David Ghandehari | 9e5b587 | 2016-07-28 09:50:04 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2014 Google Inc. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license that can be |
| 5 | * found in the LICENSE file. |
| 6 | */ |
| 7 | |
| 8 | #ifndef SkTextBlob_DEFINED |
| 9 | #define SkTextBlob_DEFINED |
| 10 | |
| 11 | #include "SkPaint.h" |
| 12 | #include "SkRefCnt.h" |
| 13 | #include "SkTArray.h" |
| 14 | #include "SkTDArray.h" |
| 15 | |
| 16 | class SkReadBuffer; |
| 17 | class SkWriteBuffer; |
| 18 | |
| 19 | /** \class SkTextBlob |
| 20 | |
| 21 | SkTextBlob combines multiple text runs into an immutable, ref-counted structure. |
| 22 | */ |
| 23 | class SK_API SkTextBlob : public SkRefCnt { |
| 24 | public: |
| 25 | /** |
| 26 | * Returns the blob bounding box. |
| 27 | */ |
| 28 | const SkRect& bounds() const { return fBounds; } |
| 29 | |
| 30 | /** |
| 31 | * Return a non-zero, unique value representing the text blob. |
| 32 | */ |
| 33 | uint32_t uniqueID() const; |
| 34 | |
| 35 | /** |
| 36 | * Serialize to a buffer. |
| 37 | */ |
| 38 | void flatten(SkWriteBuffer&) const; |
| 39 | |
| 40 | /** |
| 41 | * Recreate an SkTextBlob that was serialized into a buffer. |
| 42 | * |
| 43 | * @param SkReadBuffer Serialized blob data. |
| 44 | * @return A new SkTextBlob representing the serialized data, or NULL if the buffer is |
| 45 | * invalid. |
| 46 | */ |
| 47 | static const SkTextBlob* CreateFromBuffer(SkReadBuffer&); |
| 48 | |
| 49 | private: |
| 50 | enum GlyphPositioning { |
| 51 | kDefault_Positioning = 0, // Default glyph advances -- zero scalars per glyph. |
| 52 | kHorizontal_Positioning = 1, // Horizontal positioning -- one scalar per glyph. |
| 53 | kFull_Positioning = 2 // Point positioning -- two scalars per glyph. |
| 54 | }; |
| 55 | |
| 56 | class RunRecord; |
| 57 | |
| 58 | class RunIterator { |
| 59 | public: |
| 60 | RunIterator(const SkTextBlob* blob); |
| 61 | |
| 62 | bool done() const; |
| 63 | void next(); |
| 64 | |
| 65 | uint32_t glyphCount() const; |
| 66 | const uint16_t* glyphs() const; |
| 67 | const SkScalar* pos() const; |
| 68 | const SkPoint& offset() const; |
| 69 | void applyFontToPaint(SkPaint*) const; |
| 70 | GlyphPositioning positioning() const; |
| 71 | |
| 72 | private: |
| 73 | const RunRecord* fCurrentRun; |
| 74 | int fRemainingRuns; |
| 75 | |
| 76 | SkDEBUGCODE(uint8_t* fStorageTop;) |
| 77 | }; |
| 78 | |
| 79 | SkTextBlob(int runCount, const SkRect& bounds); |
| 80 | |
| 81 | virtual ~SkTextBlob(); |
| 82 | virtual void internal_dispose() const SK_OVERRIDE; |
| 83 | |
| 84 | static unsigned ScalarsPerGlyph(GlyphPositioning pos); |
| 85 | |
| 86 | friend class SkBaseDevice; |
| 87 | friend class SkTextBlobBuilder; |
| 88 | friend class TextBlobTester; |
| 89 | |
| 90 | const int fRunCount; |
| 91 | const SkRect fBounds; |
| 92 | mutable uint32_t fUniqueID; |
| 93 | |
| 94 | SkDEBUGCODE(size_t fStorageSize;) |
| 95 | |
| 96 | // The actual payload resides in externally-managed storage, following the object. |
| 97 | // (see the .cpp for more details) |
| 98 | |
| 99 | typedef SkRefCnt INHERITED; |
| 100 | }; |
| 101 | |
| 102 | /** \class SkTextBlobBuilder |
| 103 | |
| 104 | Helper class for constructing SkTextBlobs. |
| 105 | */ |
| 106 | class SK_API SkTextBlobBuilder { |
| 107 | public: |
| 108 | SkTextBlobBuilder(); |
| 109 | |
| 110 | ~SkTextBlobBuilder(); |
| 111 | |
| 112 | /** |
| 113 | * Returns an immutable SkTextBlob for the current runs/glyphs. The builder is reset and |
| 114 | * can be reused. |
| 115 | */ |
| 116 | const SkTextBlob* build(); |
| 117 | |
| 118 | /** |
| 119 | * Glyph and position buffers associated with a run. |
| 120 | * |
| 121 | * A run is a sequence of glyphs sharing the same font metrics and positioning mode. |
| 122 | */ |
| 123 | struct RunBuffer { |
| 124 | uint16_t* glyphs; |
| 125 | SkScalar* pos; |
| 126 | }; |
| 127 | |
| 128 | /** |
| 129 | * Allocates a new default-positioned run and returns its writable glyph buffer |
| 130 | * for direct manipulation. |
| 131 | * |
| 132 | * @param font The font to be used for this run. |
| 133 | * @param count Number of glyphs. |
| 134 | * @param x,y Position within the blob. |
| 135 | * @param bounds Optional run bounding box. If known in advance (!= NULL), it will |
| 136 | * be used when computing the blob bounds, to avoid re-measuring. |
| 137 | * |
| 138 | * @return A writable glyph buffer, valid until the next allocRun() or |
| 139 | * build() call. The buffer is guaranteed to hold @count@ glyphs. |
| 140 | */ |
| 141 | const RunBuffer& allocRun(const SkPaint& font, int count, SkScalar x, SkScalar y, |
| 142 | const SkRect* bounds = NULL); |
| 143 | |
| 144 | /** |
| 145 | * Allocates a new horizontally-positioned run and returns its writable glyph and position |
| 146 | * buffers for direct manipulation. |
| 147 | * |
| 148 | * @param font The font to be used for this run. |
| 149 | * @param count Number of glyphs. |
| 150 | * @param y Vertical offset within the blob. |
| 151 | * @param bounds Optional run bounding box. If known in advance (!= NULL), it will |
| 152 | * be used when computing the blob bounds, to avoid re-measuring. |
| 153 | * |
| 154 | * @return Writable glyph and position buffers, valid until the next allocRun() |
| 155 | * or build() call. The buffers are guaranteed to hold @count@ elements. |
| 156 | */ |
| 157 | const RunBuffer& allocRunPosH(const SkPaint& font, int count, SkScalar y, |
| 158 | const SkRect* bounds = NULL); |
| 159 | |
| 160 | /** |
| 161 | * Allocates a new fully-positioned run and returns its writable glyph and position |
| 162 | * buffers for direct manipulation. |
| 163 | * |
| 164 | * @param font The font to be used for this run. |
| 165 | * @param count Number of glyphs. |
| 166 | * @param bounds Optional run bounding box. If known in advance (!= NULL), it will |
| 167 | * be used when computing the blob bounds, to avoid re-measuring. |
| 168 | * |
| 169 | * @return Writable glyph and position buffers, valid until the next allocRun() |
| 170 | * or build() call. The glyph buffer and position buffer are |
| 171 | * guaranteed to hold @count@ and 2 * @count@ elements, respectively. |
| 172 | */ |
| 173 | const RunBuffer& allocRunPos(const SkPaint& font, int count, const SkRect* bounds = NULL); |
| 174 | |
| 175 | private: |
| 176 | void reserve(size_t size); |
| 177 | void allocInternal(const SkPaint& font, SkTextBlob::GlyphPositioning positioning, |
| 178 | int count, SkPoint offset, const SkRect* bounds); |
| 179 | bool mergeRun(const SkPaint& font, SkTextBlob::GlyphPositioning positioning, |
| 180 | int count, SkPoint offset); |
| 181 | void updateDeferredBounds(); |
| 182 | |
| 183 | SkAutoTMalloc<uint8_t> fStorage; |
| 184 | size_t fStorageSize; |
| 185 | size_t fStorageUsed; |
| 186 | |
| 187 | SkRect fBounds; |
| 188 | int fRunCount; |
| 189 | bool fDeferredBounds; |
| 190 | size_t fLastRun; // index into fStorage |
| 191 | |
| 192 | RunBuffer fCurrentRunBuffer; |
| 193 | }; |
| 194 | |
| 195 | #endif // SkTextBlob_DEFINED |