Support more swizzles to 565 in SkCodec

src/codec/SkWebpCodec.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 "SkWebpCodec.h"
 #include "SkTemplates.h"
 
 // A WebP decoder on top of (subset of) libwebp
 // For more information on WebP image format, and libwebp library, see:
 //   https://code.google.com/speed/webp/
 //   http://www.webmproject.org/code/#libwebp-webp-image-library
 //   https://chromium.googlesource.com/webm/libwebp
 
 // If moving libwebp out of skia source tree, path for webp headers must be
@@ skipping 56 matching lines @@
 
 SkCodec* SkWebpCodec::NewFromStream(SkStream* stream) {
     SkAutoTDelete<SkStream> streamDeleter(stream);
     SkImageInfo info;
     if (webp_parse_header(stream, &info)) {
         return SkNEW_ARGS(SkWebpCodec, (info, streamDeleter.detach()));
     }
     return NULL;
 }
 
-static bool conversion_possible(const SkImageInfo& dst, const SkImageInfo& src) {
+// This version is slightly different from SkCodecPriv's version of conversion_possible. It
+// supports both byte orders for 8888.
+static bool webp_conversion_possible(const SkImageInfo& dst, const SkImageInfo& src) {
     if (dst.profileType() != src.profileType()) {
         return false;
     }
+
+    if (!valid_alpha(dst.alphaType(), src.alphaType())) {
+        return false;
+    }
+
     switch (dst.colorType()) {
         // Both byte orders are supported.
         case kBGRA_8888_SkColorType:
         case kRGBA_8888_SkColorType:
-            break;
+            return true;
         case kRGB_565_SkColorType:
-            if (src.alphaType() == kOpaque_SkAlphaType
-                && dst.alphaType() == kOpaque_SkAlphaType)
-            {
-                return true;
-            }
+            return src.alphaType() == kOpaque_SkAlphaType;
         default:
             return false;
     }
-    if (dst.alphaType() == src.alphaType()) {
-        return true;
-    }
-    return kPremul_SkAlphaType == dst.alphaType() &&
-            kUnpremul_SkAlphaType == src.alphaType();
 }
 
 SkISize SkWebpCodec::onGetScaledDimensions(float desiredScale) const {
     SkISize dim = this->getInfo().dimensions();
     // SkCodec treats zero dimensional images as errors, so the minimum size
     // that we will recommend is 1x1.
     dim.fWidth = SkTMax(1, SkScalarRoundToInt(desiredScale * dim.fWidth));
     dim.fHeight = SkTMax(1, SkScalarRoundToInt(desiredScale * dim.fHeight));
     return dim;
 }
@@ skipping 41 matching lines @@
             return kCouldNotRewind;
         case kRewound_RewindState:
             // Rewound to the beginning. Since creation only does a peek, the stream is at the
             // correct position.
             break;
         case kNoRewindNecessary_RewindState:
             // Already at the right spot for decoding.
             break;
     }
 
-    if (!conversion_possible(dstInfo, this->getInfo())) {
+    if (!webp_conversion_possible(dstInfo, this->getInfo())) {
         return kInvalidConversion;
     }
 
     WebPDecoderConfig config;
     if (0 == WebPInitDecoderConfig(&config)) {
         // ABI mismatch.
         // FIXME: New enum for this?
         return kInvalidInput;
     }
 
@@ skipping 74 matching lines @@
                 // Break out of the switch statement. Continue the loop.
                 break;
             default:
                 return kInvalidInput;
         }
     }
 }
 
 SkWebpCodec::SkWebpCodec(const SkImageInfo& info, SkStream* stream)
     : INHERITED(info, stream) {}