fmalita | 00d5c2c | 2014-08-21 08:53:26 -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 SkTextBlob |
| 17 | |
| 18 | SkTextBlob combines multiple text runs into an immutable, ref-counted structure. |
| 19 | */ |
| 20 | class SkTextBlob : public SkRefCnt { |
| 21 | public: |
| 22 | /** |
| 23 | * Returns the blob bounding box. |
| 24 | */ |
| 25 | const SkRect& bounds() const { return fBounds; } |
| 26 | |
| 27 | /** |
| 28 | * Return a non-zero, unique value representing the text blob. |
| 29 | */ |
| 30 | uint32_t uniqueID() const; |
| 31 | |
| 32 | private: |
| 33 | enum GlyphPositioning { |
| 34 | kDefault_Positioning = 0, // Default glyph advances -- zero scalars per glyph. |
| 35 | kHorizontal_Positioning = 1, // Horizontal positioning -- one scalar per glyph. |
| 36 | kFull_Positioning = 2 // Point positioning -- two scalars per glyph. |
| 37 | }; |
| 38 | |
| 39 | class RunIterator { |
| 40 | public: |
| 41 | RunIterator(const SkTextBlob* blob); |
| 42 | |
| 43 | bool done() const; |
| 44 | void next(); |
| 45 | |
| 46 | uint32_t glyphCount() const; |
| 47 | const uint16_t* glyphs() const; |
| 48 | const SkScalar* pos() const; |
| 49 | const SkPoint& offset() const; |
| 50 | const SkPaint& font() const; |
| 51 | GlyphPositioning positioning() const; |
| 52 | |
| 53 | private: |
| 54 | const SkTextBlob* fBlob; |
| 55 | int fIndex; |
| 56 | }; |
| 57 | |
| 58 | // A run is a sequence of glyphs sharing the same font metrics and positioning mode. |
| 59 | struct Run { |
| 60 | uint32_t count; |
| 61 | uint32_t glyphStart; // index into fGlyphBuffer |
| 62 | uint32_t posStart; // index into fPosBuffer |
| 63 | SkPoint offset; // run offset (unsued for fully positioned glyphs) |
| 64 | SkPaint font; |
| 65 | GlyphPositioning positioning; |
| 66 | }; |
| 67 | |
| 68 | SkTextBlob(uint16_t* glyphs, SkScalar* pos, const SkTArray<Run>* runs, const SkRect& bounds); |
| 69 | |
| 70 | friend class SkCanvas; |
| 71 | friend class SkTextBlobBuilder; |
| 72 | |
| 73 | const SkAutoTMalloc<uint16_t> fGlyphBuffer; |
| 74 | const SkAutoTMalloc<SkScalar> fPosBuffer; |
| 75 | |
| 76 | // SkTArray required here for run font destruction. |
| 77 | SkAutoTDelete<const SkTArray<Run> > fRuns; |
| 78 | const SkRect fBounds; |
| 79 | |
| 80 | mutable uint32_t fUniqueID; |
| 81 | |
| 82 | typedef SkRefCnt INHERITED; |
| 83 | }; |
| 84 | |
| 85 | /** \class SkTextBlobBuilder |
| 86 | |
| 87 | Helper class for constructing SkTextBlobs. |
| 88 | */ |
| 89 | class SkTextBlobBuilder { |
| 90 | public: |
| 91 | /** |
| 92 | * @param runs The number of runs to be added, if known. This is a storage hint and |
| 93 | * not a limit. |
| 94 | */ |
| 95 | SkTextBlobBuilder(unsigned runs = 0); |
| 96 | |
| 97 | ~SkTextBlobBuilder(); |
| 98 | |
| 99 | /** |
| 100 | * Returns an immutable SkTextBlob for the current runs/glyphs. The builder is reset and |
| 101 | * can be reused. |
| 102 | */ |
| 103 | const SkTextBlob* build(); |
| 104 | |
| 105 | /** |
| 106 | * Glyph and position buffers associated with a run. |
| 107 | * |
| 108 | * A run is a sequence of glyphs sharing the same font metrics and positioning mode. |
| 109 | */ |
| 110 | struct RunBuffer { |
| 111 | uint16_t* glyphs; |
| 112 | SkScalar* pos; |
| 113 | }; |
| 114 | |
| 115 | /** |
| 116 | * Allocates a new default-positioned run and returns its writable glyph buffer |
| 117 | * for direct manipulation. |
| 118 | * |
| 119 | * @param font The font to be used for this run. |
| 120 | * @param count Number of glyphs. |
| 121 | * @param x,y Position within the blob. |
| 122 | * @param bounds Optional run bounding box. If known in advance (!= NULL), it will |
| 123 | * be used when computing the blob bounds, to avoid re-measuring. |
| 124 | * |
| 125 | * @return A writable glyph buffer, valid until the next allocRun() or |
| 126 | * build() call. The buffer is guaranteed to hold @count@ glyphs. |
| 127 | */ |
| 128 | const RunBuffer& allocRun(const SkPaint& font, int count, SkScalar x, SkScalar y, |
| 129 | const SkRect* bounds = NULL); |
| 130 | |
| 131 | /** |
| 132 | * Allocates a new horizontally-positioned run and returns its writable glyph and position |
| 133 | * buffers for direct manipulation. |
| 134 | * |
| 135 | * @param font The font to be used for this run. |
| 136 | * @param count Number of glyphs. |
| 137 | * @param y Vertical offset within the blob. |
| 138 | * @param bounds Optional run bounding box. If known in advance (!= NULL), it will |
| 139 | * be used when computing the blob bounds, to avoid re-measuring. |
| 140 | * |
| 141 | * @return Writable glyph and position buffers, valid until the next allocRun() |
| 142 | * or build() call. The buffers are guaranteed to hold @count@ elements. |
| 143 | */ |
| 144 | const RunBuffer& allocRunPosH(const SkPaint& font, int count, SkScalar y, |
| 145 | const SkRect* bounds = NULL); |
| 146 | |
| 147 | /** |
| 148 | * Allocates a new fully-positioned run and returns its writable glyph and position |
| 149 | * buffers for direct manipulation. |
| 150 | * |
| 151 | * @param font The font to be used for this run. |
| 152 | * @param count Number of glyphs. |
| 153 | * @param bounds Optional run bounding box. If known in advance (!= NULL), it will |
| 154 | * be used when computing the blob bounds, to avoid re-measuring. |
| 155 | * |
| 156 | * @return Writable glyph and position buffers, valid until the next allocRun() |
| 157 | * or build() call. The glyph buffer and position buffer are |
| 158 | * guaranteed to hold @count@ and 2 * @count@ elements, respectively. |
| 159 | */ |
| 160 | const RunBuffer& allocRunPos(const SkPaint& font, int count, const SkRect* bounds = NULL); |
| 161 | |
| 162 | private: |
| 163 | void allocInternal(const SkPaint& font, SkTextBlob::GlyphPositioning positioning, |
| 164 | int count, SkPoint offset, const SkRect* bounds); |
| 165 | void ensureRun(const SkPaint& font, SkTextBlob::GlyphPositioning positioning, |
| 166 | const SkPoint& offset); |
| 167 | void updateDeferredBounds(); |
| 168 | |
| 169 | SkTDArray<uint16_t> fGlyphBuffer; |
| 170 | SkTDArray<SkScalar> fPosBuffer; |
| 171 | SkTArray<SkTextBlob::Run>* fRuns; |
| 172 | |
| 173 | SkRect fBounds; |
| 174 | bool fDeferredBounds; |
| 175 | |
| 176 | RunBuffer fCurrentRunBuffer; |
| 177 | }; |
| 178 | |
| 179 | #endif // SkTextBlob_DEFINED |