1 2 /* 3 * Copyright 2006 The Android Open Source Project 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10 #ifndef SkBlitter_DEFINED 11 #define SkBlitter_DEFINED 12 13 #include "SkBitmap.h" 14 #include "SkMatrix.h" 15 #include "SkPaint.h" 16 #include "SkRefCnt.h" 17 #include "SkRegion.h" 18 #include "SkMask.h" 19 20 /** SkBlitter and its subclasses are responsible for actually writing pixels 21 into memory. Besides efficiency, they handle clipping and antialiasing. 22 */ 23 class SkBlitter { 24 public: 25 virtual ~SkBlitter(); 26 27 /// Blit a horizontal run of one or more pixels. 28 virtual void blitH(int x, int y, int width); 29 /// Blit a horizontal run of antialiased pixels; runs[] is a *sparse* 30 /// zero-terminated run-length encoding of spans of constant alpha values. 31 virtual void blitAntiH(int x, int y, const SkAlpha antialias[], 32 const int16_t runs[]); 33 /// Blit a vertical run of pixels with a constant alpha value. 34 virtual void blitV(int x, int y, int height, SkAlpha alpha); 35 /// Blit a solid rectangle one or more pixels wide. 36 virtual void blitRect(int x, int y, int width, int height); 37 /** Blit a rectangle with one alpha-blended column on the left, 38 width (zero or more) opaque pixels, and one alpha-blended column 39 on the right. 40 The result will always be at least two pixels wide. 41 */ 42 virtual void blitAntiRect(int x, int y, int width, int height, 43 SkAlpha leftAlpha, SkAlpha rightAlpha); 44 /// Blit a pattern of pixels defined by a rectangle-clipped mask; 45 /// typically used for text. 46 virtual void blitMask(const SkMask&, const SkIRect& clip); 47 48 /** If the blitter just sets a single value for each pixel, return the 49 bitmap it draws into, and assign value. If not, return NULL and ignore 50 the value parameter. 51 */ 52 virtual const SkBitmap* justAnOpaqueColor(uint32_t* value); 53 54 /** 55 * Special method just to identify the null blitter, which is returned 56 * from Choose() if the request cannot be fulfilled. Default impl 57 * returns false. 58 */ 59 virtual bool isNullBlitter() const; 60 61 ///@name non-virtual helpers 62 void blitMaskRegion(const SkMask& mask, const SkRegion& clip); 63 void blitRectRegion(const SkIRect& rect, const SkRegion& clip); 64 void blitRegion(const SkRegion& clip); 65 ///@} 66 67 /** @name Factories 68 Return the correct blitter to use given the specified context. 69 */ 70 static SkBlitter* Choose(const SkBitmap& device, 71 const SkMatrix& matrix, 72 const SkPaint& paint) { 73 return Choose(device, matrix, paint, NULL, 0); 74 } 75 76 static SkBlitter* Choose(const SkBitmap& device, 77 const SkMatrix& matrix, 78 const SkPaint& paint, 79 void* storage, size_t storageSize); 80 81 static SkBlitter* ChooseSprite(const SkBitmap& device, 82 const SkPaint&, 83 const SkBitmap& src, 84 int left, int top, 85 void* storage, size_t storageSize); 86 ///@} 87 88 private: 89 }; 90 91 /** This blitter silently never draws anything. 92 */ 93 class SkNullBlitter : public SkBlitter { 94 public: 95 virtual void blitH(int x, int y, int width) SK_OVERRIDE; 96 virtual void blitAntiH(int x, int y, const SkAlpha[], 97 const int16_t runs[]) SK_OVERRIDE; 98 virtual void blitV(int x, int y, int height, SkAlpha alpha) SK_OVERRIDE; 99 virtual void blitRect(int x, int y, int width, int height) SK_OVERRIDE; 100 virtual void blitMask(const SkMask&, const SkIRect& clip) SK_OVERRIDE; 101 virtual const SkBitmap* justAnOpaqueColor(uint32_t* value) SK_OVERRIDE; 102 virtual bool isNullBlitter() const SK_OVERRIDE; 103 }; 104 105 /** Wraps another (real) blitter, and ensures that the real blitter is only 106 called with coordinates that have been clipped by the specified clipRect. 107 This means the caller need not perform the clipping ahead of time. 108 */ 109 class SkRectClipBlitter : public SkBlitter { 110 public: 111 void init(SkBlitter* blitter, const SkIRect& clipRect) { 112 SkASSERT(!clipRect.isEmpty()); 113 fBlitter = blitter; 114 fClipRect = clipRect; 115 } 116 117 virtual void blitH(int x, int y, int width) SK_OVERRIDE; 118 virtual void blitAntiH(int x, int y, const SkAlpha[], 119 const int16_t runs[]) SK_OVERRIDE; 120 virtual void blitV(int x, int y, int height, SkAlpha alpha) SK_OVERRIDE; 121 virtual void blitRect(int x, int y, int width, int height) SK_OVERRIDE; 122 virtual void blitAntiRect(int x, int y, int width, int height, 123 SkAlpha leftAlpha, SkAlpha rightAlpha) SK_OVERRIDE; 124 virtual void blitMask(const SkMask&, const SkIRect& clip) SK_OVERRIDE; 125 virtual const SkBitmap* justAnOpaqueColor(uint32_t* value) SK_OVERRIDE; 126 127 private: 128 SkBlitter* fBlitter; 129 SkIRect fClipRect; 130 }; 131 132 /** Wraps another (real) blitter, and ensures that the real blitter is only 133 called with coordinates that have been clipped by the specified clipRgn. 134 This means the caller need not perform the clipping ahead of time. 135 */ 136 class SkRgnClipBlitter : public SkBlitter { 137 public: 138 void init(SkBlitter* blitter, const SkRegion* clipRgn) { 139 SkASSERT(clipRgn && !clipRgn->isEmpty()); 140 fBlitter = blitter; 141 fRgn = clipRgn; 142 } 143 144 virtual void blitH(int x, int y, int width) SK_OVERRIDE; 145 virtual void blitAntiH(int x, int y, const SkAlpha[], 146 const int16_t runs[]) SK_OVERRIDE; 147 virtual void blitV(int x, int y, int height, SkAlpha alpha) SK_OVERRIDE; 148 virtual void blitRect(int x, int y, int width, int height) SK_OVERRIDE; 149 virtual void blitAntiRect(int x, int y, int width, int height, 150 SkAlpha leftAlpha, SkAlpha rightAlpha) SK_OVERRIDE; 151 virtual void blitMask(const SkMask&, const SkIRect& clip) SK_OVERRIDE; 152 virtual const SkBitmap* justAnOpaqueColor(uint32_t* value) SK_OVERRIDE; 153 154 private: 155 SkBlitter* fBlitter; 156 const SkRegion* fRgn; 157 }; 158 159 /** Factory to set up the appropriate most-efficient wrapper blitter 160 to apply a clip. Returns a pointer to a member, so lifetime must 161 be managed carefully. 162 */ 163 class SkBlitterClipper { 164 public: 165 SkBlitter* apply(SkBlitter* blitter, const SkRegion* clip, 166 const SkIRect* bounds = NULL); 167 168 private: 169 SkNullBlitter fNullBlitter; 170 SkRectClipBlitter fRectBlitter; 171 SkRgnClipBlitter fRgnBlitter; 172 }; 173 174 #endif 175
