michael@0: /*
michael@0:  * Copyright 2013 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #ifndef SkImageGenerator_DEFINED
michael@0: #define SkImageGenerator_DEFINED
michael@0: 
michael@0: #include "SkDiscardableMemory.h"
michael@0: #include "SkImageInfo.h"
michael@0: 
michael@0: class SkBitmap;
michael@0: class SkData;
michael@0: class SkImageGenerator;
michael@0: 
michael@0: /**
michael@0:  *  Takes ownership of SkImageGenerator.  If this method fails for
michael@0:  *  whatever reason, it will return false and immediatetely delete
michael@0:  *  the generator.  If it succeeds, it will modify destination
michael@0:  *  bitmap.
michael@0:  *
michael@0:  *  If generator is NULL, will safely return false.
michael@0:  *
michael@0:  *  If this fails or when the SkDiscardablePixelRef that is
michael@0:  *  installed into destination is destroyed, it will call
michael@0:  *  SkDELETE() on the generator.  Therefore, generator should be
michael@0:  *  allocated with SkNEW() or SkNEW_ARGS().
michael@0:  *
michael@0:  *  @param destination Upon success, this bitmap will be
michael@0:  *  configured and have a pixelref installed.
michael@0:  *
michael@0:  *  @param factory If not NULL, this object will be used as a
michael@0:  *  source of discardable memory when decoding.  If NULL, then
michael@0:  *  SkDiscardableMemory::Create() will be called.
michael@0:  *
michael@0:  *  @return true iff successful.
michael@0:  */
michael@0: SK_API bool SkInstallDiscardablePixelRef(SkImageGenerator* generator,
michael@0:                                          SkBitmap* destination,
michael@0:                                          SkDiscardableMemory::Factory* factory = NULL);
michael@0: 
michael@0: 
michael@0: /**
michael@0:  *  An interface that allows a purgeable PixelRef (such as a
michael@0:  *  SkDiscardablePixelRef) to decode and re-decode an image as needed.
michael@0:  */
michael@0: class SK_API SkImageGenerator {
michael@0: public:
michael@0:     /**
michael@0:      *  The PixelRef which takes ownership of this SkImageGenerator
michael@0:      *  will call the image generator's destructor.
michael@0:      */
michael@0:     virtual ~SkImageGenerator() { }
michael@0: 
michael@0:     /**
michael@0:      *  Return a ref to the encoded (i.e. compressed) representation,
michael@0:      *  of this data.
michael@0:      *
michael@0:      *  If non-NULL is returned, the caller is responsible for calling
michael@0:      *  unref() on the data when it is finished.
michael@0:      */
michael@0:     virtual SkData* refEncodedData() { return NULL; }
michael@0: 
michael@0:     /**
michael@0:      *  Return some information about the image, allowing the owner of
michael@0:      *  this object to allocate pixels.
michael@0:      *
michael@0:      *  Repeated calls to this function should give the same results,
michael@0:      *  allowing the PixelRef to be immutable.
michael@0:      *
michael@0:      *  @return false if anything goes wrong.
michael@0:      */
michael@0:     virtual bool getInfo(SkImageInfo* info) = 0;
michael@0: 
michael@0:     /**
michael@0:      *  Decode into the given pixels, a block of memory of size at
michael@0:      *  least (info.fHeight - 1) * rowBytes + (info.fWidth *
michael@0:      *  bytesPerPixel)
michael@0:      *
michael@0:      *  Repeated calls to this function should give the same results,
michael@0:      *  allowing the PixelRef to be immutable.
michael@0:      *
michael@0:      *  @param info A description of the format (config, size)
michael@0:      *         expected by the caller.  This can simply be identical
michael@0:      *         to the info returned by getInfo().
michael@0:      *
michael@0:      *         This contract also allows the caller to specify
michael@0:      *         different output-configs, which the implementation can
michael@0:      *         decide to support or not.
michael@0:      *
michael@0:      *  @return false if anything goes wrong or if the image info is
michael@0:      *          unsupported.
michael@0:      */
michael@0:     virtual bool getPixels(const SkImageInfo& info,
michael@0:                            void* pixels,
michael@0:                            size_t rowBytes) = 0;
michael@0: };
michael@0: 
michael@0: #endif  // SkImageGenerator_DEFINED