src/core/SkGlyphCache.h - platform/external/skia - Git at Google

 /* libs/graphics/sgl/SkGlyphCache.h
 **
 ** Copyright 2006, The Android Open Source Project
 **
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 **
 **     http://www.apache.org/licenses/LICENSE-2.0
 **
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 */

 #ifndef SkGlyphCache_DEFINED
 #define SkGlyphCache_DEFINED

 #include "SkBitmap.h"
 #include "SkChunkAlloc.h"
 #include "SkDescriptor.h"
 #include "SkScalerContext.h"
 #include "SkTemplates.h"

 class SkPaint;

 class SkGlyphCache_Globals;

 /** \class SkGlyphCache

     This class represents a strike: a specific combination of typeface, size,
     matrix, etc., and holds the glyphs for that strike. Calling any of the
     getUnichar.../getGlyphID... methods will return the requested glyph,
     either instantly if it is already cahced, or by first generating it and then
     adding it to the strike.

     The strikes are held in a global list, available to all threads. To interact
     with one, call either VisitCache() or DetachCache().
 */
 class SkGlyphCache {
 public:
     /** Returns a glyph with valid fAdvance and fDevKern fields.
         The remaining fields may be valid, but that is not guaranteed. If you
         require those, call getUnicharMetrics or getGlyphIDMetrics instead.
     */
     const SkGlyph& getUnicharAdvance(SkUnichar);
     const SkGlyph& getGlyphIDAdvance(uint16_t);

     /** Returns a glyph with all fields valid except fImage and fPath, which
         may be null. If they are null, call findImage or findPath for those.
         If they are not null, then they are valid.

         This call is potentially slower than the matching ...Advance call. If
         you only need the fAdvance/fDevKern fields, call those instead.
     */
     const SkGlyph& getUnicharMetrics(SkUnichar);
     const SkGlyph& getGlyphIDMetrics(uint16_t);

     /** These are variants that take the device position of the glyph. Call
         these only if you are drawing in subpixel mode. Passing 0, 0 is
         effectively the same as calling the variants w/o the extra params, tho
         a tiny bit slower.
     */
     const SkGlyph& getUnicharMetrics(SkUnichar, SkFixed x, SkFixed y);
     const SkGlyph& getGlyphIDMetrics(uint16_t, SkFixed x, SkFixed y);

     /** Return the glyphID for the specified Unichar. If the char has already
         been seen, use the existing cache entry. If not, ask the scalercontext
         to compute it for us.
     */
     uint16_t unicharToGlyph(SkUnichar);

     /** Return the image associated with the glyph. If it has not been generated
         this will trigger that.
     */
     const void* findImage(const SkGlyph&);
     /** Return the Path associated with the glyph. If it has not been generated
         this will trigger that.
     */
     const SkPath* findPath(const SkGlyph&);

     /** Return the vertical metrics for this strike.
     */
     const SkPaint::FontMetrics& getFontMetricsY() const {
         return fFontMetricsY;
     }

     /*  AuxProc/Data allow a client to associate data with this cache entry.
         Multiple clients can use this, as their data is keyed with a function
         pointer. In addition to serving as a key, the function pointer is called
         with the data when the glyphcache object is deleted, so the client can
         cleanup their data as well. NOTE: the auxProc must not try to access
         this glyphcache in any way, since it may be in the process of being
         deleted.
     */

     //! If the proc is found, return true and set *dataPtr to its data
     bool getAuxProcData(void (*auxProc)(void*), void** dataPtr) const;
     //! Add a proc/data pair to the glyphcache. proc should be non-null
     void setAuxProc(void (*auxProc)(void*), void* auxData);
     //! If found, remove the proc/data pair from the glyphcache (does not
     //  call the proc)
     void removeAuxProc(void (*auxProc)(void*));

     /** Call proc on all cache entries, stopping early if proc returns true.
         The proc should not create or delete caches, since it could produce
         deadlock.
     */
     static void VisitAllCaches(bool (*proc)(SkGlyphCache*, void*), void* ctx);

     /** Find a matching cache entry, and call proc() with it. If none is found
         create a new one. If the proc() returns true, detach the cache and
         return it, otherwise leave it and return NULL.
     */
     static SkGlyphCache* VisitCache(const SkDescriptor* desc,
                                     bool (*proc)(const SkGlyphCache*, void*),
                                     void* context);

     /** Given a strike that was returned by either VisitCache() or DetachCache()
         add it back into the global cache list (after which the caller should
         not reference it anymore.
     */
     static void AttachCache(SkGlyphCache*);

     /** Detach a strike from the global cache matching the specified descriptor.
         Once detached, it can be queried/modified by the current thread, and
         when finished, be reattached to the global cache with AttachCache().
         While detached, if another request is made with the same descriptor,
         a different strike will be generated. This is fine. It does mean we
         can have more than 1 strike for the same descriptor, but that will
         eventually get purged, and the win is that different thread will never
         block each other while a strike is being used.
     */
     static SkGlyphCache* DetachCache(const SkDescriptor* desc) {
         return VisitCache(desc, DetachProc, NULL);
     }

     /** Return the approximate number of bytes used by the font cache
     */
     static size_t GetCacheUsed();

     /** This can be called to purge old font data, in an attempt to free
         enough bytes such that the font cache is not using more than the
         specified number of bytes. It is thread-safe, and may be called at
         any time.
         Return true if some amount of the cache was purged.
     */
     static bool SetCacheUsed(size_t bytesUsed);

 private:
     SkGlyphCache(const SkDescriptor*);
     ~SkGlyphCache();

     enum MetricsType {
         kJustAdvance_MetricsType,
         kFull_MetricsType
     };

     SkGlyph* lookupMetrics(uint32_t id, MetricsType);
     static bool DetachProc(const SkGlyphCache*, void*) { return true; }

     void detach(SkGlyphCache** head) {
         if (fPrev) {
             fPrev->fNext = fNext;
         } else {
             *head = fNext;
         }
         if (fNext) {
             fNext->fPrev = fPrev;
         }
         fPrev = fNext = NULL;
     }

     void attachToHead(SkGlyphCache** head) {
         SkASSERT(NULL == fPrev && NULL == fNext);
         if (*head) {
             (*head)->fPrev = this;
             fNext = *head;
         }
         *head = this;
     }

     SkGlyphCache*       fNext, *fPrev;
     SkDescriptor*       fDesc;
     SkScalerContext*    fScalerContext;
     SkPaint::FontMetrics fFontMetricsY;

     enum {
         kHashBits   = 8,
         kHashCount  = 1 << kHashBits,
         kHashMask   = kHashCount - 1
     };
     SkGlyph*            fGlyphHash[kHashCount];
     SkTDArray<SkGlyph*> fGlyphArray;
     SkChunkAlloc        fGlyphAlloc;
     SkChunkAlloc        fImageAlloc;

     int fMetricsCount, fAdvanceCount;

     struct CharGlyphRec {
         uint32_t    fID;    // unichar + subpixel
         SkGlyph*    fGlyph;
     };
     // no reason to use the same kHashCount as fGlyphHash, but we do for now
     CharGlyphRec    fCharToGlyphHash[kHashCount];

     enum {
         // shift so that the top bits fall into kHashBits region
         kShiftForHashIndex = SkGlyph::kSubShift +
                              SkGlyph::kSubBits*2 -
                              kHashBits
     };

     static inline unsigned ID2HashIndex(uint32_t id) {
         return (id ^ (id >> kShiftForHashIndex)) & kHashMask;
     }

     // used to track (approx) how much ram is tied-up in this cache
     size_t  fMemoryUsed;

     struct AuxProcRec {
         AuxProcRec* fNext;
         void (*fProc)(void*);
         void* fData;
     };
     AuxProcRec* fAuxProcList;
     void invokeAndRemoveAuxProcs();

     // This relies on the caller to have already acquired the mutex to access the global cache
     static size_t InternalFreeCache(SkGlyphCache_Globals*, size_t bytesNeeded);

     inline static SkGlyphCache* FindTail(SkGlyphCache* head);
     static size_t ComputeMemoryUsed(const SkGlyphCache* head);

     friend class SkGlyphCache_Globals;
 };

 class SkAutoGlyphCache {
 public:
     SkAutoGlyphCache(SkGlyphCache* cache) : fCache(cache) {}
     SkAutoGlyphCache(const SkDescriptor* desc)
     {
         fCache = SkGlyphCache::DetachCache(desc);
     }
     SkAutoGlyphCache(const SkPaint& paint, const SkMatrix* matrix)
     {
         fCache = paint.detachCache(matrix);
     }
     ~SkAutoGlyphCache()
     {
         if (fCache)
             SkGlyphCache::AttachCache(fCache);
     }

     SkGlyphCache*   getCache() const { return fCache; }

     void release()
     {
         if (fCache)
         {
             SkGlyphCache::AttachCache(fCache);
             fCache = NULL;
         }
     }
 private:
     SkGlyphCache*   fCache;

     static bool DetachProc(const SkGlyphCache*, void*);
 };

 #endif
	/* libs/graphics/sgl/SkGlyphCache.h
	**
	** Copyright 2006, The Android Open Source Project
	**
	** Licensed under the Apache License, Version 2.0 (the "License");
	** you may not use this file except in compliance with the License.
	** You may obtain a copy of the License at
	**
	** http://www.apache.org/licenses/LICENSE-2.0
	**
	** Unless required by applicable law or agreed to in writing, software
	** distributed under the License is distributed on an "AS IS" BASIS,
	** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	** See the License for the specific language governing permissions and
	** limitations under the License.
	*/

	#ifndef SkGlyphCache_DEFINED
	#define SkGlyphCache_DEFINED

	#include "SkBitmap.h"
	#include "SkChunkAlloc.h"
	#include "SkDescriptor.h"
	#include "SkScalerContext.h"
	#include "SkTemplates.h"

	class SkPaint;

	class SkGlyphCache_Globals;

	/** \class SkGlyphCache

	This class represents a strike: a specific combination of typeface, size,
	matrix, etc., and holds the glyphs for that strike. Calling any of the
	getUnichar.../getGlyphID... methods will return the requested glyph,
	either instantly if it is already cahced, or by first generating it and then
	adding it to the strike.

	The strikes are held in a global list, available to all threads. To interact
	with one, call either VisitCache() or DetachCache().
	*/
	class SkGlyphCache {
	public:
	/** Returns a glyph with valid fAdvance and fDevKern fields.
	The remaining fields may be valid, but that is not guaranteed. If you
	require those, call getUnicharMetrics or getGlyphIDMetrics instead.
	*/
	const SkGlyph& getUnicharAdvance(SkUnichar);
	const SkGlyph& getGlyphIDAdvance(uint16_t);

	/** Returns a glyph with all fields valid except fImage and fPath, which
	may be null. If they are null, call findImage or findPath for those.
	If they are not null, then they are valid.

	This call is potentially slower than the matching ...Advance call. If
	you only need the fAdvance/fDevKern fields, call those instead.
	*/
	const SkGlyph& getUnicharMetrics(SkUnichar);
	const SkGlyph& getGlyphIDMetrics(uint16_t);

	/** These are variants that take the device position of the glyph. Call
	these only if you are drawing in subpixel mode. Passing 0, 0 is
	effectively the same as calling the variants w/o the extra params, tho
	a tiny bit slower.
	*/
	const SkGlyph& getUnicharMetrics(SkUnichar, SkFixed x, SkFixed y);
	const SkGlyph& getGlyphIDMetrics(uint16_t, SkFixed x, SkFixed y);

	/** Return the glyphID for the specified Unichar. If the char has already
	been seen, use the existing cache entry. If not, ask the scalercontext
	to compute it for us.
	*/
	uint16_t unicharToGlyph(SkUnichar);

	/** Return the image associated with the glyph. If it has not been generated
	this will trigger that.
	*/
	const void* findImage(const SkGlyph&);
	/** Return the Path associated with the glyph. If it has not been generated
	this will trigger that.
	*/
	const SkPath* findPath(const SkGlyph&);

	/** Return the vertical metrics for this strike.
	*/
	const SkPaint::FontMetrics& getFontMetricsY() const {
	return fFontMetricsY;
	}

	/* AuxProc/Data allow a client to associate data with this cache entry.
	Multiple clients can use this, as their data is keyed with a function
	pointer. In addition to serving as a key, the function pointer is called
	with the data when the glyphcache object is deleted, so the client can
	cleanup their data as well. NOTE: the auxProc must not try to access
	this glyphcache in any way, since it may be in the process of being
	deleted.
	*/

	//! If the proc is found, return true and set *dataPtr to its data
	bool getAuxProcData(void (auxProc)(void), void** dataPtr) const;
	//! Add a proc/data pair to the glyphcache. proc should be non-null
	void setAuxProc(void (auxProc)(void), void* auxData);
	//! If found, remove the proc/data pair from the glyphcache (does not
	// call the proc)
	void removeAuxProc(void (auxProc)(void));

	/** Call proc on all cache entries, stopping early if proc returns true.
	The proc should not create or delete caches, since it could produce
	deadlock.
	*/
	static void VisitAllCaches(bool (proc)(SkGlyphCache, void), void ctx);

	/** Find a matching cache entry, and call proc() with it. If none is found
	create a new one. If the proc() returns true, detach the cache and
	return it, otherwise leave it and return NULL.
	*/
	static SkGlyphCache* VisitCache(const SkDescriptor* desc,
	bool (proc)(const SkGlyphCache, void*),
	void* context);

	/** Given a strike that was returned by either VisitCache() or DetachCache()
	add it back into the global cache list (after which the caller should
	not reference it anymore.
	*/
	static void AttachCache(SkGlyphCache*);

	/** Detach a strike from the global cache matching the specified descriptor.
	Once detached, it can be queried/modified by the current thread, and
	when finished, be reattached to the global cache with AttachCache().
	While detached, if another request is made with the same descriptor,
	a different strike will be generated. This is fine. It does mean we
	can have more than 1 strike for the same descriptor, but that will
	eventually get purged, and the win is that different thread will never
	block each other while a strike is being used.
	*/
	static SkGlyphCache* DetachCache(const SkDescriptor* desc) {
	return VisitCache(desc, DetachProc, NULL);
	}

	/** Return the approximate number of bytes used by the font cache
	*/
	static size_t GetCacheUsed();

	/** This can be called to purge old font data, in an attempt to free
	enough bytes such that the font cache is not using more than the
	specified number of bytes. It is thread-safe, and may be called at
	any time.
	Return true if some amount of the cache was purged.
	*/
	static bool SetCacheUsed(size_t bytesUsed);

	private:
	SkGlyphCache(const SkDescriptor*);
	~SkGlyphCache();

	enum MetricsType {
	kJustAdvance_MetricsType,
	kFull_MetricsType
	};

	SkGlyph* lookupMetrics(uint32_t id, MetricsType);
	static bool DetachProc(const SkGlyphCache, void) { return true; }

	void detach(SkGlyphCache** head) {
	if (fPrev) {
	fPrev->fNext = fNext;
	} else {
	*head = fNext;
	}
	if (fNext) {
	fNext->fPrev = fPrev;
	}
	fPrev = fNext = NULL;
	}

	void attachToHead(SkGlyphCache** head) {
	SkASSERT(NULL == fPrev && NULL == fNext);
	if (*head) {
	(*head)->fPrev = this;
	fNext = *head;
	}
	*head = this;
	}

	SkGlyphCache* fNext, *fPrev;
	SkDescriptor* fDesc;
	SkScalerContext* fScalerContext;
	SkPaint::FontMetrics fFontMetricsY;

	enum {
	kHashBits = 8,
	kHashCount = 1 << kHashBits,
	kHashMask = kHashCount - 1
	};
	SkGlyph* fGlyphHash[kHashCount];
	SkTDArray<SkGlyph*> fGlyphArray;
	SkChunkAlloc fGlyphAlloc;
	SkChunkAlloc fImageAlloc;

	int fMetricsCount, fAdvanceCount;

	struct CharGlyphRec {
	uint32_t fID; // unichar + subpixel
	SkGlyph* fGlyph;
	};
	// no reason to use the same kHashCount as fGlyphHash, but we do for now
	CharGlyphRec fCharToGlyphHash[kHashCount];

	enum {
	// shift so that the top bits fall into kHashBits region
	kShiftForHashIndex = SkGlyph::kSubShift +
	SkGlyph::kSubBits*2 -
	kHashBits
	};

	static inline unsigned ID2HashIndex(uint32_t id) {
	return (id ^ (id >> kShiftForHashIndex)) & kHashMask;
	}

	// used to track (approx) how much ram is tied-up in this cache
	size_t fMemoryUsed;

	struct AuxProcRec {
	AuxProcRec* fNext;
	void (fProc)(void);
	void* fData;
	};
	AuxProcRec* fAuxProcList;
	void invokeAndRemoveAuxProcs();

	// This relies on the caller to have already acquired the mutex to access the global cache
	static size_t InternalFreeCache(SkGlyphCache_Globals*, size_t bytesNeeded);

	inline static SkGlyphCache* FindTail(SkGlyphCache* head);
	static size_t ComputeMemoryUsed(const SkGlyphCache* head);

	friend class SkGlyphCache_Globals;
	};

	class SkAutoGlyphCache {
	public:
	SkAutoGlyphCache(SkGlyphCache* cache) : fCache(cache) {}
	SkAutoGlyphCache(const SkDescriptor* desc)
	{
	fCache = SkGlyphCache::DetachCache(desc);
	}
	SkAutoGlyphCache(const SkPaint& paint, const SkMatrix* matrix)
	{
	fCache = paint.detachCache(matrix);
	}
	~SkAutoGlyphCache()
	{
	if (fCache)
	SkGlyphCache::AttachCache(fCache);
	}

	SkGlyphCache* getCache() const { return fCache; }

	void release()
	{
	if (fCache)
	{
	SkGlyphCache::AttachCache(fCache);
	fCache = NULL;
	}
	}
	private:
	SkGlyphCache* fCache;

	static bool DetachProc(const SkGlyphCache, void);
	};

	#endif