeSelector.prototype.reserveSpace_ = function(e) {
 115   if (this.getOption_('showRangeSelector')) {
 116     e.reserveSpaceBottom(this.getOption_('rangeSelectorHeight') + 4);
 117   }
 118 };
 119
 120 /**
 121  * @private
 122  * Renders the static portion of the range selector at the predraw stage.
 123  */
 124 rangeSelector.prototype.renderStaticLayer_ = function() {
 125   if (!this.updateVisibility_()) {
 126     return;
 127   }
 128   this.resize_();
 129   this.drawStaticLayer_();
 130 };
 131
 132 /**
 133  * @private
 134  * Renders the interactive portion of the range selector after the chart has been drawn.
 135  */
 136 rangeSelector.prototype.renderInteractiveLayer_ = function() {
 137   if (!this.updateVisibility_() || this.isChangingRange_) {
 138     return;
 139   }
 140   this.placeZoomHandles_();
 141   this.drawInteractiveLayer_();
 142 };
 143
 144 /**
 145  * @private
 146  * Check to see if the range selector is enabled/disabled and update visibility accordingly.
 147  */
 148 rangeSelector.prototype.updateVisibility_ = function() {
 149   var enabled = this.getOption_('showRangeSelector');
 150   if (enabled) {
 151     if (!this.interfaceCreated_) {
 152       this.createInterface_();
 153     } else if (!this.graphDiv_ || !this.graphDiv_.parentNode) {
 154       this.addToGraph_();
 155     }
 156   } else if (this.graphDiv_) {
 157     this.removeFromGraph_();
 158     var dygraph = this.dygraph_;
 159     setTimeout(function() { dygraph.width_ = 0; dygraph.resize(); }, 1);
 160   }
 161   return enabled;
 162 };
 163
 164 /**
 165  * @private
 166  * Resizes the range selector.
 167  */
 168 rangeSelector.prototype.resize_ = function() {
 169   function setElementRect(canvas, rect) {
 170     canvas.style.top = rect.y + 'px';
 171     canvas.style.left = rect.x + 'px';
 172     canvas.width = rect.w;
 173     canvas.height = rect.h;
 174     canvas.style.width = canvas.width + 'px';    // for IE
 175     canvas.style.height = canvas.height + 'px';  // for IE
 176   }
 177
 178   var plotArea = this.dygraph_.layout_.getPlotArea();
 179   var xAxisLabelHeight = this.getOption_('xAxisHeight') || (this.getOption_('axisLabelFontSize') + 2 * this.getOption_('axisTickSize'));
 180   this.canvasRect_ = {
 181     x: plotArea.x,
 182     y: plotArea.y + plotArea.h + xAxisLabelHeight + 4,
 183     w: plotArea.w,
 184     h: this.getOption_('rangeSelectorHeight')
 185   };
 186
 187   setElementRect(this.bgcanvas_, this.canvasRect_);
 188   setElementRect(this.fgcanvas_, this.canvasRect_);
 189 };
 190
 191 /**
 192  * @private
 193  * Creates the background and foreground canvases.
 194  */
 195 rangeSelector.prototype.createCanvases_ = function() {
 196   this.bgcanvas_ = Dygraph.createCanvas();
 197   this.bgcanvas_.className = 'dygraph-rangesel-bgcanvas';
 198   this.bgcanvas_.style.position = 'absolute';
 199   this.bgcanvas_.style.zIndex = 9;
 200   this.bgcanvas_ctx_ = Dygraph.getContext(this.bgcanvas_);
 201
 202   this.fgcanvas_ = Dygraph.createCanvas();
 203   this.fgcanvas_.className = 'dygraph-rangesel-fgcanvas';
 204   this.fgcanvas_.style.position = 'absolute';
 205   this.fgcanvas_.style.zIndex = 9;
 206   this.fgcanvas_.style.cursor = 'default';
 207   this.fgcanvas_ctx_ = Dygraph.getContext(this.fgcanvas_);
 208 };
 209
 210 /**
 211  * @private
 212  * Creates overlay divs for IE/Excanvas so that mouse events are handled properly.
 213  */
 214 rangeSelector.prototype.createIEPanOverlay_ = function() {
 215   this.iePanOverlay_ = document.createElement("div");
 216   this.iePanOverlay_.style.position = 'absolute';
 217   this.iePanOverlay_.style.backgroundColor = 'white';
 218   this.iePanOverlay_.style.filter = 'alpha(opacity=0)';
 219   this.iePanOverlay_.style.display = 'none';
 220   this.iePanOverlay_.style.cursor = 'move';
 221   this.fgcanvas_.appendChild(this.iePanOverlay_);
 222 };
 223
 224 /**
 225  * @private
 226  * Creates the zoom handle elements.
 227  */
 228 rangeSelector.prototype.createZoomHandles_ = function() {
 229   var img = new Image();
 230   img.className = 'dygraph-rangesel-zoomhandle';
 231   img.style.position = 'absolute';
 232   img.style.zIndex = 10;
 233   img.style.visibility = 'hidden'; // Initially hidden so they don't show up in the wrong place.
 234   img.style.cursor = 'col-resize';
 235
 236   if (/MSIE 7/.test(navigator.userAgent)) { // IE7 doesn't support embedded src data.
 237     img.width = 7;
 238     img.height = 14;
 239     img.style.backgroundColor = 'white';
 240     img.style.border = '1px solid #333333'; // Just show box in IE7.
 241   } else {
 242     img.width = 9;
 243     img.height = 16;
 244     img.src = 'data:image/png;base64,' +
 245 'iVBORw0KGgoAAAANSUhEUgAAAAkAAAAQCAYAAADESFVDAAAAAXNSR0IArs4c6QAAAAZiS0dEANAA' +
 246 'zwDP4Z7KegAAAAlwSFlzAAAOxAAADsQBlSsOGwAAAAd0SU1FB9sHGw0cMqdt1UwAAAAZdEVYdENv' +
 247 'bW1lbnQAQ3JlYXRlZCB3aXRoIEdJTVBXgQ4XAAAAaElEQVQoz+3SsRFAQBCF4Z9WJM8KCDVwownl' +
 248 '6YXsTmCUsyKGkZzcl7zkz3YLkypgAnreFmDEpHkIwVOMfpdi9CEEN2nGpFdwD03yEqDtOgCaun7s' +
 249 'qSTDH32I1pQA2Pb9sZecAxc5r3IAb21d6878xsAAAAAASUVORK5CYII=';
 250   }
 251
 252   if (this.isMobileDevice_) {
 253     img.width *= 2;
 254     img.height *= 2;
 255   }
 256
 257   this.leftZoomHandle_ = img;
 258   this.rightZoomHandle_ = img.cloneNode(false);
 259 };
 260
 261 /**
 262  * @private
 263  * Sets up the interaction for the range selector.
 264  */
 265 rangeSelector.prototype.initInteraction_ = function() {
 266   var self = this;
 267   var topElem = this.isIE_ ? document : window;
 268   var pageXLast = 0;
 269   var handle = null;
 270   var isZooming = false;
 271   var isPanning = false;
 272   var dynamic = !this.isMobileDevice_ && !this.isUsingExcanvas_;
 273
 274   // We cover iframes during mouse interactions. See comments in
 275   // dygraph-utils.js for more info on why this is a good idea.
 276   var tarp = new Dygraph.IFrameTarp();
 277
 278   // functions, defined below.  Defining them this way (rather than with
 279   // "function foo() {...}" makes JSHint happy.
 280   var toXDataWindow, onZoomStart, onZoom, onZoomEnd, doZoom, isMouseInPanZone,
 281       onPanStart, onPan, onPanEnd, doPan, onCanvasHover, getCursorPageX;
 282
 283   // Touch event functions
 284   var onZoomHandleTouchEvent, onCanvasTouchEvent, addTouchEvents;
 285
 286   toXDataWindow = function(zoomHandleStatus) {
 287     var xDataLimits = self.dygraph_.xAxisExtremes();
 288     var fact = (xDataLimits[1] - xDataLimits[0])/self.canvasRect_.w;
 289     var xDataMin = xDataLimits[0] + (zoomHandleStatus.leftHandlePos - self.canvasRect_.x)*fact;
 290     var xDataMax = xDataLimits[0] + (zoomHandleStatus.rightHandlePos - self.canvasRect_.x)*fact;
 291     return [xDataMin, xDataMax];
 292   };
 293
 294   getCursorPageX = function(e) {
 295     if (e.pageX !== null) {
 296       return e.pageX;
 297     } else {
 298       // Taken from jQuery.
 299       var target = e.target || e.srcElement || document;
 300       var eventDoc = target.ownerDocument || target.document || document;
 301       var doc = eventDoc.documentElement, body = eventDoc.body;
 302       return e.clientX + (doc && doc.scrollLeft || body && body.scrollLeft || 0) - (doc && doc.clientLeft || body && body.clientLeft || 0);
 303     }
 304   };
 305
 306   onZoomStart = function(e) {
 307     Dygraph.cancelEvent(e);
 308     isZooming = true;
 309     pageXLast = getCursorPageX(e);
 310     handle = e.target ? e.target : e.srcElement;
 311     if (e.type === 'mousedown' || e.type === 'dragstart') {
 312       // These events are removed manually.
 313       Dygraph.addEvent(topElem, 'mousemove', onZoom);
 314       Dygraph.addEvent(topElem, 'mouseup', onZoomEnd);
 315     }
 316     self.fgcanvas_.style.cursor = 'col-resize';
 317     tarp.cover();
 318     return true;
 319   };
 320
 321   onZoom = function(e) {
 322     if (!isZooming) {
 323       return false;
 324     }
 325     Dygraph.cancelEvent(e);
 326
 327     var pageX = getCursorPageX(e);
 328     var delX = pageX - pageXLast;
 329     if (Math.abs(delX) < 4) {
 330       return true;
 331     }
 332     pageXLast = pageX;
 333
 334     // Move handle.
 335     var zoomHandleStatus = self.getZoomHandleStatus_();
 336     var newPos;
 337     if (handle == self.leftZoomHandle_) {
 338       newPos = pageX;
 339       newPos = Math.min(newPos, zoomHandleStatus.rightHandlePos - handle.width - 3);
 340       newPos = Math.max(newPos, self.canvasRect_.x);
 341     } else {
 342       newPos = pageX;
 343       newPos = Math.min(newPos, self.canvasRect_.x + self.canvasRect_.w);
 344       newPos = Math.max(newPos, zoomHandleStatus.leftHandlePos + handle.width + 3);
 345     }
 346     var halfHandleWidth = handle.width/2;
 347     handle.style.left = (newPos - halfHandleWidth) + 'px';
 348     self.drawInteractiveLayer_();
 349
 350     // Zoom on the fly (if not using excanvas).
 351     if (dynamic) {
 352       doZoom();
 353     }
 354     return true;
 355   };
 356
 357   onZoomEnd = function(e) {
 358     if (!isZooming) {
 359       return false;
 360     }
 361     isZooming = false;
 362     tarp.uncover();
 363     Dygraph.removeEvent(topElem, 'mousemove', onZoom);
 364     Dygraph.removeEvent(topElem, 'mouseup', onZoomEnd);
 365     self.fgcanvas_.style.cursor = 'default';
 366
 367     // If using excanvas, Zoom now.
 368     if (!dynamic) {
 369       doZoom();
 370     }
 371     return true;
 372   };
 373
 374   doZoom = function() {
 375     try {
 376       var zoomHandleStatus = self.getZoomHandleStatus_();
 377       self.isChangingRange_ = true;
 378       if (!zoomHandleStatus.isZoomed) {
 379         self.dygraph_.resetZoom();
 380       } else {
 381         var xDataWindow = toXDataWindow(zoomHandleStatus);
 382         self.dygraph_.doZoomXDates_(xDataWindow[0], xDataWindow[1]);
 383       }
 384     } finally {
 385       self.isChangingRange_ = false;
 386     }
 387   };
 388
 389   isMouseInPanZone = function(e) {
 390     if (self.isUsingExcanvas_) {
 391         return e.srcElement == self.iePanOverlay_;
 392     } else {
 393       var rect = self.leftZoomHandle_.getBoundingClientRect();
 394       var leftHandleClientX = rect.left + rect.width/2;
 395       rect = self.rightZoomHandle_.getBoundingClientRect();
 396       var rightHandleClientX = rect.left + rect.width/2;
 397       return (e.clientX > leftHandleClientX && e.clientX < rightHandleClientX);
 398     }
 399   };
 400
 401   onPanStart = function(e) {
 402     if (!isPanning && isMouseInPanZone(e) && self.getZoomHandleStatus_().isZoomed) {
 403       Dygraph.cancelEvent(e);
 404       isPanning = true;
 405       pageXLast = getCursorPageX(e);
 406       if (e.type === 'mousedown') {
 407         // These events are removed manually.
 408         Dygraph.addEvent(topElem, 'mousemove', onPan);
 409         Dygraph.addEvent(topElem, 'mouseup', onPanEnd);
 410       }
 411       return true;
 412     }
 413     return false;
 414   };
 415
 416   onPan = function(e) {
 417     if (!isPanning) {
 418       return false;
 419     }
 420     Dygraph.cancelEvent(e);
 421
 422     var pageX = getCursorPageX(e);
 423     var delX = pageX - pageXLast;
 424     if (Math.abs(delX) < 4) {
 425       return true;
 426     }
 427     pageXLast = pageX;
 428
 429     // Move range view
 430     var zoomHandleStatus = self.getZoomHandleStatus_();
 431     var leftHandlePos = zoomHandleStatus.leftHandlePos;
 432     var rightHandlePos = zoomHandleStatus.rightHandlePos;
 433     var rangeSize = rightHandlePos - leftHandlePos;
 434     if (leftHandlePos + delX <= self.canvasRect_.x) {
 435       leftHandlePos = self.canvasRect_.x;
 436       rightHandlePos = leftHandlePos + rangeSize;
 437     } else if (rightHandlePos + delX >= self.canvasRect_.x + self.canvasRect_.w) {
 438       rightHandlePos = self.canvasRect_.x + self.canvasRect_.w;
 439       leftHandlePos = rightHandlePos - rangeSize;
 440     } else {
 441       leftHandlePos += delX;
 442       rightHandlePos += delX;
 443     }
 444     var halfHandleWidth = self.leftZoomHandle_.width/2;
 445     self.leftZoomHandle_.style.left = (leftHandlePos - halfHandleWidth) + 'px';
 446     self.rightZoomHandle_.style.left = (rightHandlePos - halfHandleWidth) + 'px';
 447     self.drawInteractiveLayer_();
 448
 449     // Do pan on the fly (if not using excanvas).
 450     if (dynamic) {
 451       doPan();
 452     }
 453     return true;
 454   };
 455
 456   onPanEnd = function(e) {
 457     if (!isPanning) {
 458       return false;
 459     }
 460     isPanning = false;
 461     Dygraph.removeEvent(topElem, 'mousemove', onPan);
 462     Dygraph.removeEvent(topElem, 'mouseup', onPanEnd);
 463     // If using excanvas, do pan now.
 464     if (!dynamic) {
 465       doPan();
 466     }
 467     return true;
 468   };
 469
 470   doPan = function() {
 471     try {
 472       self.isChangingRange_ = true;
 473       self.dygraph_.dateWindow_ = toXDataWindow(self.getZoomHandleStatus_());
 474       self.dygraph_.drawGraph_(false);
 475     } finally {
 476       self.isChangingRange_ = false;
 477     }
 478   };
 479
 480   onCanvasHover = function(e) {
 481     if (isZooming || isPanning) {
 482       return;
 483     }
 484     var cursor = isMouseInPanZone(e) ? 'move' : 'default';
 485     if (cursor != self.fgcanvas_.style.cursor) {
 486       self.fgcanvas_.style.cursor = cursor;
 487     }
 488   };
 489
 490   onZoomHandleTouchEvent = function(e) {
 491     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 492       if (onZoomStart(e.targetTouches[0])) {
 493         Dygraph.cancelEvent(e);
 494       }
 495     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 496       if (onZoom(e.targetTouches[0])) {
 497         Dygraph.cancelEvent(e);
 498       }
 499     } else {
 500       onZoomEnd(e);
 501     }
 502   };
 503
 504   onCanvasTouchEvent = function(e) {
 505     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 506       if (onPanStart(e.targetTouches[0])) {
 507         Dygraph.cancelEvent(e);
 508       }
 509     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 510       if (onPan(e.targetTouches[0])) {
 511         Dygraph.cancelEvent(e);
 512       }
 513     } else {
 514       onPanEnd(e);
 515     }
 516   };
 517
 518   addTouchEvents = function(elem, fn) {
 519     var types = ['touchstart', 'touchend', 'touchmove', 'touchcancel'];
 520     for (var i = 0; i < types.length; i++) {
 521       self.dygraph_.addEvent(elem, types[i], fn);
 522     }
 523   };
 524
 525   this.setDefaultOption_('interactionModel', Dygraph.Interaction.dragIsPanInteractionModel);
 526   this.setDefaultOption_('panEdgeFraction', 0.0001);
 527
 528   var dragStartEvent = window.opera ? 'mousedown' : 'dragstart';
 529   this.dygraph_.addEvent(this.leftZoomHandle_, dragStartEvent, onZoomStart);
 530   this.dygraph_.addEvent(this.rightZoomHandle_, dragStartEvent, onZoomStart);
 531
 532   if (this.isUsingExcanvas_) {
 533     this.dygraph_.addEvent(this.iePanOverlay_, 'mousedown', onPanStart);
 534   } else {
 535     this.dygraph_.addEvent(this.fgcanvas_, 'mousedown', onPanStart);
 536     this.dygraph_.addEvent(this.fgcanvas_, 'mousemove', onCanvasHover);
 537   }
 538
 539   // Touch events
 540   if (this.hasTouchInterface_) {
 541     addTouchEvents(this.leftZoomHandle_, onZoomHandleTouchEvent);
 542     addTouchEvents(this.rightZoomHandle_, onZoomHandleTouchEvent);
 543     addTouchEvents(this.fgcanvas_, onCanvasTouchEvent);
 544   }
 545 };
 546
 547 /**
 548  * @private
 549  * Draws the static layer in the background canvas.
 550  */
 551 rangeSelector.prototype.drawStaticLayer_ = function() {
 552   var ctx = this.bgcanvas_ctx_;
 553   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 554   try {
 555     this.drawMiniPlot_();
 556   } catch(ex) {
 557     Dygraph.warn(ex);
 558   }
 559
 560   var margin = 0.5;
 561   this.bgcanvas_ctx_.lineWidth = 1;
 562   ctx.strokeStyle = 'gray';
 563   ctx.beginPath();
 564   ctx.moveTo(margin, margin);
 565   ctx.lineTo(margin, this.canvasRect_.h-margin);
 566   ctx.lineTo(this.canvasRect_.w-margin, this.canvasRect_.h-margin);
 567   ctx.lineTo(this.canvasRect_.w-margin, margin);
 568   ctx.stroke();
 569 };
 570
 571
 572 /**
 573  * @private
 574  * Draws the mini plot in the background canvas.
 575  */
 576 rangeSelector.prototype.drawMiniPlot_ = function() {
 577   var fillStyle = this.getOption_('rangeSelectorPlotFillColor');
 578   var strokeStyle = this.getOption_('rangeSelectorPlotStrokeColor');
 579   if (!fillStyle && !strokeStyle) {
 580     return;
 581   }
 582
 583   var stepPlot = this.getOption_('stepPlot');
 584
 585   var combinedSeriesData = this.computeCombinedSeriesAndLimits_();
 586   var yRange = combinedSeriesData.yMax - combinedSeriesData.yMin;
 587
 588   // Draw the mini plot.
 589   var ctx = this.bgcanvas_ctx_;
 590   var margin = 0.5;
 591
 592   var xExtremes = this.dygraph_.xAxisExtremes();
 593   var xRange = Math.max(xExtremes[1] - xExtremes[0], 1.e-30);
 594   var xFact = (this.canvasRect_.w - margin)/xRange;
 595   var yFact = (this.canvasRect_.h - margin)/yRange;
 596   var canvasWidth = this.canvasRect_.w - margin;
 597   var canvasHeight = this.canvasRect_.h - margin;
 598
 599   var prevX = null, prevY = null;
 600
 601   ctx.beginPath();
 602   ctx.moveTo(margin, canvasHeight);
 603   for (var i = 0; i < combinedSeriesData.data.length; i++) {
 604     var dataPoint = combinedSeriesData.data[i];
 605     var x = ((dataPoint[0] !== null) ? ((dataPoint[0] - xExtremes[0])*xFact) : NaN);
 606     var y = ((dataPoint[1] !== null) ? (canvasHeight - (dataPoint[1] - combinedSeriesData.yMin)*yFact) : NaN);
 607     if (isFinite(x) && isFinite(y)) {
 608       if(prevX === null) {
 609         ctx.lineTo(x, canvasHeight);
 610       }
 611       else if (stepPlot) {
 612         ctx.lineTo(x, prevY);
 613       }
 614       ctx.lineTo(x, y);
 615       prevX = x;
 616       prevY = y;
 617     }
 618     else {
 619       if(prevX !== null) {
 620         if (stepPlot) {
 621           ctx.lineTo(x, prevY);
 622           ctx.lineTo(x, canvasHeight);
 623         }
 624         else {
 625           ctx.lineTo(prevX, canvasHeight);
 626         }
 627       }
 628       prevX = prevY = null;
 629     }
 630   }
 631   ctx.lineTo(canvasWidth, canvasHeight);
 632   ctx.closePath();
 633
 634   if (fillStyle) {
 635     var lingrad = this.bgcanvas_ctx_.createLinearGradient(0, 0, 0, canvasHeight);
 636     lingrad.addColorStop(0, 'white');
 637     lingrad.addColorStop(1, fillStyle);
 638     this.bgcanvas_ctx_.fillStyle = lingrad;
 639     ctx.fill();
 640   }
 641
 642   if (strokeStyle) {
 643     this.bgcanvas_ctx_.strokeStyle = strokeStyle;
 644     this.bgcanvas_ctx_.lineWidth = 1.5;
 645     ctx.stroke();
 646   }
 647 };
 648
 649 /**
 650  * @private
 651  * Computes and returns the combinded series data along with min/max for the mini plot.
 652  * @return {Object} An object containing combinded series array, ymin, ymax.
 653  */
 654 rangeSelector.prototype.computeCombinedSeriesAndLimits_ = function() {
 655   var data = this.dygraph_.rawData_;
 656   var logscale = this.getOption_('logscale');
 657
 658   // Create a combined series (average of all series values).
 659   var combinedSeries = [];
 660   var sum;
 661   var count;
 662   var mutipleValues;
 663   var i, j, k;
 664   var xVal, yVal;
 665
 666   // Find out if data has multiple values per datapoint.
 667   // Go to first data point that actually has values (see http://code.google.com/p/dygraphs/issues/detail?id=246)
 668   for (i = 0; i < data.length; i++) {
 669     if (data[i].length > 1 && data[i][1] !== null) {
 670       mutipleValues = typeof data[i][1] != 'number';
 671       if (mutipleValues) {
 672         sum = [];
 673         count = [];
 674         for (k = 0; k < data[i][1].length; k++) {
 675           sum.push(0);
 676           count.push(0);
 677         }
 678       }
 679       break;
 680     }
 681   }
 682
 683   for (i = 0; i < data.length; i++) {
 684     var dataPoint = data[i];
 685     xVal = dataPoint[0];
 686
 687     if (mutipleValues) {
 688       for (k = 0; k < sum.length; k++) {
 689         sum[k] = count[k] = 0;
 690       }
 691     } else {
 692       sum = count = 0;
 693     }
 694
 695     for (j = 1; j < dataPoint.length; j++) {
 696       if (this.dygraph_.visibility()[j-1]) {
 697         var y;
 698         if (mutipleValues) {
 699           for (k = 0; k < sum.length; k++) {
 700             y = dataPoint[j][k];
 701             if (y === null || isNaN(y)) continue;
 702             sum[k] += y;
 703             count[k]++;
 704           }
 705         } else {
 706           y = dataPoint[j];
 707           if (y === null || isNaN(y)) continue;
 708           sum += y;
 709           count++;
 710         }
 711       }
 712     }
 713
 714     if (mutipleValues) {
 715       for (k = 0; k < sum.length; k++) {
 716         sum[k] /= count[k];
 717       }
 718       yVal = sum.slice(0);
 719     } else {
 720       yVal = sum/count;
 721     }
 722
 723     combinedSeries.push([xVal, yVal]);
 724   }
 725
 726   // Account for roll period, fractions.
 727   combinedSeries = this.dygraph_.rollingAverage(combinedSeries, this.dygraph_.rollPeriod_);
 728
 729   if (typeof combinedSeries[0][1] != 'number') {
 730     for (i = 0; i < combinedSeries.length; i++) {
 731       yVal = combinedSeries[i][1];
 732       combinedSeries[i][1] = yVal[0];
 733     }
 734   }
 735
 736   // Compute the y range.
 737   var yMin = Number.MAX_VALUE;
 738   var yMax = -Number.MAX_VALUE;
 739   for (i = 0; i < combinedSeries.length; i++) {
 740     yVal = combinedSeries[i][1];
 741     if (yVal !== null && isFinite(yVal) && (!logscale || yVal > 0)) {
 742       yMin = Math.min(yMin, yVal);
 743       yMax = Math.max(yMax, yVal);
 744     }
 745   }
 746
 747   // Convert Y data to log scale if needed.
 748   // Also, expand the Y range to compress the mini plot a little.
 749   var extraPercent = 0.25;
 750   if (logscale) {
 751     yMax = Dygraph.log10(yMax);
 752     yMax += yMax*extraPercent;
 753     yMin = Dygraph.log10(yMin);
 754     for (i = 0; i < combinedSeries.length; i++) {
 755       combinedSeries[i][1] = Dygraph.log10(combinedSeries[i][1]);
 756     }
 757   } else {
 758     var yExtra;
 759     var yRange = yMax - yMin;
 760     if (yRange <= Number.MIN_VALUE) {
 761       yExtra = yMax*extraPercent;
 762     } else {
 763       yExtra = yRange*extraPercent;
 764     }
 765     yMax += yExtra;
 766     yMin -= yExtra;
 767   }
 768
 769   return {data: combinedSeries, yMin: yMin, yMax: yMax};
 770 };
 771
 772 /**
 773  * @private
 774  * Places the zoom handles in the proper position based on the current X data window.
 775  */
 776 rangeSelector.prototype.placeZoomHandles_ = function() {
 777   var xExtremes = this.dygraph_.xAxisExtremes();
 778   var xWindowLimits = this.dygraph_.xAxisRange();
 779   var xRange = xExtremes[1] - xExtremes[0];
 780   var leftPercent = Math.max(0, (xWindowLimits[0] - xExtremes[0])/xRange);
 781   var rightPercent = Math.max(0, (xExtremes[1] - xWindowLimits[1])/xRange);
 782   var leftCoord = this.canvasRect_.x + this.canvasRect_.w*leftPercent;
 783   var rightCoord = this.canvasRect_.x + this.canvasRect_.w*(1 - rightPercent);
 784   var handleTop = Math.max(this.canvasRect_.y, this.canvasRect_.y + (this.canvasRect_.h - this.leftZoomHandle_.height)/2);
 785   var halfHandleWidth = this.leftZoomHandle_.width/2;
 786   this.leftZoomHandle_.style.left = (leftCoord - halfHandleWidth) + 'px';
 787   this.leftZoomHandle_.style.top = handleTop + 'px';
 788   this.rightZoomHandle_.style.left = (rightCoord - halfHandleWidth) + 'px';
 789   this.rightZoomHandle_.style.top = this.leftZoomHandle_.style.top;
 790
 791   this.leftZoomHandle_.style.visibility = 'visible';
 792   this.rightZoomHandle_.style.visibility = 'visible';
 793 };
 794
 795 /**
 796  * @private
 797  * Draws the interactive layer in the foreground canvas.
 798  */
 799 rangeSelector.prototype.drawInteractiveLayer_ = function() {
 800   var ctx = this.fgcanvas_ctx_;
 801   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 802   var margin = 1;
 803   var width = this.canvasRect_.w - margin;
 804   var height = this.canvasRect_.h - margin;
 805   var zoomHandleStatus = this.getZoomHandleStatus_();
 806
 807   ctx.strokeStyle = 'black';
 808   if (!zoomHandleStatus.isZoomed) {
 809     ctx.beginPath();
 810     ctx.moveTo(margin, margin);
 811     ctx.lineTo(margin, height);
 812     ctx.lineTo(width, height);
 813     ctx.lineTo(width, margin);
 814     ctx.stroke();
 815     if (this.iePanOverlay_) {
 816       this.iePanOverlay_.style.display = 'none';
 817     }
 818   } else {
 819     var leftHandleCanvasPos = Math.max(margin, zoomHandleStatus.leftHandlePos - this.canvasRect_.x);
 820     var rightHandleCanvasPos = Math.min(width, zoomHandleStatus.rightHandlePos - this.canvasRect_.x);
 821
 822     ctx.fillStyle = 'rgba(240, 240, 240, 0.6)';
 823     ctx.fillRect(0, 0, leftHandleCanvasPos, this.canvasRect_.h);
 824     ctx.fillRect(rightHandleCanvasPos, 0, this.canvasRect_.w - rightHandleCanvasPos, this.canvasRect_.h);
 825
 826     ctx.beginPath();
 827     ctx.moveTo(margin, margin);
 828     ctx.lineTo(leftHandleCanvasPos, margin);
 829     ctx.lineTo(leftHandleCanvasPos, height);
 830     ctx.lineTo(rightHandleCanvasPos, height);
 831     ctx.lineTo(rightHandleCanvasPos, margin);
 832     ctx.lineTo(width, margin);
 833     ctx.stroke();
 834
 835     if (this.isUsingExcanvas_) {
 836       this.iePanOverlay_.style.width = (rightHandleCanvasPos - leftHandleCanvasPos) + 'px';
 837       this.iePanOverlay_.style.left = leftHandleCanvasPos + 'px';
 838       this.iePanOverlay_.style.height = height + 'px';
 839       this.iePanOverlay_.style.display = 'inline';
 840     }
 841   }
 842 };
 843
 844 /**
 845  * @private
 846  * Returns the current zoom handle position information.
 847  * @return {Object} The zoom handle status.
 848  */
 849 rangeSelector.prototype.getZoomHandleStatus_ = function() {
 850   var halfHandleWidth = this.leftZoomHandle_.width/2;
 851   var leftHandlePos = parseFloat(this.leftZoomHandle_.style.left) + halfHandleWidth;
 852   var rightHandlePos = parseFloat(this.rightZoomHandle_.style.left) + halfHandleWidth;
 853   return {
 854       leftHandlePos: leftHandlePos,
 855       rightHandlePos: rightHandlePos,
 856       isZoomed: (leftHandlePos - 1 > this.canvasRect_.x || rightHandlePos + 1 < this.canvasRect_.x+this.canvasRect_.w)
 857   };
 858 };
 859
 860 return rangeSelector;
 861
 862 })();