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 SkEdge_DEFINED 11 #define SkEdge_DEFINED 12 13 #include "SkRect.h" 14 #include "SkFDot6.h" 15 #include "SkMath.h" 16 17 #ifdef SK_IGNORE_SETLINE_FIX 18 #define SkEdge_Compute_DY(top, y0) ((32 - (y0)) & 63) 19 #else 20 // This is correct, as it favors the lower-pixel when y0 is on a 1/2 pixel 21 // boundary, returning 64 instead of the old code, which returns 0. 22 #define SkEdge_Compute_DY(top, y0) ((top << 6) + 32 - (y0)) 23 #endif 24 25 struct SkEdge { 26 enum Type { 27 kLine_Type, 28 kQuad_Type, 29 kCubic_Type 30 }; 31 32 SkEdge* fNext; 33 SkEdge* fPrev; 34 35 SkFixed fX; 36 SkFixed fDX; 37 int32_t fFirstY; 38 int32_t fLastY; 39 int8_t fCurveCount; // only used by kQuad(+) and kCubic(-) 40 uint8_t fCurveShift; // appled to all Dx/DDx/DDDx except for fCubicDShift exception 41 uint8_t fCubicDShift; // applied to fCDx and fCDy only in cubic 42 int8_t fWinding; // 1 or -1 43 44 int setLine(const SkPoint& p0, const SkPoint& p1, const SkIRect* clip, 45 int shiftUp); 46 // call this version if you know you don't have a clip 47 inline int setLine(const SkPoint& p0, const SkPoint& p1, int shiftUp); 48 inline int updateLine(SkFixed ax, SkFixed ay, SkFixed bx, SkFixed by); 49 void chopLineWithClip(const SkIRect& clip); 50 51 inline bool intersectsClip(const SkIRect& clip) const { 52 SkASSERT(fFirstY < clip.fBottom); 53 return fLastY >= clip.fTop; 54 } 55 56 #ifdef SK_DEBUG 57 void dump() const { 58 SkDebugf("edge: firstY:%d lastY:%d x:%g dx:%g w:%d\n", fFirstY, fLastY, SkFixedToFloat(fX), SkFixedToFloat(fDX), fWinding); 59 } 60 61 void validate() const { 62 SkASSERT(fPrev && fNext); 63 SkASSERT(fPrev->fNext == this); 64 SkASSERT(fNext->fPrev == this); 65 66 SkASSERT(fFirstY <= fLastY); 67 SkASSERT(SkAbs32(fWinding) == 1); 68 } 69 #endif 70 }; 71 72 struct SkQuadraticEdge : public SkEdge { 73 SkFixed fQx, fQy; 74 SkFixed fQDx, fQDy; 75 SkFixed fQDDx, fQDDy; 76 SkFixed fQLastX, fQLastY; 77 78 int setQuadratic(const SkPoint pts[3], int shiftUp); 79 int updateQuadratic(); 80 }; 81 82 struct SkCubicEdge : public SkEdge { 83 SkFixed fCx, fCy; 84 SkFixed fCDx, fCDy; 85 SkFixed fCDDx, fCDDy; 86 SkFixed fCDDDx, fCDDDy; 87 SkFixed fCLastX, fCLastY; 88 89 int setCubic(const SkPoint pts[4], const SkIRect* clip, int shiftUp); 90 int updateCubic(); 91 }; 92 93 int SkEdge::setLine(const SkPoint& p0, const SkPoint& p1, int shift) { 94 SkFDot6 x0, y0, x1, y1; 95 96 { 97 #ifdef SK_SCALAR_IS_FLOAT 98 float scale = float(1 << (shift + 6)); 99 x0 = int(p0.fX * scale); 100 y0 = int(p0.fY * scale); 101 x1 = int(p1.fX * scale); 102 y1 = int(p1.fY * scale); 103 #else 104 shift = 10 - shift; 105 x0 = p0.fX >> shift; 106 y0 = p0.fY >> shift; 107 x1 = p1.fX >> shift; 108 y1 = p1.fY >> shift; 109 #endif 110 } 111 112 int winding = 1; 113 114 if (y0 > y1) { 115 SkTSwap(x0, x1); 116 SkTSwap(y0, y1); 117 winding = -1; 118 } 119 120 int top = SkFDot6Round(y0); 121 int bot = SkFDot6Round(y1); 122 123 // are we a zero-height line? 124 if (top == bot) { 125 return 0; 126 } 127 128 SkFixed slope = SkFDot6Div(x1 - x0, y1 - y0); 129 const int dy = SkEdge_Compute_DY(top, y0); 130 131 fX = SkFDot6ToFixed(x0 + SkFixedMul(slope, dy)); // + SK_Fixed1/2 132 fDX = slope; 133 fFirstY = top; 134 fLastY = bot - 1; 135 fCurveCount = 0; 136 fWinding = SkToS8(winding); 137 fCurveShift = 0; 138 return 1; 139 } 140 141 142 #endif 143
