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Diffstat (limited to 'src/deps/skia/include/core/SkBlendMode.h')
-rw-r--r-- | src/deps/skia/include/core/SkBlendMode.h | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/src/deps/skia/include/core/SkBlendMode.h b/src/deps/skia/include/core/SkBlendMode.h new file mode 100644 index 000000000..07640cf55 --- /dev/null +++ b/src/deps/skia/include/core/SkBlendMode.h @@ -0,0 +1,110 @@ +/* + * 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 { + kClear, //!< r = 0 + kSrc, //!< r = s + kDst, //!< r = d + kSrcOver, //!< r = s + (1-sa)*d + kDstOver, //!< r = d + (1-da)*s + kSrcIn, //!< r = s * da + kDstIn, //!< r = d * sa + kSrcOut, //!< r = s * (1-da) + kDstOut, //!< r = d * (1-sa) + kSrcATop, //!< r = s*da + d*(1-sa) + kDstATop, //!< r = d*sa + s*(1-da) + kXor, //!< r = s*(1-da) + d*(1-sa) + kPlus, //!< r = min(s + d, 1) + kModulate, //!< r = s*d + kScreen, //!< r = s + d - s*d + + kOverlay, //!< multiply or screen, depending on destination + kDarken, //!< rc = s + d - max(s*da, d*sa), ra = kSrcOver + kLighten, //!< rc = s + d - min(s*da, d*sa), ra = kSrcOver + kColorDodge, //!< brighten destination to reflect source + kColorBurn, //!< darken destination to reflect source + kHardLight, //!< multiply or screen, depending on source + kSoftLight, //!< lighten or darken, depending on source + kDifference, //!< rc = s + d - 2*(min(s*da, d*sa)), ra = kSrcOver + kExclusion, //!< rc = s + d - two(s*d), ra = kSrcOver + kMultiply, //!< r = s*(1-da) + d*(1-sa) + s*d + + kHue, //!< hue of source with saturation and luminosity of destination + kSaturation, //!< saturation of source with hue and luminosity of destination + kColor, //!< hue and saturation of source with luminosity of destination + kLuminosity, //!< luminosity of source with hue and saturation of destination + + kLastCoeffMode = kScreen, //!< last porter duff blend mode + kLastSeparableMode = kMultiply, //!< last blend mode operating separately on components + kLastMode = kLuminosity, //!< last valid value +}; + +/** + * 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 { + kZero, /** 0 */ + kOne, /** 1 */ + kSC, /** src color */ + kISC, /** inverse src color (i.e. 1 - sc) */ + kDC, /** dst color */ + kIDC, /** inverse dst color (i.e. 1 - dc) */ + kSA, /** src alpha */ + kISA, /** inverse src alpha (i.e. 1 - sa) */ + kDA, /** dst alpha */ + kIDA, /** inverse dst alpha (i.e. 1 - da) */ + + kCoeffCount +}; + +/** + * 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 |