1 /*
2  * Copyright 2018 Google Inc.
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 SkCoverageMode_DEFINED
9 #define SkCoverageMode_DEFINED
10 
11 #include "SkTypes.h"
12 
13 /**
14  *  Describes geometric operations (ala SkRegion::Op) that can be applied to coverage bytes.
15  *  These can be thought of as variants of porter-duff (SkBlendMode) modes, but only applied
16  *  to the alpha channel.
17  *
18  *  See SkMaskFilter for ways to use these when combining two different masks.
19  */
20 enum class SkCoverageMode {
21     kUnion,             // A ∪ B    A+B-A*B
22     kIntersect,         // A ∪ B    A*B
23     kDifference,        // A - B    A*(1-B)
24     kReverseDifference, // B - A    B*(1-A)
25     kXor,               // A ⊕ B    A+B-2*A*B
26 
27     kLast = kXor
28 };
29 
30 #endif
31