1 /* screen.cpp
2  * Copyright (C) 2006 Jean-Sebastien Senecal (js@drone.ws)
3  * This file is a Frei0r plugin.
4  * The code is a modified version of code from the Gimp.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20 
21 #include "frei0r.hpp"
22 #include "frei0r_math.h"
23 
24 #define NBYTES 4
25 #define ALPHA 3
26 
27 class screen : public frei0r::mixer2
28 {
29 public:
screen(unsigned int width,unsigned int height)30   screen(unsigned int width, unsigned int height)
31   {
32   }
33 
34   /**
35    *
36    * Perform an RGB[A] screen operation between the pixel sources
37    * in1 and in2, using the generalised algorithm:
38    *
39    * D = 255 - (255 - A) * (255 - B)
40    *
41    **/
update(double time,uint32_t * out,const uint32_t * in1,const uint32_t * in2)42   void update(double time,
43               uint32_t* out,
44               const uint32_t* in1,
45               const uint32_t* in2)
46   {
47     const uint8_t *src1 = reinterpret_cast<const uint8_t*>(in1);
48     const uint8_t *src2 = reinterpret_cast<const uint8_t*>(in2);
49     uint8_t *dst = reinterpret_cast<uint8_t*>(out);
50     uint32_t sizeCounter = size;
51 
52     uint32_t b, tmp;
53 
54     while (sizeCounter--)
55       {
56         for (b = 0; b < ALPHA; b++)
57           dst[b] = 255 - INT_MULT((255 - src1[b]), (255 - src2[b]), tmp);
58 
59         dst[ALPHA] = MIN(src1[ALPHA], src2[ALPHA]);
60 
61         src1 += NBYTES;
62         src2 += NBYTES;
63         dst += NBYTES;
64       }
65   }
66 
67 
68 
69 };
70 
71 
72 frei0r::construct<screen> plugin("screen",
73                                  "Perform an RGB[A] screen operation between the pixel sources, using the generalised algorithm:\n"
74 								 "D = 255 - (255 - A) * (255 - B)",
75                                  "Jean-Sebastien Senecal",
76                                  0,2,
77                                  F0R_COLOR_MODEL_RGBA8888);
78 
79