Factory methods for heap-allocated SkImageFilter objects.

include/effects/SkMatrixConvolutionImageFilter.h

Index: include/effects/SkMatrixConvolutionImageFilter.h
diff --git a/include/effects/SkMatrixConvolutionImageFilter.h b/include/effects/SkMatrixConvolutionImageFilter.h
index 59af83e025275ed29b934fa624151481602f784a..7344420848e0b9fee3fc64f04fb77474b0dfcbfc 100644
--- a/include/effects/SkMatrixConvolutionImageFilter.h
+++ b/include/effects/SkMatrixConvolutionImageFilter.h
@@ -28,6 +28,8 @@ public:
       kClampToBlack_TileMode,  /*!< Fill with transparent black. */
     };
 
+    virtual ~SkMatrixConvolutionImageFilter();
+
     /** Construct a matrix convolution image filter.
         @param kernelSize  The kernel size in pixels, in each dimension (N by M).
         @param kernel      The image processing kernel.  Must contain N * M
@@ -49,17 +51,19 @@ public:
                            passed to filterImage() is used instead.
         @param cropRect    The rectangle to which the output processing will be limited.
     */
-
-    SkMatrixConvolutionImageFilter(const SkISize& kernelSize,
-                                   const SkScalar* kernel,
-                                   SkScalar gain,
-                                   SkScalar bias,
-                                   const SkIPoint& target,
-                                   TileMode tileMode,
-                                   bool convolveAlpha,
-                                   SkImageFilter* input = NULL,
-                                   const CropRect* cropRect = NULL);
-    virtual ~SkMatrixConvolutionImageFilter();
+    static SkMatrixConvolutionImageFilter* Create(const SkISize& kernelSize,
+                                                  const SkScalar* kernel,
+                                                  SkScalar gain,
+                                                  SkScalar bias,
+                                                  const SkIPoint& target,

[reed1, 2014/03/04 16:56:42]

Nit: Seems funny to separate kernelSize and kernalTarget (my label) by 4
parameters.

Also, this seems like a good place for the factory to sanity check the inputs...
if the kernelTarget is outside of [0..kernelSize]...

[Stephen White, 2014/03/04 18:18:00]

I think that was just the order they appeared in the SVG spec. Moving it up
SGTM. Blink calls target "targetOffset". If we're going to go with something
different than those two, I'd prefer "kernelOffset".
Sounds good.

[Dominik Grewe, 2014/03/07 16:43:38]

There didn't seem to be a clear consensus here so I just went ahead a renamed
everything to kernelOffset for now.

+                                                  TileMode tileMode,
+                                                  bool convolveAlpha,
+                                                  SkImageFilter* input = NULL,
+                                                  const CropRect* cropRect = NULL) {
+        return SkNEW_ARGS(SkMatrixConvolutionImageFilter, (kernelSize, kernel, gain, bias,
+                                                           target, tileMode, convolveAlpha,
+                                                           input, cropRect));
+    }
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkMatrixConvolutionImageFilter)
 
@@ -77,6 +81,19 @@ protected:
                              const SkIRect& bounds) const SK_OVERRIDE;
 #endif
 
+#ifdef SK_SUPPORT_LEGACY_PUBLICEFFECTCONSTRUCTORS
+public:
+#endif
+    SkMatrixConvolutionImageFilter(const SkISize& kernelSize,
+                                   const SkScalar* kernel,
+                                   SkScalar gain,
+                                   SkScalar bias,
+                                   const SkIPoint& target,
+                                   TileMode tileMode,
+                                   bool convolveAlpha,
+                                   SkImageFilter* input = NULL,
+                                   const CropRect* cropRect = NULL);
+
 private:
     SkISize   fKernelSize;
     SkScalar* fKernel;