reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 1 | /* libs/graphics/sgl/SkGlyphCache.h |
| 2 | ** |
| 3 | ** Copyright 2006, The Android Open Source Project |
| 4 | ** |
| 5 | ** Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | ** you may not use this file except in compliance with the License. |
| 7 | ** You may obtain a copy of the License at |
| 8 | ** |
| 9 | ** http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | ** |
| 11 | ** Unless required by applicable law or agreed to in writing, software |
| 12 | ** distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | ** See the License for the specific language governing permissions and |
| 15 | ** limitations under the License. |
| 16 | */ |
| 17 | |
| 18 | #ifndef SkGlyphCache_DEFINED |
| 19 | #define SkGlyphCache_DEFINED |
| 20 | |
| 21 | #include "SkBitmap.h" |
| 22 | #include "SkChunkAlloc.h" |
| 23 | #include "SkDescriptor.h" |
| 24 | #include "SkScalerContext.h" |
| 25 | #include "SkTemplates.h" |
| 26 | |
| 27 | class SkPaint; |
| 28 | |
| 29 | class SkGlyphCache_Globals; |
| 30 | |
| 31 | /** \class SkGlyphCache |
| 32 | |
| 33 | This class represents a strike: a specific combination of typeface, size, |
| 34 | matrix, etc., and holds the glyphs for that strike. Calling any of the |
| 35 | getUnichar.../getGlyphID... methods will return the requested glyph, |
| 36 | either instantly if it is already cahced, or by first generating it and then |
| 37 | adding it to the strike. |
| 38 | |
| 39 | The strikes are held in a global list, available to all threads. To interact |
| 40 | with one, call either VisitCache() or DetachCache(). |
| 41 | */ |
| 42 | class SkGlyphCache { |
| 43 | public: |
| 44 | /** Returns a glyph with valid fAdvance and fDevKern fields. |
| 45 | The remaining fields may be valid, but that is not guaranteed. If you |
| 46 | require those, call getUnicharMetrics or getGlyphIDMetrics instead. |
| 47 | */ |
| 48 | const SkGlyph& getUnicharAdvance(SkUnichar); |
| 49 | const SkGlyph& getGlyphIDAdvance(uint16_t); |
| 50 | |
| 51 | /** Returns a glyph with all fields valid except fImage and fPath, which |
| 52 | may be null. If they are null, call findImage or findPath for those. |
| 53 | If they are not null, then they are valid. |
| 54 | |
| 55 | This call is potentially slower than the matching ...Advance call. If |
| 56 | you only need the fAdvance/fDevKern fields, call those instead. |
| 57 | */ |
| 58 | const SkGlyph& getUnicharMetrics(SkUnichar); |
| 59 | const SkGlyph& getGlyphIDMetrics(uint16_t); |
| 60 | |
| 61 | /** These are variants that take the device position of the glyph. Call |
| 62 | these only if you are drawing in subpixel mode. Passing 0, 0 is |
| 63 | effectively the same as calling the variants w/o the extra params, tho |
| 64 | a tiny bit slower. |
| 65 | */ |
| 66 | const SkGlyph& getUnicharMetrics(SkUnichar, SkFixed x, SkFixed y); |
| 67 | const SkGlyph& getGlyphIDMetrics(uint16_t, SkFixed x, SkFixed y); |
| 68 | |
| 69 | /** Return the glyphID for the specified Unichar. If the char has already |
| 70 | been seen, use the existing cache entry. If not, ask the scalercontext |
| 71 | to compute it for us. |
| 72 | */ |
| 73 | uint16_t unicharToGlyph(SkUnichar); |
| 74 | |
| 75 | /** Return the image associated with the glyph. If it has not been generated |
| 76 | this will trigger that. |
| 77 | */ |
| 78 | const void* findImage(const SkGlyph&); |
| 79 | /** Return the Path associated with the glyph. If it has not been generated |
| 80 | this will trigger that. |
| 81 | */ |
| 82 | const SkPath* findPath(const SkGlyph&); |
| 83 | |
| 84 | /** Return the vertical metrics for this strike. |
| 85 | */ |
| 86 | const SkPaint::FontMetrics& getFontMetricsY() const { |
| 87 | return fFontMetricsY; |
| 88 | } |
| 89 | |
| 90 | /* AuxProc/Data allow a client to associate data with this cache entry. |
| 91 | Multiple clients can use this, as their data is keyed with a function |
| 92 | pointer. In addition to serving as a key, the function pointer is called |
| 93 | with the data when the glyphcache object is deleted, so the client can |
| 94 | cleanup their data as well. NOTE: the auxProc must not try to access |
| 95 | this glyphcache in any way, since it may be in the process of being |
| 96 | deleted. |
| 97 | */ |
| 98 | |
| 99 | //! If the proc is found, return true and set *dataPtr to its data |
| 100 | bool getAuxProcData(void (*auxProc)(void*), void** dataPtr) const; |
| 101 | //! Add a proc/data pair to the glyphcache. proc should be non-null |
| 102 | void setAuxProc(void (*auxProc)(void*), void* auxData); |
| 103 | //! If found, remove the proc/data pair from the glyphcache (does not |
| 104 | // call the proc) |
| 105 | void removeAuxProc(void (*auxProc)(void*)); |
| 106 | |
| 107 | /** Call proc on all cache entries, stopping early if proc returns true. |
| 108 | The proc should not create or delete caches, since it could produce |
| 109 | deadlock. |
| 110 | */ |
| 111 | static void VisitAllCaches(bool (*proc)(SkGlyphCache*, void*), void* ctx); |
| 112 | |
| 113 | /** Find a matching cache entry, and call proc() with it. If none is found |
| 114 | create a new one. If the proc() returns true, detach the cache and |
| 115 | return it, otherwise leave it and return NULL. |
| 116 | */ |
| 117 | static SkGlyphCache* VisitCache(const SkDescriptor* desc, |
| 118 | bool (*proc)(const SkGlyphCache*, void*), |
| 119 | void* context); |
| 120 | |
| 121 | /** Given a strike that was returned by either VisitCache() or DetachCache() |
| 122 | add it back into the global cache list (after which the caller should |
| 123 | not reference it anymore. |
| 124 | */ |
| 125 | static void AttachCache(SkGlyphCache*); |
| 126 | |
| 127 | /** Detach a strike from the global cache matching the specified descriptor. |
| 128 | Once detached, it can be queried/modified by the current thread, and |
| 129 | when finished, be reattached to the global cache with AttachCache(). |
| 130 | While detached, if another request is made with the same descriptor, |
| 131 | a different strike will be generated. This is fine. It does mean we |
| 132 | can have more than 1 strike for the same descriptor, but that will |
| 133 | eventually get purged, and the win is that different thread will never |
| 134 | block each other while a strike is being used. |
| 135 | */ |
| 136 | static SkGlyphCache* DetachCache(const SkDescriptor* desc) { |
| 137 | return VisitCache(desc, DetachProc, NULL); |
| 138 | } |
| 139 | |
| 140 | /** Return the approximate number of bytes used by the font cache |
| 141 | */ |
| 142 | static size_t GetCacheUsed(); |
| 143 | |
| 144 | /** This can be called to purge old font data, in an attempt to free |
| 145 | enough bytes such that the font cache is not using more than the |
| 146 | specified number of bytes. It is thread-safe, and may be called at |
| 147 | any time. |
| 148 | Return true if some amount of the cache was purged. |
| 149 | */ |
| 150 | static bool SetCacheUsed(size_t bytesUsed); |
| 151 | |
| 152 | private: |
| 153 | SkGlyphCache(const SkDescriptor*); |
| 154 | ~SkGlyphCache(); |
| 155 | |
| 156 | enum MetricsType { |
| 157 | kJustAdvance_MetricsType, |
| 158 | kFull_MetricsType |
| 159 | }; |
| 160 | |
| 161 | SkGlyph* lookupMetrics(uint32_t id, MetricsType); |
| 162 | static bool DetachProc(const SkGlyphCache*, void*) { return true; } |
| 163 | |
| 164 | void detach(SkGlyphCache** head) { |
| 165 | if (fPrev) { |
| 166 | fPrev->fNext = fNext; |
| 167 | } else { |
| 168 | *head = fNext; |
| 169 | } |
| 170 | if (fNext) { |
| 171 | fNext->fPrev = fPrev; |
| 172 | } |
| 173 | fPrev = fNext = NULL; |
| 174 | } |
| 175 | |
| 176 | void attachToHead(SkGlyphCache** head) { |
| 177 | SkASSERT(NULL == fPrev && NULL == fNext); |
| 178 | if (*head) { |
| 179 | (*head)->fPrev = this; |
| 180 | fNext = *head; |
| 181 | } |
| 182 | *head = this; |
| 183 | } |
| 184 | |
| 185 | SkGlyphCache* fNext, *fPrev; |
| 186 | SkDescriptor* fDesc; |
| 187 | SkScalerContext* fScalerContext; |
| 188 | SkPaint::FontMetrics fFontMetricsY; |
| 189 | |
| 190 | enum { |
| 191 | kHashBits = 8, |
| 192 | kHashCount = 1 << kHashBits, |
| 193 | kHashMask = kHashCount - 1 |
| 194 | }; |
| 195 | SkGlyph* fGlyphHash[kHashCount]; |
| 196 | SkTDArray<SkGlyph*> fGlyphArray; |
| 197 | SkChunkAlloc fGlyphAlloc; |
| 198 | SkChunkAlloc fImageAlloc; |
| 199 | |
| 200 | int fMetricsCount, fAdvanceCount; |
| 201 | |
| 202 | struct CharGlyphRec { |
| 203 | uint32_t fID; // unichar + subpixel |
| 204 | SkGlyph* fGlyph; |
| 205 | }; |
| 206 | // no reason to use the same kHashCount as fGlyphHash, but we do for now |
| 207 | CharGlyphRec fCharToGlyphHash[kHashCount]; |
| 208 | |
| 209 | enum { |
| 210 | // shift so that the top bits fall into kHashBits region |
| 211 | kShiftForHashIndex = SkGlyph::kSubShift + |
| 212 | SkGlyph::kSubBits*2 - |
| 213 | kHashBits |
| 214 | }; |
| 215 | |
| 216 | static inline unsigned ID2HashIndex(uint32_t id) { |
| 217 | return (id ^ (id >> kShiftForHashIndex)) & kHashMask; |
| 218 | } |
| 219 | |
| 220 | // used to track (approx) how much ram is tied-up in this cache |
| 221 | size_t fMemoryUsed; |
| 222 | |
| 223 | struct AuxProcRec { |
| 224 | AuxProcRec* fNext; |
| 225 | void (*fProc)(void*); |
| 226 | void* fData; |
| 227 | }; |
| 228 | AuxProcRec* fAuxProcList; |
| 229 | void invokeAndRemoveAuxProcs(); |
| 230 | |
| 231 | // This relies on the caller to have already acquired the mutex to access the global cache |
| 232 | static size_t InternalFreeCache(SkGlyphCache_Globals*, size_t bytesNeeded); |
| 233 | |
| 234 | inline static SkGlyphCache* FindTail(SkGlyphCache* head); |
| 235 | static size_t ComputeMemoryUsed(const SkGlyphCache* head); |
| 236 | |
| 237 | friend class SkGlyphCache_Globals; |
| 238 | }; |
| 239 | |
| 240 | class SkAutoGlyphCache { |
| 241 | public: |
| 242 | SkAutoGlyphCache(SkGlyphCache* cache) : fCache(cache) {} |
| 243 | SkAutoGlyphCache(const SkDescriptor* desc) |
| 244 | { |
| 245 | fCache = SkGlyphCache::DetachCache(desc); |
| 246 | } |
| 247 | SkAutoGlyphCache(const SkPaint& paint, const SkMatrix* matrix) |
| 248 | { |
| 249 | fCache = paint.detachCache(matrix); |
| 250 | } |
| 251 | ~SkAutoGlyphCache() |
| 252 | { |
| 253 | if (fCache) |
| 254 | SkGlyphCache::AttachCache(fCache); |
| 255 | } |
| 256 | |
| 257 | SkGlyphCache* getCache() const { return fCache; } |
| 258 | |
| 259 | void release() |
| 260 | { |
| 261 | if (fCache) |
| 262 | { |
| 263 | SkGlyphCache::AttachCache(fCache); |
| 264 | fCache = NULL; |
| 265 | } |
| 266 | } |
| 267 | private: |
| 268 | SkGlyphCache* fCache; |
| 269 | |
| 270 | static bool DetachProc(const SkGlyphCache*, void*); |
| 271 | }; |
| 272 | |
| 273 | #endif |
| 274 | |