Add SkSpecialImage::extractSubset & NewFromPixmap

src/core/SkSpecialImage.h

Index: src/core/SkSpecialImage.h
diff --git a/src/core/SkSpecialImage.h b/src/core/SkSpecialImage.h
index e90de097fb8d185275c13dd6fcf9a6d5656dd5ae..0a12062c8b26a257ed68288bbd8ee8eee8cb9b98 100644
--- a/src/core/SkSpecialImage.h
+++ b/src/core/SkSpecialImage.h
@@ -63,16 +63,27 @@ public:
                                       uint32_t uniqueID,
                                       GrTexture*, 
                                       SkAlphaType at = kPremul_SkAlphaType);
+    static SkSpecialImage* NewFromPixmap(SkImageFilter::Proxy*,
+                                         const SkIRect& subset,
+                                         const SkPixmap&,
+                                         void (*releaseProc)(void* addr, void* context),
+                                         void* context);
 
     /**
      *  Create a new surface with a backend that is compatible with this image.
      */
     SkSpecialSurface* newSurface(const SkImageInfo&) const;
 
+    /**
+     * Extract a subset of this special image and return it as a special image.
+     * It may or may not point to the same backing memory.
+     */
+    SkSpecialImage* extractSubset(const SkIRect& subset) const;
+
     // These three internal methods will go away (see skbug.com/4965)
     bool internal_getBM(SkBitmap* result);
     static SkSpecialImage* internal_fromBM(SkImageFilter::Proxy*, const SkBitmap&);
-    SkImageFilter::Proxy* internal_getProxy();
+    SkImageFilter::Proxy* internal_getProxy() const;
 
     // TODO: hide this when GrLayerHoister uses SkSpecialImages more fully (see skbug.com/5063)
     /**
@@ -81,6 +92,19 @@ public:
      */
     GrTexture* peekTexture() const;
 
+    // TODO: hide this whe the imagefilter all have a consistent draw path (see skbug.com/5063)
+    /**
+     *  If the SpecialImage is backed by cpu pixels, return the const address

[bsalomon, 2016/03/16 13:52:13]

and color table?

[robertphillips, 2016/03/16 15:31:58]

Done.

+     *  of those pixels and, if not null, return the ImageInfo and rowBytes.
+     *  The returned address is only valid while the image object is in scope.
+     *
+     *  The returned ImageInfo represents the backing memory. Use 'subset'
+     *  to get the active portion's dimensions.
+     *
+     *  On failure, return false and ignore the pixmap parameter.
+     */
+    bool peekPixels(SkPixmap*) const;
+
 protected:
     SkSpecialImage(SkImageFilter::Proxy* proxy, const SkIRect& subset, uint32_t uniqueID)
         : fSubset(subset)
@@ -93,18 +117,6 @@ protected:
     friend class TestingSpecialImageAccess;
     friend class TestingSpecialSurfaceAccess;
 
-    /**
-     *  If the SpecialImage is backed by cpu pixels, return the const address
-     *  of those pixels and, if not null, return the ImageInfo and rowBytes.
-     *  The returned address is only valid while the image object is in scope.
-     *
-     *  The returned ImageInfo represents the backing memory. Use 'subset'
-     *  to get the active portion's dimensions.
-     *
-     *  On failure, return false and ignore the pixmap parameter.
-     */
-    bool testingOnlyPeekPixels(SkPixmap*) const;
-
     // This entry point is for testing only. It does a readback from VRAM for
     // GPU-backed special images.
     bool testingOnlyGetROPixels(SkBitmap*) const;