Focus SkScaledCodec on BitmapRegionDecoder

src/codec/SkScaledCodec.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCodecPriv.h"
 #include "SkScaledCodec.h"
 #include "SkStream.h"
 #include "SkWebpCodec.h"
 
 
 SkCodec* SkScaledCodec::NewFromStream(SkStream* stream) {
-    bool isWebp = SkWebpCodec::IsWebp(stream);
-    if (!stream->rewind()) {
-        return nullptr;
-    }
-    if (isWebp) {
-        // Webp codec supports scaling and subsetting natively
-        return SkWebpCodec::NewFromStream(stream);  
-    }
-
     SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(stream));
     if (nullptr == codec) {
         return nullptr;
     }
 
-    // wrap in new SkScaledCodec
-    return new SkScaledCodec(codec.detach());
+    switch (codec->getEncodedFormat()) {
+        case kWEBP_SkEncodedFormat:
+            // Webp codec supports scaling and subsetting natively
+            return codec.detach();
+        case kPNG_SkEncodedFormat:
+        case kJPEG_SkEncodedFormat:
+            // wrap in new SkScaledCodec
+            return new SkScaledCodec(codec.detach());
+        default:
+            // FIXME: SkScaledCodec is temporarily disabled for other formats
+            // while focusing on the formats that are supported by
+            // BitmapRegionDecoder.
+            return nullptr;
+    }
 }
 
 SkCodec* SkScaledCodec::NewFromData(SkData* data) {
     if (!data) {
         return nullptr;
     }
     return NewFromStream(new SkMemoryStream(data));
 }
 
 SkScaledCodec::SkScaledCodec(SkCodec* codec)
@@ skipping 255 matching lines @@
                 storagePtr += sampleY * rowBytes;
                 dst = SkTAddOffset<void>(dst, rowBytes);
             }
             return result;
         }
         default:
             SkASSERT(false);
             return kUnimplemented;
     }
 }