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 /*

  * Copyright 2008 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 SkPixelRef_DEFINED

 #define SkPixelRef_DEFINED

 #include "SkBitmap.h"

 #include "SkRefCnt.h"

 #include "SkString.h"

 #include "SkFlattenable.h"

 #include "SkImageInfo.h"

 #include "SkTDArray.h"

 //#define xed

 #ifdef SK_DEBUG

     /**

      *  Defining SK_IGNORE_PIXELREF_SETPRELOCKED will force all pixelref

      *  subclasses to correctly handle lock/unlock pixels. For performance

      *  reasons, simple malloc-based subclasses call setPreLocked() to skip

      *  the overhead of implementing these calls.

      *

      *  This build-flag disables that optimization, to add in debugging our

      *  call-sites, to ensure that they correctly balance their calls of

      *  lock and unlock.

      */

 //    #define SK_IGNORE_PIXELREF_SETPRELOCKED

 #endif

 class SkColorTable;

 class SkData;

 struct SkIRect;

 class SkMutex;

 class GrTexture;

 /** \class SkPixelRef

     This class is the smart container for pixel memory, and is used with

     SkBitmap. A pixelref is installed into a bitmap, and then the bitmap can

     access the actual pixel memory by calling lockPixels/unlockPixels.

     This class can be shared/accessed between multiple threads.

 */

 class SK_API SkPixelRef : public SkFlattenable {

 public:

     SK_DECLARE_INST_COUNT(SkPixelRef)

     explicit SkPixelRef(const SkImageInfo&);

     SkPixelRef(const SkImageInfo&, SkBaseMutex* mutex);

     virtual ~SkPixelRef();

     const SkImageInfo& info() const {

         return fInfo;

     }

     /** Return the pixel memory returned from lockPixels, or null if the

         lockCount is 0.

     */

     void* pixels() const { return fRec.fPixels; }

     /** Return the current colorTable (if any) if pixels are locked, or null.

     */

     SkColorTable* colorTable() const { return fRec.fColorTable; }

     size_t rowBytes() const { return fRec.fRowBytes; }

     /**

      *  To access the actual pixels of a pixelref, it must be "locked".

      *  Calling lockPixels returns a LockRec struct (on success).

      */

     struct LockRec {

         void*           fPixels;

         SkColorTable*   fColorTable;

         size_t          fRowBytes;

         void zero() { sk_bzero(this, sizeof(*this)); }

         bool isZero() const {

             return NULL == fPixels && NULL == fColorTable && 0 == fRowBytes;

         }

     };

     /**

      *  Returns true if the lockcount > 0

      */

     bool isLocked() const { return fLockCount > 0; }

     SkDEBUGCODE(int getLockCount() const { return fLockCount; })

     /**

      *  Call to access the pixel memory. Return true on success. Balance this

      *  with a call to unlockPixels().

      */

     bool lockPixels();

     /**

      *  Call to access the pixel memory. On success, return true and fill out

      *  the specified rec. On failure, return false and ignore the rec parameter.

      *  Balance this with a call to unlockPixels().

      */

     bool lockPixels(LockRec* rec);

     /** Call to balanace a previous call to lockPixels(). Returns the pixels

         (or null) after the unlock. NOTE: lock calls can be nested, but the

         matching number of unlock calls must be made in order to free the

         memory (if the subclass implements caching/deferred-decoding.)

     */

     void unlockPixels();

     /**

      *  Some bitmaps can return a copy of their pixels for lockPixels(), but

      *  that copy, if modified, will not be pushed back. These bitmaps should

      *  not be used as targets for a raster device/canvas (since all pixels

      *  modifications will be lost when unlockPixels() is called.)

      */

     bool lockPixelsAreWritable() const;

     /** Returns a non-zero, unique value corresponding to the pixels in this

         pixelref. Each time the pixels are changed (and notifyPixelsChanged is

         called), a different generation ID will be returned.

     */

     uint32_t getGenerationID() const;

     /**

      *  Call this if you have changed the contents of the pixels. This will in-

      *  turn cause a different generation ID value to be returned from

      *  getGenerationID().

      */

     void notifyPixelsChanged();

     /**

      *  Change the info's AlphaType. Note that this does not automatically

      *  invalidate the generation ID. If the pixel values themselves have

      *  changed, then you must explicitly call notifyPixelsChanged() as well.

      */

     void changeAlphaType(SkAlphaType at);

     /** Returns true if this pixelref is marked as immutable, meaning that the

         contents of its pixels will not change for the lifetime of the pixelref.

     */

     bool isImmutable() const { return fIsImmutable; }

     /** Marks this pixelref is immutable, meaning that the contents of its

         pixels will not change for the lifetime of the pixelref. This state can

         be set on a pixelref, but it cannot be cleared once it is set.

     */

     void setImmutable();

     /** Return the optional URI string associated with this pixelref. May be

         null.

     */

     const char* getURI() const { return fURI.size() ? fURI.c_str() : NULL; }

     /** Copy a URI string to this pixelref, or clear the URI if the uri is null

      */

     void setURI(const char uri[]) {

         fURI.set(uri);

     }

     /** Copy a URI string to this pixelref

      */

     void setURI(const char uri[], size_t len) {

         fURI.set(uri, len);

     }

     /** Assign a URI string to this pixelref.

     */

     void setURI(const SkString& uri) { fURI = uri; }

     /**

      *  If the pixelRef has an encoded (i.e. compressed) representation,

      *  return a ref to its data. If the pixelRef

      *  is uncompressed or otherwise does not have this form, return NULL.

      *

      *  If non-null is returned, the caller is responsible for calling unref()

      *  on the data when it is finished.

      */

     SkData* refEncodedData() {

         return this->onRefEncodedData();

     }

     /**

      *  Experimental -- tells the caller if it is worth it to call decodeInto().

      *  Just an optimization at this point, to avoid checking the cache first.

      *  We may remove/change this call in the future.

      */

     bool implementsDecodeInto() {

         return this->onImplementsDecodeInto();

     }

     /**

      *  Return a decoded instance of this pixelRef in bitmap. If this cannot be

      *  done, return false and the bitmap parameter is ignored/unchanged.

      *

      *  pow2 is the requeste power-of-two downscale that the caller needs. This

      *  can be ignored, and the "original" size can be returned, but if the

      *  underlying codec can efficiently return a smaller size, that should be

      *  done. Some examples:

      *

      *  To request the "base" version (original scale), pass 0 for pow2

      *  To request 1/2 scale version (1/2 width, 1/2 height), pass 1 for pow2

      *  To request 1/4 scale version (1/4 width, 1/4 height), pass 2 for pow2

      *  ...

      *

      *  If this returns true, then bitmap must be "locked" such that

      *  bitmap->getPixels() will return the correct address.

      */

     bool decodeInto(int pow2, SkBitmap* bitmap) {

         SkASSERT(pow2 >= 0);

         return this->onDecodeInto(pow2, bitmap);

     }

     /** Are we really wrapping a texture instead of a bitmap?

      */

     virtual GrTexture* getTexture() { return NULL; }

     bool readPixels(SkBitmap* dst, const SkIRect* subset = NULL);

     /**

      *  Makes a deep copy of this PixelRef, respecting the requested config.

      *  @param config Desired config.

      *  @param subset Subset of this PixelRef to copy. Must be fully contained within the bounds of

      *         of this PixelRef.

      *  @return A new SkPixelRef, or NULL if either there is an error (e.g. the destination could

      *          not be created with the given config), or this PixelRef does not support deep

      *          copies.

      */

     virtual SkPixelRef* deepCopy(SkBitmap::Config config, const SkIRect* subset = NULL) {

         return NULL;

     }

 #ifdef SK_BUILD_FOR_ANDROID

     /**

      *  Acquire a "global" ref on this object.

      *  The default implementation just calls ref(), but subclasses can override

      *  this method to implement additional behavior.

      */

     virtual void globalRef(void* data=NULL);

     /**

      *  Release a "global" ref on this object.

      *  The default implementation just calls unref(), but subclasses can override

      *  this method to implement additional behavior.

      */

     virtual void globalUnref();

 #endif

     SK_DEFINE_FLATTENABLE_TYPE(SkPixelRef)

     // Register a listener that may be called the next time our generation ID changes.

     //

     // We'll only call the listener if we're confident that we are the only SkPixelRef with this

     // generation ID.  If our generation ID changes and we decide not to call the listener, we'll

     // never call it: you must add a new listener for each generation ID change.  We also won't call

     // the listener when we're certain no one knows what our generation ID is.

     //

     // This can be used to invalidate caches keyed by SkPixelRef generation ID.

     struct GenIDChangeListener {

         virtual ~GenIDChangeListener() {}

         virtual void onChange() = 0;

     };

     // Takes ownership of listener.

     void addGenIDChangeListener(GenIDChangeListener* listener);

 protected:

     /**

      *  On success, returns true and fills out the LockRec for the pixels. On

      *  failure returns false and ignores the LockRec parameter.

      *

      *  The caller will have already acquired a mutex for thread safety, so this

      *  method need not do that.

      */

     virtual bool onNewLockPixels(LockRec*) = 0;

     /**

      *  Balancing the previous successful call to onNewLockPixels. The locked

      *  pixel address will no longer be referenced, so the subclass is free to

      *  move or discard that memory.

      *

      *  The caller will have already acquired a mutex for thread safety, so this

      *  method need not do that.

      */

     virtual void onUnlockPixels() = 0;

     /** Default impl returns true */

     virtual bool onLockPixelsAreWritable() const;

     // returns false;

     virtual bool onImplementsDecodeInto();

     // returns false;

     virtual bool onDecodeInto(int pow2, SkBitmap* bitmap);

     /**

      *  For pixelrefs that don't have access to their raw pixels, they may be

      *  able to make a copy of them (e.g. if the pixels are on the GPU).

      *

      *  The base class implementation returns false;

      */

     virtual bool onReadPixels(SkBitmap* dst, const SkIRect* subsetOrNull);

     // default impl returns NULL.

     virtual SkData* onRefEncodedData();

     /**

      *  Returns the size (in bytes) of the internally allocated memory.

      *  This should be implemented in all serializable SkPixelRef derived classes.

      *  SkBitmap::fPixelRefOffset + SkBitmap::getSafeSize() should never overflow this value,

      *  otherwise the rendering code may attempt to read memory out of bounds.

      *

      *  @return default impl returns 0.

      */

     virtual size_t getAllocatedSizeInBytes() const;

     /** Return the mutex associated with this pixelref. This value is assigned

         in the constructor, and cannot change during the lifetime of the object.

     */

     SkBaseMutex* mutex() const { return fMutex; }

     // serialization

     SkPixelRef(SkReadBuffer&, SkBaseMutex*);

     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;

     // only call from constructor. Flags this to always be locked, removing

     // the need to grab the mutex and call onLockPixels/onUnlockPixels.

     // Performance tweak to avoid those calls (esp. in multi-thread use case).

     void setPreLocked(void*, size_t rowBytes, SkColorTable*);

 private:

     SkBaseMutex*    fMutex; // must remain in scope for the life of this object

     // mostly const. fInfo.fAlpahType can be changed at runtime.

     const SkImageInfo fInfo;

     // LockRec is only valid if we're in a locked state (isLocked())

     LockRec         fRec;

     int             fLockCount;

     mutable uint32_t fGenerationID;

     mutable bool     fUniqueGenerationID;

     SkTDArray<GenIDChangeListener*> fGenIDChangeListeners;  // pointers are owned

     SkString    fURI;

     // can go from false to true, but never from true to false

     bool    fIsImmutable;

     // only ever set in constructor, const after that

     bool    fPreLocked;

     void needsNewGenID();

     void callGenIDChangeListeners();

     void setMutex(SkBaseMutex* mutex);

     // When copying a bitmap to another with the same shape and config, we can safely

     // clone the pixelref generation ID too, which makes them equivalent under caching.

     friend class SkBitmap;  // only for cloneGenID

     void cloneGenID(const SkPixelRef&);

     typedef SkFlattenable INHERITED;

 };

 class SkPixelRefFactory : public SkRefCnt {

 public:

     /**

      *  Allocate a new pixelref matching the specified ImageInfo, allocating

      *  the memory for the pixels. If the ImageInfo requires a ColorTable,

      *  the pixelref will ref() the colortable.

      *  On failure return NULL.

      */

     virtual SkPixelRef* create(const SkImageInfo&, SkColorTable*) = 0;

 };

 #endif