Merge branch '69-blurry-png-and-jpeg' of https://github.com/iqdoq-dfischer/dom-to-image into iqdoq-dfischer-69-blurry-png-and-jpeg

# Conflicts:
#	src/dom-to-image.js

Author: Aleksander Burzec

src/dom-to-image.js

@@ -44,7 +44,10 @@
      * @param {Number} options.width - width to be applied to node before rendering.
      * @param {Number} options.height - height to be applied to node before rendering.
      * @param {Object} options.style - an object whose properties to be copied to node's style before rendering.
-     * @param {Number} options.quality - a Number between 0 and 1 indicating image quality (applicable to JPEG only), defaults to 1.0.
+     * @param {Number} options.quality - a Number between 0 and 1 indicating image quality (applicable to JPEG only),
+                defaults to 1.0.
+     * @param {Number} options.scale - scale factor for image quality rendering (to unblurry JPEG and PNG output),
+                default = unset = no scaling applied = 1.0.
      * @param {String} options.imagePlaceholder - dataURL to use as a placeholder for failed images, default behaviour is to fail fast on images we can't fetch
      * @param {Boolean} options.cacheBust - set to true to cache bust by appending the time to the request url
      * @return {Promise} - A promise that is fulfilled with a SVG image data URL
@@ -155,15 +158,23 @@
             .then(function (image) {
                 var canvas = newCanvas(domNode);
                 var ctx = canvas.getContext('2d');
-                ctx.scale(window.devicePixelRatio, window.devicePixelRatio);
+                if (options.scale) {
+                    ctx.scale(options.scale, options.scale);
+                }
                 ctx.drawImage(image, 0, 0);
                 return canvas;
             });
 
         function newCanvas(domNode) {
             var canvas = document.createElement('canvas');
-            canvas.width = options.width || window.devicePixelRatio * util.width(domNode);
-            canvas.height = options.height || window.devicePixelRatio * util.height(domNode);
+            if (options.scale) {
+                canvas.width = options.width || options.scale * util.width(domNode);
+                canvas.height = options.height || options.scale * util.height(domNode);
+            }
+            else {
+                canvas.width = options.width || util.width(domNode);
+                canvas.height = options.height || util.height(domNode);
+            }
 
             if (options.bgcolor) {
                 var ctx = canvas.getContext('2d');