1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
|
/* ============================================================
*
* This file is a part of digiKam project
* http://www.digikam.org
*
* Date : 2006-03-02
* Description : DColor methods for composing
*
* Copyright (C) 2006-2007 by Marcel Wiesweg <[email protected]>
*
* 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 2, 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.
*
* ============================================================ */
#ifndef DCOLORCOMPOSER_H
#define DCOLORCOMPOSER_H
// Local includes.
#include "dcolor.h"
#include "digikam_export.h"
namespace Digikam
{
class DIGIKAM_EXPORT DColorComposer
{
public:
/** The available rules to combine src and destination color.
For the Porter-Duff rules, the formula is
component = (source * fs + destination * fd)
where
fs, fd according to the following table with
sa = source alpha,
da = destination alpha:
None fs: sa fd: 1.0-sa
Clear fs: 0.0 fd: 0.0
Src fs: 1.0 fd: 0.0
Src Over fs: 1.0 fd: 1.0-sa
Dst Over fs: 1.0-da fd: 1.0
Src In fs: da fd: 0.0
Dst In fs: 0.0 fd: sa
Src Out fs: 1.0-da fd: 0.0
Dst Out fs: 0.0 fd: 1.0-sa
Src Atop fs: da fd: 1.0-sa
Dst Atop fs: 1.0-da fd: sa
Xor fs: 1.0-da fd: 1.0-sa
None is the default, classical blending mode, a "Src over" simplification:
Blend non-premultiplied RGBA data "src over" a fully opaque background.
Src is the painter's algorithm.
All other operations require premultiplied colors.
The documentation of java.awt.AlphaComposite (Java 1.5)
provides a good introduction and documentation on Porter Duff.
*/
enum CompositingOperation
{
PorterDuffNone,
PorterDuffClear,
PorterDuffSrc,
PorterDuffSrcOver,
PorterDuffDstOver,
PorterDuffSrcIn,
PorterDuffDstIn,
PorterDuffSrcOut,
PorterDuffDstOut,
PorterDuffSrcAtop,
PorterDuffDstAtop,
PorterDuffXor
};
enum MultiplicationFlags
{
NoMultiplication = 0x00,
PremultiplySrc = 0x01,
PremultiplyDst = 0x02,
DemultiplyDst = 0x04,
MultiplicationFlagsDImg = PremultiplySrc | PremultiplyDst | DemultiplyDst,
MultiplicationFlagsPremultipliedColorOnDImg = PremultiplyDst | DemultiplyDst
};
/**
Retrieve a DColorComposer object for one of the predefined rules.
The object needs to be deleted by the caller.
*/
static DColorComposer *getComposer(CompositingOperation rule);
/**
Carry out the actual composition process.
Src and Dest are composed and the result is written to dest.
No pre-/demultiplication is done by this method, use the other overloaded
methods, which call this method, if you need pre- or demultiplication
(you need it if any of the colors are read from or written to a DImg).
If you just pass the object to a DImg method, you do not need to call this.
Call this function if you want to compose two colors.
Implement this function if you create a custom DColorComposer.
The bit depth of source and destination color must be identical.
*/
virtual void compose(DColor &dest, DColor src) = 0;
/**
Compose the two colors by calling compose(dest, src).
Pre- and demultiplication operations are done as specified.
For PorterDuff operations except PorterDuffNone, you need
- PremultiplySrc if src is not premultiplied (read from a DImg)
- PremultiplyDst if dst is not premultiplied (read from a DImg)
- DemultiplyDst if dst will be written to non-premultiplied data (a DImg)
*/
virtual void compose(DColor &dest, DColor src, MultiplicationFlags multiplicationFlags);
virtual ~DColorComposer(){};
};
} // namespace Digikam
#endif // DCOLORCOMPOSER_H
|
