1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
/*
* mate-thumbnail-pixbuf-utils.c: Utilities for handling pixbufs when thumbnailing
*
* Copyright (C) 2002 Red Hat, Inc.
*
* This file is part of the Mate Library.
*
* The Mate Library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* The Mate Library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with the Mate Library; see the file COPYING.LIB. If not,
* write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
* Author: Alexander Larsson <alexl@redhat.com>
*/
#include <config.h>
#include <stdlib.h>
#include <string.h>
#include <glib.h>
#define MATE_DESKTOP_USE_UNSTABLE_API
#include "mate-desktop-thumbnail.h"
#define LOAD_BUFFER_SIZE 65536
/**
* mate_desktop_thumbnail_scale_down_pixbuf:
* @pixbuf: a #GdkPixbuf
* @dest_width: the desired new width
* @dest_height: the desired new height
*
* Scales the pixbuf to the desired size. This function
* is a lot faster than gdk-pixbuf when scaling down by
* large amounts.
*
* Return value: (transfer full): a scaled pixbuf
*
* Since: 2.2
**/
GdkPixbuf *
mate_desktop_thumbnail_scale_down_pixbuf (GdkPixbuf *pixbuf,
int dest_width,
int dest_height)
{
int source_width, source_height;
int s_x1, s_y1, s_x2, s_y2;
int s_xfrac, s_yfrac;
int dx, dx_frac, dy, dy_frac;
div_t ddx, ddy;
int x, y;
int r, g, b, a;
int n_pixels;
gboolean has_alpha;
guchar *dest, *src, *xsrc, *src_pixels;
GdkPixbuf *dest_pixbuf;
int pixel_stride;
int source_rowstride, dest_rowstride;
if (dest_width == 0 || dest_height == 0) {
return NULL;
}
source_width = gdk_pixbuf_get_width (pixbuf);
source_height = gdk_pixbuf_get_height (pixbuf);
g_assert (source_width >= dest_width);
g_assert (source_height >= dest_height);
ddx = div (source_width, dest_width);
dx = ddx.quot;
dx_frac = ddx.rem;
ddy = div (source_height, dest_height);
dy = ddy.quot;
dy_frac = ddy.rem;
has_alpha = gdk_pixbuf_get_has_alpha (pixbuf);
source_rowstride = gdk_pixbuf_get_rowstride (pixbuf);
src_pixels = gdk_pixbuf_get_pixels (pixbuf);
dest_pixbuf = gdk_pixbuf_new (GDK_COLORSPACE_RGB, has_alpha, 8,
dest_width, dest_height);
dest = gdk_pixbuf_get_pixels (dest_pixbuf);
dest_rowstride = gdk_pixbuf_get_rowstride (dest_pixbuf);
pixel_stride = (has_alpha)?4:3;
s_y1 = 0;
s_yfrac = -dest_height/2;
while (s_y1 < source_height) {
s_y2 = s_y1 + dy;
s_yfrac += dy_frac;
if (s_yfrac > 0) {
s_y2++;
s_yfrac -= dest_height;
}
s_x1 = 0;
s_xfrac = -dest_width/2;
while (s_x1 < source_width) {
s_x2 = s_x1 + dx;
s_xfrac += dx_frac;
if (s_xfrac > 0) {
s_x2++;
s_xfrac -= dest_width;
}
/* Average block of [x1,x2[ x [y1,y2[ and store in dest */
r = g = b = a = 0;
n_pixels = 0;
src = src_pixels + s_y1 * source_rowstride + s_x1 * pixel_stride;
for (y = s_y1; y < s_y2; y++) {
xsrc = src;
if (has_alpha) {
for (x = 0; x < s_x2-s_x1; x++) {
n_pixels++;
r += xsrc[3] * xsrc[0];
g += xsrc[3] * xsrc[1];
b += xsrc[3] * xsrc[2];
a += xsrc[3];
xsrc += 4;
}
} else {
for (x = 0; x < s_x2-s_x1; x++) {
n_pixels++;
r += *xsrc++;
g += *xsrc++;
b += *xsrc++;
}
}
src += source_rowstride;
}
if (has_alpha) {
if (a != 0) {
*dest++ = r / a;
*dest++ = g / a;
*dest++ = b / a;
*dest++ = a / n_pixels;
} else {
*dest++ = 0;
*dest++ = 0;
*dest++ = 0;
*dest++ = 0;
}
} else {
*dest++ = r / n_pixels;
*dest++ = g / n_pixels;
*dest++ = b / n_pixels;
}
s_x1 = s_x2;
}
s_y1 = s_y2;
dest += dest_rowstride - dest_width * pixel_stride;
}
return dest_pixbuf;
}
|
