GGI_PIXELFORMAT(3)

NAME
ggi_pixelformat - LibGGI pixel format description

SYNOPSIS
#include <ggi/ggi.h>

DESCRIPTION
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		bitmeaning[sizeof(ggi_pixel)*8];
	uint32		flags;		/* Pixelformat flags */
	uint32		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

This structure describes the internal format of pixel values for a visual. Use the ggiGetPixelFormat function.

SEE ALSO
ggiGetPixelFormat(3)