Add reallyHasAlpha() to SkAndroidCodec

include/codec/SkAndroidCodec.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkAndroidCodec_DEFINED
 #define SkAndroidCodec_DEFINED
 
@@ skipping 32 matching lines @@
     static SkAndroidCodec* NewFromData(SkData*, SkPngChunkReader* = NULL);
 
     virtual ~SkAndroidCodec() {}
 
 
     const SkImageInfo& getInfo() const { return fInfo; }
 
     /**
      *  Format of the encoded data.
      */
-    SkEncodedFormat getEncodedFormat() const { return this->onGetEncodedFormat(); }
+    SkEncodedFormat getEncodedFormat() const { return fCodec->getEncodedFormat(); }
 
     /**
      *  Returns the dimensions of the scaled output image, for an input
      *  sampleSize.
      *
      *  When the sample size divides evenly into the original dimensions, the
      *  scaled output dimensions will simply be equal to the original
      *  dimensions divided by the sample size.
      *
      *  When the sample size does not divide even into the original
@@ skipping 137 matching lines @@
             const AndroidOptions* options);
 
     /**
      *  Simplified version of getAndroidPixels() where we supply the default AndroidOptions.
      *
      *  This will return an error if the info is kIndex_8_SkColorType and also will not perform
      *  any scaling or subsetting.
      */
     SkCodec::Result getAndroidPixels(const SkImageInfo& info, void* pixels, size_t rowBytes);
 
+    /**
+     *  Some images may initially report that they have alpha due to the format
+     *  of the encoded data, but then never use any colors which have alpha
+     *  less than 100%. This function can be called *after* decoding to
+     *  determine if such an image truly had alpha. Calling it before decoding
+     *  is undefined.
+     *  FIXME: see skbug.com/3582.
+     */
+    bool reallyHasAlpha() const {
+        return fCodec->reallyHasAlpha();
+    }
+
 protected:
 
-    SkAndroidCodec(const SkImageInfo&);
+    SkAndroidCodec(SkCodec*);
 
-    virtual SkEncodedFormat onGetEncodedFormat() const = 0;
+    SkCodec* codec() const { return fCodec.get(); }
 
     virtual SkISize onGetSampledDimensions(int sampleSize) const = 0;
 
     virtual bool onGetSupportedSubset(SkIRect* desiredSubset) const = 0;
 
     virtual SkCodec::Result onGetAndroidPixels(const SkImageInfo& info, void* pixels,
             size_t rowBytes, const AndroidOptions& options) = 0;
 
 private:
 
     // This will always be a reference to the info that is contained by the
     // embedded SkCodec.
     const SkImageInfo& fInfo;
+
+    SkAutoTDelete<SkCodec> fCodec;
 };
 #endif // SkAndroidCodec_DEFINED