Initial KTX file decoder

src/gpu/SkGr.cpp

Index: src/gpu/SkGr.cpp
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index 9dc215c735d5e243a5ec981a02ebb23954031eb5..4b771aa30ab6e3f054f28d0b4c5eadefea6615e3 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -9,6 +9,7 @@
 #include "SkColorFilter.h"
 #include "SkConfig8888.h"
 #include "SkData.h"
+#include "SkKTXFile.h"
 #include "SkMessageBus.h"
 #include "SkPixelRef.h"
 #include "GrResourceCache.h"
@@ -144,24 +145,40 @@ static GrTexture *load_etc1_texture(GrContext* ctx,
 
     // Is this a valid PKM encoded data?
     const uint8_t *bytes = data->bytes();
-    if (!etc1_pkm_is_valid(bytes)) {
-        return NULL;
-    }
+    if (etc1_pkm_is_valid(bytes)) {
+        uint32_t encodedWidth = etc1_pkm_get_width(bytes);
+        uint32_t encodedHeight = etc1_pkm_get_height(bytes);
+
+        // Does the data match the dimensions of the bitmap? If not,
+        // then we don't know how to scale the image to match it...
+        if (encodedWidth != static_cast<uint32_t>(bm.width()) ||
+            encodedHeight != static_cast<uint32_t>(bm.height())) {
+            return NULL;
+        }
+
+        // Everything seems good... skip ahead to the data.
+        bytes += ETC_PKM_HEADER_SIZE;
+        desc.fConfig = kETC1_GrPixelConfig;
+    } else if (SkKTXFile::is_ktx(bytes)) {
+        SkKTXFile ktx(bytes, data->size());
 
-    uint32_t encodedWidth = etc1_pkm_get_width(bytes);
-    uint32_t encodedHeight = etc1_pkm_get_height(bytes);
+        // Is it actually an ETC1 texture?
+        if (!ktx.isETC1()) {
+            return NULL;
+        }
+
+        // Does the data match the dimensions of the bitmap? If not,
+        // then we don't know how to scale the image to match it...
+        if (ktx.width() != bm.width() || ktx.height() != bm.height()) {
+            return NULL;
+        }        
 
-    // Does the data match the dimensions of the bitmap? If not,
-    // then we don't know how to scale the image to match it...
-    if (encodedWidth != static_cast<uint32_t>(bm.width()) ||
-        encodedHeight != static_cast<uint32_t>(bm.height())) {
+        bytes = ktx.pixelData();
+        desc.fConfig = kETC1_GrPixelConfig;
+    } else {
         return NULL;
     }
 
-    // Everything seems good... skip ahead to the data.
-    bytes += ETC_PKM_HEADER_SIZE;
-    desc.fConfig = kETC1_GrPixelConfig;
-
     // This texture is likely to be used again so leave it in the cache
     GrCacheID cacheID;
     generate_bitmap_cache_id(bm, &cacheID);