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

src/utils/SkTextureCompressor_LATC.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_LATC.h"
 #include "SkTextureCompressor_Blitter.h"
 
@@ skipping 396 matching lines @@
     block >>= 16;
     for (int j = 0; j < 4; ++j) {
         for (int i = 0; i < 4; ++i) {
             dst[i] = palette[block & 0x7];
             block >>= 3;
         }
         dst += dstRowBytes;
     }
 }
 
+// This is the type passed as the CompressorType argument of the compressed
+// blitter for the LATC format. The static functions required to be in this
+// struct are documented in SkTextureCompressor_Blitter.h
+struct CompressorLATC {
+    static inline void CompressA8Vertical(uint8_t* dst, const uint8_t block[]) {
+        compress_a8_latc_block<PackColumnMajor>(&dst, block, 4);
+    }
+
+    static inline void CompressA8Horizontal(uint8_t* dst, const uint8_t* src,
+                                            int srcRowBytes) {
+        compress_a8_latc_block<PackRowMajor>(&dst, src, srcRowBytes);
+    }
+
+    static inline void UpdateBlock(uint8_t* dst, const uint8_t* src) {
+    }
+};
+
 ////////////////////////////////////////////////////////////////////////////////
 
 namespace SkTextureCompressor {
 
 bool CompressA8ToLATC(uint8_t* dst, const uint8_t* src, int width, int height, int rowBytes) {
 #if COMPRESS_LATC_FAST
     return compress_4x4_a8_latc(dst, src, width, height, rowBytes);
 #elif COMPRESS_LATC_SLOW
     return compress_4x4_a8_to_64bit(dst, src, width, height, rowBytes, compress_latc_block);
 #else
@@ skipping 10 matching lines @@
 #if COMPRESS_LATC_FAST
     // Memset the output buffer to an encoding that decodes to zero. We must do this
     // in order to avoid having uninitialized values in the buffer if the blitter
     // decides not to write certain scanlines (and skip entire rows of blocks).
     // In the case of LATC, if everything is zero, then LUM0 and LUM1 are also zero,
     // and they will only be non-zero (0xFF) if the index is 7. So bzero will do just fine.
     // (8 bytes per block) * (w * h / 16 blocks) = w * h / 2
     sk_bzero(outputBuffer, width * height / 2);
 
     return allocator->createT<
-        SkTCompressedAlphaBlitter<4, 8, CompressA8LATCBlockVertical>, int, int, void* >
+        SkTCompressedAlphaBlitter<4, 8, CompressorLATC>, int, int, void* >
         (width, height, outputBuffer);
 #elif COMPRESS_LATC_SLOW
     // TODO (krajcevski)
     return NULL;
 #endif
 }
 
 void DecompressLATC(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_latc_block(dst + i, dstRowBytes, src);
             src += 8;
         }
         dst += 4 * dstRowBytes;
     }
 }
 
 }  // SkTextureCompressor