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
   7 /**
   8  * @fileoverview This file contains the RangeSelector plugin used to provide
   9  * a timeline range selector widget for dygraphs.
  10  */
  11
  12 Dygraph.Plugins.RangeSelector = (function() {
  13
  14 /*jshint globalstrict: true */
  15 /*global Dygraph:false */
  16 "use strict";
  17
  18 // Range selector status values
  19 var NOT_CREATED = 0; // Range selector interface has not been created
  20 var CREATED = 1 << 0; // Range selector interface has been created
  21 var ADDED_TO_GRAPH = 1 << 1; // Range selector elements have been added to the graph
  22
  23 var rangeSelector = function() {
  24   this.isIE_ = /MSIE/.test(navigator.userAgent) && !window.opera;
  25   this.hasTouchInterface_ = typeof(TouchEvent) != 'undefined';
  26   this.isMobileDevice_ = /mobile|android/gi.test(navigator.appVersion);
  27   this.status_ = NOT_CREATED;
  28 };
  29
  30 rangeSelector.prototype.toString = function() {
  31   return "RangeSelector Plugin";
  32 };
  33
  34 rangeSelector.prototype.activate = function(dygraph) {
  35   this.dygraph_ = dygraph;
  36   this.layout_ = dygraph.layout_;
  37   this.graphDiv_ = dygraph.graphDiv;
  38   this.isUsingExcanvas_ = dygraph.isUsingExcanvas_;
  39   if (this.getOption_('showRangeSelector')) {
  40     this.createInterface_();
  41   }
  42   return {
  43     layout: this.reserveSpace_,
  44     predraw: this.renderStaticLayer_,
  45     didDrawChart: this.renderInteractiveLayer_
  46   };
  47 };
  48
  49 rangeSelector.prototype.destroy = function() {
  50   this.bgcanvas_ = null;
  51   this.fgcanvas_ = null;
  52   this.leftZoomHandle_ = null;
  53   this.rightZoomHandle_ = null;
  54   this.iePanOverlay_ = null;
  55 };
  56
  57 //------------------------------------------------------------------
  58 // Private methods
  59 //------------------------------------------------------------------
  60
  61 rangeSelector.prototype.getOption_ = function(name) {
  62   return this.dygraph_.getOption(name);
  63 };
  64
  65 rangeSelector.prototype.setDefaultOption_ = function(name, value) {
  66   return this.dygraph_.attrs_[name] = value;
  67 };
  68
  69 /**
  70  * @private
  71  * Creates the range selector elements and adds them to the graph.
  72  */
  73 rangeSelector.prototype.createInterface_ = function() {
  74   this.createCanvases_();
  75   if (this.isUsingExcanvas_) {
  76     this.createIEPanOverlay_();
  77   }
  78   this.createZoomHandles_();
  79   this.initInteraction_();
  80
  81   // Range selector and animatedZooms have a bad interaction. See issue 359.
  82   if (this.getOption_('animatedZooms')) {
  83     this.dygraph_.warn('Animated zooms and range selector are not compatible; disabling animatedZooms.');
  84     this.dygraph_.updateOptions({animatedZooms: false}, true);
  85   }
  86
  87   this.addToGraph_();
  88   this.status_ = CREATED;
  89 };
  90
  91 /**
  92  * @private
  93  * Adds the range selector to the graph.
  94  */
  95 rangeSelector.prototype.addToGraph_ = function() {
  96   var graphDiv = this.graphDiv_;
  97   graphDiv.appendChild(this.bgcanvas_);
  98   graphDiv.appendChild(this.fgcanvas_);
  99   graphDiv.appendChild(this.leftZoomHandle_);
 100   graphDiv.appendChild(this.rightZoomHandle_);
 101   this.status_ |= ADDED_TO_GRAPH;
 102 };
 103
 104 /**
 105  * @private
 106  * Removes the range selector from the graph.
 107  */
 108 rangeSelector.prototype.removeFromGraph_ = function() {
 109   var graphDiv = this.graphDiv_;
 110   graphDiv.removeChild(this.bgcanvas_);
 111   graphDiv.removeChild(this.fgcanvas_);
 112   graphDiv.removeChild(this.leftZoomHandle_);
 113   graphDiv.removeChild(this.rightZoomHandle_);
 114   this.status_ ^= ADDED_TO_GRAPH;
 115 };
 116
 117 /**
 118  * @private
 119  * Called by Layout to allow range selector to reserve its space.
 120  */
 121 rangeSelector.prototype.reserveSpace_ = function(e) {
 122   if (this.getOption_('showRangeSelector')) {
 123     e.reserveSpaceBottom(this.getOption_('rangeSelectorHeight') + 4);
 124   }
 125 };
 126
 127 /**
 128  * @private
 129  * Renders the static portion of the range selector at the predraw stage.
 130  */
 131 rangeSelector.prototype.renderStaticLayer_ = function() {
 132   if (!this.updateInterfaceStatus_()) {
 133     return;
 134   }
 135   this.resize_();
 136   this.drawStaticLayer_();
 137 };
 138
 139 /**
 140  * @private
 141  * Renders the interactive portion of the range selector after the chart has been drawn.
 142  */
 143 rangeSelector.prototype.renderInteractiveLayer_ = function() {
 144   if (!this.updateInterfaceStatus_() || this.isChangingRange_) {
 145     return;
 146   }
 147   this.placeZoomHandles_();
 148   this.drawInteractiveLayer_();
 149 };
 150
 151 /**
 152  * @private
 153  * Check to see if the range selector is enabled/disabled and update interface accordingly.
 154  */
 155 rangeSelector.prototype.updateInterfaceStatus_ = function() {
 156   var enabled = this.getOption_('showRangeSelector');
 157   if (enabled) {
 158     if (!(this.status_ & CREATED)) {
 159       this.createInterface_();
 160     } else if (!(this.status_ & ADDED_TO_GRAPH)) {
 161       this.addToGraph_();
 162     }
 163   } else if (this.status_ & ADDED_TO_GRAPH) {
 164     this.removeFromGraph_();
 165     var dygraph = this.dygraph_;
 166     setTimeout(function() { dygraph.width_ = 0; dygraph.resize(); }, 1);
 167   }
 168   return enabled;
 169 }
 170
 171 /**
 172  * @private
 173  * Resizes the range selector.
 174  */
 175 rangeSelector.prototype.resize_ = function() {
 176   function setElementRect(canvas, rect) {
 177     canvas.style.top = rect.y + 'px';
 178     canvas.style.left = rect.x + 'px';
 179     canvas.width = rect.w;
 180     canvas.height = rect.h;
 181     canvas.style.width = canvas.width + 'px';    // for IE
 182     canvas.style.height = canvas.height + 'px';  // for IE
 183   }
 184
 185   var plotArea = this.layout_.getPlotArea();
 186   var xAxisLabelHeight = this.getOption_('xAxisHeight') || (this.getOption_('axisLabelFontSize') + 2 * this.getOption_('axisTickSize'));
 187   this.canvasRect_ = {
 188     x: plotArea.x,
 189     y: plotArea.y + plotArea.h + xAxisLabelHeight + 4,
 190     w: plotArea.w,
 191     h: this.getOption_('rangeSelectorHeight')
 192   };
 193
 194   setElementRect(this.bgcanvas_, this.canvasRect_);
 195   setElementRect(this.fgcanvas_, this.canvasRect_);
 196 };
 197
 198 /**
 199  * @private
 200  * Creates the background and foreground canvases.
 201  */
 202 rangeSelector.prototype.createCanvases_ = function() {
 203   this.bgcanvas_ = Dygraph.createCanvas();
 204   this.bgcanvas_.className = 'dygraph-rangesel-bgcanvas';
 205   this.bgcanvas_.style.position = 'absolute';
 206   this.bgcanvas_.style.zIndex = 9;
 207   this.bgcanvas_ctx_ = Dygraph.getContext(this.bgcanvas_);
 208
 209   this.fgcanvas_ = Dygraph.createCanvas();
 210   this.fgcanvas_.className = 'dygraph-rangesel-fgcanvas';
 211   this.fgcanvas_.style.position = 'absolute';
 212   this.fgcanvas_.style.zIndex = 9;
 213   this.fgcanvas_.style.cursor = 'default';
 214   this.fgcanvas_ctx_ = Dygraph.getContext(this.fgcanvas_);
 215 };
 216
 217 /**
 218  * @private
 219  * Creates overlay divs for IE/Excanvas so that mouse events are handled properly.
 220  */
 221 rangeSelector.prototype.createIEPanOverlay_ = function() {
 222   this.iePanOverlay_ = document.createElement("div");
 223   this.iePanOverlay_.style.position = 'absolute';
 224   this.iePanOverlay_.style.backgroundColor = 'white';
 225   this.iePanOverlay_.style.filter = 'alpha(opacity=0)';
 226   this.iePanOverlay_.style.display = 'none';
 227   this.iePanOverlay_.style.cursor = 'move';
 228   this.fgcanvas_.appendChild(this.iePanOverlay_);
 229 };
 230
 231 /**
 232  * @private
 233  * Creates the zoom handle elements.
 234  */
 235 rangeSelector.prototype.createZoomHandles_ = function() {
 236   var img = new Image();
 237   img.className = 'dygraph-rangesel-zoomhandle';
 238   img.style.position = 'absolute';
 239   img.style.zIndex = 10;
 240   img.style.visibility = 'hidden'; // Initially hidden so they don't show up in the wrong place.
 241   img.style.cursor = 'col-resize';
 242
 243   if (/MSIE 7/.test(navigator.userAgent)) { // IE7 doesn't support embedded src data.
 244     img.width = 7;
 245     img.height = 14;
 246     img.style.backgroundColor = 'white';
 247     img.style.border = '1px solid #333333'; // Just show box in IE7.
 248   } else {
 249     img.width = 9;
 250     img.height = 16;
 251     img.src = 'data:image/png;base64,' +
 252 'iVBORw0KGgoAAAANSUhEUgAAAAkAAAAQCAYAAADESFVDAAAAAXNSR0IArs4c6QAAAAZiS0dEANAA' +
 253 'zwDP4Z7KegAAAAlwSFlzAAAOxAAADsQBlSsOGwAAAAd0SU1FB9sHGw0cMqdt1UwAAAAZdEVYdENv' +
 254 'bW1lbnQAQ3JlYXRlZCB3aXRoIEdJTVBXgQ4XAAAAaElEQVQoz+3SsRFAQBCF4Z9WJM8KCDVwownl' +
 255 '6YXsTmCUsyKGkZzcl7zkz3YLkypgAnreFmDEpHkIwVOMfpdi9CEEN2nGpFdwD03yEqDtOgCaun7s' +
 256 'qSTDH32I1pQA2Pb9sZecAxc5r3IAb21d6878xsAAAAAASUVORK5CYII=';
 257   }
 258
 259   if (this.isMobileDevice_) {
 260     img.width *= 2;
 261     img.height *= 2;
 262   }
 263
 264   this.leftZoomHandle_ = img;
 265   this.rightZoomHandle_ = img.cloneNode(false);
 266 };
 267
 268 /**
 269  * @private
 270  * Sets up the interaction for the range selector.
 271  */
 272 rangeSelector.prototype.initInteraction_ = function() {
 273   var self = this;
 274   var topElem = this.isIE_ ? document : window;
 275   var xLast = 0;
 276   var handle = null;
 277   var isZooming = false;
 278   var isPanning = false;
 279   var dynamic = !this.isMobileDevice_ && !this.isUsingExcanvas_;
 280
 281   // We cover iframes during mouse interactions. See comments in
 282   // dygraph-utils.js for more info on why this is a good idea.
 283   var tarp = new Dygraph.IFrameTarp();
 284
 285   // functions, defined below.  Defining them this way (rather than with
 286   // "function foo() {...}" makes JSHint happy.
 287   var toXDataWindow, onZoomStart, onZoom, onZoomEnd, doZoom, isMouseInPanZone,
 288       onPanStart, onPan, onPanEnd, doPan, onCanvasMouseMove, applyBrowserZoomLevel;
 289
 290   // Touch event functions
 291   var onZoomHandleTouchEvent, onCanvasTouchEvent, addTouchEvents;
 292
 293   toXDataWindow = function(zoomHandleStatus) {
 294     var xDataLimits = self.dygraph_.xAxisExtremes();
 295     var fact = (xDataLimits[1] - xDataLimits[0])/self.canvasRect_.w;
 296     var xDataMin = xDataLimits[0] + (zoomHandleStatus.leftHandlePos - self.canvasRect_.x)*fact;
 297     var xDataMax = xDataLimits[0] + (zoomHandleStatus.rightHandlePos - self.canvasRect_.x)*fact;
 298     return [xDataMin, xDataMax];
 299   };
 300
 301   applyBrowserZoomLevel = function(delX) {
 302     var zoom = window.outerWidth/document.documentElement.clientWidth;
 303     if (!isNaN(zoom)) {
 304       return delX/zoom;
 305     } else {
 306       return delX;
 307     }
 308   };
 309
 310   onZoomStart = function(e) {
 311     Dygraph.cancelEvent(e);
 312     isZooming = true;
 313     xLast = e.screenX;
 314     handle = e.target ? e.target : e.srcElement;
 315     self.dygraph_.addEvent(topElem, 'mousemove', onZoom);
 316     self.dygraph_.addEvent(topElem, 'mouseup', onZoomEnd);
 317     self.fgcanvas_.style.cursor = 'col-resize';
 318     tarp.cover();
 319     return true;
 320   };
 321
 322   onZoom = function(e) {
 323     if (!isZooming) {
 324       return false;
 325     }
 326     Dygraph.cancelEvent(e);
 327     var delX = e.screenX - xLast;
 328     if (Math.abs(delX) < 4 || e.screenX === 0) {
 329       // First iPad move event seems to have screenX = 0
 330       return true;
 331     }
 332     xLast = e.screenX;
 333     delX = applyBrowserZoomLevel(delX);
 334
 335     // Move handle.
 336     var zoomHandleStatus = self.getZoomHandleStatus_();
 337     var newPos;
 338     if (handle == self.leftZoomHandle_) {
 339       newPos = zoomHandleStatus.leftHandlePos + delX;
 340       newPos = Math.min(newPos, zoomHandleStatus.rightHandlePos - handle.width - 3);
 341       newPos = Math.max(newPos, self.canvasRect_.x);
 342     } else {
 343       newPos = zoomHandleStatus.rightHandlePos + delX;
 344       newPos = Math.min(newPos, self.canvasRect_.x + self.canvasRect_.w);
 345       newPos = Math.max(newPos, zoomHandleStatus.leftHandlePos + handle.width + 3);
 346     }
 347     var halfHandleWidth = handle.width/2;
 348     handle.style.left = (newPos - halfHandleWidth) + 'px';
 349     self.drawInteractiveLayer_();
 350
 351     // Zoom on the fly (if not using excanvas).
 352     if (dynamic) {
 353       doZoom();
 354     }
 355     return true;
 356   };
 357
 358   onZoomEnd = function(e) {
 359     if (!isZooming) {
 360       return false;
 361     }
 362     isZooming = false;
 363     tarp.uncover();
 364     Dygraph.removeEvent(topElem, 'mousemove', onZoom);
 365     Dygraph.removeEvent(topElem, 'mouseup', onZoomEnd);
 366     self.fgcanvas_.style.cursor = 'default';
 367
 368     // If using excanvas, Zoom now.
 369     if (!dynamic) {
 370       doZoom();
 371     }
 372     return true;
 373   };
 374
 375   doZoom = function() {
 376     try {
 377       var zoomHandleStatus = self.getZoomHandleStatus_();
 378       self.isChangingRange_ = true;
 379       if (!zoomHandleStatus.isZoomed) {
 380         self.dygraph_.resetZoom();
 381       } else {
 382         var xDataWindow = toXDataWindow(zoomHandleStatus);
 383         self.dygraph_.doZoomXDates_(xDataWindow[0], xDataWindow[1]);
 384       }
 385     } finally {
 386       self.isChangingRange_ = false;
 387     }
 388   };
 389
 390   isMouseInPanZone = function(e) {
 391     if (self.isUsingExcanvas_) {
 392         return e.srcElement == self.iePanOverlay_;
 393     } else {
 394       var rect = self.leftZoomHandle_.getBoundingClientRect();
 395       var leftHandleClientX = rect.left + rect.width/2;
 396       rect = self.rightZoomHandle_.getBoundingClientRect();
 397       var rightHandleClientX = rect.left + rect.width/2;
 398       return (e.clientX > leftHandleClientX && e.clientX < rightHandleClientX);
 399     }
 400   };
 401
 402   onPanStart = function(e) {
 403     if (!isPanning && isMouseInPanZone(e) && self.getZoomHandleStatus_().isZoomed) {
 404       Dygraph.cancelEvent(e);
 405       isPanning = true;
 406       xLast = e.screenX;
 407       self.dygraph_.addEvent(topElem, 'mousemove', onPan);
 408       self.dygraph_.addEvent(topElem, 'mouseup', onPanEnd);
 409       return true;
 410     }
 411     return false;
 412   };
 413
 414   onPan = function(e) {
 415     if (!isPanning) {
 416       return false;
 417     }
 418     Dygraph.cancelEvent(e);
 419
 420     var delX = e.screenX - xLast;
 421     if (Math.abs(delX) < 4) {
 422       return true;
 423     }
 424     xLast = e.screenX;
 425     delX = applyBrowserZoomLevel(delX);
 426
 427     // Move range view
 428     var zoomHandleStatus = self.getZoomHandleStatus_();
 429     var leftHandlePos = zoomHandleStatus.leftHandlePos;
 430     var rightHandlePos = zoomHandleStatus.rightHandlePos;
 431     var rangeSize = rightHandlePos - leftHandlePos;
 432     if (leftHandlePos + delX <= self.canvasRect_.x) {
 433       leftHandlePos = self.canvasRect_.x;
 434       rightHandlePos = leftHandlePos + rangeSize;
 435     } else if (rightHandlePos + delX >= self.canvasRect_.x + self.canvasRect_.w) {
 436       rightHandlePos = self.canvasRect_.x + self.canvasRect_.w;
 437       leftHandlePos = rightHandlePos - rangeSize;
 438     } else {
 439       leftHandlePos += delX;
 440       rightHandlePos += delX;
 441     }
 442     var halfHandleWidth = self.leftZoomHandle_.width/2;
 443     self.leftZoomHandle_.style.left = (leftHandlePos - halfHandleWidth) + 'px';
 444     self.rightZoomHandle_.style.left = (rightHandlePos - halfHandleWidth) + 'px';
 445     self.drawInteractiveLayer_();
 446
 447     // Do pan on the fly (if not using excanvas).
 448     if (dynamic) {
 449       doPan();
 450     }
 451     return true;
 452   };
 453
 454   onPanEnd = function(e) {
 455     if (!isPanning) {
 456       return false;
 457     }
 458     isPanning = false;
 459     Dygraph.removeEvent(topElem, 'mousemove', onPan);
 460     Dygraph.removeEvent(topElem, 'mouseup', onPanEnd);
 461     // If using excanvas, do pan now.
 462     if (!dynamic) {
 463       doPan();
 464     }
 465     return true;
 466   };
 467
 468   doPan = function() {
 469     try {
 470       self.isChangingRange_ = true;
 471       self.dygraph_.dateWindow_ = toXDataWindow(self.getZoomHandleStatus_());
 472       self.dygraph_.drawGraph_(false);
 473     } finally {
 474       self.isChangingRange_ = false;
 475     }
 476   };
 477
 478   onCanvasMouseMove = function(e) {
 479     if (isZooming || isPanning) {
 480       return;
 481     }
 482     var cursor = isMouseInPanZone(e) ? 'move' : 'default';
 483     if (cursor != self.fgcanvas_.style.cursor) {
 484       self.fgcanvas_.style.cursor = cursor;
 485     }
 486   };
 487
 488   onZoomHandleTouchEvent = function(e) {
 489     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 490       if (onZoomStart(e.targetTouches[0])) {
 491         Dygraph.cancelEvent(e);
 492       }
 493     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 494       if (onZoom(e.targetTouches[0])) {
 495         Dygraph.cancelEvent(e);
 496       }
 497     } else {
 498       onZoomEnd(e);
 499     }
 500   };
 501
 502   onCanvasTouchEvent = function(e) {
 503     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 504       if (onPanStart(e.targetTouches[0])) {
 505         Dygraph.cancelEvent(e);
 506       }
 507     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 508       if (onPan(e.targetTouches[0])) {
 509         Dygraph.cancelEvent(e);
 510       }
 511     } else {
 512       onPanEnd(e);
 513     }
 514   };
 515
 516   addTouchEvents = function(elem, fn) {
 517     var types = ['touchstart', 'touchend', 'touchmove', 'touchcancel'];
 518     for (var i = 0; i < types.length; i++) {
 519       self.dygraph_.addEvent(elem, types[i], fn);
 520     }
 521   };
 522
 523   this.setDefaultOption_('interactionModel', Dygraph.Interaction.dragIsPanInteractionModel);
 524   this.setDefaultOption_('panEdgeFraction', 0.0001);
 525
 526   var dragStartEvent = window.opera ? 'mousedown' : 'dragstart';
 527   this.dygraph_.addEvent(this.leftZoomHandle_, dragStartEvent, onZoomStart);
 528   this.dygraph_.addEvent(this.rightZoomHandle_, dragStartEvent, onZoomStart);
 529
 530   if (this.isUsingExcanvas_) {
 531     this.dygraph_.addEvent(this.iePanOverlay_, 'mousedown', onPanStart);
 532   } else {
 533     this.dygraph_.addEvent(this.fgcanvas_, 'mousedown', onPanStart);
 534     this.dygraph_.addEvent(this.fgcanvas_, 'mousemove', onCanvasMouseMove);
 535   }
 536
 537   // Touch events
 538   if (this.hasTouchInterface_) {
 539     addTouchEvents(this.leftZoomHandle_, onZoomHandleTouchEvent);
 540     addTouchEvents(this.rightZoomHandle_, onZoomHandleTouchEvent);
 541     addTouchEvents(this.fgcanvas_, onCanvasTouchEvent);
 542   }
 543 };
 544
 545 /**
 546  * @private
 547  * Draws the static layer in the background canvas.
 548  */
 549 rangeSelector.prototype.drawStaticLayer_ = function() {
 550   var ctx = this.bgcanvas_ctx_;
 551   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 552   try {
 553     this.drawMiniPlot_();
 554   } catch(ex) {
 555     Dygraph.warn(ex);
 556   }
 557
 558   var margin = 0.5;
 559   this.bgcanvas_ctx_.lineWidth = 1;
 560   ctx.strokeStyle = 'gray';
 561   ctx.beginPath();
 562   ctx.moveTo(margin, margin);
 563   ctx.lineTo(margin, this.canvasRect_.h-margin);
 564   ctx.lineTo(this.canvasRect_.w-margin, this.canvasRect_.h-margin);
 565   ctx.lineTo(this.canvasRect_.w-margin, margin);
 566   ctx.stroke();
 567 };
 568
 569
 570 /**
 571  * @private
 572  * Draws the mini plot in the background canvas.
 573  */
 574 rangeSelector.prototype.drawMiniPlot_ = function() {
 575   var fillStyle = this.getOption_('rangeSelectorPlotFillColor');
 576   var strokeStyle = this.getOption_('rangeSelectorPlotStrokeColor');
 577   if (!fillStyle && !strokeStyle) {
 578     return;
 579   }
 580
 581   var stepPlot = this.getOption_('stepPlot');
 582
 583   var combinedSeriesData = this.computeCombinedSeriesAndLimits_();
 584   var yRange = combinedSeriesData.yMax - combinedSeriesData.yMin;
 585
 586   // Draw the mini plot.
 587   var ctx = this.bgcanvas_ctx_;
 588   var margin = 0.5;
 589
 590   var xExtremes = this.dygraph_.xAxisExtremes();
 591   var xRange = Math.max(xExtremes[1] - xExtremes[0], 1.e-30);
 592   var xFact = (this.canvasRect_.w - margin)/xRange;
 593   var yFact = (this.canvasRect_.h - margin)/yRange;
 594   var canvasWidth = this.canvasRect_.w - margin;
 595   var canvasHeight = this.canvasRect_.h - margin;
 596
 597   var prevX = null, prevY = null;
 598
 599   ctx.beginPath();
 600   ctx.moveTo(margin, canvasHeight);
 601   for (var i = 0; i < combinedSeriesData.data.length; i++) {
 602     var dataPoint = combinedSeriesData.data[i];
 603     var x = ((dataPoint[0] !== null) ? ((dataPoint[0] - xExtremes[0])*xFact) : NaN);
 604     var y = ((dataPoint[1] !== null) ? (canvasHeight - (dataPoint[1] - combinedSeriesData.yMin)*yFact) : NaN);
 605     if (isFinite(x) && isFinite(y)) {
 606       if(prevX === null) {
 607         ctx.lineTo(x, canvasHeight);
 608       }
 609       else if (stepPlot) {
 610         ctx.lineTo(x, prevY);
 611       }
 612       ctx.lineTo(x, y);
 613       prevX = x;
 614       prevY = y;
 615     }
 616     else {
 617       if(prevX !== null) {
 618         if (stepPlot) {
 619           ctx.lineTo(x, prevY);
 620           ctx.lineTo(x, canvasHeight);
 621         }
 622         else {
 623           ctx.lineTo(prevX, canvasHeight);
 624         }
 625       }
 626       prevX = prevY = null;
 627     }
 628   }
 629   ctx.lineTo(canvasWidth, canvasHeight);
 630   ctx.closePath();
 631
 632   if (fillStyle) {
 633     var lingrad = this.bgcanvas_ctx_.createLinearGradient(0, 0, 0, canvasHeight);
 634     lingrad.addColorStop(0, 'white');
 635     lingrad.addColorStop(1, fillStyle);
 636     this.bgcanvas_ctx_.fillStyle = lingrad;
 637     ctx.fill();
 638   }
 639
 640   if (strokeStyle) {
 641     this.bgcanvas_ctx_.strokeStyle = strokeStyle;
 642     this.bgcanvas_ctx_.lineWidth = 1.5;
 643     ctx.stroke();
 644   }
 645 };
 646
 647 /**
 648  * @private
 649  * Computes and returns the combinded series data along with min/max for the mini plot.
 650  * @return {Object} An object containing combinded series array, ymin, ymax.
 651  */
 652 rangeSelector.prototype.computeCombinedSeriesAndLimits_ = function() {
 653   var data = this.dygraph_.rawData_;
 654   var logscale = this.getOption_('logscale');
 655
 656   // Create a combined series (average of all series values).
 657   var combinedSeries = [];
 658   var sum;
 659   var count;
 660   var mutipleValues;
 661   var i, j, k;
 662   var xVal, yVal;
 663
 664   // Find out if data has multiple values per datapoint.
 665   // Go to first data point that actually has values (see http://code.google.com/p/dygraphs/issues/detail?id=246)
 666   for (i = 0; i < data.length; i++) {
 667     if (data[i].length > 1 && data[i][1] !== null) {
 668       mutipleValues = typeof data[i][1] != 'number';
 669       if (mutipleValues) {
 670         sum = [];
 671         count = [];
 672         for (k = 0; k < data[i][1].length; k++) {
 673           sum.push(0);
 674           count.push(0);
 675         }
 676       }
 677       break;
 678     }
 679   }
 680
 681   for (i = 0; i < data.length; i++) {
 682     var dataPoint = data[i];
 683     xVal = dataPoint[0];
 684
 685     if (mutipleValues) {
 686       for (k = 0; k < sum.length; k++) {
 687         sum[k] = count[k] = 0;
 688       }
 689     } else {
 690       sum = count = 0;
 691     }
 692
 693     for (j = 1; j < dataPoint.length; j++) {
 694       if (this.dygraph_.visibility()[j-1]) {
 695         var y;
 696         if (mutipleValues) {
 697           for (k = 0; k < sum.length; k++) {
 698             y = dataPoint[j][k];
 699             if (y === null || isNaN(y)) continue;
 700             sum[k] += y;
 701             count[k]++;
 702           }
 703         } else {
 704           y = dataPoint[j];
 705           if (y === null || isNaN(y)) continue;
 706           sum += y;
 707           count++;
 708         }
 709       }
 710     }
 711
 712     if (mutipleValues) {
 713       for (k = 0; k < sum.length; k++) {
 714         sum[k] /= count[k];
 715       }
 716       yVal = sum.slice(0);
 717     } else {
 718       yVal = sum/count;
 719     }
 720
 721     combinedSeries.push([xVal, yVal]);
 722   }
 723
 724   // Account for roll period, fractions.
 725   combinedSeries = this.dygraph_.rollingAverage(combinedSeries, this.dygraph_.rollPeriod_);
 726
 727   if (typeof combinedSeries[0][1] != 'number') {
 728     for (i = 0; i < combinedSeries.length; i++) {
 729       yVal = combinedSeries[i][1];
 730       combinedSeries[i][1] = yVal[0];
 731     }
 732   }
 733
 734   // Compute the y range.
 735   var yMin = Number.MAX_VALUE;
 736   var yMax = -Number.MAX_VALUE;
 737   for (i = 0; i < combinedSeries.length; i++) {
 738     yVal = combinedSeries[i][1];
 739     if (yVal !== null && isFinite(yVal) && (!logscale || yVal > 0)) {
 740       yMin = Math.min(yMin, yVal);
 741       yMax = Math.max(yMax, yVal);
 742     }
 743   }
 744
 745   // Convert Y data to log scale if needed.
 746   // Also, expand the Y range to compress the mini plot a little.
 747   var extraPercent = 0.25;
 748   if (logscale) {
 749     yMax = Dygraph.log10(yMax);
 750     yMax += yMax*extraPercent;
 751     yMin = Dygraph.log10(yMin);
 752     for (i = 0; i < combinedSeries.length; i++) {
 753       combinedSeries[i][1] = Dygraph.log10(combinedSeries[i][1]);
 754     }
 755   } else {
 756     var yExtra;
 757     var yRange = yMax - yMin;
 758     if (yRange <= Number.MIN_VALUE) {
 759       yExtra = yMax*extraPercent;
 760     } else {
 761       yExtra = yRange*extraPercent;
 762     }
 763     yMax += yExtra;
 764     yMin -= yExtra;
 765   }
 766
 767   return {data: combinedSeries, yMin: yMin, yMax: yMax};
 768 };
 769
 770 /**
 771  * @private
 772  * Places the zoom handles in the proper position based on the current X data window.
 773  */
 774 rangeSelector.prototype.placeZoomHandles_ = function() {
 775   var xExtremes = this.dygraph_.xAxisExtremes();
 776   var xWindowLimits = this.dygraph_.xAxisRange();
 777   var xRange = xExtremes[1] - xExtremes[0];
 778   var leftPercent = Math.max(0, (xWindowLimits[0] - xExtremes[0])/xRange);
 779   var rightPercent = Math.max(0, (xExtremes[1] - xWindowLimits[1])/xRange);
 780   var leftCoord = this.canvasRect_.x + this.canvasRect_.w*leftPercent;
 781   var rightCoord = this.canvasRect_.x + this.canvasRect_.w*(1 - rightPercent);
 782   var handleTop = Math.max(this.canvasRect_.y, this.canvasRect_.y + (this.canvasRect_.h - this.leftZoomHandle_.height)/2);
 783   var halfHandleWidth = this.leftZoomHandle_.width/2;
 784   this.leftZoomHandle_.style.left = (leftCoord - halfHandleWidth) + 'px';
 785   this.leftZoomHandle_.style.top = handleTop + 'px';
 786   this.rightZoomHandle_.style.left = (rightCoord - halfHandleWidth) + 'px';
 787   this.rightZoomHandle_.style.top = this.leftZoomHandle_.style.top;
 788
 789   this.leftZoomHandle_.style.visibility = 'visible';
 790   this.rightZoomHandle_.style.visibility = 'visible';
 791 };
 792
 793 /**
 794  * @private
 795  * Draws the interactive layer in the foreground canvas.
 796  */
 797 rangeSelector.prototype.drawInteractiveLayer_ = function() {
 798   var ctx = this.fgcanvas_ctx_;
 799   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 800   var margin = 1;
 801   var width = this.canvasRect_.w - margin;
 802   var height = this.canvasRect_.h - margin;
 803   var zoomHandleStatus = this.getZoomHandleStatus_();
 804
 805   ctx.strokeStyle = 'black';
 806   if (!zoomHandleStatus.isZoomed) {
 807     ctx.beginPath();
 808     ctx.moveTo(margin, margin);
 809     ctx.lineTo(margin, height);
 810     ctx.lineTo(width, height);
 811     ctx.lineTo(width, margin);
 812     ctx.stroke();
 813     if (this.iePanOverlay_) {
 814       this.iePanOverlay_.style.display = 'none';
 815     }
 816   } else {
 817     var leftHandleCanvasPos = Math.max(margin, zoomHandleStatus.leftHandlePos - this.canvasRect_.x);
 818     var rightHandleCanvasPos = Math.min(width, zoomHandleStatus.rightHandlePos - this.canvasRect_.x);
 819
 820     ctx.fillStyle = 'rgba(240, 240, 240, 0.6)';
 821     ctx.fillRect(0, 0, leftHandleCanvasPos, this.canvasRect_.h);
 822     ctx.fillRect(rightHandleCanvasPos, 0, this.canvasRect_.w - rightHandleCanvasPos, this.canvasRect_.h);
 823
 824     ctx.beginPath();
 825     ctx.moveTo(margin, margin);
 826     ctx.lineTo(leftHandleCanvasPos, margin);
 827     ctx.lineTo(leftHandleCanvasPos, height);
 828     ctx.lineTo(rightHandleCanvasPos, height);
 829     ctx.lineTo(rightHandleCanvasPos, margin);
 830     ctx.lineTo(width, margin);
 831     ctx.stroke();
 832
 833     if (this.isUsingExcanvas_) {
 834       this.iePanOverlay_.style.width = (rightHandleCanvasPos - leftHandleCanvasPos) + 'px';
 835       this.iePanOverlay_.style.left = leftHandleCanvasPos + 'px';
 836       this.iePanOverlay_.style.height = height + 'px';
 837       this.iePanOverlay_.style.display = 'inline';
 838     }
 839   }
 840 };
 841
 842 /**
 843  * @private
 844  * Returns the current zoom handle position information.
 845  * @return {Object} The zoom handle status.
 846  */
 847 rangeSelector.prototype.getZoomHandleStatus_ = function() {
 848   var halfHandleWidth = this.leftZoomHandle_.width/2;
 849   var leftHandlePos = parseInt(this.leftZoomHandle_.style.left, 10) + halfHandleWidth;
 850   var rightHandlePos = parseInt(this.rightZoomHandle_.style.left, 10) + halfHandleWidth;
 851   return {
 852       leftHandlePos: leftHandlePos,
 853       rightHandlePos: rightHandlePos,
 854       isZoomed: (leftHandlePos - 1 > this.canvasRect_.x || rightHandlePos + 1 < this.canvasRect_.x+this.canvasRect_.w)
 855   };
 856 };
 857
 858 return rangeSelector;
 859
 860 })();