gp_pixel.h File Reference

A pixel description. More...

#include <stdint.h>
#include <core/gp_types.h>
#include <core/gp_common.h>
#include <core/gp_pixel.gen.h>
#include <core/gp_pixel_channel.gen.h>
#include <core/gp_pixel_alias.h>
#include <core/gp_get_set_bits.h>

Go to the source code of this file.

Data Structures
struct	gp_pixel_channel
	Description of one pixel channel. More...
struct	gp_pixel_type_desc
	A description of a gp_pixel_type Assumes name with at most 15 chars. More...

Typedefs
typedef struct gp_pixel_channel	gp_pixel_channel
	Description of one pixel channel.
typedef enum gp_pixel_flags	gp_pixel_flags
	Pixel type flags for various pixel properties.

Enumerations
enum	gp_pixel_flags {   GP_PIXEL_HAS_ALPHA = 0x01 , GP_PIXEL_IS_RGB = 0x02 , GP_PIXEL_IS_PALETTE = 0x04 , GP_PIXEL_IS_CMYK = 0x08 ,   GP_PIXEL_IS_GRAYSCALE = 0x10 }
	Pixel type flags for various pixel properties. More...

Functions
static const gp_pixel_type_desc *	gp_pixel_desc (gp_pixel_type type)
	Returns a pixel type description for a pixel type enum.
static unsigned int	gp_pixel_channel_count (gp_pixel_type type)
	Returns a numbers of pixel channels.
static uint8_t	gp_pixel_channel_bits (gp_pixel_type type, uint8_t channel)
	Returns number of bits for a pixel channel.
static uint8_t	gp_pixel_channel_lin_bits (gp_pixel_type type, uint8_t channel)
	Returns number of bits for a linearized pixel channel.
static const char *	gp_pixel_channel_name (gp_pixel_type type, uint8_t channel)
	Returns number of bits for a pixel channel.
static int	gp_pixel_channel_is_alpha (gp_pixel_type type, uint8_t channel)
	Returns true if pixel channel is alpha channel.
gp_pixel_type	gp_pixel_rgb_match (gp_pixel rmask, gp_pixel gmask, gp_pixel bmask, gp_pixel amask, uint8_t bits_per_pixel)
	Matches a RGB pixel type againts known pixel types.
gp_pixel_type	gp_pixel_rgb_lookup (uint32_t rsize, uint32_t roff, uint32_t gsize, uint32_t goff, uint32_t bsize, uint32_t boff, uint32_t asize, uint32_t aoff, uint8_t bits_per_pixel)
	Looks up a RGB pixel type against know pixel types.
int	gp_pixel_has_flags (gp_pixel_type pixel_type, gp_pixel_flags flags)
	Function to determine pixel attributes.
gp_pixel	gp_pixel_chan_mask (gp_pixel_type pixel_type, const char *chan_name)
	Returns channel mask for a given pixel type and channel name.
gp_pixel	gp_pixel_chans_add (gp_pixel_type pixel_type, gp_pixel pixel, int add)
	Does per-channel saturated addition.

Variables
const gp_pixel_type_desc	gp_pixel_types [GP_PIXEL_MAX]
	Array with description for all pixel types.

Detailed Description

A pixel description.

Definition in file gp_pixel.h.

Typedef Documentation

gp_pixel_channel

typedef struct gp_pixel_channel gp_pixel_channel

Description of one pixel channel.

Assumes all the channel names to be at most 7 chars long

The common channel names are:

R, G, B - RGB as usual C, M, Y, K - CMYK V - value, for grayscale A - opacity (0=transparent) P - palette (index)

Enumeration Type Documentation

gp_pixel_flags

enum gp_pixel_flags

Pixel type flags for various pixel properties.

Enumerator
GP_PIXEL_HAS_ALPHA	Pixel has an alpha channel.
GP_PIXEL_IS_RGB	Pixel has RGB channels.
GP_PIXEL_IS_PALETTE	Pixel is palette.
GP_PIXEL_IS_CMYK	Pixel has CMYK channels.
GP_PIXEL_IS_GRAYSCALE	Pixel is grayscale.

Definition at line 62 of file gp_pixel.h.

Function Documentation

gp_pixel_chan_mask()

gp_pixel gp_pixel_chan_mask	(	gp_pixel_type	pixel_type,
		const char *	chan_name
	)

Returns channel mask for a given pixel type and channel name.

Parameters

pixel_type	A pixel type.
chan_name	A channel name, e.g. "R" or "A".

Returns

A channel mask or zero if channel is not present.

gp_pixel_channel_bits()

static uint8_t gp_pixel_channel_bits ( gp_pixel_type  type, uint8_t  channel  )

inlinestatic

Returns number of bits for a pixel channel.

Parameters

type	A pixel type.
channel	A channel index.

Returns

Number of bits the channel uses.

Definition at line 157 of file gp_pixel.h.

References gp_pixel_type_desc::channels, gp_pixel_types, and gp_pixel_channel::size.

gp_pixel_channel_count()

static unsigned int gp_pixel_channel_count ( gp_pixel_type  type )

inlinestatic

Returns a numbers of pixel channels.

Parameters

type	A pixel type.

Returns

A number of pixel channels.

Definition at line 144 of file gp_pixel.h.

References gp_pixel_types, and gp_pixel_type_desc::numchannels.

gp_pixel_channel_is_alpha()

static int gp_pixel_channel_is_alpha ( gp_pixel_type  type, uint8_t  channel  )

inlinestatic

Returns true if pixel channel is alpha channel.

Parameters

type	A pixel type.
channel	A channel index.

Returns

True if channel is alpha channel.

Definition at line 197 of file gp_pixel.h.

References gp_pixel_type_desc::channels, gp_pixel_types, and gp_pixel_channel::name.

gp_pixel_channel_lin_bits()

static uint8_t gp_pixel_channel_lin_bits ( gp_pixel_type  type, uint8_t  channel  )

inlinestatic

Returns number of bits for a linearized pixel channel.

Parameters

type	A pixel type.
channel	A channel index.

Returns

Number of bits the channel uses after linearized with a gamma function.

Definition at line 170 of file gp_pixel.h.

References gp_pixel_type_desc::channels, gp_pixel_types, and gp_pixel_channel::lin_size.

gp_pixel_channel_name()

static const char * gp_pixel_channel_name ( gp_pixel_type  type, uint8_t  channel  )

inlinestatic

Returns number of bits for a pixel channel.

Parameters

type	A pixel type.
channel	A channel index.

Returns

Number of bits the channel uses.

Definition at line 183 of file gp_pixel.h.

References gp_pixel_type_desc::channels, gp_pixel_types, and gp_pixel_channel::name.

gp_pixel_chans_add()

gp_pixel gp_pixel_chans_add	(	gp_pixel_type	pixel_type,
		gp_pixel	pixel,
		int	add
	)

Does per-channel saturated addition.

The alpha channel is left untouched.

Parameters

pixel_type	A pixel type.
pixel	A pixel value.
add	An addition in percets of the maximal channel value.

Returns

A pixel value after addition.

gp_pixel_desc()

static const gp_pixel_type_desc * gp_pixel_desc ( gp_pixel_type  type )

inlinestatic

Returns a pixel type description for a pixel type enum.

Parameters

type	A pixel type.

Returns

A pixel type description structure.

Definition at line 132 of file gp_pixel.h.

References gp_pixel_types.

gp_pixel_has_flags()

int gp_pixel_has_flags	(	gp_pixel_type	pixel_type,
		gp_pixel_flags	flags
	)

Function to determine pixel attributes.

Parameters

pixel_type	A pixel type to check.
flags	Bitwise or of attributes to check.

Returns

True if all flags are present.

Example use:

if (gp_pixel_has_flags(pixel_type, GP_PIXEL_IS_RGB | GP_PIXEL_HAS_ALPHA))
     ...

gp_pixel_rgb_lookup()

gp_pixel_type gp_pixel_rgb_lookup	(	uint32_t	rsize,
		uint32_t	roff,
		uint32_t	gsize,
		uint32_t	goff,
		uint32_t	bsize,
		uint32_t	boff,
		uint32_t	asize,
		uint32_t	aoff,
		uint8_t	bits_per_pixel
	)

Looks up a RGB pixel type against know pixel types.

This is the same as gp_pixel_rgb_match() but with sizes and offsets instead of masks.

Parameters

rsize	A size of the red channel.
roff	An offset for the red channel.
gsize	A size of the green channel.
goff	An offset for the green channel.
bsize	A size of the blue channel.
boff	An offset for the blue channel.
asize	A size of the alpha channel, if set to zero the pixel does not have alpha channel.
aoff	An offset for the alpha channel.
bits_per_pixel	The size of the pixel in bits.

Returns

Either valid gp_pixel_type or GP_PIXEL_UNKNOWN.

gp_pixel_rgb_match()

gp_pixel_type gp_pixel_rgb_match	(	gp_pixel	rmask,
		gp_pixel	gmask,
		gp_pixel	bmask,
		gp_pixel	amask,
		uint8_t	bits_per_pixel
	)

Matches a RGB pixel type againts known pixel types.

This is the same as gp_pixel_rgb_lookup() but with masks instead of sizes and offsets.

Parameters

rmask	A mask for the red channel.
gmask	A mask for the green channel.
bmask	A mask for the blue channel.
amask	A mask for the alpha channel, if set to zero the pixel does not have alpha channel.
bits_per_pixel	The size of the pixel in bits.

Returns

Either valid gp_pixel_type or GP_PIXEL_UNKNOWN.

Referenced by gp_pixmap_from_sdl_surface().