Image File Formats: Grx Reference Manual

Image File Formats

Image File Formats — Loading and saving image data to standard formats (JPEG, PNG, PNM)

Types and Values

enum	GrxPnmFormat

Includes

#include <grx-3.0.h>

Description

These functions are used to load data from disk and store data to disk using standard file formats.

Functions

grx_context_save_to_pbm ()

gboolean
grx_context_save_to_pbm (GrxContext *context,
                         const gchar *filename,
                         const gchar *comment,
                         GError **error);

Dump a context in a PBM file (black and white)

This routine works both in RGB and palette modes If the pixel color isn't Black it asumes White

Parameters

context	Context to be saved or `NULL` to use the global context.	[nullable]
filename	Name of pbm file.	[type filename]
comment	string saved like a comment in the pbm file.	[nullable]
error	pointer to hold an error or `NULL` to ignore

Returns

TRUE on success, otherwise FALSE

grx_context_save_to_pgm ()

gboolean
grx_context_save_to_pgm (GrxContext *context,
                         const gchar *filename,
                         const gchar *comment,
                         GError **error);

Dump a context in a PGM file (gray scale)

This routine works both in RGB and palette modes The colors are quantized to gray scale using .299r + .587g + .114b

Parameters

context	Context to be saved or `NULL` to use the global context.	[nullable]
filename	Name of pgm file.	[type filename]
comment	string saved like a comment in the pgm file.	[nullable]
error	pointer to hold an error or `NULL` to ignore

Returns

TRUE on success, otherwise FALSE

grx_context_save_to_ppm ()

gboolean
grx_context_save_to_ppm (GrxContext *context,
                         const gchar *filename,
                         const gchar *comment,
                         GError **error);

Dump a context in a PPM file (real color)

This routine works both in RGB and palette modes

Parameters

context	Context to be saved or `NULL` to use the global context.	[nullable]
filename	Name of ppm file.	[type filename]
comment	string saved like a comment in the ppm file.	[nullable]
error	pointer to hold an error or `NULL` to ignore

Returns

TRUE on success, otherwise FALSE

grx_context_load_from_pnm ()

gboolean
grx_context_load_from_pnm (GrxContext *context,
                           const gchar *filename,
                           GError **error);

Load a context from a PNM file.

Support only PBM, PGM and PPM binary files with maxval < 256

If context dimensions are less than pnm dimensions, the routine loads as much as it can

If color mode is not in RGB mode, the routine allocates as many colors as it can

Parameters

context	Context to be loaded or `NULL` to use the global context.	[nullable]
filename	Name of pnm file.	[type filename]
error	pointer to hold an error or `NULL` to ignore

Returns

TRUE on success, otherwise FALSE

grx_query_pnm_file ()

gboolean
grx_query_pnm_file (const gchar *filename,
                    GrxPnmFormat *format,
                    gint *width,
                    gint *height,
                    gint *maxval);

Query format, width and height data from a PNM file

Parameters

filename	Name of pnm file.	[type filename]
format	the GrxPnmFormat of the file.	[out]
width	return pnm width.	[out]
height	return pnm height.	[out]
maxval	max color component value.	[out]

Returns

TRUE on success, otherwise FALSE

grx_context_load_from_pnm_data ()

gboolean
grx_context_load_from_pnm_data (GrxContext *context,
                                const guint8 *buffer);

Load a context from a PNM buffer

Support only PBM, PGM and PPM binary buffers with maxval < 256

If context dimensions are lesser than pnm dimensions, the routine loads as much as it can

If color mode is not in RGB mode, the routine allocates as much colors as it can

Parameters

context	Context to be loaded or `NULL` to use the global context.	[nullable]
buffer	Buffer that holds data

Returns

TRUE on success, otherwise FALSE

grx_query_pnm_data ()

gboolean
grx_query_pnm_data (GByteArray *data,
                    GrxPnmFormat *format,
                    gint *width,
                    gint *height,
                    gint *maxval);

Query format, width and height data from a PNM buffer

Parameters

data	The image data
format	the GrxPnmFormat of the file.	[out]
width	return pnm width.	[out]
height	return pnm height.	[out]
maxval	max color component value.	[out]

Returns

TRUE on success, otherwise FALSE

grx_context_save_to_png ()

gboolean
grx_context_save_to_png (GrxContext *context,
                         const gchar *filename,
                         GError **error);

Dump a context in a PNG file

This routine works both in RGB and palette modes

Parameters

context	Context to be saved or `NULL` to use the global context.	[nullable]
filename	Name of png file.	[type filename]
error	pointer to hold an error or `NULL` to ignore

Returns

TRUE on success, otherwise FALSE

grx_context_load_from_png ()

gboolean
grx_context_load_from_png (GrxContext *context,
                           const gchar *filename,
                           gboolean use_alpha,
                           GError **error);

Load a context from a PNG file

If context dimensions are less than png dimensions, the routine loads as much as it can

If color mode is not in RGB mode, the routine allocates as many colors as it can

Parameters

context	Context to be loaded or `NULL` to use the global context.	[nullable]
filename	Name of jpeg file.	[type filename]
use_alpha	if `TRUE`, use alpha channel if available
error	pointer to hold an error or `NULL` to ignore

Returns

TRUE on success, otherwise FALSE

grx_query_png_file ()

gboolean
grx_query_png_file (const gchar *filename,
                    gint *width,
                    gint *height);

Query width and height data from a PNG file

Parameters

filename	Name of jpeg file.	[type filename]
width	return pnm width.	[out]
height	return pnm height.	[out]

Returns

TRUE on success, otherwise FALSE

grx_context_load_from_jpeg ()

gboolean
grx_context_load_from_jpeg (GrxContext *context,
                            const gchar *filename,
                            gint scale,
                            GError **error);

Load a context from a JPEG file.

If context dimensions are less than jpeg dimensions, the function loads as much of the image as it can.

If color mode is not in RGB mode, the functions allocates as many colors as it can.

Parameters

context	Context to be loaded or `NULL` to use the global context.	[nullable]
filename	Name of jpeg file.	[type filename]
scale	scale the image to 1/scale, only 1, 2, 4 and 8 are supported
error	pointer to hold an error or `NULL` to ignore

Returns

TRUE on success, otherwise FALSE

grx_context_load_from_jpeg_data ()

gboolean
grx_context_load_from_jpeg_data (GrxContext *context,
                                 GByteArray *data,
                                 gint scale,
                                 GError **error);

Load a context from JPEG data.

If context dimensions are less than jpeg dimensions, the function loads as much of the image as it can.

If color mode is not in RGB mode, the functions allocates as many colors as it can.

Parameters

context	Context to be loaded or `NULL` to use the global context.	[nullable]
data	The jpeg data
scale	scale the image to 1/scale, only 1, 2, 4 and 8 are supported
error	pointer to hold an error or `NULL` to ignore

Returns

TRUE on success, otherwise FALSE

grx_query_jpeg_file ()

gboolean
grx_query_jpeg_file (const gchar *filename,
                     gint *width,
                     gint *height);

Query width and height data from a JPEG file

Parameters

filename	Name of jpeg file.	[type filename]
width	return image width.	[out]
height	return image height.	[out]

Returns

TRUE on success, otherwise FALSE

grx_query_jpeg_data ()

gboolean
grx_query_jpeg_data (GByteArray *data,
                     gint *width,
                     gint *height);

Query width and height data from a JPEG file

Parameters

data	The image data
width	return image width.	[out]
height	return image height.	[out]

Returns

TRUE on success, otherwise FALSE

grx_context_save_to_jpeg ()

gboolean
grx_context_save_to_jpeg (GrxContext *context,
                          const gchar *filename,
                          gint quality,
                          GError **error);

Dump a context in a JPEG file

This routine works both in RGB and palette modes

Parameters

context	Context to be saved or `NULL` to use the global context.	[nullable]
filename	Name of jpeg file.	[type filename]
quality	quality scaling (1 to 100) the normal value is 75
error	pointer to hold an error or `NULL` to ignore

Returns

TRUE on success, otherwise FALSE

grx_context_save_to_jpeg_grayscale ()

gboolean
grx_context_save_to_jpeg_grayscale (GrxContext *context,
                                    const gchar *filename,
                                    gint quality,
                                    GError **error);

Dump a context in a Gray JPEG file

This routine works both in RGB and palette modes

Parameters

context	Context to be saved or `NULL` to use the global context.	[nullable]
filename	Name of jpeg file.	[type filename]
quality	quality scaling (1 to 100) the normal value is 75
error	pointer to hold an error or `NULL` to ignore

Returns

TRUE on success, otherwise FALSE

Types and Values

enum GrxPnmFormat

PNM file formats.

Note: GRX supports load/save of binaries formats (4,5,6) only.

Members

GRX_PNM_FORMAT_ASCII_PBM	P1: black and white (1bpp) ascii file format
GRX_PNM_FORMAT_ASCII_PGM	P2: grayscale ascii file format
GRX_PNM_FORMAT_ASCII_PPM	P3: RGB ascii file format
GRX_PNM_FORMAT_BINARY_PBM	P4: black and white (1bpp) binary file format
GRX_PNM_FORMAT_BINARY_PGM	P5: grayscale binary file format
GRX_PNM_FORMAT_BINARY_PPM	P6: RGB binary file format

gboolean	grx_context_save_to_pbm ()
gboolean	grx_context_save_to_pgm ()
gboolean	grx_context_save_to_ppm ()
gboolean	grx_context_load_from_pnm ()
gboolean	grx_query_pnm_file ()
gboolean	grx_context_load_from_pnm_data ()
gboolean	grx_query_pnm_data ()
gboolean	grx_context_save_to_png ()
gboolean	grx_context_load_from_png ()
gboolean	grx_query_png_file ()
gboolean	grx_context_load_from_jpeg ()
gboolean	grx_context_load_from_jpeg_data ()
gboolean	grx_query_jpeg_file ()
gboolean	grx_query_jpeg_data ()
gboolean	grx_context_save_to_jpeg ()
gboolean	grx_context_save_to_jpeg_grayscale ()