FreeBSD Manual Pages
getpixel(3) Allegro manual getpixel(3) NAME getpixel - Reads a pixel from a bitmap. Allegro game programming li- brary. SYNOPSIS #include <allegro.h> int getpixel(BITMAP *bmp, int x, int y); DESCRIPTION Reads a pixel from point (x, y) in the bitmap. RETURN VALUE Returns -1 if the point lies outside the bitmap (ignoring the clipping rectangle), otherwise the value of the pixel in the color format of the bitmap. Warning: -1 is also a valid value for pixels contained in 32-bit bitmaps with alpha channel (when R,G,B,A are all equal to 255) so you can't use the test against -1 as a predicate for such bitmaps. In this cases, the only reliable predicate is is_inside_bitmap(). To extract the individual color components, use the getr() / getg() / getb() / geta() family of functions. SEE ALSO putpixel(3), _getpixel(3), is_inside_bitmap(3), getr(3), getg(3), getb(3), geta(3), ex12bit(3), exalpha(3), exflame(3), exlights(3) Allegro version 4.4.3 getpixel(3)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=getpixel&sektion=3&manpath=FreeBSD+Ports+14.3.quarterly>