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      1 /* libs/graphics/sgl/SkEdge.h
      2 **
      3 ** Copyright 2006, The Android Open Source Project
      4 **
      5 ** Licensed under the Apache License, Version 2.0 (the "License");
      6 ** you may not use this file except in compliance with the License.
      7 ** You may obtain a copy of the License at
      8 **
      9 **     http://www.apache.org/licenses/LICENSE-2.0
     10 **
     11 ** Unless required by applicable law or agreed to in writing, software
     12 ** distributed under the License is distributed on an "AS IS" BASIS,
     13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14 ** See the License for the specific language governing permissions and
     15 ** limitations under the License.
     16 */
     17 
     18 #ifndef SkEdge_DEFINED
     19 #define SkEdge_DEFINED
     20 
     21 #include "SkRect.h"
     22 
     23 struct SkEdge {
     24     enum Type {
     25         kLine_Type,
     26         kQuad_Type,
     27         kCubic_Type
     28     };
     29 
     30     SkEdge* fNext;
     31     SkEdge* fPrev;
     32 
     33     SkFixed fX;
     34     SkFixed fDX;
     35     int32_t fFirstY;
     36     int32_t fLastY;
     37     int8_t fCurveCount;    // only used by kQuad(+) and kCubic(-)
     38     uint8_t fCurveShift;    // appled to all Dx/DDx/DDDx except for fCubicDShift exception
     39     uint8_t fCubicDShift;   // applied to fCDx and fCDy only in cubic
     40     int8_t  fWinding;       // 1 or -1
     41 
     42     int setLine(const SkPoint& p0, const SkPoint& p1, const SkIRect* clip,
     43                 int shiftUp);
     44     inline int updateLine(SkFixed ax, SkFixed ay, SkFixed bx, SkFixed by);
     45     void chopLineWithClip(const SkIRect& clip);
     46 
     47     inline bool intersectsClip(const SkIRect& clip) const {
     48         SkASSERT(fFirstY < clip.fBottom);
     49         return fLastY >= clip.fTop;
     50     }
     51 
     52 #ifdef SK_DEBUG
     53     void dump() const {
     54     #ifdef SK_CAN_USE_FLOAT
     55         SkDebugf("edge: firstY:%d lastY:%d x:%g dx:%g w:%d\n", fFirstY, fLastY, SkFixedToFloat(fX), SkFixedToFloat(fDX), fWinding);
     56     #else
     57         SkDebugf("edge: firstY:%d lastY:%d x:%x dx:%x w:%d\n", fFirstY, fLastY, fX, fDX, fWinding);
     58     #endif
     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 #endif
     94