/
showimage.c
147 lines (129 loc) · 3.82 KB
/
showimage.c
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
/*
SHOW: A test application for the SDL image loading library.
Copyright (C) 1999 Sam Lantinga
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Sam Lantinga
5635-34 Springhouse Dr.
Pleasanton, CA 94588 (USA)
slouken@devolution.com
*/
#include <stdlib.h>
#include <stdio.h>
#include "SDL.h"
#include "SDL_image.h"
/* Draw a Gimpish background pattern to show transparency in the image */
void draw_background(SDL_Surface *screen)
{
Uint8 *dst = screen->pixels;
int x, y;
int bpp = screen->format->BytesPerPixel;
Uint32 col[2];
col[0] = SDL_MapRGB(screen->format, 0x66, 0x66, 0x66);
col[1] = SDL_MapRGB(screen->format, 0x99, 0x99, 0x99);
for(y = 0; y < screen->h; y++) {
for(x = 0; x < screen->w; x++) {
/* use an 8x8 checkerboard pattern */
Uint32 c = col[((x ^ y) >> 3) & 1];
switch(bpp) {
case 1:
dst[x] = c;
break;
case 2:
((Uint16 *)dst)[x] = c;
break;
case 3:
if(SDL_BYTEORDER == SDL_LIL_ENDIAN) {
dst[x * 3] = c;
dst[x * 3 + 1] = c >> 8;
dst[x * 3 + 2] = c >> 16;
} else {
dst[x * 3] = c >> 16;
dst[x * 3 + 1] = c >> 8;
dst[x * 3 + 2] = c;
}
break;
case 4:
((Uint32 *)dst)[x] = c;
break;
}
}
dst += screen->pitch;
}
}
int main(int argc, char *argv[])
{
SDL_Surface *screen, *image;
int i, depth;
/* Check command line usage */
if ( ! argv[1] ) {
fprintf(stderr, "Usage: %s <image_file>\n", argv[0]);
exit(1);
}
/* Initialize the SDL library */
if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
exit(255);
}
/* Open the image file */
image = IMG_Load(argv[1]);
if ( image == NULL ) {
fprintf(stderr,"Couldn't load %s: %s\n",argv[1],SDL_GetError());
SDL_Quit();
exit(2);
}
SDL_WM_SetCaption(argv[1], "showimage");
/* Create a display for the image */
depth = SDL_VideoModeOK(image->w, image->h, 32, SDL_SWSURFACE);
/* Use the deepest native mode, except that we emulate 32bpp for
viewing non-indexed images on 8bpp screens */
if ( (image->format->BytesPerPixel > 1) && (depth == 8) ) {
depth = 32;
}
screen = SDL_SetVideoMode(image->w, image->h, depth, SDL_SWSURFACE);
if ( screen == NULL ) {
fprintf(stderr,"Couldn't set %dx%dx%d video mode: %s\n",
image->w, image->h, depth, SDL_GetError());
SDL_Quit();
exit(3);
}
/* Set the palette, if one exists */
if ( image->format->palette ) {
SDL_SetColors(screen, image->format->palette->colors,
0, image->format->palette->ncolors);
}
/* Draw a background pattern if the surface has transparency */
if(image->flags & (SDL_SRCALPHA | SDL_SRCCOLORKEY))
draw_background(screen);
/* Display the image */
SDL_BlitSurface(image, NULL, screen, NULL);
SDL_UpdateRect(screen, 0, 0, 0, 0);
/* Wait for any keyboard or mouse input */
for ( i=SDL_NOEVENT; i<SDL_NUMEVENTS; ++i ) {
switch (i) {
case SDL_KEYDOWN:
case SDL_MOUSEBUTTONDOWN:
case SDL_QUIT:
/* Valid event, keep it */
break;
default:
/* We don't want this event */
SDL_EventState(i, SDL_IGNORE);
break;
}
}
SDL_WaitEvent(NULL);
/* We're done! */
SDL_FreeSurface(image);
SDL_Quit();
exit(0);
}