skia2/include/core/SkPixelRef.h
reed@google.com ea033606a0 add per-draw checks for lockcounts
Review URL: https://codereview.appspot.com/6943056

git-svn-id: http://skia.googlecode.com/svn/trunk@6815 2bbb7eff-a529-9590-31e7-b0007b416f81
2012-12-14 13:13:55 +00:00

252 lines
8.4 KiB
C++

/*
* 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"
#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;
// this is an opaque class, not interpreted by skia
class SkGpuTexture;
/** \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(SkBaseMutex* mutex = NULL);
/** Return the pixel memory returned from lockPixels, or null if the
lockCount is 0.
*/
void* pixels() const { return fPixels; }
/** Return the current colorTable (if any) if pixels are locked, or null.
*/
SkColorTable* colorTable() const { return fColorTable; }
/**
* Returns true if the lockcount > 0
*/
bool isLocked() const { return fLockCount > 0; }
SkDEBUGCODE(int getLockCount() const { return fLockCount; })
/** Call to access the pixel memory, which is returned. Balance with a call
to unlockPixels().
*/
void lockPixels();
/** 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();
/** 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();
}
/** Are we really wrapping a texture instead of a bitmap?
*/
virtual SkGpuTexture* 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
protected:
/** Called when the lockCount goes from 0 to 1. The caller will have already
acquire a mutex for thread safety, so this method need not do that.
*/
virtual void* onLockPixels(SkColorTable**) = 0;
/** Called when the lock count goes from 1 to 0. The caller will have
already acquire a mutex for thread safety, so this method need not do
that.
*/
virtual void onUnlockPixels() = 0;
/** Default impl returns true */
virtual bool onLockPixelsAreWritable() const;
/**
* 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();
/** 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(SkFlattenableReadBuffer&, SkBaseMutex*);
virtual void flatten(SkFlattenableWriteBuffer&) 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* pixels, SkColorTable* ctable);
/**
* If a subclass passed a particular mutex to the base constructor, it can
* override that to go back to the default mutex by calling this. However,
* this should only be called from within the subclass' constructor.
*/
void useDefaultMutex() { this->setMutex(NULL); }
private:
SkBaseMutex* fMutex; // must remain in scope for the life of this object
void* fPixels;
SkColorTable* fColorTable; // we do not track ownership, subclass does
int fLockCount;
mutable uint32_t fGenerationID;
// SkBitmap is only a friend so that when copying, it can modify the new SkPixelRef to have the
// same fGenerationID as the original.
friend class SkBitmap;
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 setMutex(SkBaseMutex* mutex);
typedef SkFlattenable INHERITED;
};
#endif