1
2 /* Bring up a window and manipulate the gamma on it */
3
4 #include <stdlib.h>
5 #include <stdio.h>
6 #include <string.h>
7 #include <math.h>
8
9 #include "SDL.h"
10
11 /* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
quit(int rc)12 static void quit(int rc)
13 {
14 SDL_Quit();
15 exit(rc);
16 }
17
18 /* Turn a normal gamma value into an appropriate gamma ramp */
CalculateGamma(double gamma,Uint16 * ramp)19 void CalculateGamma(double gamma, Uint16 *ramp)
20 {
21 int i, value;
22
23 gamma = 1.0 / gamma;
24 for ( i=0; i<256; ++i ) {
25 value = (int)(pow((double)i/256.0, gamma)*65535.0 + 0.5);
26 if ( value > 65535 ) {
27 value = 65535;
28 }
29 ramp[i] = (Uint16)value;
30 }
31 }
32
33 /* This can be used as a general routine for all of the test programs */
get_video_args(char * argv[],int * w,int * h,int * bpp,Uint32 * flags)34 int get_video_args(char *argv[], int *w, int *h, int *bpp, Uint32 *flags)
35 {
36 int i;
37
38 *w = 640;
39 *h = 480;
40 *bpp = 0;
41 *flags = SDL_SWSURFACE;
42
43 for ( i=1; argv[i]; ++i ) {
44 if ( strcmp(argv[i], "-width") == 0 ) {
45 if ( argv[i+1] ) {
46 *w = atoi(argv[++i]);
47 }
48 } else
49 if ( strcmp(argv[i], "-height") == 0 ) {
50 if ( argv[i+1] ) {
51 *h = atoi(argv[++i]);
52 }
53 } else
54 if ( strcmp(argv[i], "-bpp") == 0 ) {
55 if ( argv[i+1] ) {
56 *bpp = atoi(argv[++i]);
57 }
58 } else
59 if ( strcmp(argv[i], "-fullscreen") == 0 ) {
60 *flags |= SDL_FULLSCREEN;
61 } else
62 if ( strcmp(argv[i], "-hw") == 0 ) {
63 *flags |= SDL_HWSURFACE;
64 } else
65 if ( strcmp(argv[i], "-hwpalette") == 0 ) {
66 *flags |= SDL_HWPALETTE;
67 } else
68 break;
69 }
70 return i;
71 }
72
main(int argc,char * argv[])73 int main(int argc, char *argv[])
74 {
75 SDL_Surface *screen;
76 SDL_Surface *image;
77 float gamma;
78 int i;
79 int w, h, bpp;
80 Uint32 flags;
81 Uint16 ramp[256];
82 Uint16 red_ramp[256];
83 Uint32 then, timeout;
84
85 /* Check command line arguments */
86 argv += get_video_args(argv, &w, &h, &bpp, &flags);
87
88 /* Initialize SDL */
89 if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
90 fprintf(stderr,
91 "Couldn't initialize SDL: %s\n", SDL_GetError());
92 return(1);
93 }
94
95 /* Initialize the display, always use hardware palette */
96 screen = SDL_SetVideoMode(w, h, bpp, flags | SDL_HWPALETTE);
97 if ( screen == NULL ) {
98 fprintf(stderr, "Couldn't set %dx%d video mode: %s\n",
99 w, h, SDL_GetError());
100 quit(1);
101 }
102
103 /* Set the window manager title bar */
104 SDL_WM_SetCaption("SDL gamma test", "testgamma");
105
106 /* Set the desired gamma, if any */
107 gamma = 1.0f;
108 if ( *argv ) {
109 gamma = (float)atof(*argv);
110 }
111 if ( SDL_SetGamma(gamma, gamma, gamma) < 0 ) {
112 fprintf(stderr, "Unable to set gamma: %s\n", SDL_GetError());
113 quit(1);
114 }
115
116 #if 0 /* This isn't supported. Integrating the gamma ramps isn't exact */
117 /* See what gamma was actually set */
118 float real[3];
119 if ( SDL_GetGamma(&real[0], &real[1], &real[2]) < 0 ) {
120 printf("Couldn't get gamma: %s\n", SDL_GetError());
121 } else {
122 printf("Set gamma values: R=%2.2f, G=%2.2f, B=%2.2f\n",
123 real[0], real[1], real[2]);
124 }
125 #endif
126
127 /* Do all the drawing work */
128 image = SDL_LoadBMP("sample.bmp");
129 if ( image ) {
130 SDL_Rect dst;
131
132 dst.x = (screen->w - image->w)/2;
133 dst.y = (screen->h - image->h)/2;
134 dst.w = image->w;
135 dst.h = image->h;
136 SDL_BlitSurface(image, NULL, screen, &dst);
137 SDL_UpdateRects(screen, 1, &dst);
138 }
139
140 /* Wait a bit, handling events */
141 then = SDL_GetTicks();
142 timeout = (5*1000);
143 while ( (SDL_GetTicks()-then) < timeout ) {
144 SDL_Event event;
145
146 while ( SDL_PollEvent(&event) ) {
147 switch (event.type) {
148 case SDL_QUIT: /* Quit now */
149 timeout = 0;
150 break;
151 case SDL_KEYDOWN:
152 switch (event.key.keysym.sym) {
153 case SDLK_SPACE: /* Go longer.. */
154 timeout += (5*1000);
155 break;
156 case SDLK_UP:
157 gamma += 0.2f;
158 SDL_SetGamma(gamma, gamma, gamma);
159 break;
160 case SDLK_DOWN:
161 gamma -= 0.2f;
162 SDL_SetGamma(gamma, gamma, gamma);
163 break;
164 case SDLK_ESCAPE:
165 timeout = 0;
166 break;
167 default:
168 break;
169 }
170 break;
171 }
172 }
173 }
174
175 /* Perform a gamma flash to red using color ramps */
176 while ( gamma < 10.0 ) {
177 /* Increase the red gamma and decrease everything else... */
178 gamma += 0.1f;
179 CalculateGamma(gamma, red_ramp);
180 CalculateGamma(1.0/gamma, ramp);
181 SDL_SetGammaRamp(red_ramp, ramp, ramp);
182 }
183 /* Finish completely red */
184 memset(red_ramp, 255, sizeof(red_ramp));
185 memset(ramp, 0, sizeof(ramp));
186 SDL_SetGammaRamp(red_ramp, ramp, ramp);
187
188 /* Now fade out to black */
189 for ( i=(red_ramp[0] >> 8); i >= 0; --i ) {
190 memset(red_ramp, i, sizeof(red_ramp));
191 SDL_SetGammaRamp(red_ramp, NULL, NULL);
192 }
193 SDL_Delay(1*1000);
194
195 SDL_Quit();
196 return(0);
197 }
198