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_('xAxisHeight') || (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) {
 225       // First iPad move event seems to have screenX = 0
 226       return true;
 227     }
 228     xLast = e.screenX;
 229     delX = applyBrowserZoomLevel(delX);
 230
 231     // Move handle.
 232     var zoomHandleStatus = self.getZoomHandleStatus_();
 233     var newPos;
 234     if (handle == self.leftZoomHandle_) {
 235       newPos = zoomHandleStatus.leftHandlePos + delX;
 236       newPos = Math.min(newPos, zoomHandleStatus.rightHandlePos - handle.width - 3);
 237       newPos = Math.max(newPos, self.canvasRect_.x);
 238     } else {
 239       newPos = zoomHandleStatus.rightHandlePos + delX;
 240       newPos = Math.min(newPos, self.canvasRect_.x + self.canvasRect_.w);
 241       newPos = Math.max(newPos, zoomHandleStatus.leftHandlePos + handle.width + 3);
 242     }
 243     var halfHandleWidth = handle.width/2;
 244     handle.style.left = (newPos - halfHandleWidth) + 'px';
 245     self.drawInteractiveLayer_();
 246
 247     // Zoom on the fly (if not using excanvas).
 248     if (dynamic) {
 249       doZoom();
 250     }
 251     return true;
 252   };
 253
 254   onZoomEnd = function(e) {
 255     if (!isZooming) {
 256       return false;
 257     }
 258     isZooming = false;
 259     Dygraph.removeEvent(topElem, 'mousemove', onZoom);
 260     Dygraph.removeEvent(topElem, 'mouseup', onZoomEnd);
 261     self.fgcanvas_.style.cursor = 'default';
 262
 263     // If using excanvas, Zoom now.
 264     if (!dynamic) {
 265       doZoom();
 266     }
 267     return true;
 268   };
 269
 270   doZoom = function() {
 271     try {
 272       var zoomHandleStatus = self.getZoomHandleStatus_();
 273       self.isChangingRange_ = true;
 274       if (!zoomHandleStatus.isZoomed) {
 275         self.dygraph_.doUnzoom_();
 276       } else {
 277         var xDataWindow = toXDataWindow(zoomHandleStatus);
 278         self.dygraph_.doZoomXDates_(xDataWindow[0], xDataWindow[1]);
 279       }
 280     } finally {
 281       self.isChangingRange_ = false;
 282     }
 283   };
 284
 285   isMouseInPanZone = function(e) {
 286     if (self.isUsingExcanvas_) {
 287         return e.srcElement == self.iePanOverlay_;
 288     } else {
 289       var rect = self.leftZoomHandle_.getBoundingClientRect();
 290       var leftHandleClientX = rect.left + rect.width/2;
 291       rect = self.rightZoomHandle_.getBoundingClientRect();
 292       var rightHandleClientX = rect.left + rect.width/2;
 293       return (e.clientX > leftHandleClientX && e.clientX < rightHandleClientX);
 294     }
 295   };
 296
 297   onPanStart = function(e) {
 298     if (!isPanning && isMouseInPanZone(e) && self.getZoomHandleStatus_().isZoomed) {
 299       Dygraph.cancelEvent(e);
 300       isPanning = true;
 301       xLast = e.screenX;
 302       self.dygraph_.addEvent(topElem, 'mousemove', onPan);
 303       self.dygraph_.addEvent(topElem, 'mouseup', onPanEnd);
 304       return true;
 305     }
 306     return false;
 307   };
 308
 309   onPan = function(e) {
 310     if (!isPanning) {
 311       return false;
 312     }
 313     Dygraph.cancelEvent(e);
 314
 315     var delX = e.screenX - xLast;
 316     if (Math.abs(delX) < 4) {
 317       return true;
 318     }
 319     xLast = e.screenX;
 320     delX = applyBrowserZoomLevel(delX);
 321
 322     // Move range view
 323     var zoomHandleStatus = self.getZoomHandleStatus_();
 324     var leftHandlePos = zoomHandleStatus.leftHandlePos;
 325     var rightHandlePos = zoomHandleStatus.rightHandlePos;
 326     var rangeSize = rightHandlePos - leftHandlePos;
 327     if (leftHandlePos + delX <= self.canvasRect_.x) {
 328       leftHandlePos = self.canvasRect_.x;
 329       rightHandlePos = leftHandlePos + rangeSize;
 330     } else if (rightHandlePos + delX >= self.canvasRect_.x + self.canvasRect_.w) {
 331       rightHandlePos = self.canvasRect_.x + self.canvasRect_.w;
 332       leftHandlePos = rightHandlePos - rangeSize;
 333     } else {
 334       leftHandlePos += delX;
 335       rightHandlePos += delX;
 336     }
 337     var halfHandleWidth = self.leftZoomHandle_.width/2;
 338     self.leftZoomHandle_.style.left = (leftHandlePos - halfHandleWidth) + 'px';
 339     self.rightZoomHandle_.style.left = (rightHandlePos - halfHandleWidth) + 'px';
 340     self.drawInteractiveLayer_();
 341
 342     // Do pan on the fly (if not using excanvas).
 343     if (dynamic) {
 344       doPan();
 345     }
 346     return true;
 347   };
 348
 349   onPanEnd = function(e) {
 350     if (!isPanning) {
 351       return false;
 352     }
 353     isPanning = false;
 354     Dygraph.removeEvent(topElem, 'mousemove', onPan);
 355     Dygraph.removeEvent(topElem, 'mouseup', onPanEnd);
 356     // If using excanvas, do pan now.
 357     if (!dynamic) {
 358       doPan();
 359     }
 360     return true;
 361   };
 362
 363   doPan = function() {
 364     try {
 365       self.isChangingRange_ = true;
 366       self.dygraph_.dateWindow_ = toXDataWindow(self.getZoomHandleStatus_());
 367       self.dygraph_.drawGraph_(false);
 368     } finally {
 369       self.isChangingRange_ = false;
 370     }
 371   };
 372
 373   onCanvasMouseMove = function(e) {
 374     if (isZooming || isPanning) {
 375       return;
 376     }
 377     var cursor = isMouseInPanZone(e) ? 'move' : 'default';
 378     if (cursor != self.fgcanvas_.style.cursor) {
 379       self.fgcanvas_.style.cursor = cursor;
 380     }
 381   };
 382
 383   onZoomHandleTouchEvent = function(e) {
 384     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 385       if (onZoomStart(e.targetTouches[0])) {
 386         Dygraph.cancelEvent(e);
 387       }
 388     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 389       if (onZoom(e.targetTouches[0])) {
 390         Dygraph.cancelEvent(e);
 391       }
 392     } else {
 393       onZoomEnd(e);
 394     }
 395   };
 396
 397   onCanvasTouchEvent = function(e) {
 398     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 399       if (onPanStart(e.targetTouches[0])) {
 400         Dygraph.cancelEvent(e);
 401       }
 402     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 403       if (onPan(e.targetTouches[0])) {
 404         Dygraph.cancelEvent(e);
 405       }
 406     } else {
 407       onPanEnd(e);
 408     }
 409   };
 410
 411   addTouchEvents = function(elem, fn) {
 412     var types = ['touchstart', 'touchend', 'touchmove', 'touchcancel'];
 413     for (var i = 0; i < types.length; i++) {
 414       self.dygraph_.addEvent(elem, types[i], fn);
 415     }
 416   };
 417
 418   this.dygraph_.attrs_.interactionModel =
 419       Dygraph.Interaction.dragIsPanInteractionModel;
 420   this.dygraph_.attrs_.panEdgeFraction = 0.0001;
 421
 422   var dragStartEvent = window.opera ? 'mousedown' : 'dragstart';
 423   this.dygraph_.addEvent(this.leftZoomHandle_, dragStartEvent, onZoomStart);
 424   this.dygraph_.addEvent(this.rightZoomHandle_, dragStartEvent, onZoomStart);
 425
 426   if (this.isUsingExcanvas_) {
 427     this.dygraph_.addEvent(this.iePanOverlay_, 'mousedown', onPanStart);
 428   } else {
 429     this.dygraph_.addEvent(this.fgcanvas_, 'mousedown', onPanStart);
 430     this.dygraph_.addEvent(this.fgcanvas_, 'mousemove', onCanvasMouseMove);
 431   }
 432
 433   // Touch events
 434   if (this.hasTouchInterface_) {
 435     addTouchEvents(this.leftZoomHandle_, onZoomHandleTouchEvent);
 436     addTouchEvents(this.rightZoomHandle_, onZoomHandleTouchEvent);
 437     addTouchEvents(this.fgcanvas_, onCanvasTouchEvent);
 438   }
 439 };
 440
 441 /**
 442  * @private
 443  * Draws the static layer in the background canvas.
 444  */
 445 DygraphRangeSelector.prototype.drawStaticLayer_ = function() {
 446   var ctx = this.bgcanvas_ctx_;
 447   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 448   try {
 449     this.drawMiniPlot_();
 450   } catch(ex) {
 451     Dygraph.warn(ex);
 452   }
 453
 454   var margin = 0.5;
 455   this.bgcanvas_ctx_.lineWidth = 1;
 456   ctx.strokeStyle = 'gray';
 457   ctx.beginPath();
 458   ctx.moveTo(margin, margin);
 459   ctx.lineTo(margin, this.canvasRect_.h-margin);
 460   ctx.lineTo(this.canvasRect_.w-margin, this.canvasRect_.h-margin);
 461   ctx.lineTo(this.canvasRect_.w-margin, margin);
 462   ctx.stroke();
 463 };
 464
 465
 466 /**
 467  * @private
 468  * Draws the mini plot in the background canvas.
 469  */
 470 DygraphRangeSelector.prototype.drawMiniPlot_ = function() {
 471   var fillStyle = this.attr_('rangeSelectorPlotFillColor');
 472   var strokeStyle = this.attr_('rangeSelectorPlotStrokeColor');
 473   if (!fillStyle && !strokeStyle) {
 474     return;
 475   }
 476
 477   var combinedSeriesData = this.computeCombinedSeriesAndLimits_();
 478   var yRange = combinedSeriesData.yMax - combinedSeriesData.yMin;
 479
 480   // Draw the mini plot.
 481   var ctx = this.bgcanvas_ctx_;
 482   var margin = 0.5;
 483
 484   var xExtremes = this.dygraph_.xAxisExtremes();
 485   var xRange = Math.max(xExtremes[1] - xExtremes[0], 1.e-30);
 486   var xFact = (this.canvasRect_.w - margin)/xRange;
 487   var yFact = (this.canvasRect_.h - margin)/yRange;
 488   var canvasWidth = this.canvasRect_.w - margin;
 489   var canvasHeight = this.canvasRect_.h - margin;
 490
 491   ctx.beginPath();
 492   ctx.moveTo(margin, canvasHeight);
 493   for (var i = 0; i < combinedSeriesData.data.length; i++) {
 494     var dataPoint = combinedSeriesData.data[i];
 495     var x = (dataPoint[0] - xExtremes[0])*xFact;
 496     var y = canvasHeight - (dataPoint[1] - combinedSeriesData.yMin)*yFact;
 497     if (isFinite(x) && isFinite(y)) {
 498       ctx.lineTo(x, y);
 499     }
 500   }
 501   ctx.lineTo(canvasWidth, canvasHeight);
 502   ctx.closePath();
 503
 504   if (fillStyle) {
 505     var lingrad = this.bgcanvas_ctx_.createLinearGradient(0, 0, 0, canvasHeight);
 506     lingrad.addColorStop(0, 'white');
 507     lingrad.addColorStop(1, fillStyle);
 508     this.bgcanvas_ctx_.fillStyle = lingrad;
 509     ctx.fill();
 510   }
 511
 512   if (strokeStyle) {
 513     this.bgcanvas_ctx_.strokeStyle = strokeStyle;
 514     this.bgcanvas_ctx_.lineWidth = 1.5;
 515     ctx.stroke();
 516   }
 517 };
 518
 519 /**
 520  * @private
 521  * Computes and returns the combinded series data along with min/max for the mini plot.
 522  * @return {Object} An object containing combinded series array, ymin, ymax.
 523  */
 524 DygraphRangeSelector.prototype.computeCombinedSeriesAndLimits_ = function() {
 525   var data = this.dygraph_.rawData_;
 526   var logscale = this.attr_('logscale');
 527
 528   // Create a combined series (average of all series values).
 529   var combinedSeries = [];
 530   var sum;
 531   var count;
 532   var mutipleValues;
 533   var i, j, k;
 534   var xVal, yVal;
 535
 536   // Find out if data has multiple values per datapoint.
 537   // Go to first data point that actually has values (see http://code.google.com/p/dygraphs/issues/detail?id=246)
 538   for (i = 0; i < data.length; i++) {
 539     if (data[i].length > 1 && data[i][1] !== null) {
 540       mutipleValues = typeof data[i][1] != 'number';
 541       if (mutipleValues) {
 542         sum = [];
 543         count = [];
 544         for (k = 0; k < data[i][1].length; k++) {
 545           sum.push(0);
 546           count.push(0);
 547         }
 548       }
 549       break;
 550     }
 551   }
 552
 553   for (i = 0; i < data.length; i++) {
 554     var dataPoint = data[i];
 555     xVal = dataPoint[0];
 556
 557     if (mutipleValues) {
 558       for (k = 0; k < sum.length; k++) {
 559         sum[k] = count[k] = 0;
 560       }
 561     } else {
 562       sum = count = 0;
 563     }
 564
 565     for (j = 1; j < dataPoint.length; j++) {
 566       if (this.dygraph_.visibility()[j-1]) {
 567         var y;
 568         if (mutipleValues) {
 569           for (k = 0; k < sum.length; k++) {
 570             y = dataPoint[j][k];
 571             if (y === null || isNaN(y)) continue;
 572             sum[k] += y;
 573             count[k]++;
 574           }
 575         } else {
 576           y = dataPoint[j];
 577           if (y === null || isNaN(y)) continue;
 578           sum += y;
 579           count++;
 580         }
 581       }
 582     }
 583
 584     if (mutipleValues) {
 585       for (k = 0; k < sum.length; k++) {
 586         sum[k] /= count[k];
 587       }
 588       yVal = sum.slice(0);
 589     } else {
 590       yVal = sum/count;
 591     }
 592
 593     combinedSeries.push([xVal, yVal]);
 594   }
 595
 596   // Account for roll period, fractions.
 597   combinedSeries = this.dygraph_.rollingAverage(combinedSeries, this.dygraph_.rollPeriod_);
 598
 599   if (typeof combinedSeries[0][1] != 'number') {
 600     for (i = 0; i < combinedSeries.length; i++) {
 601       yVal = combinedSeries[i][1];
 602       combinedSeries[i][1] = yVal[0];
 603     }
 604   }
 605
 606   // Compute the y range.
 607   var yMin = Number.MAX_VALUE;
 608   var yMax = -Number.MAX_VALUE;
 609   for (i = 0; i < combinedSeries.length; i++) {
 610     yVal = combinedSeries[i][1];
 611     if (yVal !== null && isFinite(yVal) && (!logscale || yVal > 0)) {
 612       yMin = Math.min(yMin, yVal);
 613       yMax = Math.max(yMax, yVal);
 614     }
 615   }
 616
 617   // Convert Y data to log scale if needed.
 618   // Also, expand the Y range to compress the mini plot a little.
 619   var extraPercent = 0.25;
 620   if (logscale) {
 621     yMax = Dygraph.log10(yMax);
 622     yMax += yMax*extraPercent;
 623     yMin = Dygraph.log10(yMin);
 624     for (i = 0; i < combinedSeries.length; i++) {
 625       combinedSeries[i][1] = Dygraph.log10(combinedSeries[i][1]);
 626     }
 627   } else {
 628     var yExtra;
 629     var yRange = yMax - yMin;
 630     if (yRange <= Number.MIN_VALUE) {
 631       yExtra = yMax*extraPercent;
 632     } else {
 633       yExtra = yRange*extraPercent;
 634     }
 635     yMax += yExtra;
 636     yMin -= yExtra;
 637   }
 638
 639   return {data: combinedSeries, yMin: yMin, yMax: yMax};
 640 };
 641
 642 /**
 643  * @private
 644  * Places the zoom handles in the proper position based on the current X data window.
 645  */
 646 DygraphRangeSelector.prototype.placeZoomHandles_ = function() {
 647   var xExtremes = this.dygraph_.xAxisExtremes();
 648   var xWindowLimits = this.dygraph_.xAxisRange();
 649   var xRange = xExtremes[1] - xExtremes[0];
 650   var leftPercent = Math.max(0, (xWindowLimits[0] - xExtremes[0])/xRange);
 651   var rightPercent = Math.max(0, (xExtremes[1] - xWindowLimits[1])/xRange);
 652   var leftCoord = this.canvasRect_.x + this.canvasRect_.w*leftPercent;
 653   var rightCoord = this.canvasRect_.x + this.canvasRect_.w*(1 - rightPercent);
 654   var handleTop = Math.max(this.canvasRect_.y, this.canvasRect_.y + (this.canvasRect_.h - this.leftZoomHandle_.height)/2);
 655   var halfHandleWidth = this.leftZoomHandle_.width/2;
 656   this.leftZoomHandle_.style.left = (leftCoord - halfHandleWidth) + 'px';
 657   this.leftZoomHandle_.style.top = handleTop + 'px';
 658   this.rightZoomHandle_.style.left = (rightCoord - halfHandleWidth) + 'px';
 659   this.rightZoomHandle_.style.top = this.leftZoomHandle_.style.top;
 660
 661   this.leftZoomHandle_.style.visibility = 'visible';
 662   this.rightZoomHandle_.style.visibility = 'visible';
 663 };
 664
 665 /**
 666  * @private
 667  * Draws the interactive layer in the foreground canvas.
 668  */
 669 DygraphRangeSelector.prototype.drawInteractiveLayer_ = function() {
 670   var ctx = this.fgcanvas_ctx_;
 671   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 672   var margin = 1;
 673   var width = this.canvasRect_.w - margin;
 674   var height = this.canvasRect_.h - margin;
 675   var zoomHandleStatus = this.getZoomHandleStatus_();
 676
 677   ctx.strokeStyle = 'black';
 678   if (!zoomHandleStatus.isZoomed) {
 679     ctx.beginPath();
 680     ctx.moveTo(margin, margin);
 681     ctx.lineTo(margin, height);
 682     ctx.lineTo(width, height);
 683     ctx.lineTo(width, margin);
 684     ctx.stroke();
 685     if (this.iePanOverlay_) {
 686       this.iePanOverlay_.style.display = 'none';
 687     }
 688   } else {
 689     var leftHandleCanvasPos = Math.max(margin, zoomHandleStatus.leftHandlePos - this.canvasRect_.x);
 690     var rightHandleCanvasPos = Math.min(width, zoomHandleStatus.rightHandlePos - this.canvasRect_.x);
 691
 692     ctx.fillStyle = 'rgba(240, 240, 240, 0.6)';
 693     ctx.fillRect(0, 0, leftHandleCanvasPos, this.canvasRect_.h);
 694     ctx.fillRect(rightHandleCanvasPos, 0, this.canvasRect_.w - rightHandleCanvasPos, this.canvasRect_.h);
 695
 696     ctx.beginPath();
 697     ctx.moveTo(margin, margin);
 698     ctx.lineTo(leftHandleCanvasPos, margin);
 699     ctx.lineTo(leftHandleCanvasPos, height);
 700     ctx.lineTo(rightHandleCanvasPos, height);
 701     ctx.lineTo(rightHandleCanvasPos, margin);
 702     ctx.lineTo(width, margin);
 703     ctx.stroke();
 704
 705     if (this.isUsingExcanvas_) {
 706       this.iePanOverlay_.style.width = (rightHandleCanvasPos - leftHandleCanvasPos) + 'px';
 707       this.iePanOverlay_.style.left = leftHandleCanvasPos + 'px';
 708       this.iePanOverlay_.style.height = height + 'px';
 709       this.iePanOverlay_.style.display = 'inline';
 710     }
 711   }
 712 };
 713
 714 /**
 715  * @private
 716  * Returns the current zoom handle position information.
 717  * @return {Object} The zoom handle status.
 718  */
 719 DygraphRangeSelector.prototype.getZoomHandleStatus_ = function() {
 720   var halfHandleWidth = this.leftZoomHandle_.width/2;
 721   var leftHandlePos = parseInt(this.leftZoomHandle_.style.left, 10) + halfHandleWidth;
 722   var rightHandlePos = parseInt(this.rightZoomHandle_.style.left, 10) + halfHandleWidth;
 723   return {
 724       leftHandlePos: leftHandlePos,
 725       rightHandlePos: rightHandlePos,
 726       isZoomed: (leftHandlePos - 1 > this.canvasRect_.x || rightHandlePos + 1 < this.canvasRect_.x+this.canvasRect_.w)
 727   };
 728 };