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