Add read/write-Pixels to GrDrawContext

include/gpu/GrDrawContext.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrDrawContext_DEFINED
 #define GrDrawContext_DEFINED
 
@@ skipping 266 matching lines @@
                           int imageHeight,
                           std::unique_ptr<SkLatticeIter> iter,
                           const SkRect& dst);
 
     /**
      * After this returns any pending surface IO will be issued to the backend 3D API and
      * if the surface has MSAA it will be resolved.
      */
     void prepareForExternalIO();
 
+    /**
+     * Reads a rectangle of pixels from the draw context.
+     * @param dstInfo       image info for the destination
+     * @param dstBuffer     destination pixels for the read
+     * @param dstRowBytes   bytes in a row of 'dstBuffer'
+     * @param x             x offset w/in the draw context from which to read
+     * @param y             y offset w/in the draw context from which to read
+     *
+     * @return true if the read succeeded, false if not. The read can fail because of an
+     *              unsupported pixel config.
+     */
+    bool readPixels(const SkImageInfo& dstInfo, void* dstBuffer, size_t dstRowBytes, int x, int y);
+
+    /**
+     * Writes a rectangle of pixels [srcInfo, srcBuffer, srcRowbytes] into the 
+     * drawContext at the specified position.
+     * @param srcInfo       image info for the source pixels
+     * @param srcBuffer     source for the write
+     * @param srcRowBytes   bytes in a row of 'srcBuffer'
+     * @param x             x offset w/in the draw context at which to write
+     * @param y             y offset w/in the draw context at which to write
+     *
+     * @return true if the write succeeded, false if not. The write can fail because of an
+     *              unsupported pixel config.
+     */
+    bool writePixels(const SkImageInfo& srcInfo, const void* srcBuffer, size_t srcRowBytes,
+                     int x, int y);
+
     bool isStencilBufferMultisampled() const {
         return fRenderTarget->isStencilBufferMultisampled();
     }
     bool isUnifiedMultisampled() const { return fRenderTarget->isUnifiedMultisampled(); }
     bool hasMixedSamples() const { return fRenderTarget->isMixedSampled(); }
 
     bool mustUseHWAA(const GrPaint& paint) const {
         return paint.isAntiAlias() && fRenderTarget->isUnifiedMultisampled();
     }
 
@@ skipping 100 matching lines @@
 
     sk_sp<SkColorSpace>               fColorSpace;
     SkSurfaceProps                    fSurfaceProps;
     GrAuditTrail*                     fAuditTrail;
 
     // In debug builds we guard against improper thread handling
     SkDEBUGCODE(mutable GrSingleOwner* fSingleOwner;)
 };
 
 #endif