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 ///@name non-virtual helpers 55 void blitMaskRegion(const SkMask& mask, const SkRegion& clip); 56 void blitRectRegion(const SkIRect& rect, const SkRegion& clip); 57 void blitRegion(const SkRegion& clip); 58 ///@} 59 60 /** @name Factories 61 Return the correct blitter to use given the specified context. 62 */ 63 static SkBlitter* Choose(const SkBitmap& device, 64 const SkMatrix& matrix, 65 const SkPaint& paint) { 66 return Choose(device, matrix, paint, NULL, 0); 67 } 68 69 static SkBlitter* Choose(const SkBitmap& device, 70 const SkMatrix& matrix, 71 const SkPaint& paint, 72 void* storage, size_t storageSize); 73 74 static SkBlitter* ChooseSprite(const SkBitmap& device, 75 const SkPaint&, 76 const SkBitmap& src, 77 int left, int top, 78 void* storage, size_t storageSize); 79 ///@} 80 81 private: 82 }; 83 84 /** This blitter silently never draws anything. 85 */ 86 class SkNullBlitter : public SkBlitter { 87 public: 88 virtual void blitH(int x, int y, int width) SK_OVERRIDE; 89 virtual void blitAntiH(int x, int y, const SkAlpha[], 90 const int16_t runs[]) SK_OVERRIDE; 91 virtual void blitV(int x, int y, int height, SkAlpha alpha) SK_OVERRIDE; 92 virtual void blitRect(int x, int y, int width, int height) SK_OVERRIDE; 93 virtual void blitMask(const SkMask&, const SkIRect& clip) SK_OVERRIDE; 94 virtual const SkBitmap* justAnOpaqueColor(uint32_t* value) SK_OVERRIDE; 95 }; 96 97 /** Wraps another (real) blitter, and ensures that the real blitter is only 98 called with coordinates that have been clipped by the specified clipRect. 99 This means the caller need not perform the clipping ahead of time. 100 */ 101 class SkRectClipBlitter : public SkBlitter { 102 public: 103 void init(SkBlitter* blitter, const SkIRect& clipRect) { 104 SkASSERT(!clipRect.isEmpty()); 105 fBlitter = blitter; 106 fClipRect = clipRect; 107 } 108 109 virtual void blitH(int x, int y, int width) SK_OVERRIDE; 110 virtual void blitAntiH(int x, int y, const SkAlpha[], 111 const int16_t runs[]) SK_OVERRIDE; 112 virtual void blitV(int x, int y, int height, SkAlpha alpha) SK_OVERRIDE; 113 virtual void blitRect(int x, int y, int width, int height) SK_OVERRIDE; 114 virtual void blitAntiRect(int x, int y, int width, int height, 115 SkAlpha leftAlpha, SkAlpha rightAlpha) SK_OVERRIDE; 116 virtual void blitMask(const SkMask&, const SkIRect& clip) SK_OVERRIDE; 117 virtual const SkBitmap* justAnOpaqueColor(uint32_t* value) SK_OVERRIDE; 118 119 private: 120 SkBlitter* fBlitter; 121 SkIRect fClipRect; 122 }; 123 124 /** Wraps another (real) blitter, and ensures that the real blitter is only 125 called with coordinates that have been clipped by the specified clipRgn. 126 This means the caller need not perform the clipping ahead of time. 127 */ 128 class SkRgnClipBlitter : public SkBlitter { 129 public: 130 void init(SkBlitter* blitter, const SkRegion* clipRgn) { 131 SkASSERT(clipRgn && !clipRgn->isEmpty()); 132 fBlitter = blitter; 133 fRgn = clipRgn; 134 } 135 136 virtual void blitH(int x, int y, int width) SK_OVERRIDE; 137 virtual void blitAntiH(int x, int y, const SkAlpha[], 138 const int16_t runs[]) SK_OVERRIDE; 139 virtual void blitV(int x, int y, int height, SkAlpha alpha) SK_OVERRIDE; 140 virtual void blitRect(int x, int y, int width, int height) SK_OVERRIDE; 141 virtual void blitAntiRect(int x, int y, int width, int height, 142 SkAlpha leftAlpha, SkAlpha rightAlpha) SK_OVERRIDE; 143 virtual void blitMask(const SkMask&, const SkIRect& clip) SK_OVERRIDE; 144 virtual const SkBitmap* justAnOpaqueColor(uint32_t* value) SK_OVERRIDE; 145 146 private: 147 SkBlitter* fBlitter; 148 const SkRegion* fRgn; 149 }; 150 151 /** Factory to set up the appropriate most-efficient wrapper blitter 152 to apply a clip. Returns a pointer to a member, so lifetime must 153 be managed carefully. 154 */ 155 class SkBlitterClipper { 156 public: 157 SkBlitter* apply(SkBlitter* blitter, const SkRegion* clip, 158 const SkIRect* bounds = NULL); 159 160 private: 161 SkNullBlitter fNullBlitter; 162 SkRectClipBlitter fRectBlitter; 163 SkRgnClipBlitter fRgnBlitter; 164 }; 165 166 #endif 167
