1 /* Libart_LGPL - library of basic graphic primitives
2 * Copyright (C) 1998 Raph Levien
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
18 */
19
20 #include "config.h"
21 #include "art_rgb_a_affine.h"
22
23 #include <math.h>
24
25 #include "art_affine.h"
26 #include "art_point.h"
27 #include "art_rgb_affine_private.h"
28
29 /* This module handles compositing of affine-transformed alpha only images
30 over rgb pixel buffers. */
31
32 /* Composite the source image over the destination image, applying the
33 affine transform. */
34
35 /**
36 * art_rgb_a_affine: Affine transform source Alpha image and composite.
37 * @dst: Destination image RGB buffer.
38 * @x0: Left coordinate of destination rectangle.
39 * @y0: Top coordinate of destination rectangle.
40 * @x1: Right coordinate of destination rectangle.
41 * @y1: Bottom coordinate of destination rectangle.
42 * @dst_rowstride: Rowstride of @dst buffer.
43 * @src: Source image alpha buffer.
44 * @src_width: Width of source image.
45 * @src_height: Height of source image.
46 * @src_rowstride: Rowstride of @src buffer.
47 * @rgb: RGB foreground color, in 0xRRGGBB.
48 * @affine: Affine transform.
49 * @level: Filter level.
50 * @alphagamma: #ArtAlphaGamma for gamma-correcting the compositing.
51 *
52 * Affine transform the solid color rgb with alpha specified by the
53 * source image stored in @src, compositing over the area of destination
54 * image @dst specified by the rectangle (@x0, @y0) - (@x1, @y1).
55 * As usual in libart, the left and top edges of this rectangle are
56 * included, and the right and bottom edges are excluded.
57 *
58 * The @alphagamma parameter specifies that the alpha compositing be
59 * done in a gamma-corrected color space. In the current
60 * implementation, it is ignored.
61 *
62 * The @level parameter specifies the speed/quality tradeoff of the
63 * image interpolation. Currently, only ART_FILTER_NEAREST is
64 * implemented.
65 **/
66 void
art_rgb_a_affine(art_u8 * dst,int x0,int y0,int x1,int y1,int dst_rowstride,const art_u8 * src,int src_width,int src_height,int src_rowstride,art_u32 rgb,const double affine[6],ArtFilterLevel level,ArtAlphaGamma * alphagamma)67 art_rgb_a_affine (art_u8 *dst,
68 int x0, int y0, int x1, int y1, int dst_rowstride,
69 const art_u8 *src,
70 int src_width, int src_height, int src_rowstride,
71 art_u32 rgb,
72 const double affine[6],
73 ArtFilterLevel level,
74 ArtAlphaGamma *alphagamma)
75 {
76 /* Note: this is a slow implementation, and is missing all filter
77 levels other than NEAREST. It is here for clarity of presentation
78 and to establish the interface. */
79 int x, y;
80 double inv[6];
81 art_u8 *dst_p, *dst_linestart;
82 const art_u8 *src_p;
83 ArtPoint pt, src_pt;
84 int src_x, src_y;
85 int alpha;
86 art_u8 bg_r, bg_g, bg_b;
87 art_u8 fg_r, fg_g, fg_b;
88 int tmp;
89 int run_x0, run_x1;
90 art_u8 r, g, b;
91
92 r = (rgb>>16)&0xff;
93 g = (rgb>>8)&0xff;
94 b = (rgb)&0xff;
95
96 dst_linestart = dst;
97 art_affine_invert (inv, affine);
98 for (y = y0; y < y1; y++)
99 {
100 pt.y = y + 0.5;
101 run_x0 = x0;
102 run_x1 = x1;
103 art_rgb_affine_run (&run_x0, &run_x1, y, src_width, src_height,
104 inv);
105 dst_p = dst_linestart + (run_x0 - x0) * 3;
106 for (x = run_x0; x < run_x1; x++)
107 {
108 pt.x = x + 0.5;
109 art_affine_point (&src_pt, &pt, inv);
110 src_x = floor (src_pt.x);
111 src_y = floor (src_pt.y);
112 src_p = src + (src_y * src_rowstride) + src_x;
113 if (src_x >= 0 && src_x < src_width &&
114 src_y >= 0 && src_y < src_height)
115 {
116
117 alpha = *src_p;
118 if (alpha)
119 {
120 if (alpha == 255)
121 {
122 dst_p[0] = r;
123 dst_p[1] = g;
124 dst_p[2] = b;
125 }
126 else
127 {
128 bg_r = dst_p[0];
129 bg_g = dst_p[1];
130 bg_b = dst_p[2];
131
132 tmp = (r - bg_r) * alpha;
133 fg_r = bg_r + ((tmp + (tmp >> 8) + 0x80) >> 8);
134 tmp = (g - bg_g) * alpha;
135 fg_g = bg_g + ((tmp + (tmp >> 8) + 0x80) >> 8);
136 tmp = (b - bg_b) * alpha;
137 fg_b = bg_b + ((tmp + (tmp >> 8) + 0x80) >> 8);
138
139 dst_p[0] = fg_r;
140 dst_p[1] = fg_g;
141 dst_p[2] = fg_b;
142 }
143 }
144 } else { dst_p[0] = 255; dst_p[1] = 0; dst_p[2] = 0; }
145 dst_p += 3;
146 }
147 dst_linestart += dst_rowstride;
148 }
149 }
150