1/*
2 * Copyright 2011 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 SkArithmeticMode_DEFINED
9#define SkArithmeticMode_DEFINED
10
11#include "SkFlattenable.h"
12#include "SkScalar.h"
13
14class SkXfermode;
15
16class SK_API SkArithmeticMode {
17public:
18    /**
19     *  result = clamp[k1 * src * dst + k2 * src + k3 * dst + k4]
20     *
21     *  src and dst are treated as being [0.0 .. 1.0]. The polynomial is
22     *  evaluated on their unpremultiplied components.
23     *
24     *  k1=k2=k3=0, k4=1.0 results in returning opaque white
25     *  k1=k3=k4=0, k2=1.0 results in returning the src
26     *  k1=k2=k4=0, k3=1.0 results in returning the dst
27     */
28    static SkXfermode* Create(SkScalar k1, SkScalar k2,
29                              SkScalar k3, SkScalar k4,
30                              bool enforcePMColor = true);
31
32    SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP();
33
34private:
35    SkArithmeticMode(); // can't be instantiated
36};
37
38#endif
39