Add enableRetinaScaling to cloneAsImage

src/shapes/object.class.js

@@ -1306,10 +1306,12 @@
     /**
      * Creates an instance of fabric.Image out of an object
      * @param {Function} callback callback, invoked with an instance as a first argument
+     * @param {Object} [options] for clone as image, passed to toDataURL
+     * @param {Boolean} [options.enableRetinaScaling] enable retina scaling for the cloned image
      * @return {fabric.Object} thisArg
      */
-    cloneAsImage: function(callback) {
-      var dataUrl = this.toDataURL();
+    cloneAsImage: function(callback, options) {
+      var dataUrl = this.toDataURL(options);
       fabric.util.loadImage(dataUrl, function(img) {
         if (callback) {
           callback(new fabric.Image(img));
@@ -1328,6 +1330,7 @@
      * @param {Number} [options.top] Cropping top offset. Introduced in v1.2.14
      * @param {Number} [options.width] Cropping width. Introduced in v1.2.14
      * @param {Number} [options.height] Cropping height. Introduced in v1.2.14
+     * @param {Boolean} [options.enableRetina] Enable retina scaling for clone image. Introduce in 1.6.4
      * @return {String} Returns a data: URL containing a representation of the object in the format specified by options.format
      */
     toDataURL: function(options) {
@@ -1340,7 +1343,7 @@
       el.height = boundingRect.height;
 
       fabric.util.wrapElement(el, 'div');
-      var canvas = new fabric.StaticCanvas(el);
+      var canvas = new fabric.StaticCanvas(el, { enableRetinaScaling: options.enableRetinaScaling });
 
       // to avoid common confusion https://github.com/kangax/fabric.js/issues/806
       if (options.format === 'jpg') {

test/unit/object.js

@@ -566,7 +566,7 @@ test('getBoundingRectWithStroke', function() {
   });
 
   asyncTest('cloneAsImage', function() {
-    var cObj = new fabric.Rect({ width: 100, height: 100, fill: 'red' });
+    var cObj = new fabric.Rect({ width: 100, height: 100, fill: 'red', strokeWidth: 0 });
 
     ok(typeof cObj.cloneAsImage == 'function');
 
@@ -580,6 +580,7 @@ test('getBoundingRectWithStroke', function() {
       setTimeout(function() {
         ok(image);
         ok(image instanceof fabric.Image);
+        equal(image.width, 100, 'the image has same dimension of object');
         start();
       }, 500);
 
@@ -589,6 +590,30 @@ test('getBoundingRectWithStroke', function() {
     }
   });
 
+  asyncTest('cloneAsImage with retina scaling enabled', function() {
+    var cObj = new fabric.Rect({ width: 100, height: 100, fill: 'red', strokeWidth: 0 });
+    fabric.devicePixelRatio = 2;
+    if (!fabric.Canvas.supports('toDataURL')) {
+      fabric.log('`toDataURL` is not supported by this environment; skipping `cloneAsImage` test (as it relies on `toDataURL`)');
+      start();
+    }
+    else {
+      var image;
+
+      setTimeout(function() {
+        ok(image);
+        ok(image instanceof fabric.Image);
+        equal(image.width, 200, 'the image has been scaled by retina');
+        fabric.devicePixelRatio = 1;
+        start();
+      }, 500);
+
+      cObj.cloneAsImage(function(i) {
+        image = i;
+      }, { enableRetinaScaling: true });
+    }
+  });
+
   test('toDataURL', function() {
     // var data =
     //   'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAGQA'+
@@ -601,7 +626,7 @@ test('getBoundingRectWithStroke', function() {
     //   'JC0eQCGpM0DMCRtHsDjB5K06yueJFXJAAAAAElFTkSuQmCC';
 
     var cObj = new fabric.Rect({
-      width: 100, height: 100, fill: 'red'
+      width: 100, height: 100, fill: 'red', strokeWidth: 0
     });
 
     ok(typeof cObj.toDataURL == 'function');