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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
//=============================================================================
//
// Graphic definitions and type/unit conversions.
//
//=============================================================================
#ifndef AGS_SHARED_GFX_GFX_DEF_H
#define AGS_SHARED_GFX_GFX_DEF_H
namespace AGS3 {
namespace AGS {
namespace Shared {
enum GraphicFlip {
kFlip_None,
kFlip_Horizontal, // this means - mirror over horizontal middle line
kFlip_Vertical, // this means - mirror over vertical middle line
kFlip_Both // mirror over diagonal (horizontal and vertical)
};
enum BlendMode {
// free blending (ARGB -> ARGB) modes
kBlendMode_NoAlpha = 0, // ignore alpha channel
kBlendMode_Alpha, // alpha-blend src to dest, combining src & dest alphas
// NOTE: add new modes here
kNumBlendModes
};
namespace GfxDef {
// Converts percentage of transparency into alpha
inline int Trans100ToAlpha255(int transparency) {
return ((100 - transparency) * 255) / 100;
}
// Converts alpha into percentage of transparency
inline int Alpha255ToTrans100(int alpha) {
return 100 - ((alpha * 100) / 255);
}
// Special formulae to reduce precision loss and support flawless forth &
// reverse conversion for multiplies of 10%
inline int Trans100ToAlpha250(int transparency) {
return ((100 - transparency) * 25) / 10;
}
inline int Alpha250ToTrans100(int alpha) {
return 100 - ((alpha * 10) / 25);
}
// Convert correct 100-ranged transparency into legacy 255-ranged
// transparency; legacy inconsistent transparency value range:
// 0 = opaque,
// 255 = invisible,
// 1 -to- 254 = barely visible -to- mostly visible (as proper alpha)
inline int Trans100ToLegacyTrans255(int transparency) {
switch (transparency) {
case 0:
return 0; // this means opaque
case 100:
return 255; // this means invisible
default:
// the rest of the range works as alpha
return Trans100ToAlpha250(transparency);
}
}
// Convert legacy 255-ranged "incorrect" transparency into proper
// 100-ranged transparency.
inline int LegacyTrans255ToTrans100(int legacy_transparency) {
switch (legacy_transparency) {
case 0:
return 0; // this means opaque
case 255:
return 100; // this means invisible
default:
// the rest of the range works as alpha
return Alpha250ToTrans100(legacy_transparency);
}
}
// Convert legacy 100-ranged transparency into proper 255-ranged alpha
// 0 => alpha 255
// 100 => alpha 0
// 1 - 99 => alpha 1 - 244
inline int LegacyTrans100ToAlpha255(int legacy_transparency) {
switch (legacy_transparency) {
case 0:
return 255; // this means opaque
case 100:
return 0; // this means invisible
default:
// the rest of the range works as alpha (only 100-ranged)
return legacy_transparency * 255 / 100;
}
}
// Convert legacy 255-ranged transparency into proper 255-ranged alpha
inline int LegacyTrans255ToAlpha255(int legacy_transparency) {
switch (legacy_transparency) {
case 0:
return 255; // this means opaque
case 255:
return 0; // this means invisible
default:
// the rest of the range works as alpha
return legacy_transparency;
}
}
// Convert 255-ranged alpha into legacy 255-ranged transparency
inline int Alpha255ToLegacyTrans255(int alpha) {
switch (alpha) {
case 255:
return 0; // this means opaque
case 0:
return 255; // this means invisible
default:
// the rest of the range works as alpha
return alpha;
}
}
} // namespace GfxDef
} // namespace Shared
} // namespace AGS
} // namespace AGS3
#endif
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