New API for encoding bitmaps during serialization.

include/core/SkPicture.h

 
 /*
  * Copyright 2007 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 SkPicture_DEFINED
 #define SkPicture_DEFINED
 
 #include "SkBitmap.h"
 #include "SkRefCnt.h"
 
 class SkBBoxHierarchy;
 class SkCanvas;
+class SkData;
 class SkPicturePlayback;
 class SkPictureRecord;
 class SkStream;
 class SkWStream;
 
 /** \class SkPicture
 
     The SkPicture class records the drawing commands made to a canvas, to
     be played back at a later time.
 */
@@ skipping 133 matching lines @@
     */
     int width() const { return fWidth; }
 
     /** Return the height of the picture's recording canvas. This
         value reflects what was passed to setSize(), and does not necessarily
         reflect the bounds of what has been recorded into the picture.
         @return the height of the picture's recording canvas
     */
     int height() const { return fHeight; }
 
+    enum RecordPixelRefOffset {
+        kYes_RecordPixelRefOffset,
+        kNo_RecordPixelRefOffset,
+    };
+
     /**
-     *  Function to encode an SkBitmap to an SkWStream. A function with this
-     *  signature can be passed to serialize() and SkOrderedWriteBuffer. The
-     *  function should return true if it succeeds. Otherwise it should return
-     *  false so that SkOrderedWriteBuffer can switch to another method of
-     *  storing SkBitmaps.
+     *  Function to encode an SkBitmap to an SkData. A function with this
+     *  signature can be passed to serialize() and SkOrderedWriteBuffer.
+     *  Returning NULL will tell the SkOrderedWriteBuffer to use
+     *  SkBitmap::flatten() to store the bitmap.
+     *  @param RecordPixelRefOffset Output parameter, telling the
+     *      SkOrderedWriteBuffer whether to record the bitmap's pixelRefOffset.
+     *      If set to kYes_RecordPixelRefOffset, the returned SkData contains
+     *      compressed data containing the entire image, so the pixelRefOffset
+     *      should also be recorded to the stream. If set to
+     *      kNo_RecordPixelRefOffset, only the extracted subset is written to
+     *      the returned SkData, so the offset should not be written to the
+     *      stream.
+     *  @return SkData If non-NULL, holds encoded data representing the passed
+     *      in bitmap. The caller is responsible for calling unref().
      */
-    typedef bool (*EncodeBitmap)(SkWStream*, const SkBitmap&);
+    typedef SkData* (*EncodeBitmap)(RecordPixelRefOffset*, const SkBitmap&);

[scroggo, 2013/05/20 19:50:52]

Mike, you mentioned perhaps wanting to use the same signature in other places.
In that case, I think RecordPixelRefOffset should be changed to something more
general. Maybe ContainsLargerImage, or something that makes it clear that the
SkData represents a superset of the pixels used by the SkBitmap.

 
     /**
      *  Serialize to a stream. If non NULL, encoder will be used to encode
      *  any bitmaps in the picture.
      */
     void serialize(SkWStream*, EncodeBitmap encoder = NULL) const;
 
 #ifdef SK_BUILD_FOR_ANDROID
     /** Signals that the caller is prematurely done replaying the drawing
         commands. This can be called from a canvas virtual while the picture
@@ skipping 52 matching lines @@
     */
     SkCanvas* getRecordingCanvas() const { return fCanvas; }
 
 private:
     SkPicture*  fPicture;
     SkCanvas*   fCanvas;
 };
 
 
 #endif