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      1 
      2 /*
      3  * Copyright 2011 Google Inc.
      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 #include "SkPorterDuff.h"
     11 #include "SkXfermode.h"
     12 
     13 /*  This file just exists as a compatibility layer, gluing the PorterDuff API
     14     into the (extended) SkXfermode API
     15  */
     16 
     17 #define MAKE_PAIR(mode) { SkPorterDuff::k##mode##_Mode, SkXfermode::k##mode##_Mode }
     18 
     19 // this table must be in SkPorterDuff::Mode order, so it can be indexed directly
     20 // with a porterduff mode.
     21 static const struct Pair {
     22     SkPorterDuff::Mode  fPD;
     23     SkXfermode::Mode    fXF;
     24 } gPairs[] = {
     25     MAKE_PAIR(Clear),
     26     MAKE_PAIR(Src),
     27     MAKE_PAIR(Dst),
     28     MAKE_PAIR(SrcOver),
     29     MAKE_PAIR(DstOver),
     30     MAKE_PAIR(SrcIn),
     31     MAKE_PAIR(DstIn),
     32     MAKE_PAIR(SrcOut),
     33     MAKE_PAIR(DstOut),
     34     MAKE_PAIR(SrcATop),
     35     MAKE_PAIR(DstATop),
     36     MAKE_PAIR(Xor),
     37     MAKE_PAIR(Darken),
     38     MAKE_PAIR(Lighten),
     39     MAKE_PAIR(Modulate),
     40     MAKE_PAIR(Screen),
     41     { SkPorterDuff::kAdd_Mode, SkXfermode::kPlus_Mode },
     42 #ifdef SK_BUILD_FOR_ANDROID
     43     MAKE_PAIR(Overlay),
     44 #endif
     45 };
     46 
     47 static bool find_pdmode(SkXfermode::Mode src, SkPorterDuff::Mode* dst) {
     48     const Pair* pairs = gPairs;
     49     for (size_t i = 0; i < SK_ARRAY_COUNT(gPairs); i++) {
     50         if (pairs[i].fXF == src) {
     51             if (dst) {
     52                 *dst = pairs[i].fPD;
     53             }
     54             return true;
     55         }
     56     }
     57     return false;
     58 }
     59 
     60 SkXfermode::Mode SkPorterDuff::ToXfermodeMode(Mode mode) {
     61     SkASSERT((unsigned)mode < SkPorterDuff::kModeCount);
     62     const Pair& pair = gPairs[mode];
     63     SkASSERT(pair.fPD == mode);
     64     return pair.fXF;
     65 }
     66 
     67 SkXfermode* SkPorterDuff::CreateXfermode(SkPorterDuff::Mode mode) {
     68     const Pair& pair = gPairs[mode];
     69     SkASSERT(pair.fPD == mode);
     70     return SkXfermode::Create(pair.fXF);
     71 }
     72 
     73 bool SkPorterDuff::IsMode(SkXfermode* xfer, Mode* pdmode) {
     74     SkXfermode::Mode xfmode;
     75     if (!SkXfermode::IsMode(xfer, &xfmode)) {
     76         return false;
     77     }
     78     return find_pdmode(xfmode, pdmode);
     79 }
     80 
     81 SkXfermodeProc SkPorterDuff::GetXfermodeProc(Mode mode) {
     82     return SkXfermode::GetProc(gPairs[mode].fXF);
     83 }
     84 
     85 SkXfermodeProc16 SkPorterDuff::GetXfermodeProc16(Mode mode, SkColor srcColor) {
     86     return SkXfermode::GetProc16(gPairs[mode].fXF, srcColor);
     87 }
     88