Factory methods for heap-allocated SkImageFilter objects.

include/effects/SkDropShadowImageFilter.h

Index: include/effects/SkDropShadowImageFilter.h
diff --git a/include/effects/SkDropShadowImageFilter.h b/include/effects/SkDropShadowImageFilter.h
index aba2017eef6d61f648ece238e97de36958e052c0..58043862941e84f5a20a1261fe6995e10a0a8c03 100644
--- a/include/effects/SkDropShadowImageFilter.h
+++ b/include/effects/SkDropShadowImageFilter.h
@@ -11,8 +11,17 @@
 
 class SK_API SkDropShadowImageFilter : public SkImageFilter {
 public:
-    SkDropShadowImageFilter(SkScalar dx, SkScalar dy, SkScalar sigma, SkColor, SkImageFilter* input = NULL);
-    SkDropShadowImageFilter(SkScalar dx, SkScalar dy, SkScalar sigmaX, SkScalar sigmaY, SkColor, SkImageFilter* input = NULL, const CropRect* cropRect = NULL);
+    static SkDropShadowImageFilter* Create(SkScalar dx, SkScalar dy, SkScalar sigma,
+                                           SkColor color, SkImageFilter* input = NULL) {
+        return SkNEW_ARGS(SkDropShadowImageFilter, (dx, dy, sigma, color, input));

[reed1, 2014/03/03 18:23:19]

Perhaps not needed in this CL, but the filter team should be encouraged to
document (now that we're using factories) that the factory might return NULL for
mal-formed parameters (not just dropshadow, but in general).

Factories also enable us to use specialized/alternate impls based on input,
rather than forcing us to create the actual subclass the client thought they
were asking for.

[Stephen White, 2014/03/03 19:48:04]

Yep! It would be great to move to factories for deserialization (SkReadBuffer
construction) too, so that we can fail gracefully without having to early-out
and an invalid object.

+    }
+    static SkDropShadowImageFilter* Create(SkScalar dx, SkScalar dy,
+                                           SkScalar sigmaX, SkScalar sigmaY, SkColor color,
+                                           SkImageFilter* input = NULL,
+                                           const CropRect* cropRect = NULL) {
+        return SkNEW_ARGS(SkDropShadowImageFilter, (dx, dy, sigmaX, sigmaY,
+                                                    color, input, cropRect));
+    }
     virtual void computeFastBounds(const SkRect&, SkRect*) const SK_OVERRIDE;
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkDropShadowImageFilter)
 
@@ -23,7 +32,13 @@ protected:
     virtual bool onFilterBounds(const SkIRect& src, const SkMatrix&,
                                 SkIRect* dst) const SK_OVERRIDE;
 
-
+#ifdef SK_SUPPORT_LEGACY_PUBLICEFFECTCONSTRUCTORS
+public:
+#endif
+    SkDropShadowImageFilter(SkScalar dx, SkScalar dy, SkScalar sigma, SkColor,
+                            SkImageFilter* input = NULL);
+    SkDropShadowImageFilter(SkScalar dx, SkScalar dy, SkScalar sigmaX, SkScalar sigmaY, SkColor,
+                            SkImageFilter* input = NULL, const CropRect* cropRect = NULL);
 
 private:
     SkScalar fDx, fDy, fSigmaX, fSigmaY;