dygraph-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
   7 /**
   8  * @fileoverview This file contains the DygraphRangeSelector class used to provide
   9  * a timeline range selector widget for dygraphs.
  10  */
  11
  12 /*jshint globalstrict: true */
  13 /*global Dygraph:false */
  14 "use strict";
  15
  16 /**
  17  * The DygraphRangeSelector class provides a timeline range selector widget.
  18  * @param {Dygraph} dygraph The dygraph object
  19  * @constructor
  20  */
  21 var DygraphRangeSelector = function(dygraph) {
  22   this.isIE_ = /MSIE/.test(navigator.userAgent) && !window.opera;
  23   this.isUsingExcanvas_ = dygraph.isUsingExcanvas_;
  24   this.dygraph_ = dygraph;
  25   this.hasTouchInterface_ = typeof(TouchEvent) != 'undefined';
  26   this.isMobileDevice_ = /mobile|android/gi.test(navigator.appVersion);
  27   this.createCanvases_();
  28   if (this.isUsingExcanvas_) {
  29     this.createIEPanOverlay_();
  30   }
  31   this.createZoomHandles_();
  32   this.initInteraction_();
  33 };
  34
  35 /**
  36  * Adds the range selector to the dygraph.
  37  * @param {Object} graphDiv The container div for the range selector.
  38  * @param {DygraphLayout} layout The DygraphLayout object for this graph.
  39  */
  40 DygraphRangeSelector.prototype.addToGraph = function(graphDiv, layout) {
  41   this.layout_ = layout;
  42   this.resize_();
  43   graphDiv.appendChild(this.bgcanvas_);
  44   graphDiv.appendChild(this.fgcanvas_);
  45   graphDiv.appendChild(this.leftZoomHandle_);
  46   graphDiv.appendChild(this.rightZoomHandle_);
  47 };
  48
  49 /**
  50  * Renders the static background portion of the range selector.
  51  */
  52 DygraphRangeSelector.prototype.renderStaticLayer = function() {
  53   this.resize_();
  54   this.drawStaticLayer_();
  55 };
  56
  57 /**
  58  * Renders the interactive foreground portion of the range selector.
  59  */
  60 DygraphRangeSelector.prototype.renderInteractiveLayer = function() {
  61   if (this.isChangingRange_) {
  62     return;
  63   }
  64   this.placeZoomHandles_();
  65   this.drawInteractiveLayer_();
  66 };
  67
  68 /**
  69  * @private
  70  * Resizes the range selector.
  71  */
  72 DygraphRangeSelector.prototype.resize_ = function() {
  73   function setElementRect(canvas, rect) {
  74     canvas.style.top = rect.y + 'px';
  75     canvas.style.left = rect.x + 'px';
  76     canvas.width = rect.w;
  77     canvas.height = rect.h;
  78     canvas.style.width = canvas.width + 'px';    // for IE
  79     canvas.style.height = canvas.height + 'px';  // for IE
  80   }
  81
  82   var plotArea = this.layout_.getPlotArea();
  83   var xAxisLabelHeight = this.attr_('axisLabelFontSize') + 2 * this.attr_('axisTickSize');
  84   this.canvasRect_ = {
  85     x: plotArea.x,
  86     y: plotArea.y + plotArea.h + xAxisLabelHeight + 4,
  87     w: plotArea.w,
  88     h: this.attr_('rangeSelectorHeight')
  89   };
  90
  91   setElementRect(this.bgcanvas_, this.canvasRect_);
  92   setElementRect(this.fgcanvas_, this.canvasRect_);
  93 };
  94
  95 DygraphRangeSelector.prototype.attr_ = function(name) {
  96   return this.dygraph_.attr_(name);
  97 };
  98
  99 /**
 100  * @private
 101  * Creates the background and foreground canvases.
 102  */
 103 DygraphRangeSelector.prototype.createCanvases_ = function() {
 104   this.bgcanvas_ = Dygraph.createCanvas();
 105   this.bgcanvas_.className = 'dygraph-rangesel-bgcanvas';
 106   this.bgcanvas_.style.position = 'absolute';
 107   this.bgcanvas_.style.zIndex = 9;
 108   this.bgcanvas_ctx_ = Dygraph.getContext(this.bgcanvas_);
 109
 110   this.fgcanvas_ = Dygraph.createCanvas();
 111   this.fgcanvas_.className = 'dygraph-rangesel-fgcanvas';
 112   this.fgcanvas_.style.position = 'absolute';
 113   this.fgcanvas_.style.zIndex = 9;
 114   this.fgcanvas_.style.cursor = 'default';
 115   this.fgcanvas_ctx_ = Dygraph.getContext(this.fgcanvas_);
 116 };
 117
 118 /**
 119  * @private
 120  * Creates overlay divs for IE/Excanvas so that mouse events are handled properly.
 121  */
 122 DygraphRangeSelector.prototype.createIEPanOverlay_ = function() {
 123   this.iePanOverlay_ = document.createElement("div");
 124   this.iePanOverlay_.style.position = 'absolute';
 125   this.iePanOverlay_.style.backgroundColor = 'white';
 126   this.iePanOverlay_.style.filter = 'alpha(opacity=0)';
 127   this.iePanOverlay_.style.display = 'none';
 128   this.iePanOverlay_.style.cursor = 'move';
 129   this.fgcanvas_.appendChild(this.iePanOverlay_);
 130 };
 131
 132 /**
 133  * @private
 134  * Creates the zoom handle elements.
 135  */
 136 DygraphRangeSelector.prototype.createZoomHandles_ = function() {
 137   var img = new Image();
 138   img.className = 'dygraph-rangesel-zoomhandle';
 139   img.style.position = 'absolute';
 140   img.style.zIndex = 10;
 141   img.style.visibility = 'hidden'; // Initially hidden so they don't show up in the wrong place.
 142   img.style.cursor = 'col-resize';
 143
 144   if (/MSIE 7/.test(navigator.userAgent)) { // IE7 doesn't support embedded src data.
 145     img.width = 7;
 146     img.height = 14;
 147     img.style.backgroundColor = 'white';
 148     img.style.border = '1px solid #333333'; // Just show box in IE7.
 149   } else {
 150     img.width = 9;
 151     img.height = 16;
 152     img.src = 'data:image/png;base64,' +
 153 'iVBORw0KGgoAAAANSUhEUgAAAAkAAAAQCAYAAADESFVDAAAAAXNSR0IArs4c6QAAAAZiS0dEANAA' +
 154 'zwDP4Z7KegAAAAlwSFlzAAAOxAAADsQBlSsOGwAAAAd0SU1FB9sHGw0cMqdt1UwAAAAZdEVYdENv' +
 155 'bW1lbnQAQ3JlYXRlZCB3aXRoIEdJTVBXgQ4XAAAAaElEQVQoz+3SsRFAQBCF4Z9WJM8KCDVwownl' +
 156 '6YXsTmCUsyKGkZzcl7zkz3YLkypgAnreFmDEpHkIwVOMfpdi9CEEN2nGpFdwD03yEqDtOgCaun7s' +
 157 'qSTDH32I1pQA2Pb9sZecAxc5r3IAb21d6878xsAAAAAASUVORK5CYII=';
 158   }
 159
 160   if (this.isMobileDevice_) {
 161     img.width *= 2;
 162     img.height *= 2;
 163   }
 164
 165   this.leftZoomHandle_ = img;
 166   this.rightZoomHandle_ = img.cloneNode(false);
 167 };
 168
 169 /**
 170  * @private
 171  * Sets up the interaction for the range selector.
 172  */
 173 DygraphRangeSelector.prototype.initInteraction_ = function() {
 174   var self = this;
 175   var topElem = this.isIE_ ? document : window;
 176   var xLast = 0;
 177   var handle = null;
 178   var isZooming = false;
 179   var isPanning = false;
 180   var dynamic = !this.isMobileDevice_ && !this.isUsingExcanvas_;
 181
 182   // functions, defined below.  Defining them this way (rather than with
 183   // "function foo() {...}" makes JSHint happy.
 184   var toXDataWindow, onZoomStart, onZoom, onZoomEnd, doZoom, isMouseInPanZone,
 185       onPanStart, onPan, onPanEnd, doPan, onCanvasMouseMove, applyBrowserZoomLevel;
 186
 187   // Touch event functions
 188   var onZoomHandleTouchEvent, onCanvasTouchEvent, addTouchEvents;
 189
 190   toXDataWindow = function(zoomHandleStatus) {
 191     var xDataLimits = self.dygraph_.xAxisExtremes();
 192     var fact = (xDataLimits[1] - xDataLimits[0])/self.canvasRect_.w;
 193     var xDataMin = xDataLimits[0] + (zoomHandleStatus.leftHandlePos - self.canvasRect_.x)*fact;
 194     var xDataMax = xDataLimits[0] + (zoomHandleStatus.rightHandlePos - self.canvasRect_.x)*fact;
 195     return [xDataMin, xDataMax];
 196   };
 197
 198   applyBrowserZoomLevel = function(delX) {
 199     var zoom = window.outerWidth/document.documentElement.clientWidth;
 200     if (!isNaN(zoom)) {
 201       return delX/zoom;
 202     } else {
 203       return delX;
 204     }
 205   };
 206
 207   onZoomStart = function(e) {
 208     Dygraph.cancelEvent(e);
 209     isZooming = true;
 210     xLast = e.screenX;
 211     handle = e.target ? e.target : e.srcElement;
 212     self.dygraph_.addEvent(topElem, 'mousemove', onZoom);
 213     self.dygraph_.addEvent(topElem, 'mouseup', onZoomEnd);
 214     self.fgcanvas_.style.cursor = 'col-resize';
 215     return true;
 216   };
 217
 218   onZoom = function(e) {
 219     if (!isZooming) {
 220       return false;
 221     }
 222     Dygraph.cancelEvent(e);
 223     var delX = e.screenX - xLast;
 224     if (Math.abs(delX) < 4 || e.screenX == 0) { // First iPad move event seems to have screenX = 0
 225       return true;
 226     }
 227     xLast = e.screenX;
 228     delX = applyBrowserZoomLevel(delX);
 229
 230     // Move handle.
 231     var zoomHandleStatus = self.getZoomHandleStatus_();
 232     var newPos;
 233     if (handle == self.leftZoomHandle_) {
 234       newPos = zoomHandleStatus.leftHandlePos + delX;
 235       newPos = Math.min(newPos, zoomHandleStatus.rightHandlePos - handle.width - 3);
 236       newPos = Math.max(newPos, self.canvasRect_.x);
 237     } else {
 238       newPos = zoomHandleStatus.rightHandlePos + delX;
 239       newPos = Math.min(newPos, self.canvasRect_.x + self.canvasRect_.w);
 240       newPos = Math.max(newPos, zoomHandleStatus.leftHandlePos + handle.width + 3);
 241     }
 242     var halfHandleWidth = handle.width/2;
 243     handle.style.left = (newPos - halfHandleWidth) + 'px';
 244     self.drawInteractiveLayer_();
 245
 246     // Zoom on the fly (if not using excanvas).
 247     if (dynamic) {
 248       doZoom();
 249     }
 250     return true;
 251   };
 252
 253   onZoomEnd = function(e) {
 254     if (!isZooming) {
 255       return false;
 256     }
 257     isZooming = false;
 258     Dygraph.removeEvent(topElem, 'mousemove', onZoom);
 259     Dygraph.removeEvent(topElem, 'mouseup', onZoomEnd);
 260     self.fgcanvas_.style.cursor = 'default';
 261
 262     // If using excanvas, Zoom now.
 263     if (!dynamic) {
 264       doZoom();
 265     }
 266     return true;
 267   };
 268
 269   doZoom = function() {
 270     try {
 271       var zoomHandleStatus = self.getZoomHandleStatus_();
 272       self.isChangingRange_ = true;
 273       if (!zoomHandleStatus.isZoomed) {
 274         self.dygraph_.doUnzoom_();
 275       } else {
 276         var xDataWindow = toXDataWindow(zoomHandleStatus);
 277         self.dygraph_.doZoomXDates_(xDataWindow[0], xDataWindow[1]);
 278       }
 279     } finally {
 280       self.isChangingRange_ = false;
 281     }
 282   };
 283
 284   isMouseInPanZone = function(e) {
 285     if (self.isUsingExcanvas_) {
 286         return e.srcElement == self.iePanOverlay_;
 287     } else {
 288       var rect = self.leftZoomHandle_.getBoundingClientRect();
 289       var leftHandleClientX = rect.left + rect.width/2;
 290       rect = self.rightZoomHandle_.getBoundingClientRect();
 291       var rightHandleClientX = rect.left + rect.width/2;
 292       return (e.clientX > leftHandleClientX && e.clientX < rightHandleClientX);
 293     }
 294   };
 295
 296   onPanStart = function(e) {
 297     if (!isPanning && isMouseInPanZone(e) && self.getZoomHandleStatus_().isZoomed) {
 298       Dygraph.cancelEvent(e);
 299       isPanning = true;
 300       xLast = e.screenX;
 301       self.dygraph_.addEvent(topElem, 'mousemove', onPan);
 302       self.dygraph_.addEvent(topElem, 'mouseup', onPanEnd);
 303       return true;
 304     }
 305     return false;
 306   };
 307
 308   onPan = function(e) {
 309     if (!isPanning) {
 310       return false;
 311     }
 312     Dygraph.cancelEvent(e);
 313
 314     var delX = e.screenX - xLast;
 315     if (Math.abs(delX) < 4) {
 316       return true;
 317     }
 318     xLast = e.screenX;
 319     delX = applyBrowserZoomLevel(delX);
 320
 321     // Move range view
 322     var zoomHandleStatus = self.getZoomHandleStatus_();
 323     var leftHandlePos = zoomHandleStatus.leftHandlePos;
 324     var rightHandlePos = zoomHandleStatus.rightHandlePos;
 325     var rangeSize = rightHandlePos - leftHandlePos;
 326     if (leftHandlePos + delX <= self.canvasRect_.x) {
 327       leftHandlePos = self.canvasRect_.x;
 328       rightHandlePos = leftHandlePos + rangeSize;
 329     } else if (rightHandlePos + delX >= self.canvasRect_.x + self.canvasRect_.w) {
 330       rightHandlePos = self.canvasRect_.x + self.canvasRect_.w;
 331       leftHandlePos = rightHandlePos - rangeSize;
 332     } else {
 333       leftHandlePos += delX;
 334       rightHandlePos += delX;
 335     }
 336     var halfHandleWidth = self.leftZoomHandle_.width/2;
 337     self.leftZoomHandle_.style.left = (leftHandlePos - halfHandleWidth) + 'px';
 338     self.rightZoomHandle_.style.left = (rightHandlePos - halfHandleWidth) + 'px';
 339     self.drawInteractiveLayer_();
 340
 341     // Do pan on the fly (if not using excanvas).
 342     if (dynamic) {
 343       doPan();
 344     }
 345     return true;
 346   };
 347
 348   onPanEnd = function(e) {
 349     if (!isPanning) {
 350       return false;
 351     }
 352     isPanning = false;
 353     Dygraph.removeEvent(topElem, 'mousemove', onPan);
 354     Dygraph.removeEvent(topElem, 'mouseup', onPanEnd);
 355     // If using excanvas, do pan now.
 356     if (!dynamic) {
 357       doPan();
 358     }
 359     return true;
 360   };
 361
 362   doPan = function() {
 363     try {
 364       self.isChangingRange_ = true;
 365       self.dygraph_.dateWindow_ = toXDataWindow(self.getZoomHandleStatus_());
 366       self.dygraph_.drawGraph_(false);
 367     } finally {
 368       self.isChangingRange_ = false;
 369     }
 370   };
 371
 372   onCanvasMouseMove = function(e) {
 373     if (isZooming || isPanning) {
 374       return;
 375     }
 376     var cursor = isMouseInPanZone(e) ? 'move' : 'default';
 377     if (cursor != self.fgcanvas_.style.cursor) {
 378       self.fgcanvas_.style.cursor = cursor;
 379     }
 380   };
 381
 382   onZoomHandleTouchEvent = function(e) {
 383     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 384       if (onZoomStart(e.targetTouches[0])) {
 385         Dygraph.cancelEvent(e);
 386       }
 387     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 388       if (onZoom(e.targetTouches[0])) {
 389         Dygraph.cancelEvent(e);
 390       }
 391     } else {
 392       onZoomEnd(e);
 393     }
 394   };
 395
 396   onCanvasTouchEvent = function(e) {
 397     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 398       if (onPanStart(e.targetTouches[0])) {
 399         Dygraph.cancelEvent(e);
 400       }
 401     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 402       if (onPan(e.targetTouches[0])) {
 403         Dygraph.cancelEvent(e);
 404       }
 405     } else {
 406       onPanEnd(e);
 407     }
 408   };
 409
 410   addTouchEvents = function(elem, fn) {
 411     var types = ['touchstart', 'touchend', 'touchmove', 'touchcancel'];
 412     for (var i = 0; i < types.length; i++) {
 413       self.dygraph_.addEvent(elem, types[i], fn);
 414     }
 415   };
 416
 417   this.dygraph_.attrs_.interactionModel =
 418       Dygraph.Interaction.dragIsPanInteractionModel;
 419   this.dygraph_.attrs_.panEdgeFraction = 0.0001;
 420
 421   var dragStartEvent = window.opera ? 'mousedown' : 'dragstart';
 422   this.dygraph_.addEvent(this.leftZoomHandle_, dragStartEvent, onZoomStart);
 423   this.dygraph_.addEvent(this.rightZoomHandle_, dragStartEvent, onZoomStart);
 424
 425   if (this.isUsingExcanvas_) {
 426     this.dygraph_.addEvent(this.iePanOverlay_, 'mousedown', onPanStart);
 427   } else {
 428     this.dygraph_.addEvent(this.fgcanvas_, 'mousedown', onPanStart);
 429     this.dygraph_.addEvent(this.fgcanvas_, 'mousemove', onCanvasMouseMove);
 430   }
 431
 432   // Touch events
 433   if (this.hasTouchInterface_) {
 434     addTouchEvents(this.leftZoomHandle_, onZoomHandleTouchEvent);
 435     addTouchEvents(this.rightZoomHandle_, onZoomHandleTouchEvent);
 436     addTouchEvents(this.fgcanvas_, onCanvasTouchEvent);
 437   }
 438 };
 439
 440 /**
 441  * @private
 442  * Draws the static layer in the background canvas.
 443  */
 444 DygraphRangeSelector.prototype.drawStaticLayer_ = function() {
 445   var ctx = this.bgcanvas_ctx_;
 446   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 447   try {
 448     this.drawMiniPlot_();
 449   } catch(ex) {
 450     Dygraph.warn(ex);
 451   }
 452
 453   var margin = 0.5;
 454   this.bgcanvas_ctx_.lineWidth = 1;
 455   ctx.strokeStyle = 'gray';
 456   ctx.beginPath();
 457   ctx.moveTo(margin, margin);
 458   ctx.lineTo(margin, this.canvasRect_.h-margin);
 459   ctx.lineTo(this.canvasRect_.w-margin, this.canvasRect_.h-margin);
 460   ctx.lineTo(this.canvasRect_.w-margin, margin);
 461   ctx.stroke();
 462 };
 463
 464
 465 /**
 466  * @private
 467  * Draws the mini plot in the background canvas.
 468  */
 469 DygraphRangeSelector.prototype.drawMiniPlot_ = function() {
 470   var fillStyle = this.attr_('rangeSelectorPlotFillColor');
 471   var strokeStyle = this.attr_('rangeSelectorPlotStrokeColor');
 472   if (!fillStyle && !strokeStyle) {
 473     return;
 474   }
 475
 476   var combinedSeriesData = this.computeCombinedSeriesAndLimits_();
 477   var yRange = combinedSeriesData.yMax - combinedSeriesData.yMin;
 478
 479   // Draw the mini plot.
 480   var ctx = this.bgcanvas_ctx_;
 481   var margin = 0.5;
 482
 483   var xExtremes = this.dygraph_.xAxisExtremes();
 484   var xRange = Math.max(xExtremes[1] - xExtremes[0], 1.e-30);
 485   var xFact = (this.canvasRect_.w - margin)/xRange;
 486   var yFact = (this.canvasRect_.h - margin)/yRange;
 487   var canvasWidth = this.canvasRect_.w - margin;
 488   var canvasHeight = this.canvasRect_.h - margin;
 489
 490   ctx.beginPath();
 491   ctx.moveTo(margin, canvasHeight);
 492   for (var i = 0; i < combinedSeriesData.data.length; i++) {
 493     var dataPoint = combinedSeriesData.data[i];
 494     var x = (dataPoint[0] - xExtremes[0])*xFact;
 495     var y = canvasHeight - (dataPoint[1] - combinedSeriesData.yMin)*yFact;
 496     if (isFinite(x) && isFinite(y)) {
 497       ctx.lineTo(x, y);
 498     }
 499   }
 500   ctx.lineTo(canvasWidth, canvasHeight);
 501   ctx.closePath();
 502
 503   if (fillStyle) {
 504     var lingrad = this.bgcanvas_ctx_.createLinearGradient(0, 0, 0, canvasHeight);
 505     lingrad.addColorStop(0, 'white');
 506     lingrad.addColorStop(1, fillStyle);
 507     this.bgcanvas_ctx_.fillStyle = lingrad;
 508     ctx.fill();
 509   }
 510
 511   if (strokeStyle) {
 512     this.bgcanvas_ctx_.strokeStyle = strokeStyle;
 513     this.bgcanvas_ctx_.lineWidth = 1.5;
 514     ctx.stroke();
 515   }
 516 };
 517
 518 /**
 519  * @private
 520  * Computes and returns the combinded series data along with min/max for the mini plot.
 521  * @return {Object} An object containing combinded series array, ymin, ymax.
 522  */
 523 DygraphRangeSelector.prototype.computeCombinedSeriesAndLimits_ = function() {
 524   var data = this.dygraph_.rawData_;
 525   var logscale = this.attr_('logscale');
 526
 527   // Create a combined series (average of all series values).
 528   var combinedSeries = [];
 529   var sum;
 530   var count;
 531   var mutipleValues;
 532   var i, j, k;
 533   var xVal, yVal;
 534
 535   // Find out if data has multiple values per datapoint.
 536   // Go to first data point that actually has values (see http://code.google.com/p/dygraphs/issues/detail?id=246)
 537   for (i = 0; i < data.length; i++) {
 538     if (data[i].length > 1 && data[i][1] !== null) {
 539       mutipleValues = typeof data[i][1] != 'number';
 540       if (mutipleValues) {
 541         sum = [];
 542         count = [];
 543         for (k = 0; k < data[i][1].length; k++) {
 544           sum.push(0);
 545           count.push(0);
 546         }
 547       }
 548       break;
 549     }
 550   }
 551
 552   for (i = 0; i < data.length; i++) {
 553     var dataPoint = data[i];
 554     xVal = dataPoint[0];
 555
 556     if (mutipleValues) {
 557       for (k = 0; k < sum.length; k++) {
 558         sum[k] = count[k] = 0;
 559       }
 560     } else {
 561       sum = count = 0;
 562     }
 563
 564     for (j = 1; j < dataPoint.length; j++) {
 565       if (this.dygraph_.visibility()[j-1]) {
 566         var y;
 567         if (mutipleValues) {
 568           for (k = 0; k < sum.length; k++) {
 569             y = dataPoint[j][k];
 570             if (y === null || isNaN(y)) continue;
 571             sum[k] += y;
 572             count[k]++;
 573           }
 574         } else {
 575           y = dataPoint[j];
 576           if (y === null || isNaN(y)) continue;
 577           sum += y;
 578           count++;
 579         }
 580       }
 581     }
 582
 583     if (mutipleValues) {
 584       for (k = 0; k < sum.length; k++) {
 585         sum[k] /= count[k];
 586       }
 587       yVal = sum.slice(0);
 588     } else {
 589       yVal = sum/count;
 590     }
 591
 592     combinedSeries.push([xVal, yVal]);
 593   }
 594
 595   // Account for roll period, fractions.
 596   combinedSeries = this.dygraph_.rollingAverage(combinedSeries, this.dygraph_.rollPeriod_);
 597
 598   if (typeof combinedSeries[0][1] != 'number') {
 599     for (i = 0; i < combinedSeries.length; i++) {
 600       yVal = combinedSeries[i][1];
 601       combinedSeries[i][1] = yVal[0];
 602     }
 603   }
 604
 605   // Compute the y range.
 606   var yMin = Number.MAX_VALUE;
 607   var yMax = -Number.MAX_VALUE;
 608   for (i = 0; i < combinedSeries.length; i++) {
 609     yVal = combinedSeries[i][1];
 610     if (yVal !== null && isFinite(yVal) && (!logscale || yVal > 0)) {
 611       yMin = Math.min(yMin, yVal);
 612       yMax = Math.max(yMax, yVal);
 613     }
 614   }
 615
 616   // Convert Y data to log scale if needed.
 617   // Also, expand the Y range to compress the mini plot a little.
 618   var extraPercent = 0.25;
 619   if (logscale) {
 620     yMax = Dygraph.log10(yMax);
 621     yMax += yMax*extraPercent;
 622     yMin = Dygraph.log10(yMin);
 623     for (i = 0; i < combinedSeries.length; i++) {
 624       combinedSeries[i][1] = Dygraph.log10(combinedSeries[i][1]);
 625     }
 626   } else {
 627     var yExtra;
 628     var yRange = yMax - yMin;
 629     if (yRange <= Number.MIN_VALUE) {
 630       yExtra = yMax*extraPercent;
 631     } else {
 632       yExtra = yRange*extraPercent;
 633     }
 634     yMax += yExtra;
 635     yMin -= yExtra;
 636   }
 637
 638   return {data: combinedSeries, yMin: yMin, yMax: yMax};
 639 };
 640
 641 /**
 642  * @private
 643  * Places the zoom handles in the proper position based on the current X data window.
 644  */
 645 DygraphRangeSelector.prototype.placeZoomHandles_ = function() {
 646   var xExtremes = this.dygraph_.xAxisExtremes();
 647   var xWindowLimits = this.dygraph_.xAxisRange();
 648   var xRange = xExtremes[1] - xExtremes[0];
 649   var leftPercent = Math.max(0, (xWindowLimits[0] - xExtremes[0])/xRange);
 650   var rightPercent = Math.max(0, (xExtremes[1] - xWindowLimits[1])/xRange);
 651   var leftCoord = this.canvasRect_.x + this.canvasRect_.w*leftPercent;
 652   var rightCoord = this.canvasRect_.x + this.canvasRect_.w*(1 - rightPercent);
 653   var handleTop = Math.max(this.canvasRect_.y, this.canvasRect_.y + (this.canvasRect_.h - this.leftZoomHandle_.height)/2);
 654   var halfHandleWidth = this.leftZoomHandle_.width/2;
 655   this.leftZoomHandle_.style.left = (leftCoord - halfHandleWidth) + 'px';
 656   this.leftZoomHandle_.style.top = handleTop + 'px';
 657   this.rightZoomHandle_.style.left = (rightCoord - halfHandleWidth) + 'px';
 658   this.rightZoomHandle_.style.top = this.leftZoomHandle_.style.top;
 659
 660   this.leftZoomHandle_.style.visibility = 'visible';
 661   this.rightZoomHandle_.style.visibility = 'visible';
 662 };
 663
 664 /**
 665  * @private
 666  * Draws the interactive layer in the foreground canvas.
 667  */
 668 DygraphRangeSelector.prototype.drawInteractiveLayer_ = function() {
 669   var ctx = this.fgcanvas_ctx_;
 670   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 671   var margin = 1;
 672   var width = this.canvasRect_.w - margin;
 673   var height = this.canvasRect_.h - margin;
 674   var zoomHandleStatus = this.getZoomHandleStatus_();
 675
 676   ctx.strokeStyle = 'black';
 677   if (!zoomHandleStatus.isZoomed) {
 678     ctx.beginPath();
 679     ctx.moveTo(margin, margin);
 680     ctx.lineTo(margin, height);
 681     ctx.lineTo(width, height);
 682     ctx.lineTo(width, margin);
 683     ctx.stroke();
 684     if (this.iePanOverlay_) {
 685       this.iePanOverlay_.style.display = 'none';
 686     }
 687   } else {
 688     var leftHandleCanvasPos = Math.max(margin, zoomHandleStatus.leftHandlePos - this.canvasRect_.x);
 689     var rightHandleCanvasPos = Math.min(width, zoomHandleStatus.rightHandlePos - this.canvasRect_.x);
 690
 691     ctx.fillStyle = 'rgba(240, 240, 240, 0.6)';
 692     ctx.fillRect(0, 0, leftHandleCanvasPos, this.canvasRect_.h);
 693     ctx.fillRect(rightHandleCanvasPos, 0, this.canvasRect_.w - rightHandleCanvasPos, this.canvasRect_.h);
 694
 695     ctx.beginPath();
 696     ctx.moveTo(margin, margin);
 697     ctx.lineTo(leftHandleCanvasPos, margin);
 698     ctx.lineTo(leftHandleCanvasPos, height);
 699     ctx.lineTo(rightHandleCanvasPos, height);
 700     ctx.lineTo(rightHandleCanvasPos, margin);
 701     ctx.lineTo(width, margin);
 702     ctx.stroke();
 703
 704     if (this.isUsingExcanvas_) {
 705       this.iePanOverlay_.style.width = (rightHandleCanvasPos - leftHandleCanvasPos) + 'px';
 706       this.iePanOverlay_.style.left = leftHandleCanvasPos + 'px';
 707       this.iePanOverlay_.style.height = height + 'px';
 708       this.iePanOverlay_.style.display = 'inline';
 709     }
 710   }
 711 };
 712
 713 /**
 714  * @private
 715  * Returns the current zoom handle position information.
 716  * @return {Object} The zoom handle status.
 717  */
 718 DygraphRangeSelector.prototype.getZoomHandleStatus_ = function() {
 719   var halfHandleWidth = this.leftZoomHandle_.width/2;
 720   var leftHandlePos = parseInt(this.leftZoomHandle_.style.left, 10) + halfHandleWidth;
 721   var rightHandlePos = parseInt(this.rightZoomHandle_.style.left, 10) + halfHandleWidth;
 722   return {
 723       leftHandlePos: leftHandlePos,
 724       rightHandlePos: rightHandlePos,
 725       isZoomed: (leftHandlePos - 1 > this.canvasRect_.x || rightHandlePos + 1 < this.canvasRect_.x+this.canvasRect_.w)
 726   };
 727 };