Fix a bug in recent caching changes (#4051)

* small fix
* fixed and added tests
* comeon andrea wake up

src/shapes/group.class.js

@@ -340,7 +340,7 @@
      */
     willDrawShadow: function() {
       if (this.shadow) {
-        return true;
+        return this.callSuper('willDrawShadow');
       }
       for (var i = 0, len = this._objects.length; i < len; i++) {
         if (this._objects[i].willDrawShadow()) {

src/shapes/object.class.js

@@ -945,15 +945,15 @@
         if (shouldResizeCanvas) {
           this._cacheCanvas.width = Math.max(Math.ceil(width) + additionalWidth, minCacheSize);
           this._cacheCanvas.height = Math.max(Math.ceil(height) + additionalHeight, minCacheSize);
-          this.cacheWidth = width;
-          this.cacheHeight = height;
           this.cacheTranslationX = (width + additionalWidth) / 2;
           this.cacheTranslationY = (height + additionalHeight) / 2;
         }
         else {
           this._cacheContext.setTransform(1, 0, 0, 1, 0, 0);
           this._cacheContext.clearRect(0, 0, this._cacheCanvas.width, this._cacheCanvas.height);
         }
+        this.cacheWidth = width;
+        this.cacheHeight = height;
         this._cacheContext.translate(this.cacheTranslationX, this.cacheTranslationY);
         this._cacheContext.scale(zoomX, zoomY);
         this.zoomX = zoomX;
@@ -1268,7 +1268,7 @@
      * @return {Boolean}
      */
     willDrawShadow: function() {
-      return !!this.shadow;
+      return !!this.shadow && (this.shadow.offsetX !== 0 || this.shadow.offsetY !== 0);
     },
 
     /**

test/unit/group.js

@@ -612,18 +612,40 @@
         group3 = new fabric.Group([group, group2]);
 
     equal(group3.willDrawShadow(), false, 'group will not cast shadow because objects do not have it');
-    group3.shadow = {};
+    group3.shadow = { offsetX: 1, offsetY: 2, };
     equal(group3.willDrawShadow(), true, 'group will cast shadow because group itself has shadow');
     delete group3.shadow;
-    group2.shadow =  {};
+    group2.shadow = { offsetX: 1, offsetY: 2, };
     equal(group3.willDrawShadow(), true, 'group will cast shadow because inner group2 has shadow');
     delete group2.shadow;
-    rect1.shadow = {};
+    rect1.shadow = { offsetX: 1, offsetY: 2, };
     equal(group3.willDrawShadow(), true, 'group will cast shadow because inner rect1 has shadow');
     equal(group.willDrawShadow(), true, 'group will cast shadow because inner rect1 has shadow');
     equal(group2.willDrawShadow(), false, 'group will not cast shadow because no child has shadow');
   });
 
+  test('group willDrawShadow with no offsets', function() {
+    var rect1 = new fabric.Rect({ top: 1, left: 1, width: 2, height: 2, strokeWidth: 0, fill: 'red', opacity: 1, objectCaching: false}),
+        rect2 = new fabric.Rect({ top: 5, left: 5, width: 2, height: 2, strokeWidth: 0, fill: 'red', opacity: 1, objectCaching: false}),
+        rect3 = new fabric.Rect({ top: 5, left: 5, width: 2, height: 2, strokeWidth: 0, fill: 'red', opacity: 1, objectCaching: false}),
+        rect4 = new fabric.Rect({ top: 5, left: 5, width: 2, height: 2, strokeWidth: 0, fill: 'red', opacity: 1, objectCaching: false}),
+        group = new fabric.Group([rect1, rect2]),
+        group2 = new fabric.Group([rect3, rect4]),
+        group3 = new fabric.Group([group, group2]);
+
+    equal(group3.willDrawShadow(), false, 'group will not cast shadow because objects do not have it');
+    group3.shadow = { offsetX: 0, offsetY: 0 };
+    equal(group3.willDrawShadow(), false, 'group will NOT cast shadow because group itself has shadow but not offsets');
+    group3.shadow = { offsetX: 2, offsetY: 0 };
+    equal(group3.willDrawShadow(), true, 'group will cast shadow because group itself has shadow and one offsetX different than 0');
+    group3.shadow = { offsetX: 0, offsetY: 2 };
+    equal(group3.willDrawShadow(), true, 'group will cast shadow because group itself has shadow and one offsetY different than 0');
+    group3.shadow = { offsetX: -2, offsetY: 0 };
+    equal(group3.willDrawShadow(), true, 'group will cast shadow because group itself has shadow and one offsetX different than 0');
+    group3.shadow = { offsetX: 0, offsetY: -2 };
+    equal(group3.willDrawShadow(), true, 'group will cast shadow because group itself has shadow and one offsetY different than 0');
+  });
+
   test('group shouldCache', function() {
     var rect1 = new fabric.Rect({ top: 1, left: 1, width: 2, height: 2, strokeWidth: 0, fill: 'red', opacity: 1, objectCaching: true}),
         rect2 = new fabric.Rect({ top: 5, left: 5, width: 2, height: 2, strokeWidth: 0, fill: 'red', opacity: 1, objectCaching: true}),
@@ -637,8 +659,8 @@
     equal(group2.shouldCache(), false, 'group2 will not cache because is drawing on parent group3 cache');
     equal(rect3.shouldCache(), false, 'rect3 will not cache because is drawing on parent2 group cache');
 
-    group2.shadow = {};
-    rect1.shadow = {};
+    group2.shadow = { offsetX: 2, offsetY: 0 };
+    rect1.shadow = { offsetX: 0, offsetY: 2 };
 
     equal(group3.shouldCache(), false, 'group3 will cache because children have shadow');
     equal(group2.shouldCache(), true, 'group2 will cache because is not drawing on parent group3 cache and no children have shadow');

test/unit/object.js

@@ -1351,4 +1351,11 @@
     equal(context.shadowOffsetY, object.shadow.offsetY * object.scaleY * group.scaleY);
     equal(context.shadowBlur, object.shadow.blur * (object.scaleX * group.scaleX + object.scaleY * group.scaleY) / 2);
   });
+
+  test('willDrawShadow', function() {
+    var object = new fabric.Object({ shadow: { offsetX: 0, offsetY: 0 }});
+    equal(object.willDrawShadow(), false, 'object will not drawShadow');
+    object.shadow.offsetX = 1;
+    equal(object.willDrawShadow(), true, 'object will drawShadow');
+  });
 })();