extras/crosshair.js

   1 /**
   2  * @license
   3  * Copyright 2015 Petr Shevtsov (petr.shevtsov@gmail.com)
   4  * MIT-licensed (http://opensource.org/licenses/MIT)
   5  */
   6
   7 /*global Dygraph:false */
   8 /*jshint globalstrict: true */
   9 Dygraph.Plugins.Crosshair = (function() {
  10   "use strict";
  11
  12   /**
  13    * Creates the crosshair
  14    *
  15    * @constructor
  16    */
  17
  18   var crosshair = function(opt_options) {
  19     this.canvas_ = document.createElement("canvas");
  20     opt_options = opt_options || {};
  21     this.direction_ = opt_options.direction || null;
  22   };
  23
  24   crosshair.prototype.toString = function() {
  25     return "Crosshair Plugin";
  26   };
  27
  28   /**
  29    * @param {Dygraph} g Graph instance.
  30    * @return {object.<string, function(ev)>} Mapping of event names to callbacks.
  31    */
  32   crosshair.prototype.activate = function(g) {
  33     g.graphDiv.appendChild(this.canvas_);
  34
  35     return {
  36       select: this.select,
  37       deselect: this.deselect
  38     };
  39   };
  40
  41   crosshair.prototype.select = function(e) {
  42     if (this.direction_ === null) {
  43       return;
  44     }
  45
  46     var width = e.dygraph.width_;
  47     var height = e.dygraph.height_;
  48     this.canvas_.width = width;
  49     this.canvas_.height = height;
  50     this.canvas_.style.width = width + "px";    // for IE
  51     this.canvas_.style.height = height + "px";  // for IE
  52
  53     var ctx = this.canvas_.getContext("2d");
  54     ctx.clearRect(0, 0, width, height);
  55     ctx.strokeStyle = "rgba(0, 0, 0,0.3)";
  56     ctx.beginPath();
  57
  58     var canvasx = Math.floor(e.dygraph.selPoints_[0].canvasx) + 0.5; // crisper rendering
  59
  60     if (this.direction_ === "vertical" || this.direction_ === "both") {
  61       ctx.moveTo(canvasx, 0);
  62       ctx.lineTo(canvasx, height);
  63     }
  64
  65     if (this.direction_ === "horizontal" || this.direction_ === "both") {
  66       for (var i = 0; i < e.dygraph.selPoints_.length; i++) {
  67         var canvasy = Math.floor(e.dygraph.selPoints_[i].canvasy) + 0.5; // crisper rendering
  68         ctx.moveTo(0, canvasy);
  69         ctx.lineTo(width, canvasy);
  70       }
  71     }
  72
  73     ctx.stroke();
  74     ctx.closePath();
  75   };
  76
  77   crosshair.prototype.deselect = function(e) {
  78     var ctx = this.canvas_.getContext("2d");
  79     ctx.clearRect(0, 0, this.canvas_.width, this.canvas_.height);
  80   };
  81
  82   crosshair.prototype.destroy = function() {
  83     this.canvas_ = null;
  84   };
  85
  86   return crosshair;
  87 })();