source: trunk/third/libart_lgpl/art_rgb_affine.c @ 18256

Revision 18256, 3.6 KB checked in by ghudson, 22 years ago (diff)
This commit was generated by cvs2svn to compensate for changes in r18255, which included commits to RCS files with non-trunk default branches.
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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_affine.h"
22
23#include <math.h>
24#include "art_misc.h"
25#include "art_point.h"
26#include "art_affine.h"
27#include "art_rgb_affine_private.h"
28
29/* This module handles compositing of affine-transformed rgb images
30   over rgb pixel buffers. */
31
32/**
33 * art_rgb_affine: Affine transform source RGB image and composite.
34 * @dst: Destination image RGB buffer.
35 * @x0: Left coordinate of destination rectangle.
36 * @y0: Top coordinate of destination rectangle.
37 * @x1: Right coordinate of destination rectangle.
38 * @y1: Bottom coordinate of destination rectangle.
39 * @dst_rowstride: Rowstride of @dst buffer.
40 * @src: Source image RGB buffer.
41 * @src_width: Width of source image.
42 * @src_height: Height of source image.
43 * @src_rowstride: Rowstride of @src buffer.
44 * @affine: Affine transform.
45 * @level: Filter level.
46 * @alphagamma: #ArtAlphaGamma for gamma-correcting the compositing.
47 *
48 * Affine transform the source image stored in @src, compositing over
49 * the area of destination image @dst specified by the rectangle
50 * (@x0, @y0) - (@x1, @y1). As usual in libart, the left and top edges
51 * of this rectangle are included, and the right and bottom edges are
52 * excluded.
53 *
54 * The @alphagamma parameter specifies that the alpha compositing be done
55 * in a gamma-corrected color space. Since the source image is opaque RGB,
56 * this argument only affects the edges. In the current implementation,
57 * it is ignored.
58 *
59 * The @level parameter specifies the speed/quality tradeoff of the
60 * image interpolation. Currently, only ART_FILTER_NEAREST is
61 * implemented.
62 **/
63void
64art_rgb_affine (art_u8 *dst, int x0, int y0, int x1, int y1, int dst_rowstride,
65                const art_u8 *src,
66                int src_width, int src_height, int src_rowstride,
67                const double affine[6],
68                ArtFilterLevel level,
69                ArtAlphaGamma *alphagamma)
70{
71  /* Note: this is a slow implementation, and is missing all filter
72     levels other than NEAREST. It is here for clarity of presentation
73     and to establish the interface. */
74  int x, y;
75  double inv[6];
76  art_u8 *dst_p, *dst_linestart;
77  const art_u8 *src_p;
78  ArtPoint pt, src_pt;
79  int src_x, src_y;
80  int run_x0, run_x1;
81
82  dst_linestart = dst;
83  art_affine_invert (inv, affine);
84  for (y = y0; y < y1; y++)
85    {
86      pt.y = y + 0.5;
87      run_x0 = x0;
88      run_x1 = x1;
89      art_rgb_affine_run (&run_x0, &run_x1, y, src_width, src_height,
90                          inv);
91      dst_p = dst_linestart + (run_x0 - x0) * 3;
92      for (x = run_x0; x < run_x1; x++)
93        {
94          pt.x = x + 0.5;
95          art_affine_point (&src_pt, &pt, inv);
96          src_x = floor (src_pt.x);
97          src_y = floor (src_pt.y);
98          src_p = src + (src_y * src_rowstride) + src_x * 3;
99          dst_p[0] = src_p[0];
100          dst_p[1] = src_p[1];
101          dst_p[2] = src_p[2];
102          dst_p += 3;
103        }
104      dst_linestart += dst_rowstride;
105    }
106}
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