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