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