1 /* Libart_LGPL - library of basic graphic primitives
2 * Copyright (C) 1998 Raph Levien
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.
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.
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.
22 #include "art_point.h"
23 #include "art_affine.h"
24 #include "art_rgb_affine_private.h"
25 #include "art_rgb_rgba_affine.h"
27 /* This module handles compositing of affine-transformed rgba images
28 over rgb pixel buffers. */
30 /* Composite the source image over the destination image, applying the
34 * art_rgb_rgba_affine: Affine transform source RGBA image and composite.
35 * @dst: Destination image RGB buffer.
36 * @x0: Left coordinate of destination rectangle.
37 * @y0: Top coordinate of destination rectangle.
38 * @x1: Right coordinate of destination rectangle.
39 * @y1: Bottom coordinate of destination rectangle.
40 * @dst_rowstride: Rowstride of @dst buffer.
41 * @src: Source image RGBA buffer.
42 * @src_width: Width of source image.
43 * @src_height: Height of source image.
44 * @src_rowstride: Rowstride of @src buffer.
45 * @affine: Affine transform.
46 * @level: Filter level.
47 * @alphagamma: #ArtAlphaGamma for gamma-correcting the compositing.
49 * Affine transform the source image stored in @src, compositing over
50 * the area of destination image @dst specified by the rectangle
51 * (@x0, @y0) - (@x1, @y1). As usual in libart, the left and top edges
52 * of this rectangle are included, and the right and bottom edges are
55 * The @alphagamma parameter specifies that the alpha compositing be
56 * done in a gamma-corrected color space. In the current
57 * implementation, it is ignored.
59 * The @level parameter specifies the speed/quality tradeoff of the
60 * image interpolation. Currently, only ART_FILTER_NEAREST is
64 art_rgb_rgba_affine (art_u8 *dst,
65 int x0, int y0, int x1, int y1, int dst_rowstride,
67 int src_width, int src_height, int src_rowstride,
68 const double affine[6],
70 ArtAlphaGamma *alphagamma)
72 /* Note: this is a slow implementation, and is missing all filter
73 levels other than NEAREST. It is here for clarity of presentation
74 and to establish the interface. */
77 art_u8 *dst_p, *dst_linestart;
82 art_u8 bg_r, bg_g, bg_b;
83 art_u8 fg_r, fg_g, fg_b;
88 art_affine_invert (inv, affine);
89 for (y = y0; y < y1; y++)
94 art_rgb_affine_run (&run_x0, &run_x1, y, src_width, src_height,
96 dst_p = dst_linestart + (run_x0 - x0) * 3;
97 for (x = run_x0; x < run_x1; x++)
100 art_affine_point (&src_pt, &pt, inv);
101 src_x = floor (src_pt.x);
102 src_y = floor (src_pt.y);
103 src_p = src + (src_y * src_rowstride) + src_x * 4;
104 if (src_x >= 0 && src_x < src_width &&
105 src_y >= 0 && src_y < src_height)
123 tmp = (src_p[0] - bg_r) * alpha;
124 fg_r = bg_r + ((tmp + (tmp >> 8) + 0x80) >> 8);
125 tmp = (src_p[1] - bg_g) * alpha;
126 fg_g = bg_g + ((tmp + (tmp >> 8) + 0x80) >> 8);
127 tmp = (src_p[2] - bg_b) * alpha;
128 fg_b = bg_b + ((tmp + (tmp >> 8) + 0x80) >> 8);
135 } else { dst_p[0] = 255; dst_p[1] = 0; dst_p[2] = 0; }
138 dst_linestart += dst_rowstride;