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 xLast = 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, onCanvasMouseMove, applyBrowserZoomLevel;
 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   applyBrowserZoomLevel = function(delX) {
 295     var zoom = window.outerWidth/document.documentElement.clientWidth;
 296     if (!isNaN(zoom)) {
 297       return delX/zoom;
 298     } else {
 299       return delX;
 300     }
 301   };
 302
 303   onZoomStart = function(e) {
 304     Dygraph.cancelEvent(e);
 305     isZooming = true;
 306     xLast = e.screenX;
 307     handle = e.target ? e.target : e.srcElement;
 308     self.dygraph_.addEvent(topElem, 'mousemove', onZoom);
 309     self.dygraph_.addEvent(topElem, 'mouseup', onZoomEnd);
 310     self.fgcanvas_.style.cursor = 'col-resize';
 311     tarp.cover();
 312     return true;
 313   };
 314
 315   onZoom = function(e) {
 316     if (!isZooming) {
 317       return false;
 318     }
 319     Dygraph.cancelEvent(e);
 320     var delX = e.screenX - xLast;
 321     if (Math.abs(delX) < 4 || e.screenX === 0) {
 322       // First iPad move event seems to have screenX = 0
 323       return true;
 324     }
 325     xLast = e.screenX;
 326     delX = applyBrowserZoomLevel(delX);
 327
 328     // Move handle.
 329     var zoomHandleStatus = self.getZoomHandleStatus_();
 330     var newPos;
 331     if (handle == self.leftZoomHandle_) {
 332       newPos = zoomHandleStatus.leftHandlePos + delX;
 333       newPos = Math.min(newPos, zoomHandleStatus.rightHandlePos - handle.width - 3);
 334       newPos = Math.max(newPos, self.canvasRect_.x);
 335     } else {
 336       newPos = zoomHandleStatus.rightHandlePos + delX;
 337       newPos = Math.min(newPos, self.canvasRect_.x + self.canvasRect_.w);
 338       newPos = Math.max(newPos, zoomHandleStatus.leftHandlePos + handle.width + 3);
 339     }
 340     var halfHandleWidth = handle.width/2;
 341     handle.style.left = (newPos - halfHandleWidth) + 'px';
 342     self.drawInteractiveLayer_();
 343
 344     // Zoom on the fly (if not using excanvas).
 345     if (dynamic) {
 346       doZoom();
 347     }
 348     return true;
 349   };
 350
 351   onZoomEnd = function(e) {
 352     if (!isZooming) {
 353       return false;
 354     }
 355     isZooming = false;
 356     tarp.uncover();
 357     Dygraph.removeEvent(topElem, 'mousemove', onZoom);
 358     Dygraph.removeEvent(topElem, 'mouseup', onZoomEnd);
 359     self.fgcanvas_.style.cursor = 'default';
 360
 361     // If using excanvas, Zoom now.
 362     if (!dynamic) {
 363       doZoom();
 364     }
 365     return true;
 366   };
 367
 368   doZoom = function() {
 369     try {
 370       var zoomHandleStatus = self.getZoomHandleStatus_();
 371       self.isChangingRange_ = true;
 372       if (!zoomHandleStatus.isZoomed) {
 373         self.dygraph_.resetZoom();
 374       } else {
 375         var xDataWindow = toXDataWindow(zoomHandleStatus);
 376         self.dygraph_.doZoomXDates_(xDataWindow[0], xDataWindow[1]);
 377       }
 378     } finally {
 379       self.isChangingRange_ = false;
 380     }
 381   };
 382
 383   isMouseInPanZone = function(e) {
 384     if (self.isUsingExcanvas_) {
 385         return e.srcElement == self.iePanOverlay_;
 386     } else {
 387       var rect = self.leftZoomHandle_.getBoundingClientRect();
 388       var leftHandleClientX = rect.left + rect.width/2;
 389       rect = self.rightZoomHandle_.getBoundingClientRect();
 390       var rightHandleClientX = rect.left + rect.width/2;
 391       return (e.clientX > leftHandleClientX && e.clientX < rightHandleClientX);
 392     }
 393   };
 394
 395   onPanStart = function(e) {
 396     if (!isPanning && isMouseInPanZone(e) && self.getZoomHandleStatus_().isZoomed) {
 397       Dygraph.cancelEvent(e);
 398       isPanning = true;
 399       xLast = e.screenX;
 400       self.dygraph_.addEvent(topElem, 'mousemove', onPan);
 401       self.dygraph_.addEvent(topElem, 'mouseup', onPanEnd);
 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.screenX - xLast;
 414     if (Math.abs(delX) < 4) {
 415       return true;
 416     }
 417     xLast = e.screenX;
 418     delX = applyBrowserZoomLevel(delX);
 419
 420     // Move range view
 421     var zoomHandleStatus = self.getZoomHandleStatus_();
 422     var leftHandlePos = zoomHandleStatus.leftHandlePos;
 423     var rightHandlePos = zoomHandleStatus.rightHandlePos;
 424     var rangeSize = rightHandlePos - leftHandlePos;
 425     if (leftHandlePos + delX <= self.canvasRect_.x) {
 426       leftHandlePos = self.canvasRect_.x;
 427       rightHandlePos = leftHandlePos + rangeSize;
 428     } else if (rightHandlePos + delX >= self.canvasRect_.x + self.canvasRect_.w) {
 429       rightHandlePos = self.canvasRect_.x + self.canvasRect_.w;
 430       leftHandlePos = rightHandlePos - rangeSize;
 431     } else {
 432       leftHandlePos += delX;
 433       rightHandlePos += delX;
 434     }
 435     var halfHandleWidth = self.leftZoomHandle_.width/2;
 436     self.leftZoomHandle_.style.left = (leftHandlePos - halfHandleWidth) + 'px';
 437     self.rightZoomHandle_.style.left = (rightHandlePos - halfHandleWidth) + 'px';
 438     self.drawInteractiveLayer_();
 439
 440     // Do pan on the fly (if not using excanvas).
 441     if (dynamic) {
 442       doPan();
 443     }
 444     return true;
 445   };
 446
 447   onPanEnd = function(e) {
 448     if (!isPanning) {
 449       return false;
 450     }
 451     isPanning = false;
 452     Dygraph.removeEvent(topElem, 'mousemove', onPan);
 453     Dygraph.removeEvent(topElem, 'mouseup', onPanEnd);
 454     // If using excanvas, do pan now.
 455     if (!dynamic) {
 456       doPan();
 457     }
 458     return true;
 459   };
 460
 461   doPan = function() {
 462     try {
 463       self.isChangingRange_ = true;
 464       self.dygraph_.dateWindow_ = toXDataWindow(self.getZoomHandleStatus_());
 465       self.dygraph_.drawGraph_(false);
 466     } finally {
 467       self.isChangingRange_ = false;
 468     }
 469   };
 470
 471   onCanvasMouseMove = function(e) {
 472     if (isZooming || isPanning) {
 473       return;
 474     }
 475     var cursor = isMouseInPanZone(e) ? 'move' : 'default';
 476     if (cursor != self.fgcanvas_.style.cursor) {
 477       self.fgcanvas_.style.cursor = cursor;
 478     }
 479   };
 480
 481   onZoomHandleTouchEvent = function(e) {
 482     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 483       if (onZoomStart(e.targetTouches[0])) {
 484         Dygraph.cancelEvent(e);
 485       }
 486     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 487       if (onZoom(e.targetTouches[0])) {
 488         Dygraph.cancelEvent(e);
 489       }
 490     } else {
 491       onZoomEnd(e);
 492     }
 493   };
 494
 495   onCanvasTouchEvent = function(e) {
 496     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 497       if (onPanStart(e.targetTouches[0])) {
 498         Dygraph.cancelEvent(e);
 499       }
 500     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 501       if (onPan(e.targetTouches[0])) {
 502         Dygraph.cancelEvent(e);
 503       }
 504     } else {
 505       onPanEnd(e);
 506     }
 507   };
 508
 509   addTouchEvents = function(elem, fn) {
 510     var types = ['touchstart', 'touchend', 'touchmove', 'touchcancel'];
 511     for (var i = 0; i < types.length; i++) {
 512       self.dygraph_.addEvent(elem, types[i], fn);
 513     }
 514   };
 515
 516   this.setDefaultOption_('interactionModel', Dygraph.Interaction.dragIsPanInteractionModel);
 517   this.setDefaultOption_('panEdgeFraction', 0.0001);
 518
 519   var dragStartEvent = window.opera ? 'mousedown' : 'dragstart';
 520   this.dygraph_.addEvent(this.leftZoomHandle_, dragStartEvent, onZoomStart);
 521   this.dygraph_.addEvent(this.rightZoomHandle_, dragStartEvent, onZoomStart);
 522
 523   if (this.isUsingExcanvas_) {
 524     this.dygraph_.addEvent(this.iePanOverlay_, 'mousedown', onPanStart);
 525   } else {
 526     this.dygraph_.addEvent(this.fgcanvas_, 'mousedown', onPanStart);
 527     this.dygraph_.addEvent(this.fgcanvas_, 'mousemove', onCanvasMouseMove);
 528   }
 529
 530   // Touch events
 531   if (this.hasTouchInterface_) {
 532     addTouchEvents(this.leftZoomHandle_, onZoomHandleTouchEvent);
 533     addTouchEvents(this.rightZoomHandle_, onZoomHandleTouchEvent);
 534     addTouchEvents(this.fgcanvas_, onCanvasTouchEvent);
 535   }
 536 };
 537
 538 /**
 539  * @private
 540  * Draws the static layer in the background canvas.
 541  */
 542 rangeSelector.prototype.drawStaticLayer_ = function() {
 543   var ctx = this.bgcanvas_ctx_;
 544   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 545   try {
 546     this.drawMiniPlot_();
 547   } catch(ex) {
 548     Dygraph.warn(ex);
 549   }
 550
 551   var margin = 0.5;
 552   this.bgcanvas_ctx_.lineWidth = 1;
 553   ctx.strokeStyle = 'gray';
 554   ctx.beginPath();
 555   ctx.moveTo(margin, margin);
 556   ctx.lineTo(margin, this.canvasRect_.h-margin);
 557   ctx.lineTo(this.canvasRect_.w-margin, this.canvasRect_.h-margin);
 558   ctx.lineTo(this.canvasRect_.w-margin, margin);
 559   ctx.stroke();
 560 };
 561
 562
 563 /**
 564  * @private
 565  * Draws the mini plot in the background canvas.
 566  */
 567 rangeSelector.prototype.drawMiniPlot_ = function() {
 568   var fillStyle = this.getOption_('rangeSelectorPlotFillColor');
 569   var strokeStyle = this.getOption_('rangeSelectorPlotStrokeColor');
 570   if (!fillStyle && !strokeStyle) {
 571     return;
 572   }
 573
 574   var stepPlot = this.getOption_('stepPlot');
 575
 576   var combinedSeriesData = this.computeCombinedSeriesAndLimits_();
 577   var yRange = combinedSeriesData.yMax - combinedSeriesData.yMin;
 578
 579   // Draw the mini plot.
 580   var ctx = this.bgcanvas_ctx_;
 581   var margin = 0.5;
 582
 583   var xExtremes = this.dygraph_.xAxisExtremes();
 584   var xRange = Math.max(xExtremes[1] - xExtremes[0], 1.e-30);
 585   var xFact = (this.canvasRect_.w - margin)/xRange;
 586   var yFact = (this.canvasRect_.h - margin)/yRange;
 587   var canvasWidth = this.canvasRect_.w - margin;
 588   var canvasHeight = this.canvasRect_.h - margin;
 589
 590   var prevX = null, prevY = null;
 591
 592   ctx.beginPath();
 593   ctx.moveTo(margin, canvasHeight);
 594   for (var i = 0; i < combinedSeriesData.data.length; i++) {
 595     var dataPoint = combinedSeriesData.data[i];
 596     var x = ((dataPoint[0] !== null) ? ((dataPoint[0] - xExtremes[0])*xFact) : NaN);
 597     var y = ((dataPoint[1] !== null) ? (canvasHeight - (dataPoint[1] - combinedSeriesData.yMin)*yFact) : NaN);
 598     if (isFinite(x) && isFinite(y)) {
 599       if(prevX === null) {
 600         ctx.lineTo(x, canvasHeight);
 601       }
 602       else if (stepPlot) {
 603         ctx.lineTo(x, prevY);
 604       }
 605       ctx.lineTo(x, y);
 606       prevX = x;
 607       prevY = y;
 608     }
 609     else {
 610       if(prevX !== null) {
 611         if (stepPlot) {
 612           ctx.lineTo(x, prevY);
 613           ctx.lineTo(x, canvasHeight);
 614         }
 615         else {
 616           ctx.lineTo(prevX, canvasHeight);
 617         }
 618       }
 619       prevX = prevY = null;
 620     }
 621   }
 622   ctx.lineTo(canvasWidth, canvasHeight);
 623   ctx.closePath();
 624
 625   if (fillStyle) {
 626     var lingrad = this.bgcanvas_ctx_.createLinearGradient(0, 0, 0, canvasHeight);
 627     lingrad.addColorStop(0, 'white');
 628     lingrad.addColorStop(1, fillStyle);
 629     this.bgcanvas_ctx_.fillStyle = lingrad;
 630     ctx.fill();
 631   }
 632
 633   if (strokeStyle) {
 634     this.bgcanvas_ctx_.strokeStyle = strokeStyle;
 635     this.bgcanvas_ctx_.lineWidth = 1.5;
 636     ctx.stroke();
 637   }
 638 };
 639
 640 /**
 641  * @private
 642  * Computes and returns the combinded series data along with min/max for the mini plot.
 643  * @return {Object} An object containing combinded series array, ymin, ymax.
 644  */
 645 rangeSelector.prototype.computeCombinedSeriesAndLimits_ = function() {
 646   var data = this.dygraph_.rawData_;
 647   var logscale = this.getOption_('logscale');
 648
 649   // Create a combined series (average of all series values).
 650   var combinedSeries = [];
 651   var sum;
 652   var count;
 653   var mutipleValues;
 654   var i, j, k;
 655   var xVal, yVal;
 656
 657   // Find out if data has multiple values per datapoint.
 658   // Go to first data point that actually has values (see http://code.google.com/p/dygraphs/issues/detail?id=246)
 659   for (i = 0; i < data.length; i++) {
 660     if (data[i].length > 1 && data[i][1] !== null) {
 661       mutipleValues = typeof data[i][1] != 'number';
 662       if (mutipleValues) {
 663         sum = [];
 664         count = [];
 665         for (k = 0; k < data[i][1].length; k++) {
 666           sum.push(0);
 667           count.push(0);
 668         }
 669       }
 670       break;
 671     }
 672   }
 673
 674   for (i = 0; i < data.length; i++) {
 675     var dataPoint = data[i];
 676     xVal = dataPoint[0];
 677
 678     if (mutipleValues) {
 679       for (k = 0; k < sum.length; k++) {
 680         sum[k] = count[k] = 0;
 681       }
 682     } else {
 683       sum = count = 0;
 684     }
 685
 686     for (j = 1; j < dataPoint.length; j++) {
 687       if (this.dygraph_.visibility()[j-1]) {
 688         var y;
 689         if (mutipleValues) {
 690           for (k = 0; k < sum.length; k++) {
 691             y = dataPoint[j][k];
 692             if (y === null || isNaN(y)) continue;
 693             sum[k] += y;
 694             count[k]++;
 695           }
 696         } else {
 697           y = dataPoint[j];
 698           if (y === null || isNaN(y)) continue;
 699           sum += y;
 700           count++;
 701         }
 702       }
 703     }
 704
 705     if (mutipleValues) {
 706       for (k = 0; k < sum.length; k++) {
 707         sum[k] /= count[k];
 708       }
 709       yVal = sum.slice(0);
 710     } else {
 711       yVal = sum/count;
 712     }
 713
 714     combinedSeries.push([xVal, yVal]);
 715   }
 716
 717   // Account for roll period, fractions.
 718   combinedSeries = this.dygraph_.rollingAverage(combinedSeries, this.dygraph_.rollPeriod_);
 719
 720   if (typeof combinedSeries[0][1] != 'number') {
 721     for (i = 0; i < combinedSeries.length; i++) {
 722       yVal = combinedSeries[i][1];
 723       combinedSeries[i][1] = yVal[0];
 724     }
 725   }
 726
 727   // Compute the y range.
 728   var yMin = Number.MAX_VALUE;
 729   var yMax = -Number.MAX_VALUE;
 730   for (i = 0; i < combinedSeries.length; i++) {
 731     yVal = combinedSeries[i][1];
 732     if (yVal !== null && isFinite(yVal) && (!logscale || yVal > 0)) {
 733       yMin = Math.min(yMin, yVal);
 734       yMax = Math.max(yMax, yVal);
 735     }
 736   }
 737
 738   // Convert Y data to log scale if needed.
 739   // Also, expand the Y range to compress the mini plot a little.
 740   var extraPercent = 0.25;
 741   if (logscale) {
 742     yMax = Dygraph.log10(yMax);
 743     yMax += yMax*extraPercent;
 744     yMin = Dygraph.log10(yMin);
 745     for (i = 0; i < combinedSeries.length; i++) {
 746       combinedSeries[i][1] = Dygraph.log10(combinedSeries[i][1]);
 747     }
 748   } else {
 749     var yExtra;
 750     var yRange = yMax - yMin;
 751     if (yRange <= Number.MIN_VALUE) {
 752       yExtra = yMax*extraPercent;
 753     } else {
 754       yExtra = yRange*extraPercent;
 755     }
 756     yMax += yExtra;
 757     yMin -= yExtra;
 758   }
 759
 760   return {data: combinedSeries, yMin: yMin, yMax: yMax};
 761 };
 762
 763 /**
 764  * @private
 765  * Places the zoom handles in the proper position based on the current X data window.
 766  */
 767 rangeSelector.prototype.placeZoomHandles_ = function() {
 768   var xExtremes = this.dygraph_.xAxisExtremes();
 769   var xWindowLimits = this.dygraph_.xAxisRange();
 770   var xRange = xExtremes[1] - xExtremes[0];
 771   var leftPercent = Math.max(0, (xWindowLimits[0] - xExtremes[0])/xRange);
 772   var rightPercent = Math.max(0, (xExtremes[1] - xWindowLimits[1])/xRange);
 773   var leftCoord = this.canvasRect_.x + this.canvasRect_.w*leftPercent;
 774   var rightCoord = this.canvasRect_.x + this.canvasRect_.w*(1 - rightPercent);
 775   var handleTop = Math.max(this.canvasRect_.y, this.canvasRect_.y + (this.canvasRect_.h - this.leftZoomHandle_.height)/2);
 776   var halfHandleWidth = this.leftZoomHandle_.width/2;
 777   this.leftZoomHandle_.style.left = (leftCoord - halfHandleWidth) + 'px';
 778   this.leftZoomHandle_.style.top = handleTop + 'px';
 779   this.rightZoomHandle_.style.left = (rightCoord - halfHandleWidth) + 'px';
 780   this.rightZoomHandle_.style.top = this.leftZoomHandle_.style.top;
 781
 782   this.leftZoomHandle_.style.visibility = 'visible';
 783   this.rightZoomHandle_.style.visibility = 'visible';
 784 };
 785
 786 /**
 787  * @private
 788  * Draws the interactive layer in the foreground canvas.
 789  */
 790 rangeSelector.prototype.drawInteractiveLayer_ = function() {
 791   var ctx = this.fgcanvas_ctx_;
 792   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 793   var margin = 1;
 794   var width = this.canvasRect_.w - margin;
 795   var height = this.canvasRect_.h - margin;
 796   var zoomHandleStatus = this.getZoomHandleStatus_();
 797
 798   ctx.strokeStyle = 'black';
 799   if (!zoomHandleStatus.isZoomed) {
 800     ctx.beginPath();
 801     ctx.moveTo(margin, margin);
 802     ctx.lineTo(margin, height);
 803     ctx.lineTo(width, height);
 804     ctx.lineTo(width, margin);
 805     ctx.stroke();
 806     if (this.iePanOverlay_) {
 807       this.iePanOverlay_.style.display = 'none';
 808     }
 809   } else {
 810     var leftHandleCanvasPos = Math.max(margin, zoomHandleStatus.leftHandlePos - this.canvasRect_.x);
 811     var rightHandleCanvasPos = Math.min(width, zoomHandleStatus.rightHandlePos - this.canvasRect_.x);
 812
 813     ctx.fillStyle = 'rgba(240, 240, 240, 0.6)';
 814     ctx.fillRect(0, 0, leftHandleCanvasPos, this.canvasRect_.h);
 815     ctx.fillRect(rightHandleCanvasPos, 0, this.canvasRect_.w - rightHandleCanvasPos, this.canvasRect_.h);
 816
 817     ctx.beginPath();
 818     ctx.moveTo(margin, margin);
 819     ctx.lineTo(leftHandleCanvasPos, margin);
 820     ctx.lineTo(leftHandleCanvasPos, height);
 821     ctx.lineTo(rightHandleCanvasPos, height);
 822     ctx.lineTo(rightHandleCanvasPos, margin);
 823     ctx.lineTo(width, margin);
 824     ctx.stroke();
 825
 826     if (this.isUsingExcanvas_) {
 827       this.iePanOverlay_.style.width = (rightHandleCanvasPos - leftHandleCanvasPos) + 'px';
 828       this.iePanOverlay_.style.left = leftHandleCanvasPos + 'px';
 829       this.iePanOverlay_.style.height = height + 'px';
 830       this.iePanOverlay_.style.display = 'inline';
 831     }
 832   }
 833 };
 834
 835 /**
 836  * @private
 837  * Returns the current zoom handle position information.
 838  * @return {Object} The zoom handle status.
 839  */
 840 rangeSelector.prototype.getZoomHandleStatus_ = function() {
 841   var halfHandleWidth = this.leftZoomHandle_.width/2;
 842   var leftHandlePos = parseFloat(this.leftZoomHandle_.style.left) + halfHandleWidth;
 843   var rightHandlePos = parseFloat(this.rightZoomHandle_.style.left) + halfHandleWidth;
 844   return {
 845       leftHandlePos: leftHandlePos,
 846       rightHandlePos: rightHandlePos,
 847       isZoomed: (leftHandlePos - 1 > this.canvasRect_.x || rightHandlePos + 1 < this.canvasRect_.x+this.canvasRect_.w)
 848   };
 849 };
 850
 851 return rangeSelector;
 852
 853 })();