Add the lazy decoder from PictureFlags to SkImageDecoder

include/core/SkImageDecoder.h

Index: include/core/SkImageDecoder.h
diff --git a/include/core/SkImageDecoder.h b/include/core/SkImageDecoder.h
index 191fe53f4c588a0584486fee25b68ee7a2c7ab1f..f06af9588dce3e7dd76ce465a1fd06920cc48197 100644
--- a/include/core/SkImageDecoder.h
+++ b/include/core/SkImageDecoder.h
@@ -13,8 +13,10 @@
 #include "SkBitmap.h"
 #include "SkBitmapFactory.h"
 #include "SkImage.h"
+#include "SkLruImageCache.h"
 #include "SkRect.h"
 #include "SkRefCnt.h"
+#include "SkPurgeableImageCache.h"

[caryclark, 2013/07/12 18:29:39]

this may be correct but why is it required? I don't see a reference in your
changes below

[sglez, 2013/07/13 04:11:27]

Good catch. I was using it when trying to implement Leon's MyCacheSelector. I
decided to wait until I got to talk to him, but forgot to remove this include

 #include "SkTypes.h"
 
 class SkStream;
@@ -97,6 +99,13 @@ public:
     */
     bool getRequireUnpremultipliedColors() const { return fRequireUnpremultipliedColors; }
 
+    /**
+     * Returns a pointer to the LRU cache used by LazyDecodeBitmap.
+     */
+    static SkLruImageCache* getLruImageCache() {
+        return &fLruImageCache;
+    }
+
     /** \class Peeker
 
         Base class for optional callbacks to retrieve meta/chunk data out of
@@ -308,6 +317,11 @@ public:
     }
 
     /**
+     * Decode the image with DecodeMemoryToTarget but defer the process until it is needed.
+     */
+    static bool LazyDecodeBitmap(const void* buffer, size_t size, SkBitmap* bitmap);
+
+    /**
      *  Decode memory.
      *  @param info Output parameter. Returns info about the encoded image.
      *  @param target Contains the address of pixel memory to decode into
@@ -468,6 +482,10 @@ private:
     mutable bool            fShouldCancelDecode;
     bool                    fPreferQualityOverSpeed;
     bool                    fRequireUnpremultipliedColors;
+
+    static SkLruImageCache fLruImageCache;
+    static SkBitmapFactory fLazyBitmapFactory;
+
 };
 
 /** Calling newDecoder with a stream returns a new matching imagedecoder