src/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 /*global Dygraph:false */
  14 "use strict";
  15
  16 import * as utils from '../dygraph-utils';
  17 import DygraphInteraction from '../dygraph-interaction-model';
  18
  19 var rangeSelector = function() {
  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 = utils.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_ = utils.createCanvas();
 201   this.bgcanvas_.className = 'dygraph-rangesel-bgcanvas';
 202   this.bgcanvas_.style.position = 'absolute';
 203   this.bgcanvas_.style.zIndex = 9;
 204   this.bgcanvas_ctx_ = utils.getContext(this.bgcanvas_);
 205
 206   this.fgcanvas_ = utils.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_ = utils.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   img.width = 9;
 227   img.height = 16;
 228   img.src = 'data:image/png;base64,' +
 229 'iVBORw0KGgoAAAANSUhEUgAAAAkAAAAQCAYAAADESFVDAAAAAXNSR0IArs4c6QAAAAZiS0dEANAA' +
 230 'zwDP4Z7KegAAAAlwSFlzAAAOxAAADsQBlSsOGwAAAAd0SU1FB9sHGw0cMqdt1UwAAAAZdEVYdENv' +
 231 'bW1lbnQAQ3JlYXRlZCB3aXRoIEdJTVBXgQ4XAAAAaElEQVQoz+3SsRFAQBCF4Z9WJM8KCDVwownl' +
 232 '6YXsTmCUsyKGkZzcl7zkz3YLkypgAnreFmDEpHkIwVOMfpdi9CEEN2nGpFdwD03yEqDtOgCaun7s' +
 233 'qSTDH32I1pQA2Pb9sZecAxc5r3IAb21d6878xsAAAAAASUVORK5CYII=';
 234
 235   if (this.isMobileDevice_) {
 236     img.width *= 2;
 237     img.height *= 2;
 238   }
 239
 240   this.leftZoomHandle_ = img;
 241   this.rightZoomHandle_ = img.cloneNode(false);
 242 };
 243
 244 /**
 245  * @private
 246  * Sets up the interaction for the range selector.
 247  */
 248 rangeSelector.prototype.initInteraction_ = function() {
 249   var self = this;
 250   var topElem = document;
 251   var clientXLast = 0;
 252   var handle = null;
 253   var isZooming = false;
 254   var isPanning = false;
 255   var dynamic = !this.isMobileDevice_;
 256
 257   // We cover iframes during mouse interactions. See comments in
 258   // dygraph-utils.js for more info on why this is a good idea.
 259   var tarp = new utils.IFrameTarp();
 260
 261   // functions, defined below.  Defining them this way (rather than with
 262   // "function foo() {...}" makes JSHint happy.
 263   var toXDataWindow, onZoomStart, onZoom, onZoomEnd, doZoom, isMouseInPanZone,
 264       onPanStart, onPan, onPanEnd, doPan, onCanvasHover;
 265
 266   // Touch event functions
 267   var onZoomHandleTouchEvent, onCanvasTouchEvent, addTouchEvents;
 268
 269   toXDataWindow = function(zoomHandleStatus) {
 270     var xDataLimits = self.dygraph_.xAxisExtremes();
 271     var fact = (xDataLimits[1] - xDataLimits[0])/self.canvasRect_.w;
 272     var xDataMin = xDataLimits[0] + (zoomHandleStatus.leftHandlePos - self.canvasRect_.x)*fact;
 273     var xDataMax = xDataLimits[0] + (zoomHandleStatus.rightHandlePos - self.canvasRect_.x)*fact;
 274     return [xDataMin, xDataMax];
 275   };
 276
 277   onZoomStart = function(e) {
 278     utils.cancelEvent(e);
 279     isZooming = true;
 280     clientXLast = e.clientX;
 281     handle = e.target ? e.target : e.srcElement;
 282     if (e.type === 'mousedown' || e.type === 'dragstart') {
 283       // These events are removed manually.
 284       utils.addEvent(topElem, 'mousemove', onZoom);
 285       utils.addEvent(topElem, 'mouseup', onZoomEnd);
 286     }
 287     self.fgcanvas_.style.cursor = 'col-resize';
 288     tarp.cover();
 289     return true;
 290   };
 291
 292   onZoom = function(e) {
 293     if (!isZooming) {
 294       return false;
 295     }
 296     utils.cancelEvent(e);
 297
 298     var delX = e.clientX - clientXLast;
 299     if (Math.abs(delX) < 4) {
 300       return true;
 301     }
 302     clientXLast = e.clientX;
 303
 304     // Move handle.
 305     var zoomHandleStatus = self.getZoomHandleStatus_();
 306     var newPos;
 307     if (handle == self.leftZoomHandle_) {
 308       newPos = zoomHandleStatus.leftHandlePos + delX;
 309       newPos = Math.min(newPos, zoomHandleStatus.rightHandlePos - handle.width - 3);
 310       newPos = Math.max(newPos, self.canvasRect_.x);
 311     } else {
 312       newPos = zoomHandleStatus.rightHandlePos + delX;
 313       newPos = Math.min(newPos, self.canvasRect_.x + self.canvasRect_.w);
 314       newPos = Math.max(newPos, zoomHandleStatus.leftHandlePos + handle.width + 3);
 315     }
 316     var halfHandleWidth = handle.width/2;
 317     handle.style.left = (newPos - halfHandleWidth) + 'px';
 318     self.drawInteractiveLayer_();
 319
 320     // Zoom on the fly.
 321     if (dynamic) {
 322       doZoom();
 323     }
 324     return true;
 325   };
 326
 327   onZoomEnd = function(e) {
 328     if (!isZooming) {
 329       return false;
 330     }
 331     isZooming = false;
 332     tarp.uncover();
 333     utils.removeEvent(topElem, 'mousemove', onZoom);
 334     utils.removeEvent(topElem, 'mouseup', onZoomEnd);
 335     self.fgcanvas_.style.cursor = 'default';
 336
 337     // If on a slower device, zoom now.
 338     if (!dynamic) {
 339       doZoom();
 340     }
 341     return true;
 342   };
 343
 344   doZoom = function() {
 345     try {
 346       var zoomHandleStatus = self.getZoomHandleStatus_();
 347       self.isChangingRange_ = true;
 348       if (!zoomHandleStatus.isZoomed) {
 349         self.dygraph_.resetZoom();
 350       } else {
 351         var xDataWindow = toXDataWindow(zoomHandleStatus);
 352         self.dygraph_.doZoomXDates_(xDataWindow[0], xDataWindow[1]);
 353       }
 354     } finally {
 355       self.isChangingRange_ = false;
 356     }
 357   };
 358
 359   isMouseInPanZone = function(e) {
 360     var rect = self.leftZoomHandle_.getBoundingClientRect();
 361     var leftHandleClientX = rect.left + rect.width/2;
 362     rect = self.rightZoomHandle_.getBoundingClientRect();
 363     var rightHandleClientX = rect.left + rect.width/2;
 364     return (e.clientX > leftHandleClientX && e.clientX < rightHandleClientX);
 365   };
 366
 367   onPanStart = function(e) {
 368     if (!isPanning && isMouseInPanZone(e) && self.getZoomHandleStatus_().isZoomed) {
 369       utils.cancelEvent(e);
 370       isPanning = true;
 371       clientXLast = e.clientX;
 372       if (e.type === 'mousedown') {
 373         // These events are removed manually.
 374         utils.addEvent(topElem, 'mousemove', onPan);
 375         utils.addEvent(topElem, 'mouseup', onPanEnd);
 376       }
 377       return true;
 378     }
 379     return false;
 380   };
 381
 382   onPan = function(e) {
 383     if (!isPanning) {
 384       return false;
 385     }
 386     utils.cancelEvent(e);
 387
 388     var delX = e.clientX - clientXLast;
 389     if (Math.abs(delX) < 4) {
 390       return true;
 391     }
 392     clientXLast = e.clientX;
 393
 394     // Move range view
 395     var zoomHandleStatus = self.getZoomHandleStatus_();
 396     var leftHandlePos = zoomHandleStatus.leftHandlePos;
 397     var rightHandlePos = zoomHandleStatus.rightHandlePos;
 398     var rangeSize = rightHandlePos - leftHandlePos;
 399     if (leftHandlePos + delX <= self.canvasRect_.x) {
 400       leftHandlePos = self.canvasRect_.x;
 401       rightHandlePos = leftHandlePos + rangeSize;
 402     } else if (rightHandlePos + delX >= self.canvasRect_.x + self.canvasRect_.w) {
 403       rightHandlePos = self.canvasRect_.x + self.canvasRect_.w;
 404       leftHandlePos = rightHandlePos - rangeSize;
 405     } else {
 406       leftHandlePos += delX;
 407       rightHandlePos += delX;
 408     }
 409     var halfHandleWidth = self.leftZoomHandle_.width/2;
 410     self.leftZoomHandle_.style.left = (leftHandlePos - halfHandleWidth) + 'px';
 411     self.rightZoomHandle_.style.left = (rightHandlePos - halfHandleWidth) + 'px';
 412     self.drawInteractiveLayer_();
 413
 414     // Do pan on the fly.
 415     if (dynamic) {
 416       doPan();
 417     }
 418     return true;
 419   };
 420
 421   onPanEnd = function(e) {
 422     if (!isPanning) {
 423       return false;
 424     }
 425     isPanning = false;
 426     utils.removeEvent(topElem, 'mousemove', onPan);
 427     utils.removeEvent(topElem, 'mouseup', onPanEnd);
 428     // If on a slower device, do pan now.
 429     if (!dynamic) {
 430       doPan();
 431     }
 432     return true;
 433   };
 434
 435   doPan = function() {
 436     try {
 437       self.isChangingRange_ = true;
 438       self.dygraph_.dateWindow_ = toXDataWindow(self.getZoomHandleStatus_());
 439       self.dygraph_.drawGraph_(false);
 440     } finally {
 441       self.isChangingRange_ = false;
 442     }
 443   };
 444
 445   onCanvasHover = function(e) {
 446     if (isZooming || isPanning) {
 447       return;
 448     }
 449     var cursor = isMouseInPanZone(e) ? 'move' : 'default';
 450     if (cursor != self.fgcanvas_.style.cursor) {
 451       self.fgcanvas_.style.cursor = cursor;
 452     }
 453   };
 454
 455   onZoomHandleTouchEvent = function(e) {
 456     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 457       if (onZoomStart(e.targetTouches[0])) {
 458         utils.cancelEvent(e);
 459       }
 460     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 461       if (onZoom(e.targetTouches[0])) {
 462         utils.cancelEvent(e);
 463       }
 464     } else {
 465       onZoomEnd(e);
 466     }
 467   };
 468
 469   onCanvasTouchEvent = function(e) {
 470     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 471       if (onPanStart(e.targetTouches[0])) {
 472         utils.cancelEvent(e);
 473       }
 474     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 475       if (onPan(e.targetTouches[0])) {
 476         utils.cancelEvent(e);
 477       }
 478     } else {
 479       onPanEnd(e);
 480     }
 481   };
 482
 483   addTouchEvents = function(elem, fn) {
 484     var types = ['touchstart', 'touchend', 'touchmove', 'touchcancel'];
 485     for (var i = 0; i < types.length; i++) {
 486       self.dygraph_.addAndTrackEvent(elem, types[i], fn);
 487     }
 488   };
 489
 490   this.setDefaultOption_('interactionModel', DygraphInteraction.dragIsPanInteractionModel);
 491   this.setDefaultOption_('panEdgeFraction', 0.0001);
 492
 493   var dragStartEvent = window.opera ? 'mousedown' : 'dragstart';
 494   this.dygraph_.addAndTrackEvent(this.leftZoomHandle_, dragStartEvent, onZoomStart);
 495   this.dygraph_.addAndTrackEvent(this.rightZoomHandle_, dragStartEvent, onZoomStart);
 496
 497   this.dygraph_.addAndTrackEvent(this.fgcanvas_, 'mousedown', onPanStart);
 498   this.dygraph_.addAndTrackEvent(this.fgcanvas_, 'mousemove', onCanvasHover);
 499
 500   // Touch events
 501   if (this.hasTouchInterface_) {
 502     addTouchEvents(this.leftZoomHandle_, onZoomHandleTouchEvent);
 503     addTouchEvents(this.rightZoomHandle_, onZoomHandleTouchEvent);
 504     addTouchEvents(this.fgcanvas_, onCanvasTouchEvent);
 505   }
 506 };
 507
 508 /**
 509  * @private
 510  * Draws the static layer in the background canvas.
 511  */
 512 rangeSelector.prototype.drawStaticLayer_ = function() {
 513   var ctx = this.bgcanvas_ctx_;
 514   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 515   try {
 516     this.drawMiniPlot_();
 517   } catch(ex) {
 518     console.warn(ex);
 519   }
 520
 521   var margin = 0.5;
 522   this.bgcanvas_ctx_.lineWidth = this.getOption_('rangeSelectorBackgroundLineWidth');
 523   ctx.strokeStyle = this.getOption_('rangeSelectorBackgroundStrokeColor');
 524   ctx.beginPath();
 525   ctx.moveTo(margin, margin);
 526   ctx.lineTo(margin, this.canvasRect_.h-margin);
 527   ctx.lineTo(this.canvasRect_.w-margin, this.canvasRect_.h-margin);
 528   ctx.lineTo(this.canvasRect_.w-margin, margin);
 529   ctx.stroke();
 530 };
 531
 532
 533 /**
 534  * @private
 535  * Draws the mini plot in the background canvas.
 536  */
 537 rangeSelector.prototype.drawMiniPlot_ = function() {
 538   var fillStyle = this.getOption_('rangeSelectorPlotFillColor');
 539   var fillGradientStyle = this.getOption_('rangeSelectorPlotFillGradientColor');
 540   var strokeStyle = this.getOption_('rangeSelectorPlotStrokeColor');
 541   if (!fillStyle && !strokeStyle) {
 542     return;
 543   }
 544
 545   var stepPlot = this.getOption_('stepPlot');
 546
 547   var combinedSeriesData = this.computeCombinedSeriesAndLimits_();
 548   var yRange = combinedSeriesData.yMax - combinedSeriesData.yMin;
 549
 550   // Draw the mini plot.
 551   var ctx = this.bgcanvas_ctx_;
 552   var margin = 0.5;
 553
 554   var xExtremes = this.dygraph_.xAxisExtremes();
 555   var xRange = Math.max(xExtremes[1] - xExtremes[0], 1.e-30);
 556   var xFact = (this.canvasRect_.w - margin)/xRange;
 557   var yFact = (this.canvasRect_.h - margin)/yRange;
 558   var canvasWidth = this.canvasRect_.w - margin;
 559   var canvasHeight = this.canvasRect_.h - margin;
 560
 561   var prevX = null, prevY = null;
 562
 563   ctx.beginPath();
 564   ctx.moveTo(margin, canvasHeight);
 565   for (var i = 0; i < combinedSeriesData.data.length; i++) {
 566     var dataPoint = combinedSeriesData.data[i];
 567     var x = ((dataPoint[0] !== null) ? ((dataPoint[0] - xExtremes[0])*xFact) : NaN);
 568     var y = ((dataPoint[1] !== null) ? (canvasHeight - (dataPoint[1] - combinedSeriesData.yMin)*yFact) : NaN);
 569
 570     // Skip points that don't change the x-value. Overly fine-grained points
 571     // can cause major slowdowns with the ctx.fill() call below.
 572     if (!stepPlot && prevX !== null && Math.round(x) == Math.round(prevX)) {
 573       continue;
 574     }
 575
 576     if (isFinite(x) && isFinite(y)) {
 577       if(prevX === null) {
 578         ctx.lineTo(x, canvasHeight);
 579       }
 580       else if (stepPlot) {
 581         ctx.lineTo(x, prevY);
 582       }
 583       ctx.lineTo(x, y);
 584       prevX = x;
 585       prevY = y;
 586     }
 587     else {
 588       if(prevX !== null) {
 589         if (stepPlot) {
 590           ctx.lineTo(x, prevY);
 591           ctx.lineTo(x, canvasHeight);
 592         }
 593         else {
 594           ctx.lineTo(prevX, canvasHeight);
 595         }
 596       }
 597       prevX = prevY = null;
 598     }
 599   }
 600   ctx.lineTo(canvasWidth, canvasHeight);
 601   ctx.closePath();
 602
 603   if (fillStyle) {
 604     var lingrad = this.bgcanvas_ctx_.createLinearGradient(0, 0, 0, canvasHeight);
 605     if (fillGradientStyle) {
 606       lingrad.addColorStop(0, fillGradientStyle);
 607     }
 608     lingrad.addColorStop(1, fillStyle);
 609     this.bgcanvas_ctx_.fillStyle = lingrad;
 610     ctx.fill();
 611   }
 612
 613   if (strokeStyle) {
 614     this.bgcanvas_ctx_.strokeStyle = strokeStyle;
 615     this.bgcanvas_ctx_.lineWidth = this.getOption_('rangeSelectorPlotLineWidth');
 616     ctx.stroke();
 617   }
 618 };
 619
 620 /**
 621  * @private
 622  * Computes and returns the combined series data along with min/max for the mini plot.
 623  * The combined series consists of averaged values for all series.
 624  * When series have error bars, the error bars are ignored.
 625  * @return {Object} An object containing combined series array, ymin, ymax.
 626  */
 627 rangeSelector.prototype.computeCombinedSeriesAndLimits_ = function() {
 628   var g = this.dygraph_;
 629   var logscale = this.getOption_('logscale');
 630   var i;
 631
 632   // Select series to combine. By default, all series are combined.
 633   var numColumns = g.numColumns();
 634   var labels = g.getLabels();
 635   var includeSeries = new Array(numColumns);
 636   var anySet = false;
 637   for (i = 1; i < numColumns; i++) {
 638     var include = this.getOption_('showInRangeSelector', labels[i]);
 639     includeSeries[i] = include;
 640     if (include !== null) anySet = true;  // it's set explicitly for this series
 641   }
 642   if (!anySet) {
 643     for (i = 0; i < includeSeries.length; i++) includeSeries[i] = true;
 644   }
 645
 646   // Create a combined series (average of selected series values).
 647   // TODO(danvk): short-circuit if there's only one series.
 648   var rolledSeries = [];
 649   var dataHandler = g.dataHandler_;
 650   var options = g.attributes_;
 651   for (i = 1; i < g.numColumns(); i++) {
 652     if (!includeSeries[i]) continue;
 653     var series = dataHandler.extractSeries(g.rawData_, i, options);
 654     if (g.rollPeriod() > 1) {
 655       series = dataHandler.rollingAverage(series, g.rollPeriod(), options);
 656     }
 657
 658     rolledSeries.push(series);
 659   }
 660
 661   var combinedSeries = [];
 662   for (i = 0; i < rolledSeries[0].length; i++) {
 663     var sum = 0;
 664     var count = 0;
 665     for (var j = 0; j < rolledSeries.length; j++) {
 666       var y = rolledSeries[j][i][1];
 667       if (y === null || isNaN(y)) continue;
 668       count++;
 669       sum += y;
 670     }
 671     combinedSeries.push([rolledSeries[0][i][0], sum / count]);
 672   }
 673
 674   // Compute the y range.
 675   var yMin = Number.MAX_VALUE;
 676   var yMax = -Number.MAX_VALUE;
 677   for (i = 0; i < combinedSeries.length; i++) {
 678     var yVal = combinedSeries[i][1];
 679     if (yVal !== null && isFinite(yVal) && (!logscale || yVal > 0)) {
 680       yMin = Math.min(yMin, yVal);
 681       yMax = Math.max(yMax, yVal);
 682     }
 683   }
 684
 685   // Convert Y data to log scale if needed.
 686   // Also, expand the Y range to compress the mini plot a little.
 687   var extraPercent = 0.25;
 688   if (logscale) {
 689     yMax = utils.log10(yMax);
 690     yMax += yMax*extraPercent;
 691     yMin = utils.log10(yMin);
 692     for (i = 0; i < combinedSeries.length; i++) {
 693       combinedSeries[i][1] = utils.log10(combinedSeries[i][1]);
 694     }
 695   } else {
 696     var yExtra;
 697     var yRange = yMax - yMin;
 698     if (yRange <= Number.MIN_VALUE) {
 699       yExtra = yMax*extraPercent;
 700     } else {
 701       yExtra = yRange*extraPercent;
 702     }
 703     yMax += yExtra;
 704     yMin -= yExtra;
 705   }
 706
 707   return {data: combinedSeries, yMin: yMin, yMax: yMax};
 708 };
 709
 710 /**
 711  * @private
 712  * Places the zoom handles in the proper position based on the current X data window.
 713  */
 714 rangeSelector.prototype.placeZoomHandles_ = function() {
 715   var xExtremes = this.dygraph_.xAxisExtremes();
 716   var xWindowLimits = this.dygraph_.xAxisRange();
 717   var xRange = xExtremes[1] - xExtremes[0];
 718   var leftPercent = Math.max(0, (xWindowLimits[0] - xExtremes[0])/xRange);
 719   var rightPercent = Math.max(0, (xExtremes[1] - xWindowLimits[1])/xRange);
 720   var leftCoord = this.canvasRect_.x + this.canvasRect_.w*leftPercent;
 721   var rightCoord = this.canvasRect_.x + this.canvasRect_.w*(1 - rightPercent);
 722   var handleTop = Math.max(this.canvasRect_.y, this.canvasRect_.y + (this.canvasRect_.h - this.leftZoomHandle_.height)/2);
 723   var halfHandleWidth = this.leftZoomHandle_.width/2;
 724   this.leftZoomHandle_.style.left = (leftCoord - halfHandleWidth) + 'px';
 725   this.leftZoomHandle_.style.top = handleTop + 'px';
 726   this.rightZoomHandle_.style.left = (rightCoord - halfHandleWidth) + 'px';
 727   this.rightZoomHandle_.style.top = this.leftZoomHandle_.style.top;
 728
 729   this.leftZoomHandle_.style.visibility = 'visible';
 730   this.rightZoomHandle_.style.visibility = 'visible';
 731 };
 732
 733 /**
 734  * @private
 735  * Draws the interactive layer in the foreground canvas.
 736  */
 737 rangeSelector.prototype.drawInteractiveLayer_ = function() {
 738   var ctx = this.fgcanvas_ctx_;
 739   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 740   var margin = 1;
 741   var width = this.canvasRect_.w - margin;
 742   var height = this.canvasRect_.h - margin;
 743   var zoomHandleStatus = this.getZoomHandleStatus_();
 744
 745   ctx.strokeStyle = this.getOption_('rangeSelectorForegroundStrokeColor');
 746   ctx.lineWidth = this.getOption_('rangeSelectorForegroundLineWidth');
 747   if (!zoomHandleStatus.isZoomed) {
 748     ctx.beginPath();
 749     ctx.moveTo(margin, margin);
 750     ctx.lineTo(margin, height);
 751     ctx.lineTo(width, height);
 752     ctx.lineTo(width, margin);
 753     ctx.stroke();
 754   } else {
 755     var leftHandleCanvasPos = Math.max(margin, zoomHandleStatus.leftHandlePos - this.canvasRect_.x);
 756     var rightHandleCanvasPos = Math.min(width, zoomHandleStatus.rightHandlePos - this.canvasRect_.x);
 757
 758     ctx.fillStyle = 'rgba(240, 240, 240, ' + this.getOption_('rangeSelectorAlpha').toString() + ')';
 759     ctx.fillRect(0, 0, leftHandleCanvasPos, this.canvasRect_.h);
 760     ctx.fillRect(rightHandleCanvasPos, 0, this.canvasRect_.w - rightHandleCanvasPos, this.canvasRect_.h);
 761
 762     ctx.beginPath();
 763     ctx.moveTo(margin, margin);
 764     ctx.lineTo(leftHandleCanvasPos, margin);
 765     ctx.lineTo(leftHandleCanvasPos, height);
 766     ctx.lineTo(rightHandleCanvasPos, height);
 767     ctx.lineTo(rightHandleCanvasPos, margin);
 768     ctx.lineTo(width, margin);
 769     ctx.stroke();
 770   }
 771 };
 772
 773 /**
 774  * @private
 775  * Returns the current zoom handle position information.
 776  * @return {Object} The zoom handle status.
 777  */
 778 rangeSelector.prototype.getZoomHandleStatus_ = function() {
 779   var halfHandleWidth = this.leftZoomHandle_.width/2;
 780   var leftHandlePos = parseFloat(this.leftZoomHandle_.style.left) + halfHandleWidth;
 781   var rightHandlePos = parseFloat(this.rightZoomHandle_.style.left) + halfHandleWidth;
 782   return {
 783       leftHandlePos: leftHandlePos,
 784       rightHandlePos: rightHandlePos,
 785       isZoomed: (leftHandlePos - 1 > this.canvasRect_.x || rightHandlePos + 1 < this.canvasRect_.x+this.canvasRect_.w)
 786   };
 787 };
 788
 789 export default rangeSelector;