Pass compressed blitters to our mask drawing algorithm

src/utils/SkTextureCompressor_R11EAC.cpp

Index: src/utils/SkTextureCompressor_R11EAC.cpp
diff --git a/src/utils/SkTextureCompressor_R11EAC.cpp b/src/utils/SkTextureCompressor_R11EAC.cpp
index 7baa219a28de88d05e2a6966b85b9d45ab2534e6..1b0a705c10d7bff2dda78586a427162c38be1d84 100644
--- a/src/utils/SkTextureCompressor_R11EAC.cpp
+++ b/src/utils/SkTextureCompressor_R11EAC.cpp
@@ -609,6 +609,21 @@ bool CompressA8ToR11EAC(uint8_t* dst, const uint8_t* src, int width, int height,
 }
 
 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);