Reland DeferredTextureImageData low-bit-depth/dithering support

Cause DeferredTextureImageData functionality to support low bit depth
(4444, 565) image formats (with dithering).

Updated to handle colorspace + 4444 colortype correctly.

Bug: 720105
Change-Id: Ib7e14d937849f4f6b08fda6992a240bb203d0089
Reviewed-on: https://skia-review.googlesource.com/19094
Commit-Queue: Eric Karl <ericrk@chromium.org>
Reviewed-by: Brian Salomon <bsalomon@google.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/include/core/SkImage.h b/include/core/SkImage.h
index bc0597c300..ba2cc7e0f9 100644
--- a/include/core/SkImage.h
+++ b/include/core/SkImage.h
@@ -477,12 +477,18 @@ public:
      * dstColorSpace is the color space of the surface where this texture will ultimately be used.
      * If the method determines that mip-maps are needed, this helps determine the correct strategy
      * for building them (gamma-correct or not).
+     *
+     * dstColorType is the color type of the surface where this texture will ultimately be used.
+     * This determines the format with which the image will be uploaded to the GPU. If dstColorType
+     * does not support color spaces (low bit depth types such as ARGB_4444), then dstColorSpace
+     * must be null.
      */
     size_t getDeferredTextureImageData(const GrContextThreadSafeProxy&,
                                        const DeferredTextureImageUsageParams[],
                                        int paramCnt,
                                        void* buffer,
-                                       SkColorSpace* dstColorSpace = nullptr) const;
+                                       SkColorSpace* dstColorSpace = nullptr,
+                                       SkColorType dstColorType = kN32_SkColorType) const;
 
     /**
      * Returns a texture-backed image from data produced in SkImage::getDeferredTextureImageData.