FreeBSD Manual Pages
screen(3) Allegro manual screen(3) NAME screen - Global pointer to the screen hardware video memory. Allegro game programming library. SYNOPSIS #include <allegro.h> extern BITMAP *screen; DESCRIPTION Global pointer to a bitmap, sized VIRTUAL_W x VIRTUAL_H. This is cre- ated by set_gfx_mode(), and represents the hardware video memory. Only a part of this bitmap will actually be visible, sized SCREEN_W x SCREEN_H. Normally this is the top left corner of the larger virtual screen, so you can ignore the extra invisible virtual size of the bit- map if you aren't interested in hardware scrolling or page flipping. To move the visible window to other parts of the screen bitmap, call scroll_screen(). Initially the clipping rectangle will be limited to the physical screen size, so if you want to draw onto a larger virtual screen space outside this rectangle, you will need to adjust the clip- ping. For example, to draw a pixel onto the screen you would write: putpixel(screen, x, y, color); Or to implement a double-buffered system: /* Make a bitmap in RAM. */ BITMAP *bmp = create_bitmap(320, 200); /* Clean the memory bitmap. */ clear_bitmap(bmp); /* Draw onto the memory bitmap. */ putpixel(bmp, x, y, color); /* Copy it to the screen. */ blit(bmp, screen, 0, 0, 0, 0, 320, 200); Warning: be very careful when using this pointer at the same time as any bitmaps created by the create_video_bitmap() function (see the de- scription of this function for more detailed information). And never try to destroy it with destroy_bitmap(). SEE ALSO set_gfx_mode(3), is_screen_bitmap(3), create_video_bitmap(3), scroll_screen(3) Allegro version 4.4.3 screen(3)
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO
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