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/*
* Example program for the Allegro library, by Shawn Hargreaves.
*
* This program demonstrates how to use hardware scrolling and split
* screens in mode-X. The split screen part only works on DOS and Linux
* console platforms, but the scrolling should work on anything that
* supports large virtual screens.
*/
#include <stdio.h>
#include "allegro.h"
int main()
{
BITMAP *scroller, *status_bar;
int counter = 0;
char tmp[80];
RGB black = { 0, 0, 0, 0 };
int x = 0;
int next_x;
int h = 100;
int split_h = 0;
allegro_init();
install_keyboard();
#ifdef GFX_MODEX
/* create a nice wide virtual screen, and split it at line 200 */
if (set_gfx_mode(GFX_MODEX, 320, 240, 640, 240) != 0) {
if (set_gfx_mode(GFX_AUTODETECT, 320, 240, 640, 240) != 0) {
set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
allegro_message("Unable to set a 320x240 mode with 640x240 virtual dimensions\n");
return 1;
}
}
if (gfx_driver->id == GFX_MODEX) {
split_modex_screen(200);
scroll_screen(0, 40);
split_h = 40;
}
#else
/* no mode-X on this platform, so just make do the best we can */
if (set_gfx_mode(GFX_AUTODETECT, 320, 240, 640, 240) != 0) {
set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
allegro_message("Unable to set a 320x240 mode with 640x240 virtual dimensions\n");
return 1;
}
#endif
/* the scrolling area is sized 640x200 and starts at line 40 */
scroller = create_sub_bitmap(screen, 0, split_h, SCREEN_W*2, SCREEN_H-split_h);
/* the status bar is sized 320x40 and starts at line 0 */
if (split_h > 0)
status_bar = create_sub_bitmap(screen, 0, 0, SCREEN_W, split_h);
else
status_bar = NULL;
set_palette(desktop_palette);
set_color(0, &black);
if (status_bar)
textout(status_bar, font, "This area isn't scrolling", 8, 8, 1);
rectfill(scroller, 0, 0, SCREEN_W, 100, 6);
rectfill(scroller, 0, 100, SCREEN_W, SCREEN_H-split_h, 2);
do {
/* update the status bar */
if (status_bar) {
sprintf(tmp, "Counter = %d", counter++);
acquire_bitmap(status_bar);
textout(status_bar, font, tmp, 8, 20, 1);
release_bitmap(status_bar);
}
/* advance the scroller, wrapping every 320 pixels */
next_x = x + 1;
if (next_x >= 320)
next_x = 0;
/* draw another column of the landscape */
acquire_bitmap(scroller);
vline(scroller, next_x+SCREEN_W-1, 0, h, 6);
vline(scroller, next_x+SCREEN_W-1, h+1, SCREEN_H-split_h, 2);
release_bitmap(scroller);
/* scroll the screen */
scroll_screen(next_x, split_h);
/* duplicate the landscape column so we can wrap the scroller */
if (next_x > 0) {
acquire_bitmap(scroller);
vline(scroller, x, 0, h, 6);
vline(scroller, x, h+1, SCREEN_H-split_h, 2);
release_bitmap(scroller);
}
/* randomly alter the landscape position */
if (rand()&1) {
if (h > 5)
h--;
}
else {
if (h < 195)
h++;
}
x = next_x;
} while (!keypressed());
destroy_bitmap(scroller);
if (status_bar)
destroy_bitmap(status_bar);
clear_keybuf();
return 0;
}
END_OF_MAIN();
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