Qualify the return value of SkImageDecoder::decode

include/core/SkImageDecoder.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImageDecoder_DEFINED
 #define SkImageDecoder_DEFINED
 
@@ skipping 207 matching lines @@
 
     /** Passed to the decode method. If kDecodeBounds_Mode is passed, then
         only the bitmap's info need be set. If kDecodePixels_Mode
         is passed, then the bitmap must have pixels or a pixelRef.
     */
     enum Mode {
         kDecodeBounds_Mode, //!< only return info in bitmap
         kDecodePixels_Mode  //!< return entire bitmap (including pixels)
     };
 
+    /** Result of a decode. If read as a boolean, a partial success is
+        considered a success (true).
+    */
+    enum Result {
+        kFailure        = 0,    //!< Image failed to decode. bitmap will be

[reed1, 2014/10/17 21:07:26]

nit: why specify the actual numeric values? we rarely do that for simple enums.

[scroggo, 2014/10/17 21:11:44]

I suppose I could be more explicit, but that is how I accomplish the second
sentence in the description of Result, above.

If someone treats a Result as a boolean, the non-zero items will be interpreted
as true.

+                                //   unchanged.
+        kPartialSuccess = 1,    //!< Part of the image decoded. The rest is
+                                //   filled in automatically
+        kSuccess        = 2     //!< The entire image decoded.
+    };
+
     /** Given a stream, decode it into the specified bitmap.
         If the decoder can decompress the image, it calls bitmap.setInfo(),
         and then if the Mode is kDecodePixels_Mode, call allocPixelRef(),
         which will allocated a pixelRef. To access the pixel memory, the codec
         needs to call lockPixels/unlockPixels on the
         bitmap. It can then set the pixels with the decompressed image.
     *   If the image cannot be decompressed, return false. After the
     *   decoding, the function converts the decoded colortype in bitmap
     *   to pref if possible. Whether a conversion is feasible is
     *   tested by Bitmap::canCopyTo(pref).
 
         If an SkBitmap::Allocator is installed via setAllocator, it will be
         used to allocate the pixel memory. A clever allocator can be used
         to allocate the memory from a cache, volatile memory, or even from
         an existing bitmap's memory.
 
         If a Peeker is installed via setPeeker, it may be used to peek into
         meta data during the decode.
     */
-    bool decode(SkStream*, SkBitmap* bitmap, SkColorType pref, Mode);
-    bool decode(SkStream* stream, SkBitmap* bitmap, Mode mode) {
+    Result decode(SkStream*, SkBitmap* bitmap, SkColorType pref, Mode);
+    Result decode(SkStream* stream, SkBitmap* bitmap, Mode mode) {
         return this->decode(stream, bitmap, kUnknown_SkColorType, mode);
     }
 
     /**
      * Given a stream, build an index for doing tile-based decode.
      * The built index will be saved in the decoder, and the image size will
      * be returned in width and height.
      *
      * Return true for success or false on failure.
      */
@@ skipping 68 matching lines @@
                       of the decoded stream. On failure it is ignored.
      */
     static bool DecodeStream(SkStreamRewindable* stream, SkBitmap* bitmap, SkColorType pref, Mode,
                              Format* format = NULL);
     static bool DecodeStream(SkStreamRewindable* stream, SkBitmap* bitmap) {
         return DecodeStream(stream, bitmap, kUnknown_SkColorType, kDecodePixels_Mode, NULL);
     }
 
 protected:
     // must be overridden in subclasses. This guy is called by decode(...)
-    virtual bool onDecode(SkStream*, SkBitmap* bitmap, Mode) = 0;
+    virtual Result onDecode(SkStream*, SkBitmap* bitmap, Mode) = 0;
 
     // If the decoder wants to support tiled based decoding,
     // this method must be overridden. This guy is called by buildTileIndex(...)
     virtual bool onBuildTileIndex(SkStreamRewindable*, int *width, int *height) {
         return false;
     }
 
     // If the decoder wants to support tiled based decoding,
     // this method must be overridden. This guy is called by decodeRegion(...)
     virtual bool onDecodeSubset(SkBitmap* bitmap, const SkIRect& rect) {
@@ skipping 149 matching lines @@
 DECLARE_DECODER_CREATOR(PKMImageDecoder);
 DECLARE_DECODER_CREATOR(KTXImageDecoder);
 DECLARE_DECODER_CREATOR(ASTCImageDecoder);
 
 // Typedefs to make registering decoder and formatter callbacks easier.
 // These have to be defined outside SkImageDecoder. :(
 typedef SkTRegistry<SkImageDecoder*(*)(SkStreamRewindable*)>        SkImageDecoder_DecodeReg;
 typedef SkTRegistry<SkImageDecoder::Format(*)(SkStreamRewindable*)> SkImageDecoder_FormatReg;
 
 #endif