Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

getpixel(3alleg4) [v7 man page]

getpixel(3alleg4)						  Allegro manual						 getpixel(3alleg4)

NAME
getpixel - Reads a pixel from a bitmap. Allegro game programming library. 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(3alleg4), _getpixel(3alleg4), is_inside_bitmap(3alleg4), getr(3alleg4), getg(3alleg4), getb(3alleg4), geta(3alleg4), ex12bit(3alleg4), exalpha(3alleg4), exflame(3alleg4), exlights(3alleg4) Allegro version 4.4.2 getpixel(3alleg4)

Check Out this Related Man Page

getpixel(3alleg4)						  Allegro manual						 getpixel(3alleg4)

NAME
getpixel - Reads a pixel from a bitmap. Allegro game programming library. 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(3alleg4), _getpixel(3alleg4), is_inside_bitmap(3alleg4), getr(3alleg4), getg(3alleg4), getb(3alleg4), geta(3alleg4), ex12bit(3alleg4), exalpha(3alleg4), exflame(3alleg4), exlights(3alleg4) Allegro version 4.4.2 getpixel(3alleg4)
Man Page

4 More Discussions You Might Find Interesting

1. Programming

Xlib - Mapping Pixel Values to RGB Colors

Hi everyone... I'm working with XLib and I want to find out the pixel value of a particular point on screen and then map it to RGB values. I used XGetImage and XGetPixel to get the pixel value, but how do I get the RGB values of the pixel? I went through a few XLib manuals, there seems to be no... (1 Reply)
Discussion started by: thebin
1 Replies

2. Programming

Converting XImage to PNG

i was able to make a connection to X server and get a screen shot using XGetImage, now, im unable to save this XImage to any good format like PNG, i found a code that saves it to bitmap, but the resulted bitmap file is massive, is there anyway i can save this XImage to PNG directly? thanks; (7 Replies)
Discussion started by: JonhyM
7 Replies

3. Programming

SDL Image Filtering

Solved thanks for info!! (8 Replies)
Discussion started by: aLHaNz
8 Replies

4. Programming

Xlib - Rotation and interpolation of pixmap - Performance problems

I need to rotate a pixmap in XLib with some kind of interpolation to reduce the aliasing. I came up with the following code, which uses bilinear interpolation. It works fine: the rotated image looks perfect, but unfortunately it takes 5 or 6 seconds for each rotation. (in a 300x300, 16 colours... (5 Replies)
Discussion started by: mghis
5 Replies