Pass compressed blitters to our mask drawing algorithm

src/utils/SkTextureCompressor_LATC.cpp

Index: src/utils/SkTextureCompressor_LATC.cpp
diff --git a/src/utils/SkTextureCompressor_LATC.cpp b/src/utils/SkTextureCompressor_LATC.cpp
index 5db0fc6c04e609c4ad3c72a0393a3ec9ee870e51..38eb6e512c75ed03cc85657bad503bfc10e220a7 100644
--- a/src/utils/SkTextureCompressor_LATC.cpp
+++ b/src/utils/SkTextureCompressor_LATC.cpp
@@ -428,7 +428,16 @@ bool CompressA8ToLATC(uint8_t* dst, const uint8_t* src, int width, int height, i
 }
 
 SkBlitter* CreateLATCBlitter(int width, int height, void* outputBuffer) {
+    if ((width % 4) != 0 || (height % 4) != 0) {
+        return NULL;
+    }
+
 #if COMPRESS_LATC_FAST
+    // Memset the output buffer to an encoding that decodes to zero...
+    // 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.

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

// (8 bytes/block) * (w * h / 4*4) blocks = w * h / 2 bytes ?

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

Done.

+    sk_bzero(outputBuffer, width * height / 2);
+
     return new
         SkTCompressedAlphaBlitter<4, 8, CompressA8LATCBlockVertical>
         (width, height, outputBuffer);