Pass a struct of functions instead of a function to the compressed blitter

src/utils/SkTextureCompressor_R11EAC.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTextureCompressor.h"
 #include "SkTextureCompressor_Blitter.h"
 
@@ skipping 572 matching lines @@
             } else if (val > 2047) {
                 dst[i] = 0xFF;
             } else {
                 dst[i] = (val >> 3) & 0xFF;
             }
         }
         dst += dstRowBytes;
     }
 }
 
+// This is the type passed as the CompressorType argument of the compressed
+// blitter for the R11 EAC format. The static functions required to be in this
+// struct are documented in SkTextureCompressor_Blitter.h
+struct CompressorR11EAC {
+    static inline void CompressA8Vertical(uint8_t* dst, const uint8_t* src) {
+        compress_block_vertical(dst, src);
+    }
+
+    static inline void CompressA8Horizontal(uint8_t* dst, const uint8_t* src,
+                                            int srcRowBytes) {
+        *(reinterpret_cast<uint64_t*>(dst)) = compress_r11eac_block_fast(src, srcRowBytes);
+    }
+
+    static inline void UpdateBlock(uint8_t* dst, const uint8_t* src) {
+    }
+};
+
 ////////////////////////////////////////////////////////////////////////////////
 
 namespace SkTextureCompressor {
 
 bool CompressA8ToR11EAC(uint8_t* dst, const uint8_t* src, int width, int height, int rowBytes) {
 
 #if (COMPRESS_R11_EAC_SLOW) || (COMPRESS_R11_EAC_FAST)
 
     return compress_4x4_a8_to_64bit(dst, src, width, height, rowBytes, compress_r11eac_block);
 
@@ skipping 18 matching lines @@
     // decides not to write certain scanlines (and skip entire rows of blocks).
     // In the case of R11, we use the encoding from recognizing all zero pixels from above.
     const int nBlocks = (width * height / 16);  // 4x4 pixel blocks.
     uint64_t *dst = reinterpret_cast<uint64_t *>(outputBuffer);
     for (int i = 0; i < nBlocks; ++i) {
         *dst = 0x0020000000002000ULL;
         ++dst;
     }
 
     return allocator->createT<
-        SkTCompressedAlphaBlitter<4, 8, compress_block_vertical>, int, int, void*>
+        SkTCompressedAlphaBlitter<4, 8, CompressorR11EAC>, int, int, void*>
         (width, height, outputBuffer);
 }
 
 void DecompressR11EAC(uint8_t* dst, int dstRowBytes, const uint8_t* src, int width, int height) {
     for (int j = 0; j < height; j += 4) {
         for (int i = 0; i < width; i += 4) {
             decompress_r11_eac_block(dst + i, dstRowBytes, src);
             src += 8;
         }
         dst += 4 * dstRowBytes;
     }    
 }
 
 }  // namespace SkTextureCompressor