1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/src/core/SkEdge.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,129 @@
1.4 +
1.5 +/*
1.6 + * Copyright 2006 The Android Open Source Project
1.7 + *
1.8 + * Use of this source code is governed by a BSD-style license that can be
1.9 + * found in the LICENSE file.
1.10 + */
1.11 +
1.12 +
1.13 +#ifndef SkEdge_DEFINED
1.14 +#define SkEdge_DEFINED
1.15 +
1.16 +#include "SkRect.h"
1.17 +#include "SkFDot6.h"
1.18 +#include "SkMath.h"
1.19 +
1.20 +// This correctly favors the lower-pixel when y0 is on a 1/2 pixel boundary
1.21 +#define SkEdge_Compute_DY(top, y0) ((top << 6) + 32 - (y0))
1.22 +
1.23 +struct SkEdge {
1.24 + enum Type {
1.25 + kLine_Type,
1.26 + kQuad_Type,
1.27 + kCubic_Type
1.28 + };
1.29 +
1.30 + SkEdge* fNext;
1.31 + SkEdge* fPrev;
1.32 +
1.33 + SkFixed fX;
1.34 + SkFixed fDX;
1.35 + int32_t fFirstY;
1.36 + int32_t fLastY;
1.37 + int8_t fCurveCount; // only used by kQuad(+) and kCubic(-)
1.38 + uint8_t fCurveShift; // appled to all Dx/DDx/DDDx except for fCubicDShift exception
1.39 + uint8_t fCubicDShift; // applied to fCDx and fCDy only in cubic
1.40 + int8_t fWinding; // 1 or -1
1.41 +
1.42 + int setLine(const SkPoint& p0, const SkPoint& p1, const SkIRect* clip,
1.43 + int shiftUp);
1.44 + // call this version if you know you don't have a clip
1.45 + inline int setLine(const SkPoint& p0, const SkPoint& p1, int shiftUp);
1.46 + inline int updateLine(SkFixed ax, SkFixed ay, SkFixed bx, SkFixed by);
1.47 + void chopLineWithClip(const SkIRect& clip);
1.48 +
1.49 + inline bool intersectsClip(const SkIRect& clip) const {
1.50 + SkASSERT(fFirstY < clip.fBottom);
1.51 + return fLastY >= clip.fTop;
1.52 + }
1.53 +
1.54 +#ifdef SK_DEBUG
1.55 + void dump() const {
1.56 + SkDebugf("edge: firstY:%d lastY:%d x:%g dx:%g w:%d\n", fFirstY, fLastY, SkFixedToFloat(fX), SkFixedToFloat(fDX), fWinding);
1.57 + }
1.58 +
1.59 + void validate() const {
1.60 + SkASSERT(fPrev && fNext);
1.61 + SkASSERT(fPrev->fNext == this);
1.62 + SkASSERT(fNext->fPrev == this);
1.63 +
1.64 + SkASSERT(fFirstY <= fLastY);
1.65 + SkASSERT(SkAbs32(fWinding) == 1);
1.66 + }
1.67 +#endif
1.68 +};
1.69 +
1.70 +struct SkQuadraticEdge : public SkEdge {
1.71 + SkFixed fQx, fQy;
1.72 + SkFixed fQDx, fQDy;
1.73 + SkFixed fQDDx, fQDDy;
1.74 + SkFixed fQLastX, fQLastY;
1.75 +
1.76 + int setQuadratic(const SkPoint pts[3], int shiftUp);
1.77 + int updateQuadratic();
1.78 +};
1.79 +
1.80 +struct SkCubicEdge : public SkEdge {
1.81 + SkFixed fCx, fCy;
1.82 + SkFixed fCDx, fCDy;
1.83 + SkFixed fCDDx, fCDDy;
1.84 + SkFixed fCDDDx, fCDDDy;
1.85 + SkFixed fCLastX, fCLastY;
1.86 +
1.87 + int setCubic(const SkPoint pts[4], const SkIRect* clip, int shiftUp);
1.88 + int updateCubic();
1.89 +};
1.90 +
1.91 +int SkEdge::setLine(const SkPoint& p0, const SkPoint& p1, int shift) {
1.92 + SkFDot6 x0, y0, x1, y1;
1.93 +
1.94 + {
1.95 + float scale = float(1 << (shift + 6));
1.96 + x0 = int(p0.fX * scale);
1.97 + y0 = int(p0.fY * scale);
1.98 + x1 = int(p1.fX * scale);
1.99 + y1 = int(p1.fY * scale);
1.100 + }
1.101 +
1.102 + int winding = 1;
1.103 +
1.104 + if (y0 > y1) {
1.105 + SkTSwap(x0, x1);
1.106 + SkTSwap(y0, y1);
1.107 + winding = -1;
1.108 + }
1.109 +
1.110 + int top = SkFDot6Round(y0);
1.111 + int bot = SkFDot6Round(y1);
1.112 +
1.113 + // are we a zero-height line?
1.114 + if (top == bot) {
1.115 + return 0;
1.116 + }
1.117 +
1.118 + SkFixed slope = SkFDot6Div(x1 - x0, y1 - y0);
1.119 + const int dy = SkEdge_Compute_DY(top, y0);
1.120 +
1.121 + fX = SkFDot6ToFixed(x0 + SkFixedMul(slope, dy)); // + SK_Fixed1/2
1.122 + fDX = slope;
1.123 + fFirstY = top;
1.124 + fLastY = bot - 1;
1.125 + fCurveCount = 0;
1.126 + fWinding = SkToS8(winding);
1.127 + fCurveShift = 0;
1.128 + return 1;
1.129 +}
1.130 +
1.131 +
1.132 +#endif
