qt.gui.rgb source code

1 /*
2  * DQt - D bindings for the Qt Toolkit
3  *
4  * GNU Lesser General Public License Usage
5  * This file may be used under the terms of the GNU Lesser
6  * General Public License version 3 as published by the Free Software
7  * Foundation and appearing in the file LICENSE.LGPL3 included in the
8  * packaging of this file. Please review the following information to
9  * ensure the GNU Lesser General Public License version 3 requirements
10  * will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
11  */
12 module qt.gui.rgb;
13 extern(C++):
14 
15 import qt.config;
16 import qt.helpers;
17 
18 alias QRgb = uint;                        // RGB triplet
19 
20 // non-namespaced Qt global variable
21 extern(D) immutable QRgb RGB_MASK = 0x00ffffff;     // masks RGB values
22 
23 pragma(inline, true) int qRed(QRgb rgb)                     // get red part of RGB
24 { return ((rgb >> 16) & 0xff); }
25 
26 pragma(inline, true) int qGreen(QRgb rgb)                   // get green part of RGB
27 { return ((rgb >> 8) & 0xff); }
28 
29 pragma(inline, true) int qBlue(QRgb rgb)                    // get blue part of RGB
30 { return (rgb & 0xff); }
31 
32 pragma(inline, true) int qAlpha(QRgb rgb)                   // get alpha part of RGBA
33 { return rgb >> 24; }
34 
35 pragma(inline, true) QRgb qRgb(int r, int g, int b)         // set RGB value
36 { return (0xffu << 24) | ((r & 0xffu) << 16) | ((g & 0xffu) << 8) | (b & 0xffu); }
37 
38 pragma(inline, true) QRgb qRgba(int r, int g, int b, int a) // set RGBA value
39 { return ((a & 0xffu) << 24) | ((r & 0xffu) << 16) | ((g & 0xffu) << 8) | (b & 0xffu); }
40 
41 pragma(inline, true) int qGray(int r, int g, int b)         // convert R,G,B to gray 0..255
42 { return (r*11+g*16+b*5)/32; }
43 
44 pragma(inline, true) int qGray(QRgb rgb)                    // convert RGB to gray 0..255
45 { return qGray(qRed(rgb), qGreen(rgb), qBlue(rgb)); }
46 
47 pragma(inline, true) bool qIsGray(QRgb rgb)
48 { return qRed(rgb) == qGreen(rgb) && qRed(rgb) == qBlue(rgb); }
49 
50 pragma(inline, true) QRgb qPremultiply(QRgb x)
51 {
52     const(uint) a = qAlpha(x);
53     uint t = (x & 0xff00ff) * a;
54     t = (t + ((t >> 8) & 0xff00ff) + 0x800080) >> 8;
55     t &= 0xff00ff;
56 
57     x = ((x >> 8) & 0xff) * a;
58     x = (x + ((x >> 8) & 0xff) + 0x80);
59     x &= 0xff00;
60     return x | t | (a << 24);
61 }
62 
63 mixin(mangleWindows("?qt_inv_premul_factor@@3QBIB", q{
64 /+ Q_GUI_EXPORT +/ extern export __gshared const(uint)[0] qt_inv_premul_factor;
65     }));
66 
67 pragma(inline, true) QRgb qUnpremultiply(QRgb p)
68 {
69     const(uint) alpha = qAlpha(p);
70     // Alpha 255 and 0 are the two most common values, which makes them beneficial to short-cut.
71     if (alpha == 255)
72         return p;
73     if (alpha == 0)
74         return 0;
75     // (p*(0x00ff00ff/alpha)) >> 16 == (p*255)/alpha for all p and alpha <= 256.
76     const(uint) invAlpha = qt_inv_premul_factor. ptr[alpha];
77     // We add 0x8000 to get even rounding. The rounding also ensures that qPremultiply(qUnpremultiply(p)) == p for all p.
78     return qRgba((qRed(p)*invAlpha + 0x8000)>>16, (qGreen(p)*invAlpha + 0x8000)>>16, (qBlue(p)*invAlpha + 0x8000)>>16, alpha);
79 }
80