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 */
20 #include <math.h>
21 #include "art_misc.h"
22 #include "art_point.h"
23 #include "art_affine.h"
24 #include "art_rgb_affine.h"
25 #include "art_rgb_affine_private.h"
27 /* This module handles compositing of affine-transformed rgb images
28 over rgb pixel buffers. */
30 /**
31 * art_rgb_affine: Affine transform source RGB image and composite.
32 * @dst: Destination image RGB buffer.
33 * @x0: Left coordinate of destination rectangle.
34 * @y0: Top coordinate of destination rectangle.
35 * @x1: Right coordinate of destination rectangle.
36 * @y1: Bottom coordinate of destination rectangle.
37 * @dst_rowstride: Rowstride of @dst buffer.
38 * @src: Source image RGB buffer.
39 * @src_width: Width of source image.
40 * @src_height: Height of source image.
41 * @src_rowstride: Rowstride of @src buffer.
42 * @affine: Affine transform.
43 * @level: Filter level.
44 * @alphagamma: #ArtAlphaGamma for gamma-correcting the compositing.
45 *
46 * Affine transform the source image stored in @src, compositing over
47 * the area of destination image @dst specified by the rectangle
48 * (@x0, @y0) - (@x1, @y1). As usual in libart, the left and top edges
49 * of this rectangle are included, and the right and bottom edges are
50 * excluded.
51 *
52 * The @alphagamma parameter specifies that the alpha compositing be done
53 * in a gamma-corrected color space. Since the source image is opaque RGB,
54 * this argument only affects the edges. In the current implementation,
55 * it is ignored.
56 *
57 * The @level parameter specifies the speed/quality tradeoff of the
58 * image interpolation. Currently, only ART_FILTER_NEAREST is
59 * implemented.
60 **/
61 void
62 art_rgb_affine (art_u8 *dst, int x0, int y0, int x1, int y1, int dst_rowstride,
63 const art_u8 *src,
64 int src_width, int src_height, int src_rowstride,
65 const double affine[6],
66 ArtFilterLevel level,
67 ArtAlphaGamma *alphagamma)
68 {
69 /* Note: this is a slow implementation, and is missing all filter
70 levels other than NEAREST. It is here for clarity of presentation
71 and to establish the interface. */
72 int x, y;
73 double inv[6];
74 art_u8 *dst_p, *dst_linestart;
75 const art_u8 *src_p;
76 ArtPoint pt, src_pt;
77 int src_x, src_y;
78 int run_x0, run_x1;
80 dst_linestart = dst;
81 art_affine_invert (inv, affine);
82 for (y = y0; y < y1; y++)
83 {
84 pt.y = y + 0.5;
85 run_x0 = x0;
86 run_x1 = x1;
87 art_rgb_affine_run (&run_x0, &run_x1, y, src_width, src_height,
88 inv);
89 dst_p = dst_linestart + (run_x0 - x0) * 3;
90 for (x = run_x0; x < run_x1; x++)
91 {
92 pt.x = x + 0.5;
93 art_affine_point (&src_pt, &pt, inv);
94 src_x = floor (src_pt.x);
95 src_y = floor (src_pt.y);
96 src_p = src + (src_y * src_rowstride) + src_x * 3;
97 dst_p[0] = src_p[0];
98 dst_p[1] = src_p[1];
99 dst_p[2] = src_p[2];
100 dst_p += 3;
101 }
102 dst_linestart += dst_rowstride;
103 }
104 }