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/*
* Example program for the Allegro library, by Shawn Hargreaves.
*
* This program demonstrates the use of double buffering.
* It moves a circle across the screen, first just erasing and
* redrawing directly to the screen, then with a double buffer.
*/
#include "allegro.h"
int main()
{
BITMAP *buffer;
int c;
allegro_init();
install_timer();
if (set_gfx_mode(GFX_SAFE, 320, 200, 0, 0) != 0) {
set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
allegro_message("Unable to set any graphic mode\n%s\n", allegro_error);
return 1;
}
set_palette(desktop_palette);
text_mode(-1);
/* allocate the memory buffer */
buffer = create_bitmap(SCREEN_W, SCREEN_H);
/* First without any buffering...
* Note use of the global retrace_counter to control the speed. We also
* compensate screen size (GFX_SAFE) with a virtual 320 screen width.
*/
c = retrace_count+32;
while (retrace_count-c <= 320+32) {
acquire_screen();
clear_to_color(screen, makecol(255, 255, 255));
circlefill(screen, (retrace_count-c)*SCREEN_W/320, SCREEN_H/2, 32, makecol(0, 0, 0));
textprintf(screen, font, 0, 0, makecol(0, 0, 0), "No buffering (%s)",
gfx_driver->name);
release_screen();
}
/* and now with a double buffer... */
c = retrace_count+32;
while (retrace_count-c <= 320+32) {
clear_to_color(buffer, makecol(255, 255, 255));
circlefill(buffer, (retrace_count-c)*SCREEN_W/320, SCREEN_H/2, 32, makecol(0, 0, 0));
textprintf(buffer, font, 0, 0, makecol(0, 0, 0), "Double buffered (%s)",
gfx_driver->name);
blit(buffer, screen, 0, 0, 0, 0, SCREEN_W, SCREEN_H);
}
destroy_bitmap(buffer);
return 0;
}
END_OF_MAIN();
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