Pass compressed blitters to our mask drawing algorithm

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 591 matching lines @@
 #elif COMPRESS_R11_EAC_FASTEST
 
     return compress_a8_to_r11eac_fast(dst, src, width, height, rowBytes);
 
 #else
 #error "Must choose R11 EAC algorithm"
 #endif
 }
 
 SkBlitter* CreateR11EACBlitter(int width, int height, void* outputBuffer) {
+    if ((width % 4) != 0 || (height % 4) != 0) {
+        return NULL;
+    }
+
+    // Memset the output buffer to an encoding that decodes to zero...

[robertphillips, 2014/08/06 20:54:49]

ASTC -> R11 ?

[krajcevski, 2014/08/06 22:42:00]

Done.

+    // In the case of ASTC, if everything index is zero, then the interpolated value
+    // will decode to zero provided we have the right header. We use the encoding
+    // from recognizing all zero blocks from above.
+    const int nBlocks = (width * height / 16);
+    uint64_t *dst = reinterpret_cast<uint64_t *>(outputBuffer);
+    for (int i = 0; i < nBlocks; ++i) {
+        *dst = 0x0020000000002000ULL;
+        ++dst;
+    }
+
     return new
         SkTCompressedAlphaBlitter<4, 8, compress_block_vertical>
         (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