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 clientXLast = 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;
 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   onZoomStart = function(e) {
 295     Dygraph.cancelEvent(e);
 296     isZooming = true;
 297     clientXLast = e.clientX;
 298     handle = e.target ? e.target : e.srcElement;
 299     if (e.type === 'mousedown' || e.type === 'dragstart') {
 300       // These events are removed manually.
 301       Dygraph.addEvent(topElem, 'mousemove', onZoom);
 302       Dygraph.addEvent(topElem, 'mouseup', onZoomEnd);
 303     }
 304     self.fgcanvas_.style.cursor = 'col-resize';
 305     tarp.cover();
 306     return true;
 307   };
 308
 309   onZoom = function(e) {
 310     if (!isZooming) {
 311       return false;
 312     }
 313     Dygraph.cancelEvent(e);
 314
 315     var delX = e.clientX - clientXLast;
 316     if (Math.abs(delX) < 4) {
 317       return true;
 318     }
 319     clientXLast = e.clientX;
 320
 321     // Move handle.
 322     var zoomHandleStatus = self.getZoomHandleStatus_();
 323     var newPos;
 324     if (handle == self.leftZoomHandle_) {
 325       newPos = zoomHandleStatus.leftHandlePos + delX;
 326       newPos = Math.min(newPos, zoomHandleStatus.rightHandlePos - handle.width - 3);
 327       newPos = Math.max(newPos, self.canvasRect_.x);
 328     } else {
 329       newPos = zoomHandleStatus.rightHandlePos + delX;
 330       newPos = Math.min(newPos, self.canvasRect_.x + self.canvasRect_.w);
 331       newPos = Math.max(newPos, zoomHandleStatus.leftHandlePos + handle.width + 3);
 332     }
 333     var halfHandleWidth = handle.width/2;
 334     handle.style.left = (newPos - halfHandleWidth) + 'px';
 335     self.drawInteractiveLayer_();
 336
 337     // Zoom on the fly (if not using excanvas).
 338     if (dynamic) {
 339       doZoom();
 340     }
 341     return true;
 342   };
 343
 344   onZoomEnd = function(e) {
 345     if (!isZooming) {
 346       return false;
 347     }
 348     isZooming = false;
 349     tarp.uncover();
 350     Dygraph.removeEvent(topElem, 'mousemove', onZoom);
 351     Dygraph.removeEvent(topElem, 'mouseup', onZoomEnd);
 352     self.fgcanvas_.style.cursor = 'default';
 353
 354     // If using excanvas, Zoom now.
 355     if (!dynamic) {
 356       doZoom();
 357     }
 358     return true;
 359   };
 360
 361   doZoom = function() {
 362     try {
 363       var zoomHandleStatus = self.getZoomHandleStatus_();
 364       self.isChangingRange_ = true;
 365       if (!zoomHandleStatus.isZoomed) {
 366         self.dygraph_.resetZoom();
 367       } else {
 368         var xDataWindow = toXDataWindow(zoomHandleStatus);
 369         self.dygraph_.doZoomXDates_(xDataWindow[0], xDataWindow[1]);
 370       }
 371     } finally {
 372       self.isChangingRange_ = false;
 373     }
 374   };
 375
 376   isMouseInPanZone = function(e) {
 377     if (self.isUsingExcanvas_) {
 378         return e.srcElement == self.iePanOverlay_;
 379     } else {
 380       var rect = self.leftZoomHandle_.getBoundingClientRect();
 381       var leftHandleClientX = rect.left + rect.width/2;
 382       rect = self.rightZoomHandle_.getBoundingClientRect();
 383       var rightHandleClientX = rect.left + rect.width/2;
 384       return (e.clientX > leftHandleClientX && e.clientX < rightHandleClientX);
 385     }
 386   };
 387
 388   onPanStart = function(e) {
 389     if (!isPanning && isMouseInPanZone(e) && self.getZoomHandleStatus_().isZoomed) {
 390       Dygraph.cancelEvent(e);
 391       isPanning = true;
 392       clientXLast = e.clientX;
 393       if (e.type === 'mousedown') {
 394         // These events are removed manually.
 395         Dygraph.addEvent(topElem, 'mousemove', onPan);
 396         Dygraph.addEvent(topElem, 'mouseup', onPanEnd);
 397       }
 398       return true;
 399     }
 400     return false;
 401   };
 402
 403   onPan = function(e) {
 404     if (!isPanning) {
 405       return false;
 406     }
 407     Dygraph.cancelEvent(e);
 408
 409     var delX = e.clientX - clientXLast;
 410     if (Math.abs(delX) < 4) {
 411       return true;
 412     }
 413     clientXLast = e.clientX;
 414
 415     // Move range view
 416     var zoomHandleStatus = self.getZoomHandleStatus_();
 417     var leftHandlePos = zoomHandleStatus.leftHandlePos;
 418     var rightHandlePos = zoomHandleStatus.rightHandlePos;
 419     var rangeSize = rightHandlePos - leftHandlePos;
 420     if (leftHandlePos + delX <= self.canvasRect_.x) {
 421       leftHandlePos = self.canvasRect_.x;
 422       rightHandlePos = leftHandlePos + rangeSize;
 423     } else if (rightHandlePos + delX >= self.canvasRect_.x + self.canvasRect_.w) {
 424       rightHandlePos = self.canvasRect_.x + self.canvasRect_.w;
 425       leftHandlePos = rightHandlePos - rangeSize;
 426     } else {
 427       leftHandlePos += delX;
 428       rightHandlePos += delX;
 429     }
 430     var halfHandleWidth = self.leftZoomHandle_.width/2;
 431     self.leftZoomHandle_.style.left = (leftHandlePos - halfHandleWidth) + 'px';
 432     self.rightZoomHandle_.style.left = (rightHandlePos - halfHandleWidth) + 'px';
 433     self.drawInteractiveLayer_();
 434
 435     // Do pan on the fly (if not using excanvas).
 436     if (dynamic) {
 437       doPan();
 438     }
 439     return true;
 440   };
 441
 442   onPanEnd = function(e) {
 443     if (!isPanning) {
 444       return false;
 445     }
 446     isPanning = false;
 447     Dygraph.removeEvent(topElem, 'mousemove', onPan);
 448     Dygraph.removeEvent(topElem, 'mouseup', onPanEnd);
 449     // If using excanvas, do pan now.
 450     if (!dynamic) {
 451       doPan();
 452     }
 453     return true;
 454   };
 455
 456   doPan = function() {
 457     try {
 458       self.isChangingRange_ = true;
 459       self.dygraph_.dateWindow_ = toXDataWindow(self.getZoomHandleStatus_());
 460       self.dygraph_.drawGraph_(false);
 461     } finally {
 462       self.isChangingRange_ = false;
 463     }
 464   };
 465
 466   onCanvasHover = function(e) {
 467     if (isZooming || isPanning) {
 468       return;
 469     }
 470     var cursor = isMouseInPanZone(e) ? 'move' : 'default';
 471     if (cursor != self.fgcanvas_.style.cursor) {
 472       self.fgcanvas_.style.cursor = cursor;
 473     }
 474   };
 475
 476   onZoomHandleTouchEvent = function(e) {
 477     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 478       if (onZoomStart(e.targetTouches[0])) {
 479         Dygraph.cancelEvent(e);
 480       }
 481     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 482       if (onZoom(e.targetTouches[0])) {
 483         Dygraph.cancelEvent(e);
 484       }
 485     } else {
 486       onZoomEnd(e);
 487     }
 488   };
 489
 490   onCanvasTouchEvent = function(e) {
 491     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 492       if (onPanStart(e.targetTouches[0])) {
 493         Dygraph.cancelEvent(e);
 494       }
 495     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 496       if (onPan(e.targetTouches[0])) {
 497         Dygraph.cancelEvent(e);
 498       }
 499     } else {
 500       onPanEnd(e);
 501     }
 502   };
 503
 504   addTouchEvents = function(elem, fn) {
 505     var types = ['touchstart', 'touchend', 'touchmove', 'touchcancel'];
 506     for (var i = 0; i < types.length; i++) {
 507       self.dygraph_.addAndTrackEvent(elem, types[i], fn);
 508     }
 509   };
 510
 511   this.setDefaultOption_('interactionModel', Dygraph.Interaction.dragIsPanInteractionModel);
 512   this.setDefaultOption_('panEdgeFraction', 0.0001);
 513
 514   var dragStartEvent = window.opera ? 'mousedown' : 'dragstart';
 515   this.dygraph_.addAndTrackEvent(this.leftZoomHandle_, dragStartEvent, onZoomStart);
 516   this.dygraph_.addAndTrackEvent(this.rightZoomHandle_, dragStartEvent, onZoomStart);
 517
 518   if (this.isUsingExcanvas_) {
 519     this.dygraph_.addAndTrackEvent(this.iePanOverlay_, 'mousedown', onPanStart);
 520   } else {
 521     this.dygraph_.addAndTrackEvent(this.fgcanvas_, 'mousedown', onPanStart);
 522     this.dygraph_.addAndTrackEvent(this.fgcanvas_, 'mousemove', onCanvasHover);
 523   }
 524
 525   // Touch events
 526   if (this.hasTouchInterface_) {
 527     addTouchEvents(this.leftZoomHandle_, onZoomHandleTouchEvent);
 528     addTouchEvents(this.rightZoomHandle_, onZoomHandleTouchEvent);
 529     addTouchEvents(this.fgcanvas_, onCanvasTouchEvent);
 530   }
 531 };
 532
 533 /**
 534  * @private
 535  * Draws the static layer in the background canvas.
 536  */
 537 rangeSelector.prototype.drawStaticLayer_ = function() {
 538   var ctx = this.bgcanvas_ctx_;
 539   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 540   try {
 541     this.drawMiniPlot_();
 542   } catch(ex) {
 543     Dygraph.warn(ex);
 544   }
 545
 546   var margin = 0.5;
 547   this.bgcanvas_ctx_.lineWidth = 1;
 548   ctx.strokeStyle = 'gray';
 549   ctx.beginPath();
 550   ctx.moveTo(margin, margin);
 551   ctx.lineTo(margin, this.canvasRect_.h-margin);
 552   ctx.lineTo(this.canvasRect_.w-margin, this.canvasRect_.h-margin);
 553   ctx.lineTo(this.canvasRect_.w-margin, margin);
 554   ctx.stroke();
 555 };
 556
 557
 558 /**
 559  * @private
 560  * Draws the mini plot in the background canvas.
 561  */
 562 rangeSelector.prototype.drawMiniPlot_ = function() {
 563   var fillStyle = this.getOption_('rangeSelectorPlotFillColor');
 564   var strokeStyle = this.getOption_('rangeSelectorPlotStrokeColor');
 565   if (!fillStyle && !strokeStyle) {
 566     return;
 567   }
 568
 569   var stepPlot = this.getOption_('stepPlot');
 570
 571   var combinedSeriesData = this.computeCombinedSeriesAndLimits_();
 572   var yRange = combinedSeriesData.yMax - combinedSeriesData.yMin;
 573
 574   // Draw the mini plot.
 575   var ctx = this.bgcanvas_ctx_;
 576   var margin = 0.5;
 577
 578   var xExtremes = this.dygraph_.xAxisExtremes();
 579   var xRange = Math.max(xExtremes[1] - xExtremes[0], 1.e-30);
 580   var xFact = (this.canvasRect_.w - margin)/xRange;
 581   var yFact = (this.canvasRect_.h - margin)/yRange;
 582   var canvasWidth = this.canvasRect_.w - margin;
 583   var canvasHeight = this.canvasRect_.h - margin;
 584
 585   var prevX = null, prevY = null;
 586
 587   ctx.beginPath();
 588   ctx.moveTo(margin, canvasHeight);
 589   for (var i = 0; i < combinedSeriesData.data.length; i++) {
 590     var dataPoint = combinedSeriesData.data[i];
 591     var x = ((dataPoint[0] !== null) ? ((dataPoint[0] - xExtremes[0])*xFact) : NaN);
 592     var y = ((dataPoint[1] !== null) ? (canvasHeight - (dataPoint[1] - combinedSeriesData.yMin)*yFact) : NaN);
 593     if (isFinite(x) && isFinite(y)) {
 594       if(prevX === null) {
 595         ctx.lineTo(x, canvasHeight);
 596       }
 597       else if (stepPlot) {
 598         ctx.lineTo(x, prevY);
 599       }
 600       ctx.lineTo(x, y);
 601       prevX = x;
 602       prevY = y;
 603     }
 604     else {
 605       if(prevX !== null) {
 606         if (stepPlot) {
 607           ctx.lineTo(x, prevY);
 608           ctx.lineTo(x, canvasHeight);
 609         }
 610         else {
 611           ctx.lineTo(prevX, canvasHeight);
 612         }
 613       }
 614       prevX = prevY = null;
 615     }
 616   }
 617   ctx.lineTo(canvasWidth, canvasHeight);
 618   ctx.closePath();
 619
 620   if (fillStyle) {
 621     var lingrad = this.bgcanvas_ctx_.createLinearGradient(0, 0, 0, canvasHeight);
 622     lingrad.addColorStop(0, 'white');
 623     lingrad.addColorStop(1, fillStyle);
 624     this.bgcanvas_ctx_.fillStyle = lingrad;
 625     ctx.fill();
 626   }
 627
 628   if (strokeStyle) {
 629     this.bgcanvas_ctx_.strokeStyle = strokeStyle;
 630     this.bgcanvas_ctx_.lineWidth = 1.5;
 631     ctx.stroke();
 632   }
 633 };
 634
 635 /**
 636  * @private
 637  * Computes and returns the combinded series data along with min/max for the mini plot.
 638  * @return {Object} An object containing combinded series array, ymin, ymax.
 639  */
 640 rangeSelector.prototype.computeCombinedSeriesAndLimits_ = function() {
 641   var data = this.dygraph_.rawData_;
 642   var logscale = this.getOption_('logscale');
 643
 644   // Create a combined series (average of all series values).
 645   var combinedSeries = [];
 646   var sum;
 647   var count;
 648   var mutipleValues;
 649   var i, j, k;
 650   var xVal, yVal;
 651
 652   // Find out if data has multiple values per datapoint.
 653   // Go to first data point that actually has values (see http://code.google.com/p/dygraphs/issues/detail?id=246)
 654   for (i = 0; i < data.length; i++) {
 655     if (data[i].length > 1 && data[i][1] !== null) {
 656       mutipleValues = typeof data[i][1] != 'number';
 657       if (mutipleValues) {
 658         sum = [];
 659         count = [];
 660         for (k = 0; k < data[i][1].length; k++) {
 661           sum.push(0);
 662           count.push(0);
 663         }
 664       }
 665       break;
 666     }
 667   }
 668
 669   for (i = 0; i < data.length; i++) {
 670     var dataPoint = data[i];
 671     xVal = dataPoint[0];
 672
 673     if (mutipleValues) {
 674       for (k = 0; k < sum.length; k++) {
 675         sum[k] = count[k] = 0;
 676       }
 677     } else {
 678       sum = count = 0;
 679     }
 680
 681     for (j = 1; j < dataPoint.length; j++) {
 682       if (this.dygraph_.visibility()[j-1]) {
 683         var y;
 684         if (mutipleValues) {
 685           for (k = 0; k < sum.length; k++) {
 686             y = dataPoint[j][k];
 687             if (y === null || isNaN(y)) continue;
 688             sum[k] += y;
 689             count[k]++;
 690           }
 691         } else {
 692           y = dataPoint[j];
 693           if (y === null || isNaN(y)) continue;
 694           sum += y;
 695           count++;
 696         }
 697       }
 698     }
 699
 700     if (mutipleValues) {
 701       for (k = 0; k < sum.length; k++) {
 702         sum[k] /= count[k];
 703       }
 704       yVal = sum.slice(0);
 705     } else {
 706       yVal = sum/count;
 707     }
 708
 709     combinedSeries.push([xVal, yVal]);
 710   }
 711
 712   // Account for roll period, fractions.
 713   combinedSeries = this.dygraph_.rollingAverage(combinedSeries, this.dygraph_.rollPeriod_);
 714
 715   if (typeof combinedSeries[0][1] != 'number') {
 716     for (i = 0; i < combinedSeries.length; i++) {
 717       yVal = combinedSeries[i][1];
 718       combinedSeries[i][1] = yVal[0];
 719     }
 720   }
 721
 722   // Compute the y range.
 723   var yMin = Number.MAX_VALUE;
 724   var yMax = -Number.MAX_VALUE;
 725   for (i = 0; i < combinedSeries.length; i++) {
 726     yVal = combinedSeries[i][1];
 727     if (yVal !== null && isFinite(yVal) && (!logscale || yVal > 0)) {
 728       yMin = Math.min(yMin, yVal);
 729       yMax = Math.max(yMax, yVal);
 730     }
 731   }
 732
 733   // Convert Y data to log scale if needed.
 734   // Also, expand the Y range to compress the mini plot a little.
 735   var extraPercent = 0.25;
 736   if (logscale) {
 737     yMax = Dygraph.log10(yMax);
 738     yMax += yMax*extraPercent;
 739     yMin = Dygraph.log10(yMin);
 740     for (i = 0; i < combinedSeries.length; i++) {
 741       combinedSeries[i][1] = Dygraph.log10(combinedSeries[i][1]);
 742     }
 743   } else {
 744     var yExtra;
 745     var yRange = yMax - yMin;
 746     if (yRange <= Number.MIN_VALUE) {
 747       yExtra = yMax*extraPercent;
 748     } else {
 749       yExtra = yRange*extraPercent;
 750     }
 751     yMax += yExtra;
 752     yMin -= yExtra;
 753   }
 754
 755   return {data: combinedSeries, yMin: yMin, yMax: yMax};
 756 };
 757
 758 /**
 759  * @private
 760  * Places the zoom handles in the proper position based on the current X data window.
 761  */
 762 rangeSelector.prototype.placeZoomHandles_ = function() {
 763   var xExtremes = this.dygraph_.xAxisExtremes();
 764   var xWindowLimits = this.dygraph_.xAxisRange();
 765   var xRange = xExtremes[1] - xExtremes[0];
 766   var leftPercent = Math.max(0, (xWindowLimits[0] - xExtremes[0])/xRange);
 767   var rightPercent = Math.max(0, (xExtremes[1] - xWindowLimits[1])/xRange);
 768   var leftCoord = this.canvasRect_.x + this.canvasRect_.w*leftPercent;
 769   var rightCoord = this.canvasRect_.x + this.canvasRect_.w*(1 - rightPercent);
 770   var handleTop = Math.max(this.canvasRect_.y, this.canvasRect_.y + (this.canvasRect_.h - this.leftZoomHandle_.height)/2);
 771   var halfHandleWidth = this.leftZoomHandle_.width/2;
 772   this.leftZoomHandle_.style.left = (leftCoord - halfHandleWidth) + 'px';
 773   this.leftZoomHandle_.style.top = handleTop + 'px';
 774   this.rightZoomHandle_.style.left = (rightCoord - halfHandleWidth) + 'px';
 775   this.rightZoomHandle_.style.top = this.leftZoomHandle_.style.top;
 776
 777   this.leftZoomHandle_.style.visibility = 'visible';
 778   this.rightZoomHandle_.style.visibility = 'visible';
 779 };
 780
 781 /**
 782  * @private
 783  * Draws the interactive layer in the foreground canvas.
 784  */
 785 rangeSelector.prototype.drawInteractiveLayer_ = function() {
 786   var ctx = this.fgcanvas_ctx_;
 787   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 788   var margin = 1;
 789   var width = this.canvasRect_.w - margin;
 790   var height = this.canvasRect_.h - margin;
 791   var zoomHandleStatus = this.getZoomHandleStatus_();
 792
 793   ctx.strokeStyle = 'black';
 794   if (!zoomHandleStatus.isZoomed) {
 795     ctx.beginPath();
 796     ctx.moveTo(margin, margin);
 797     ctx.lineTo(margin, height);
 798     ctx.lineTo(width, height);
 799     ctx.lineTo(width, margin);
 800     ctx.stroke();
 801     if (this.iePanOverlay_) {
 802       this.iePanOverlay_.style.display = 'none';
 803     }
 804   } else {
 805     var leftHandleCanvasPos = Math.max(margin, zoomHandleStatus.leftHandlePos - this.canvasRect_.x);
 806     var rightHandleCanvasPos = Math.min(width, zoomHandleStatus.rightHandlePos - this.canvasRect_.x);
 807
 808     ctx.fillStyle = 'rgba(240, 240, 240, 0.6)';
 809     ctx.fillRect(0, 0, leftHandleCanvasPos, this.canvasRect_.h);
 810     ctx.fillRect(rightHandleCanvasPos, 0, this.canvasRect_.w - rightHandleCanvasPos, this.canvasRect_.h);
 811
 812     ctx.beginPath();
 813     ctx.moveTo(margin, margin);
 814     ctx.lineTo(leftHandleCanvasPos, margin);
 815     ctx.lineTo(leftHandleCanvasPos, height);
 816     ctx.lineTo(rightHandleCanvasPos, height);
 817     ctx.lineTo(rightHandleCanvasPos, margin);
 818     ctx.lineTo(width, margin);
 819     ctx.stroke();
 820
 821     if (this.isUsingExcanvas_) {
 822       this.iePanOverlay_.style.width = (rightHandleCanvasPos - leftHandleCanvasPos) + 'px';
 823       this.iePanOverlay_.style.left = leftHandleCanvasPos + 'px';
 824       this.iePanOverlay_.style.height = height + 'px';
 825       this.iePanOverlay_.style.display = 'inline';
 826     }
 827   }
 828 };
 829
 830 /**
 831  * @private
 832  * Returns the current zoom handle position information.
 833  * @return {Object} The zoom handle status.
 834  */
 835 rangeSelector.prototype.getZoomHandleStatus_ = function() {
 836   var halfHandleWidth = this.leftZoomHandle_.width/2;
 837   var leftHandlePos = parseFloat(this.leftZoomHandle_.style.left) + halfHandleWidth;
 838   var rightHandlePos = parseFloat(this.rightZoomHandle_.style.left) + halfHandleWidth;
 839   return {
 840       leftHandlePos: leftHandlePos,
 841       rightHandlePos: rightHandlePos,
 842       isZoomed: (leftHandlePos - 1 > this.canvasRect_.x || rightHandlePos + 1 < this.canvasRect_.x+this.canvasRect_.w)
 843   };
 844 };
 845
 846 return rangeSelector;
 847
 848 })();