| /* |
| * Copyright 2006 The Android Open Source Project |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef SkEdge_DEFINED |
| #define SkEdge_DEFINED |
| |
| #include "include/core/SkMath.h" |
| #include "include/core/SkRect.h" |
| #include "include/private/base/SkTo.h" |
| #include "src/core/SkFDot6.h" |
| |
| #include <utility> |
| |
| // This correctly favors the lower-pixel when y0 is on a 1/2 pixel boundary |
| #define SkEdge_Compute_DY(top, y0) (SkLeftShift(top, 6) + 32 - (y0)) |
| |
| struct SkEdge { |
| enum Type { |
| kLine_Type, |
| kQuad_Type, |
| kCubic_Type |
| }; |
| |
| SkEdge* fNext; |
| SkEdge* fPrev; |
| |
| SkFixed fX; |
| SkFixed fDX; |
| int32_t fFirstY; |
| int32_t fLastY; |
| Type fEdgeType; // Remembers the *initial* edge type |
| int8_t fCurveCount; // only used by kQuad(+) and kCubic(-) |
| uint8_t fCurveShift; // appled to all Dx/DDx/DDDx except for fCubicDShift exception |
| uint8_t fCubicDShift; // applied to fCDx and fCDy only in cubic |
| int8_t fWinding; // 1 or -1 |
| |
| int setLine(const SkPoint& p0, const SkPoint& p1, const SkIRect* clip, int shiftUp); |
| // call this version if you know you don't have a clip |
| inline int setLine(const SkPoint& p0, const SkPoint& p1, int shiftUp); |
| inline int updateLine(SkFixed ax, SkFixed ay, SkFixed bx, SkFixed by); |
| void chopLineWithClip(const SkIRect& clip); |
| |
| inline bool intersectsClip(const SkIRect& clip) const { |
| SkASSERT(fFirstY < clip.fBottom); |
| return fLastY >= clip.fTop; |
| } |
| |
| #ifdef SK_DEBUG |
| void dump() const; |
| void validate() const { |
| SkASSERT(fPrev && fNext); |
| SkASSERT(fPrev->fNext == this); |
| SkASSERT(fNext->fPrev == this); |
| |
| SkASSERT(fFirstY <= fLastY); |
| SkASSERT(SkAbs32(fWinding) == 1); |
| } |
| #endif |
| }; |
| |
| struct SkQuadraticEdge : public SkEdge { |
| SkFixed fQx, fQy; |
| SkFixed fQDx, fQDy; |
| SkFixed fQDDx, fQDDy; |
| SkFixed fQLastX, fQLastY; |
| |
| bool setQuadraticWithoutUpdate(const SkPoint pts[3], int shiftUp); |
| int setQuadratic(const SkPoint pts[3], int shiftUp); |
| int updateQuadratic(); |
| }; |
| |
| struct SkCubicEdge : public SkEdge { |
| SkFixed fCx, fCy; |
| SkFixed fCDx, fCDy; |
| SkFixed fCDDx, fCDDy; |
| SkFixed fCDDDx, fCDDDy; |
| SkFixed fCLastX, fCLastY; |
| |
| bool setCubicWithoutUpdate(const SkPoint pts[4], int shiftUp, bool sortY = true); |
| int setCubic(const SkPoint pts[4], int shiftUp); |
| int updateCubic(); |
| }; |
| |
| int SkEdge::setLine(const SkPoint& p0, const SkPoint& p1, int shift) { |
| SkFDot6 x0, y0, x1, y1; |
| |
| { |
| #ifdef SK_RASTERIZE_EVEN_ROUNDING |
| x0 = SkScalarRoundToFDot6(p0.fX, shift); |
| y0 = SkScalarRoundToFDot6(p0.fY, shift); |
| x1 = SkScalarRoundToFDot6(p1.fX, shift); |
| y1 = SkScalarRoundToFDot6(p1.fY, shift); |
| #else |
| float scale = float(1 << (shift + 6)); |
| x0 = int(p0.fX * scale); |
| y0 = int(p0.fY * scale); |
| x1 = int(p1.fX * scale); |
| y1 = int(p1.fY * scale); |
| #endif |
| } |
| |
| int winding = 1; |
| |
| if (y0 > y1) { |
| using std::swap; |
| swap(x0, x1); |
| swap(y0, y1); |
| winding = -1; |
| } |
| |
| int top = SkFDot6Round(y0); |
| int bot = SkFDot6Round(y1); |
| |
| // are we a zero-height line? |
| if (top == bot) { |
| return 0; |
| } |
| |
| SkFixed slope = SkFDot6Div(x1 - x0, y1 - y0); |
| const SkFDot6 dy = SkEdge_Compute_DY(top, y0); |
| |
| fX = SkFDot6ToFixed(x0 + SkFixedMul(slope, dy)); // + SK_Fixed1/2 |
| fDX = slope; |
| fFirstY = top; |
| fLastY = bot - 1; |
| fEdgeType = kLine_Type; |
| fCurveCount = 0; |
| fWinding = SkToS8(winding); |
| fCurveShift = 0; |
| return 1; |
| } |
| |
| #endif |