/* * Copyright 2016 Google Inc. * * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. */ #ifndef SkBlendMode_DEFINED #define SkBlendMode_DEFINED #include "include/core/SkTypes.h" /** * Blends are operators that take in two colors (source, destination) and return a new color. * Many of these operate the same on all 4 components: red, green, blue, alpha. For these, * we just document what happens to one component, rather than naming each one separately. * * Different SkColorTypes have different representations for color components: * 8-bit: 0..255 * 6-bit: 0..63 * 5-bit: 0..31 * 4-bit: 0..15 * floats: 0...1 * * The documentation is expressed as if the component values are always 0..1 (floats). * * For brevity, the documentation uses the following abbreviations * s : source * d : destination * sa : source alpha * da : destination alpha * * Results are abbreviated * r : if all 4 components are computed in the same manner * ra : result alpha component * rc : result "color": red, green, blue components */ enum class SkBlendMode { … }; static constexpr int kSkBlendModeCount = …; /** * For Porter-Duff SkBlendModes (those <= kLastCoeffMode), these coefficients describe the blend * equation used. Coefficient-based blend modes specify an equation: * ('dstCoeff' * dst + 'srcCoeff' * src), where the coefficient values are constants, functions of * the src or dst alpha, or functions of the src or dst color. */ enum class SkBlendModeCoeff { … }; /** * Returns true if 'mode' is a coefficient-based blend mode (<= kLastCoeffMode). If true is * returned, the mode's src and dst coefficient functions are set in 'src' and 'dst'. */ SK_API bool SkBlendMode_AsCoeff(SkBlendMode mode, SkBlendModeCoeff* src, SkBlendModeCoeff* dst); /** Returns name of blendMode as null-terminated C string. @return C string */ SK_API const char* SkBlendMode_Name(SkBlendMode blendMode); #endif