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* Copyright 2006 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 SkGlyphCache_DEFINED
#define SkGlyphCache_DEFINED
#include "SkBitmap.h"
#include "SkChunkAlloc.h"
#include "SkDescriptor.h"
#include "SkGlyph.h"
#include "SkTHash.h"
#include "SkScalerContext.h"
#include "SkTemplates.h"
#include "SkTDArray.h"
class SkPaint;
class SkTraceMemoryDump;
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 cached, 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 {
/** 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, though 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);
/** Map the glyph to its Unicode equivalent. Unmappable glyphs map to a character code of zero.
SkUnichar glyphToUnichar(uint16_t);
/** Returns the number of glyphs for this strike.
unsigned getGlyphCount() const;
/** Return the number of glyphs currently cached. */
int countCachedGlyphs() const;
/** 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
const SkPath* findPath(const SkGlyph&);
/** Return the vertical metrics for this strike.
const SkPaint::FontMetrics& getFontMetrics() const {
return fFontMetrics;
const SkDescriptor& getDescriptor() const { return *fDesc; }
SkMask::Format getMaskFormat() const {
return fScalerContext->getMaskFormat();
bool isSubpixel() const {
return fScalerContext->isSubpixel();
/** Return the approx RAM usage for this cache. */
size_t getMemoryUsed() const { return fMemoryUsed; }
void dump() const;
/** 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);
SkScalerContext* getScalerContext() const { return fScalerContext; }
/** 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
static SkGlyphCache* VisitCache(SkTypeface*, 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(SkTypeface* typeface, const SkDescriptor* desc) {
return VisitCache(typeface, desc, DetachProc, nullptr);
static void Dump();
/** Dump memory usage statistics of all the attaches caches in the process using the
SkTraceMemoryDump interface.
static void DumpMemoryStatistics(SkTraceMemoryDump* dump);
typedef void (*Visitor)(const SkGlyphCache&, void* context);
static void VisitAll(Visitor, void* context);
#ifdef SK_DEBUG
void validate() const;
void validate() const {}
class AutoValidate : SkNoncopyable {
AutoValidate(const SkGlyphCache* cache) : fCache(cache) {
if (fCache) {
~AutoValidate() {
if (fCache) {
void forget() {
fCache = nullptr;
const SkGlyphCache* fCache;
friend class SkGlyphCache_Globals;
enum {
kHashBits = 8,
kHashCount = 1 << kHashBits,
kHashMask = kHashCount - 1
typedef uint32_t PackedGlyphID; // glyph-index + subpixel-pos
typedef uint32_t PackedUnicharID; // unichar + subpixel-pos
struct CharGlyphRec {
PackedUnicharID fPackedUnicharID;
PackedGlyphID fPackedGlyphID;
struct AuxProcRec {
AuxProcRec* fNext;
void (*fProc)(void*);
void* fData;
// SkGlyphCache takes ownership of the scalercontext.
SkGlyphCache(SkTypeface*, const SkDescriptor*, SkScalerContext*);
// Return the SkGlyph* associated with MakeID. The id parameter is the
// combined glyph/x/y id generated by MakeID. If it is just a glyph id
// then x and y are assumed to be zero.
SkGlyph* lookupByPackedGlyphID(PackedGlyphID packedGlyphID);
// Return a SkGlyph* associated with unicode id and position x and y.
SkGlyph* lookupByChar(SkUnichar id, SkFixed x = 0, SkFixed y = 0);
// Return a new SkGlyph for the glyph ID and subpixel position id.
SkGlyph* allocateNewGlyph(PackedGlyphID packedGlyphID);
static bool DetachProc(const SkGlyphCache*, void*) { return true; }
// The id arg is a combined id generated by MakeID.
CharGlyphRec* getCharGlyphRec(PackedUnicharID id);
void invokeAndRemoveAuxProcs();
inline static SkGlyphCache* FindTail(SkGlyphCache* head);
SkGlyphCache* fNext;
SkGlyphCache* fPrev;
SkDescriptor* const fDesc;
SkScalerContext* const fScalerContext;
SkPaint::FontMetrics fFontMetrics;
// Map from a combined GlyphID and sub-pixel position to a SkGlyph.
SkTHashTable<SkGlyph, PackedGlyphID, SkGlyph::HashTraits> fGlyphMap;
SkChunkAlloc fGlyphAlloc;
SkAutoTArray<CharGlyphRec> fPackedUnicharIDToPackedGlyphID;
// used to track (approx) how much ram is tied-up in this cache
size_t fMemoryUsed;
AuxProcRec* fAuxProcList;
class SkAutoGlyphCacheBase {
SkGlyphCache* getCache() const { return fCache; }
void release() {
if (fCache) {
fCache = nullptr;
// Hide the constructors so we can't create one of these directly. Create SkAutoGlyphCache or
// SkAutoGlyphCacheNoCache instead.
SkAutoGlyphCacheBase(SkGlyphCache* cache) : fCache(cache) {}
SkAutoGlyphCacheBase(SkTypeface* typeface, const SkDescriptor* desc) {
fCache = SkGlyphCache::DetachCache(typeface, desc);
SkAutoGlyphCacheBase(const SkPaint& /*paint*/,
const SkSurfaceProps* /*surfaceProps*/,
const SkMatrix* /*matrix*/) {
fCache = nullptr;
SkAutoGlyphCacheBase() {
fCache = nullptr;
~SkAutoGlyphCacheBase() {
if (fCache) {
SkGlyphCache* fCache;
static bool DetachProc(const SkGlyphCache*, void*);
class SkAutoGlyphCache : public SkAutoGlyphCacheBase {
SkAutoGlyphCache(SkGlyphCache* cache) : SkAutoGlyphCacheBase(cache) {}
SkAutoGlyphCache(SkTypeface* typeface, const SkDescriptor* desc) :
SkAutoGlyphCacheBase(typeface, desc) {}
SkAutoGlyphCache(const SkPaint& paint,
const SkSurfaceProps* surfaceProps,
const SkMatrix* matrix) {
fCache = paint.detachCache(surfaceProps, matrix, false);
SkAutoGlyphCache() : SkAutoGlyphCacheBase() {}
#define SkAutoGlyphCache(...) SK_REQUIRE_LOCAL_VAR(SkAutoGlyphCache)
class SkAutoGlyphCacheNoGamma : public SkAutoGlyphCacheBase {
SkAutoGlyphCacheNoGamma(SkGlyphCache* cache) : SkAutoGlyphCacheBase(cache) {}
SkAutoGlyphCacheNoGamma(SkTypeface* typeface, const SkDescriptor* desc) :
SkAutoGlyphCacheBase(typeface, desc) {}
SkAutoGlyphCacheNoGamma(const SkPaint& paint,
const SkSurfaceProps* surfaceProps,
const SkMatrix* matrix) {
fCache = paint.detachCache(surfaceProps, matrix, true);
SkAutoGlyphCacheNoGamma() : SkAutoGlyphCacheBase() {}
#define SkAutoGlyphCacheNoGamma(...) SK_REQUIRE_LOCAL_VAR(SkAutoGlyphCacheNoGamma)