Add ol.dom.createCanvasContext2D function

src/ol/renderer/canvas/canvasmaprenderer.js

@@ -4,10 +4,10 @@ goog.provide('ol.renderer.canvas.Map');
 
 goog.require('goog.asserts');
 goog.require('goog.dom');
-goog.require('goog.dom.TagName');
 goog.require('goog.style');
 goog.require('goog.vec.Mat4');
 goog.require('ol.css');
+goog.require('ol.dom');
 goog.require('ol.layer.Image');
 goog.require('ol.layer.Tile');
 goog.require('ol.layer.Vector');
@@ -34,12 +34,18 @@ ol.renderer.canvas.Map = function(container, map) {
 
   goog.base(this, container, map);
 
+  /**
+   * @private
+   * @type {CanvasRenderingContext2D}
+   */
+  this.context_ = ol.dom.createCanvasContext2D();
+
   /**
    * @private
    * @type {HTMLCanvasElement}
    */
-  this.canvas_ = /** @type {HTMLCanvasElement} */
-      (goog.dom.createElement(goog.dom.TagName.CANVAS));
+  this.canvas_ = this.context_.canvas;
+
   this.canvas_.style.width = '100%';
   this.canvas_.style.height = '100%';
   this.canvas_.className = ol.css.CLASS_UNSELECTABLE;
@@ -51,13 +57,6 @@ ol.renderer.canvas.Map = function(container, map) {
    */
   this.renderedVisible_ = true;
 
-  /**
-   * @private
-   * @type {CanvasRenderingContext2D}
-   */
-  this.context_ = /** @type {CanvasRenderingContext2D} */
-      (this.canvas_.getContext('2d'));
-
   /**
    * @private
    * @type {!goog.vec.Mat4.Number}