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 import IFrameTarp from '../iframe-tarp';
  19
  20 var rangeSelector = function() {
  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   if (this.getOption_('showRangeSelector')) {
  33     this.createInterface_();
  34   }
  35   return {
  36     layout: this.reserveSpace_,
  37     predraw: this.renderStaticLayer_,
  38     didDrawChart: this.renderInteractiveLayer_
  39   };
  40 };
  41
  42 rangeSelector.prototype.destroy = function() {
  43   this.bgcanvas_ = null;
  44   this.fgcanvas_ = null;
  45   this.leftZoomHandle_ = null;
  46   this.rightZoomHandle_ = null;
  47 };
  48
  49 //------------------------------------------------------------------
  50 // Private methods
  51 //------------------------------------------------------------------
  52
  53 rangeSelector.prototype.getOption_ = function(name, opt_series) {
  54   return this.dygraph_.getOption(name, opt_series);
  55 };
  56
  57 rangeSelector.prototype.setDefaultOption_ = function(name, value) {
  58   this.dygraph_.attrs_[name] = value;
  59 };
  60
  61 /**
  62  * @private
  63  * Creates the range selector elements and adds them to the graph.
  64  */
  65 rangeSelector.prototype.createInterface_ = function() {
  66   this.createCanvases_();
  67   this.createZoomHandles_();
  68   this.initInteraction_();
  69
  70   // Range selector and animatedZooms have a bad interaction. See issue 359.
  71   if (this.getOption_('animatedZooms')) {
  72     console.warn('Animated zooms and range selector are not compatible; disabling animatedZooms.');
  73     this.dygraph_.updateOptions({animatedZooms: false}, true);
  74   }
  75
  76   this.interfaceCreated_ = true;
  77   this.addToGraph_();
  78 };
  79
  80 /**
  81  * @private
  82  * Adds the range selector to the graph.
  83  */
  84 rangeSelector.prototype.addToGraph_ = function() {
  85   var graphDiv = this.graphDiv_ = this.dygraph_.graphDiv;
  86   graphDiv.appendChild(this.bgcanvas_);
  87   graphDiv.appendChild(this.fgcanvas_);
  88   graphDiv.appendChild(this.leftZoomHandle_);
  89   graphDiv.appendChild(this.rightZoomHandle_);
  90 };
  91
  92 /**
  93  * @private
  94  * Removes the range selector from the graph.
  95  */
  96 rangeSelector.prototype.removeFromGraph_ = function() {
  97   var graphDiv = this.graphDiv_;
  98   graphDiv.removeChild(this.bgcanvas_);
  99   graphDiv.removeChild(this.fgcanvas_);
 100   graphDiv.removeChild(this.leftZoomHandle_);
 101   graphDiv.removeChild(this.rightZoomHandle_);
 102   this.graphDiv_ = null;
 103 };
 104
 105 /**
 106  * @private
 107  * Called by Layout to allow range selector to reserve its space.
 108  */
 109 rangeSelector.prototype.reserveSpace_ = function(e) {
 110   if (this.getOption_('showRangeSelector')) {
 111     e.reserveSpaceBottom(this.getOption_('rangeSelectorHeight') + 4);
 112   }
 113 };
 114
 115 /**
 116  * @private
 117  * Renders the static portion of the range selector at the predraw stage.
 118  */
 119 rangeSelector.prototype.renderStaticLayer_ = function() {
 120   if (!this.updateVisibility_()) {
 121     return;
 122   }
 123   this.resize_();
 124   this.drawStaticLayer_();
 125 };
 126
 127 /**
 128  * @private
 129  * Renders the interactive portion of the range selector after the chart has been drawn.
 130  */
 131 rangeSelector.prototype.renderInteractiveLayer_ = function() {
 132   if (!this.updateVisibility_() || this.isChangingRange_) {
 133     return;
 134   }
 135   this.placeZoomHandles_();
 136   this.drawInteractiveLayer_();
 137 };
 138
 139 /**
 140  * @private
 141  * Check to see if the range selector is enabled/disabled and update visibility accordingly.
 142  */
 143 rangeSelector.prototype.updateVisibility_ = function() {
 144   var enabled = this.getOption_('showRangeSelector');
 145   if (enabled) {
 146     if (!this.interfaceCreated_) {
 147       this.createInterface_();
 148     } else if (!this.graphDiv_ || !this.graphDiv_.parentNode) {
 149       this.addToGraph_();
 150     }
 151   } else if (this.graphDiv_) {
 152     this.removeFromGraph_();
 153     var dygraph = this.dygraph_;
 154     setTimeout(function() { dygraph.width_ = 0; dygraph.resize(); }, 1);
 155   }
 156   return enabled;
 157 };
 158
 159 /**
 160  * @private
 161  * Resizes the range selector.
 162  */
 163 rangeSelector.prototype.resize_ = function() {
 164   function setElementRect(canvas, context, rect, pixelRatioOption) {
 165     var canvasScale = pixelRatioOption || utils.getContextPixelRatio(context);
 166
 167     canvas.style.top = rect.y + 'px';
 168     canvas.style.left = rect.x + 'px';
 169     canvas.width = rect.w * canvasScale;
 170     canvas.height = rect.h * canvasScale;
 171     canvas.style.width = rect.w + 'px';
 172     canvas.style.height = rect.h + 'px';
 173
 174     if(canvasScale != 1) {
 175       context.scale(canvasScale, canvasScale);
 176     }
 177   }
 178
 179   var plotArea = this.dygraph_.layout_.getPlotArea();
 180
 181   var xAxisLabelHeight = 0;
 182   if (this.dygraph_.getOptionForAxis('drawAxis', 'x')) {
 183     xAxisLabelHeight = this.getOption_('xAxisHeight') || (this.getOption_('axisLabelFontSize') + 2 * this.getOption_('axisTickSize'));
 184   }
 185   this.canvasRect_ = {
 186     x: plotArea.x,
 187     y: plotArea.y + plotArea.h + xAxisLabelHeight + 4,
 188     w: plotArea.w,
 189     h: this.getOption_('rangeSelectorHeight')
 190   };
 191
 192   var pixelRatioOption = this.dygraph_.getNumericOption('pixelRatio');
 193   setElementRect(this.bgcanvas_, this.bgcanvas_ctx_, this.canvasRect_, pixelRatioOption);
 194   setElementRect(this.fgcanvas_, this.fgcanvas_ctx_, this.canvasRect_, pixelRatioOption);
 195 };
 196
 197 /**
 198  * @private
 199  * Creates the background and foreground canvases.
 200  */
 201 rangeSelector.prototype.createCanvases_ = function() {
 202   this.bgcanvas_ = utils.createCanvas();
 203   this.bgcanvas_.className = 'dygraph-rangesel-bgcanvas';
 204   this.bgcanvas_.style.position = 'absolute';
 205   this.bgcanvas_.style.zIndex = 9;
 206   this.bgcanvas_ctx_ = utils.getContext(this.bgcanvas_);
 207
 208   this.fgcanvas_ = utils.createCanvas();
 209   this.fgcanvas_.className = 'dygraph-rangesel-fgcanvas';
 210   this.fgcanvas_.style.position = 'absolute';
 211   this.fgcanvas_.style.zIndex = 9;
 212   this.fgcanvas_.style.cursor = 'default';
 213   this.fgcanvas_ctx_ = utils.getContext(this.fgcanvas_);
 214 };
 215
 216 /**
 217  * @private
 218  * Creates the zoom handle elements.
 219  */
 220 rangeSelector.prototype.createZoomHandles_ = function() {
 221   var img = new Image();
 222   img.className = 'dygraph-rangesel-zoomhandle';
 223   img.style.position = 'absolute';
 224   img.style.zIndex = 10;
 225   img.style.visibility = 'hidden'; // Initially hidden so they don't show up in the wrong place.
 226   img.style.cursor = 'col-resize';
 227   // TODO: change image to more options
 228   img.width = 9;
 229   img.height = 16;
 230   img.src = 'data:image/png;base64,' +
 231 'iVBORw0KGgoAAAANSUhEUgAAAAkAAAAQCAYAAADESFVDAAAAAXNSR0IArs4c6QAAAAZiS0dEANAA' +
 232 'zwDP4Z7KegAAAAlwSFlzAAAOxAAADsQBlSsOGwAAAAd0SU1FB9sHGw0cMqdt1UwAAAAZdEVYdENv' +
 233 'bW1lbnQAQ3JlYXRlZCB3aXRoIEdJTVBXgQ4XAAAAaElEQVQoz+3SsRFAQBCF4Z9WJM8KCDVwownl' +
 234 '6YXsTmCUsyKGkZzcl7zkz3YLkypgAnreFmDEpHkIwVOMfpdi9CEEN2nGpFdwD03yEqDtOgCaun7s' +
 235 'qSTDH32I1pQA2Pb9sZecAxc5r3IAb21d6878xsAAAAAASUVORK5CYII=';
 236
 237   if (this.isMobileDevice_) {
 238     img.width *= 2;
 239     img.height *= 2;
 240   }
 241
 242   this.leftZoomHandle_ = img;
 243   this.rightZoomHandle_ = img.cloneNode(false);
 244 };
 245
 246 /**
 247  * @private
 248  * Sets up the interaction for the range selector.
 249  */
 250 rangeSelector.prototype.initInteraction_ = function() {
 251   var self = this;
 252   var topElem = document;
 253   var clientXLast = 0;
 254   var handle = null;
 255   var isZooming = false;
 256   var isPanning = false;
 257   var dynamic = !this.isMobileDevice_;
 258
 259   // We cover iframes during mouse interactions. See comments in
 260   // dygraph-utils.js for more info on why this is a good idea.
 261   var tarp = new IFrameTarp();
 262
 263   // functions, defined below.  Defining them this way (rather than with
 264   // "function foo() {...}" makes JSHint happy.
 265   var toXDataWindow, onZoomStart, onZoom, onZoomEnd, doZoom, isMouseInPanZone,
 266       onPanStart, onPan, onPanEnd, doPan, onCanvasHover;
 267
 268   // Touch event functions
 269   var onZoomHandleTouchEvent, onCanvasTouchEvent, addTouchEvents;
 270
 271   toXDataWindow = function(zoomHandleStatus) {
 272     var xDataLimits = self.dygraph_.xAxisExtremes();
 273     var fact = (xDataLimits[1] - xDataLimits[0])/self.canvasRect_.w;
 274     var xDataMin = xDataLimits[0] + (zoomHandleStatus.leftHandlePos - self.canvasRect_.x)*fact;
 275     var xDataMax = xDataLimits[0] + (zoomHandleStatus.rightHandlePos - self.canvasRect_.x)*fact;
 276     return [xDataMin, xDataMax];
 277   };
 278
 279   onZoomStart = function(e) {
 280     utils.cancelEvent(e);
 281     isZooming = true;
 282     clientXLast = e.clientX;
 283     handle = e.target ? e.target : e.srcElement;
 284     if (e.type === 'mousedown' || e.type === 'dragstart') {
 285       // These events are removed manually.
 286       utils.addEvent(topElem, 'mousemove', onZoom);
 287       utils.addEvent(topElem, 'mouseup', onZoomEnd);
 288     }
 289     self.fgcanvas_.style.cursor = 'col-resize';
 290     tarp.cover();
 291     return true;
 292   };
 293
 294   onZoom = function(e) {
 295     if (!isZooming) {
 296       return false;
 297     }
 298     utils.cancelEvent(e);
 299
 300     var delX = e.clientX - clientXLast;
 301     if (Math.abs(delX) < 4) {
 302       return true;
 303     }
 304     clientXLast = e.clientX;
 305
 306     // Move handle.
 307     var zoomHandleStatus = self.getZoomHandleStatus_();
 308     var newPos;
 309     if (handle == self.leftZoomHandle_) {
 310       newPos = zoomHandleStatus.leftHandlePos + delX;
 311       newPos = Math.min(newPos, zoomHandleStatus.rightHandlePos - handle.width - 3);
 312       newPos = Math.max(newPos, self.canvasRect_.x);
 313     } else {
 314       newPos = zoomHandleStatus.rightHandlePos + delX;
 315       newPos = Math.min(newPos, self.canvasRect_.x + self.canvasRect_.w);
 316       newPos = Math.max(newPos, zoomHandleStatus.leftHandlePos + handle.width + 3);
 317     }
 318     var halfHandleWidth = handle.width/2;
 319     handle.style.left = (newPos - halfHandleWidth) + 'px';
 320     self.drawInteractiveLayer_();
 321
 322     // Zoom on the fly.
 323     if (dynamic) {
 324       doZoom();
 325     }
 326     return true;
 327   };
 328
 329   onZoomEnd = function(e) {
 330     if (!isZooming) {
 331       return false;
 332     }
 333     isZooming = false;
 334     tarp.uncover();
 335     utils.removeEvent(topElem, 'mousemove', onZoom);
 336     utils.removeEvent(topElem, 'mouseup', onZoomEnd);
 337     self.fgcanvas_.style.cursor = 'default';
 338
 339     // If on a slower device, zoom now.
 340     if (!dynamic) {
 341       doZoom();
 342     }
 343     return true;
 344   };
 345
 346   doZoom = function() {
 347     try {
 348       var zoomHandleStatus = self.getZoomHandleStatus_();
 349       self.isChangingRange_ = true;
 350       if (!zoomHandleStatus.isZoomed) {
 351         self.dygraph_.resetZoom();
 352       } else {
 353         var xDataWindow = toXDataWindow(zoomHandleStatus);
 354         self.dygraph_.doZoomXDates_(xDataWindow[0], xDataWindow[1]);
 355       }
 356     } finally {
 357       self.isChangingRange_ = false;
 358     }
 359   };
 360
 361   isMouseInPanZone = function(e) {
 362     var rect = self.leftZoomHandle_.getBoundingClientRect();
 363     var leftHandleClientX = rect.left + rect.width/2;
 364     rect = self.rightZoomHandle_.getBoundingClientRect();
 365     var rightHandleClientX = rect.left + rect.width/2;
 366     return (e.clientX > leftHandleClientX && e.clientX < rightHandleClientX);
 367   };
 368
 369   onPanStart = function(e) {
 370     if (!isPanning && isMouseInPanZone(e) && self.getZoomHandleStatus_().isZoomed) {
 371       utils.cancelEvent(e);
 372       isPanning = true;
 373       clientXLast = e.clientX;
 374       if (e.type === 'mousedown') {
 375         // These events are removed manually.
 376         utils.addEvent(topElem, 'mousemove', onPan);
 377         utils.addEvent(topElem, 'mouseup', onPanEnd);
 378       }
 379       return true;
 380     }
 381     return false;
 382   };
 383
 384   onPan = function(e) {
 385     if (!isPanning) {
 386       return false;
 387     }
 388     utils.cancelEvent(e);
 389
 390     var delX = e.clientX - clientXLast;
 391     if (Math.abs(delX) < 4) {
 392       return true;
 393     }
 394     clientXLast = e.clientX;
 395
 396     // Move range view
 397     var zoomHandleStatus = self.getZoomHandleStatus_();
 398     var leftHandlePos = zoomHandleStatus.leftHandlePos;
 399     var rightHandlePos = zoomHandleStatus.rightHandlePos;
 400     var rangeSize = rightHandlePos - leftHandlePos;
 401     if (leftHandlePos + delX <= self.canvasRect_.x) {
 402       leftHandlePos = self.canvasRect_.x;
 403       rightHandlePos = leftHandlePos + rangeSize;
 404     } else if (rightHandlePos + delX >= self.canvasRect_.x + self.canvasRect_.w) {
 405       rightHandlePos = self.canvasRect_.x + self.canvasRect_.w;
 406       leftHandlePos = rightHandlePos - rangeSize;
 407     } else {
 408       leftHandlePos += delX;
 409       rightHandlePos += delX;
 410     }
 411     var halfHandleWidth = self.leftZoomHandle_.width/2;
 412     self.leftZoomHandle_.style.left = (leftHandlePos - halfHandleWidth) + 'px';
 413     self.rightZoomHandle_.style.left = (rightHandlePos - halfHandleWidth) + 'px';
 414     self.drawInteractiveLayer_();
 415
 416     // Do pan on the fly.
 417     if (dynamic) {
 418       doPan();
 419     }
 420     return true;
 421   };
 422
 423   onPanEnd = function(e) {
 424     if (!isPanning) {
 425       return false;
 426     }
 427     isPanning = false;
 428     utils.removeEvent(topElem, 'mousemove', onPan);
 429     utils.removeEvent(topElem, 'mouseup', onPanEnd);
 430     // If on a slower device, do pan now.
 431     if (!dynamic) {
 432       doPan();
 433     }
 434     return true;
 435   };
 436
 437   doPan = function() {
 438     try {
 439       self.isChangingRange_ = true;
 440       self.dygraph_.dateWindow_ = toXDataWindow(self.getZoomHandleStatus_());
 441       self.dygraph_.drawGraph_(false);
 442     } finally {
 443       self.isChangingRange_ = false;
 444     }
 445   };
 446
 447   onCanvasHover = function(e) {
 448     if (isZooming || isPanning) {
 449       return;
 450     }
 451     var cursor = isMouseInPanZone(e) ? 'move' : 'default';
 452     if (cursor != self.fgcanvas_.style.cursor) {
 453       self.fgcanvas_.style.cursor = cursor;
 454     }
 455   };
 456
 457   onZoomHandleTouchEvent = function(e) {
 458     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 459       if (onZoomStart(e.targetTouches[0])) {
 460         utils.cancelEvent(e);
 461       }
 462     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 463       if (onZoom(e.targetTouches[0])) {
 464         utils.cancelEvent(e);
 465       }
 466     } else {
 467       onZoomEnd(e);
 468     }
 469   };
 470
 471   onCanvasTouchEvent = function(e) {
 472     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 473       if (onPanStart(e.targetTouches[0])) {
 474         utils.cancelEvent(e);
 475       }
 476     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 477       if (onPan(e.targetTouches[0])) {
 478         utils.cancelEvent(e);
 479       }
 480     } else {
 481       onPanEnd(e);
 482     }
 483   };
 484
 485   addTouchEvents = function(elem, fn) {
 486     var types = ['touchstart', 'touchend', 'touchmove', 'touchcancel'];
 487     for (var i = 0; i < types.length; i++) {
 488       self.dygraph_.addAndTrackEvent(elem, types[i], fn);
 489     }
 490   };
 491
 492   this.setDefaultOption_('interactionModel', DygraphInteraction.dragIsPanInteractionModel);
 493   this.setDefaultOption_('panEdgeFraction', 0.0001);
 494
 495   var dragStartEvent = window.opera ? 'mousedown' : 'dragstart';
 496   this.dygraph_.addAndTrackEvent(this.leftZoomHandle_, dragStartEvent, onZoomStart);
 497   this.dygraph_.addAndTrackEvent(this.rightZoomHandle_, dragStartEvent, onZoomStart);
 498
 499   this.dygraph_.addAndTrackEvent(this.fgcanvas_, 'mousedown', onPanStart);
 500   this.dygraph_.addAndTrackEvent(this.fgcanvas_, 'mousemove', onCanvasHover);
 501
 502   // Touch events
 503   if (this.hasTouchInterface_) {
 504     addTouchEvents(this.leftZoomHandle_, onZoomHandleTouchEvent);
 505     addTouchEvents(this.rightZoomHandle_, onZoomHandleTouchEvent);
 506     addTouchEvents(this.fgcanvas_, onCanvasTouchEvent);
 507   }
 508 };
 509
 510 /**
 511  * @private
 512  * Draws the static layer in the background canvas.
 513  */
 514 rangeSelector.prototype.drawStaticLayer_ = function() {
 515   var ctx = this.bgcanvas_ctx_;
 516   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 517   try {
 518     this.drawMiniPlot_();
 519   } catch(ex) {
 520     console.warn(ex);
 521   }
 522
 523   var margin = 0.5;
 524   this.bgcanvas_ctx_.lineWidth = this.getOption_('rangeSelectorBackgroundLineWidth');
 525   ctx.strokeStyle = this.getOption_('rangeSelectorBackgroundStrokeColor');
 526   ctx.beginPath();
 527   ctx.moveTo(margin, margin);
 528   ctx.lineTo(margin, this.canvasRect_.h-margin);
 529   ctx.lineTo(this.canvasRect_.w-margin, this.canvasRect_.h-margin);
 530   ctx.lineTo(this.canvasRect_.w-margin, margin);
 531   ctx.stroke();
 532 };
 533
 534
 535 /**
 536  * @private
 537  * Draws the mini plot in the background canvas.
 538  */
 539 rangeSelector.prototype.drawMiniPlot_ = function() {
 540   var fillStyle = this.getOption_('rangeSelectorPlotFillColor');
 541   var fillGradientStyle = this.getOption_('rangeSelectorPlotFillGradientColor');
 542   var strokeStyle = this.getOption_('rangeSelectorPlotStrokeColor');
 543   if (!fillStyle && !strokeStyle) {
 544     return;
 545   }
 546
 547   var stepPlot = this.getOption_('stepPlot');
 548
 549   var combinedSeriesData = this.computeCombinedSeriesAndLimits_();
 550   var yRange = combinedSeriesData.yMax - combinedSeriesData.yMin;
 551
 552   // Draw the mini plot.
 553   var ctx = this.bgcanvas_ctx_;
 554   var margin = 0.5;
 555
 556   var xExtremes = this.dygraph_.xAxisExtremes();
 557   var xRange = Math.max(xExtremes[1] - xExtremes[0], 1.e-30);
 558   var xFact = (this.canvasRect_.w - margin)/xRange;
 559   var yFact = (this.canvasRect_.h - margin)/yRange;
 560   var canvasWidth = this.canvasRect_.w - margin;
 561   var canvasHeight = this.canvasRect_.h - margin;
 562
 563   var prevX = null, prevY = null;
 564
 565   ctx.beginPath();
 566   ctx.moveTo(margin, canvasHeight);
 567   for (var i = 0; i < combinedSeriesData.data.length; i++) {
 568     var dataPoint = combinedSeriesData.data[i];
 569     var x = ((dataPoint[0] !== null) ? ((dataPoint[0] - xExtremes[0])*xFact) : NaN);
 570     var y = ((dataPoint[1] !== null) ? (canvasHeight - (dataPoint[1] - combinedSeriesData.yMin)*yFact) : NaN);
 571
 572     // Skip points that don't change the x-value. Overly fine-grained points
 573     // can cause major slowdowns with the ctx.fill() call below.
 574     if (!stepPlot && prevX !== null && Math.round(x) == Math.round(prevX)) {
 575       continue;
 576     }
 577
 578     if (isFinite(x) && isFinite(y)) {
 579       if(prevX === null) {
 580         ctx.lineTo(x, canvasHeight);
 581       }
 582       else if (stepPlot) {
 583         ctx.lineTo(x, prevY);
 584       }
 585       ctx.lineTo(x, y);
 586       prevX = x;
 587       prevY = y;
 588     }
 589     else {
 590       if(prevX !== null) {
 591         if (stepPlot) {
 592           ctx.lineTo(x, prevY);
 593           ctx.lineTo(x, canvasHeight);
 594         }
 595         else {
 596           ctx.lineTo(prevX, canvasHeight);
 597         }
 598       }
 599       prevX = prevY = null;
 600     }
 601   }
 602   ctx.lineTo(canvasWidth, canvasHeight);
 603   ctx.closePath();
 604
 605   if (fillStyle) {
 606     var lingrad = this.bgcanvas_ctx_.createLinearGradient(0, 0, 0, canvasHeight);
 607     if (fillGradientStyle) {
 608       lingrad.addColorStop(0, fillGradientStyle);
 609     }
 610     lingrad.addColorStop(1, fillStyle);
 611     this.bgcanvas_ctx_.fillStyle = lingrad;
 612     ctx.fill();
 613   }
 614
 615   if (strokeStyle) {
 616     this.bgcanvas_ctx_.strokeStyle = strokeStyle;
 617     this.bgcanvas_ctx_.lineWidth = this.getOption_('rangeSelectorPlotLineWidth');
 618     ctx.stroke();
 619   }
 620 };
 621
 622 /**
 623  * @private
 624  * Computes and returns the combined series data along with min/max for the mini plot.
 625  * The combined series consists of averaged values for all series.
 626  * When series have error bars, the error bars are ignored.
 627  * @return {Object} An object containing combined series array, ymin, ymax.
 628  */
 629 rangeSelector.prototype.computeCombinedSeriesAndLimits_ = function() {
 630   var g = this.dygraph_;
 631   var logscale = this.getOption_('logscale');
 632   var i;
 633
 634   // Select series to combine. By default, all series are combined.
 635   var numColumns = g.numColumns();
 636   var labels = g.getLabels();
 637   var includeSeries = new Array(numColumns);
 638   var anySet = false;
 639   var visibility = g.visibility();
 640   var inclusion = [];
 641
 642   for (i = 1; i < numColumns; i++) {
 643     var include = this.getOption_('showInRangeSelector', labels[i]);
 644     inclusion.push(include);
 645     if (include !== null) anySet = true;  // it's set explicitly for this series
 646   }
 647
 648   if (anySet) {
 649     for (i = 1; i < numColumns; i++) {
 650       includeSeries[i] = inclusion[i - 1];
 651     }
 652   } else {
 653     for (i = 1; i < numColumns; i++) {
 654       includeSeries[i] = visibility[i - 1];
 655     }
 656   }
 657
 658   // Create a combined series (average of selected series values).
 659   // TODO(danvk): short-circuit if there's only one series.
 660   var rolledSeries = [];
 661   var dataHandler = g.dataHandler_;
 662   var options = g.attributes_;
 663   for (i = 1; i < g.numColumns(); i++) {
 664     if (!includeSeries[i]) continue;
 665     var series = dataHandler.extractSeries(g.rawData_, i, options);
 666     if (g.rollPeriod() > 1) {
 667       series = dataHandler.rollingAverage(series, g.rollPeriod(), options);
 668     }
 669
 670     rolledSeries.push(series);
 671   }
 672
 673   var combinedSeries = [];
 674   for (i = 0; i < rolledSeries[0].length; i++) {
 675     var sum = 0;
 676     var count = 0;
 677     for (var j = 0; j < rolledSeries.length; j++) {
 678       var y = rolledSeries[j][i][1];
 679       if (y === null || isNaN(y)) continue;
 680       count++;
 681       sum += y;
 682     }
 683     combinedSeries.push([rolledSeries[0][i][0], sum / count]);
 684   }
 685
 686   // Compute the y range.
 687   var yMin = Number.MAX_VALUE;
 688   var yMax = -Number.MAX_VALUE;
 689   for (i = 0; i < combinedSeries.length; i++) {
 690     var yVal = combinedSeries[i][1];
 691     if (yVal !== null && isFinite(yVal) && (!logscale || yVal > 0)) {
 692       yMin = Math.min(yMin, yVal);
 693       yMax = Math.max(yMax, yVal);
 694     }
 695   }
 696
 697   // Convert Y data to log scale if needed.
 698   // Also, expand the Y range to compress the mini plot a little.
 699   var extraPercent = 0.25;
 700   if (logscale) {
 701     yMax = utils.log10(yMax);
 702     yMax += yMax*extraPercent;
 703     yMin = utils.log10(yMin);
 704     for (i = 0; i < combinedSeries.length; i++) {
 705       combinedSeries[i][1] = utils.log10(combinedSeries[i][1]);
 706     }
 707   } else {
 708     var yExtra;
 709     var yRange = yMax - yMin;
 710     if (yRange <= Number.MIN_VALUE) {
 711       yExtra = yMax*extraPercent;
 712     } else {
 713       yExtra = yRange*extraPercent;
 714     }
 715     yMax += yExtra;
 716     yMin -= yExtra;
 717   }
 718
 719   return {data: combinedSeries, yMin: yMin, yMax: yMax};
 720 };
 721
 722 /**
 723  * @private
 724  * Places the zoom handles in the proper position based on the current X data window.
 725  */
 726 rangeSelector.prototype.placeZoomHandles_ = function() {
 727   var xExtremes = this.dygraph_.xAxisExtremes();
 728   var xWindowLimits = this.dygraph_.xAxisRange();
 729   var xRange = xExtremes[1] - xExtremes[0];
 730   var leftPercent = Math.max(0, (xWindowLimits[0] - xExtremes[0])/xRange);
 731   var rightPercent = Math.max(0, (xExtremes[1] - xWindowLimits[1])/xRange);
 732   var leftCoord = this.canvasRect_.x + this.canvasRect_.w*leftPercent;
 733   var rightCoord = this.canvasRect_.x + this.canvasRect_.w*(1 - rightPercent);
 734   var handleTop = Math.max(this.canvasRect_.y, this.canvasRect_.y + (this.canvasRect_.h - this.leftZoomHandle_.height)/2);
 735   var halfHandleWidth = this.leftZoomHandle_.width/2;
 736   this.leftZoomHandle_.style.left = (leftCoord - halfHandleWidth) + 'px';
 737   this.leftZoomHandle_.style.top = handleTop + 'px';
 738   this.rightZoomHandle_.style.left = (rightCoord - halfHandleWidth) + 'px';
 739   this.rightZoomHandle_.style.top = this.leftZoomHandle_.style.top;
 740
 741   this.leftZoomHandle_.style.visibility = 'visible';
 742   this.rightZoomHandle_.style.visibility = 'visible';
 743 };
 744
 745 /**
 746  * @private
 747  * Draws the interactive layer in the foreground canvas.
 748  */
 749 rangeSelector.prototype.drawInteractiveLayer_ = function() {
 750   var ctx = this.fgcanvas_ctx_;
 751   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 752   var margin = 1;
 753   var width = this.canvasRect_.w - margin;
 754   var height = this.canvasRect_.h - margin;
 755   var zoomHandleStatus = this.getZoomHandleStatus_();
 756
 757   ctx.strokeStyle = this.getOption_('rangeSelectorForegroundStrokeColor');
 758   ctx.lineWidth = this.getOption_('rangeSelectorForegroundLineWidth');
 759   if (!zoomHandleStatus.isZoomed) {
 760     ctx.beginPath();
 761     ctx.moveTo(margin, margin);
 762     ctx.lineTo(margin, height);
 763     ctx.lineTo(width, height);
 764     ctx.lineTo(width, margin);
 765     ctx.stroke();
 766   } else {
 767     var leftHandleCanvasPos = Math.max(margin, zoomHandleStatus.leftHandlePos - this.canvasRect_.x);
 768     var rightHandleCanvasPos = Math.min(width, zoomHandleStatus.rightHandlePos - this.canvasRect_.x);
 769
 770     ctx.fillStyle = 'rgba(240, 240, 240, ' + this.getOption_('rangeSelectorAlpha').toString() + ')';
 771     ctx.fillRect(0, 0, leftHandleCanvasPos, this.canvasRect_.h);
 772     ctx.fillRect(rightHandleCanvasPos, 0, this.canvasRect_.w - rightHandleCanvasPos, this.canvasRect_.h);
 773
 774     ctx.beginPath();
 775     ctx.moveTo(margin, margin);
 776     ctx.lineTo(leftHandleCanvasPos, margin);
 777     ctx.lineTo(leftHandleCanvasPos, height);
 778     ctx.lineTo(rightHandleCanvasPos, height);
 779     ctx.lineTo(rightHandleCanvasPos, margin);
 780     ctx.lineTo(width, margin);
 781     ctx.stroke();
 782   }
 783 };
 784
 785 /**
 786  * @private
 787  * Returns the current zoom handle position information.
 788  * @return {Object} The zoom handle status.
 789  */
 790 rangeSelector.prototype.getZoomHandleStatus_ = function() {
 791   var halfHandleWidth = this.leftZoomHandle_.width/2;
 792   var leftHandlePos = parseFloat(this.leftZoomHandle_.style.left) + halfHandleWidth;
 793   var rightHandlePos = parseFloat(this.rightZoomHandle_.style.left) + halfHandleWidth;
 794   return {
 795       leftHandlePos: leftHandlePos,
 796       rightHandlePos: rightHandlePos,
 797       isZoomed: (leftHandlePos - 1 > this.canvasRect_.x || rightHandlePos + 1 < this.canvasRect_.x+this.canvasRect_.w)
 798   };
 799 };
 800
 801 export default rangeSelector;