1 /* 2 * Copyright 2006 The Android Open Source Project 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 SkEdge_DEFINED 9 #define SkEdge_DEFINED 10 11 #include "SkFDot6.h" 12 #include "SkMath.h" 13 #include "SkRect.h" 14 #include "SkTo.h" 15 16 #include <utility> 17 18 // This correctly favors the lower-pixel when y0 is on a 1/2 pixel boundary 19 #define SkEdge_Compute_DY(top, y0) (SkLeftShift(top, 6) + 32 - (y0)) 20 21 struct SkEdge { 22 enum Type { 23 kLine_Type, 24 kQuad_Type, 25 kCubic_Type 26 }; 27 28 SkEdge* fNext; 29 SkEdge* fPrev; 30 31 SkFixed fX; 32 SkFixed fDX; 33 int32_t fFirstY; 34 int32_t fLastY; 35 int8_t fCurveCount; // only used by kQuad(+) and kCubic(-) 36 uint8_t fCurveShift; // appled to all Dx/DDx/DDDx except for fCubicDShift exception 37 uint8_t fCubicDShift; // applied to fCDx and fCDy only in cubic 38 int8_t fWinding; // 1 or -1 39 40 int setLine(const SkPoint& p0, const SkPoint& p1, const SkIRect* clip, int shiftUp); 41 // call this version if you know you don't have a clip 42 inline int setLine(const SkPoint& p0, const SkPoint& p1, int shiftUp); 43 inline int updateLine(SkFixed ax, SkFixed ay, SkFixed bx, SkFixed by); 44 void chopLineWithClip(const SkIRect& clip); 45 46 inline bool intersectsClip(const SkIRect& clip) const { 47 SkASSERT(fFirstY < clip.fBottom); 48 return fLastY >= clip.fTop; 49 } 50 51 #ifdef SK_DEBUG 52 void dump() const { 53 SkDebugf("edge: firstY:%d lastY:%d x:%g dx:%g w:%d\n", fFirstY, fLastY, SkFixedToFloat(fX), SkFixedToFloat(fDX), fWinding); 54 } 55 56 void validate() const { 57 SkASSERT(fPrev && fNext); 58 SkASSERT(fPrev->fNext == this); 59 SkASSERT(fNext->fPrev == this); 60 61 SkASSERT(fFirstY <= fLastY); 62 SkASSERT(SkAbs32(fWinding) == 1); 63 } 64 #endif 65 }; 66 67 struct SkQuadraticEdge : public SkEdge { 68 SkFixed fQx, fQy; 69 SkFixed fQDx, fQDy; 70 SkFixed fQDDx, fQDDy; 71 SkFixed fQLastX, fQLastY; 72 73 bool setQuadraticWithoutUpdate(const SkPoint pts[3], int shiftUp); 74 int setQuadratic(const SkPoint pts[3], int shiftUp); 75 int updateQuadratic(); 76 }; 77 78 struct SkCubicEdge : public SkEdge { 79 SkFixed fCx, fCy; 80 SkFixed fCDx, fCDy; 81 SkFixed fCDDx, fCDDy; 82 SkFixed fCDDDx, fCDDDy; 83 SkFixed fCLastX, fCLastY; 84 85 bool setCubicWithoutUpdate(const SkPoint pts[4], int shiftUp, bool sortY = true); 86 int setCubic(const SkPoint pts[4], int shiftUp); 87 int updateCubic(); 88 }; 89 90 int SkEdge::setLine(const SkPoint& p0, const SkPoint& p1, int shift) { 91 SkFDot6 x0, y0, x1, y1; 92 93 { 94 #ifdef SK_RASTERIZE_EVEN_ROUNDING 95 x0 = SkScalarRoundToFDot6(p0.fX, shift); 96 y0 = SkScalarRoundToFDot6(p0.fY, shift); 97 x1 = SkScalarRoundToFDot6(p1.fX, shift); 98 y1 = SkScalarRoundToFDot6(p1.fY, shift); 99 #else 100 float scale = float(1 << (shift + 6)); 101 x0 = int(p0.fX * scale); 102 y0 = int(p0.fY * scale); 103 x1 = int(p1.fX * scale); 104 y1 = int(p1.fY * scale); 105 #endif 106 } 107 108 int winding = 1; 109 110 if (y0 > y1) { 111 using std::swap; 112 swap(x0, x1); 113 swap(y0, y1); 114 winding = -1; 115 } 116 117 int top = SkFDot6Round(y0); 118 int bot = SkFDot6Round(y1); 119 120 // are we a zero-height line? 121 if (top == bot) { 122 return 0; 123 } 124 125 SkFixed slope = SkFDot6Div(x1 - x0, y1 - y0); 126 const SkFDot6 dy = SkEdge_Compute_DY(top, y0); 127 128 fX = SkFDot6ToFixed(x0 + SkFixedMul(slope, dy)); // + SK_Fixed1/2 129 fDX = slope; 130 fFirstY = top; 131 fLastY = bot - 1; 132 fCurveCount = 0; 133 fWinding = SkToS8(winding); 134 fCurveShift = 0; 135 return 1; 136 } 137 138 #endif 139
