ggi_pixelformat
Section: GGI (3)
Updated: 2006-12-30
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NAME
ggi_pixelformat : LibGGI pixel format description
SYNOPSIS
#include <ggi/ggi.h>
typedef struct {
int depth; /* Number of significant bits */
int size; /* Physical size in bits */
/*
* Simple and common things first :
*
* Usage of the mask/shift pairs:
* If new_value is the _sizeof(ggi_pixel)*8bit_ value of the thing
* you want to set, you do
*
* *pointer &= ~???_mask; // Mask out old bits
* *pointer |= (new_value>>shift) & ???_mask;
*
* The reason to use 32 bit and "downshifting" is alignment
* and extensibility. You can easily adjust to other datasizes
* with a simple addition ...
*/
/* Simple colors:
*/
ggi_pixel red_mask; /* Bitmask of red bits */
int red_shift; /* Shift for red bits */
ggi_pixel green_mask; /* Bitmask of green bits */
int green_shift; /* Shift for green bits */
ggi_pixel blue_mask; /* Bitmask of blue bits */
int blue_shift; /* Shift for blue bits */
/* A few common attributes :
*/
ggi_pixel alpha_mask; /* Bitmask of alphachannel bits */
int alpha_shift; /* Shift for alpha bits */
ggi_pixel clut_mask; /* Bitmask of bits for the clut */
int clut_shift; /* Shift for bits for the clut*/
ggi_pixel fg_mask; /* Bitmask of foreground color */
int fg_shift; /* Shift for foreground color */
ggi_pixel bg_mask; /* Bitmask of background color */
int bg_shift; /* Shift for background color */
ggi_pixel texture_mask; /* Bitmask of the texture (for
textmodes - the actual character) */
int texture_shift; /* Shift for texture */
/*
* Now if this doesn't suffice you might want to parse the following
* to find out what each bit does:
*/
uint32_t bitmeaning[sizeof(ggi_pixel)*8];
uint32_t flags; /* Pixelformat flags */
uint32_t stdformat; /* Standard format identifier */
/* This one has only one use for the usermode application:
* To quickly check, if two buffers are identical. If both
* stdformats are the same and _NOT_ 0 (which means "WEIRD"),
* you may use things like memcpy between them which will have
* the desired effect ...
*/
} ggi_pixelformat;
/* Pixelformat flags */
#define GGI_PF_REVERSE_ENDIAN 0x01
#define GGI_PF_HIGHBIT_RIGHT 0x02
#define GGI_PF_HAM 0x04
#define GGI_PF_EXTENDED 0x08
DESCRIPTION
This structure describes the internal format of pixel values for a visual.
SEE ALSO
ggiGetPixelFormat(3)