dmpo.h File Reference

Decompression methods and objects. More...

#include <stdbool.h>
#include "mpo.h"

Go to the source code of this file.

Data Structures
struct	decompress_struct_extended
struct	mpo_decompress

Typedefs
typedef struct mpo_decompress	mpo_decompress_struct
typedef struct decompress_struct_extended	jpeg_decompress_struct_extended

Functions
void	mpo_create_decompress (mpo_decompress_struct *mpoinfo)
	Initializes the mpoinfo struct. More...
void	mpo_stdio_src (mpo_decompress_struct *mpoinfo, FILE *input)
	Set the source as a stdio FILE. More...
void	mpo_mem_src (mpo_decompress_struct *mpoinfo, unsigned char *inbuffer, unsigned long insize)
bool	mpo_read_header (mpo_decompress_struct *mpoinfo)
	Read the first image header. More...
int	mpo_get_number_images (mpo_decompress_struct *mpoinfo)
	Number of images of the file. More...
bool	mpo_start_decompress (mpo_decompress_struct *mpoinfo)
	Start JPEG decompression of current image.
J_COLOR_SPACE	mpo_get_color_space (mpo_decompress_struct *mpoinfo)
	the output colorspace
JDIMENSION	get_output_scanline (mpo_decompress_struct *mpoinfo)
	Next scanline to be read from jpeg_read_scanlines(). More...
JDIMENSION	get_output_width (mpo_decompress_struct *mpoinfo)
	The output width.
JDIMENSION	get_output_height (mpo_decompress_struct *mpoinfo)
	The output height.
bool	all_scanlines_processed (mpo_decompress_struct *mpoinfo)
	convenience function More...
size_t	mpo_read_scanlines (mpo_decompress_struct *mpoinfo, JSAMPARRAY scanlines, size_t max_lines)
	Read some scanlines of data from the JPEG decompressor. More...
void	mpo_skip_to_image (mpo_decompress_struct *mpoinfo, int image)
	Skips to the beggining of an image. More...
bool	mpo_finish_decompress (mpo_decompress_struct *mpoinfo)
	Finish JPEG decompression. More...
void	mpo_destroy_decompress (mpo_decompress_struct *mpoinfo)
	Destroy the mpoinfo struct.
void	mpo_decompress_error_exit (mpo_decompress_struct *mpoinfo, void exit_func(j_common_ptr))
	Function called when an error occurs in libjpeg. More...

Detailed Description

Decompression methods and objects.

Author

Lectem

Function Documentation

bool all_scanlines_processed

(

mpo_decompress_struct *

mpoinfo

)

convenience function

Returns

output_scanline >= output_height

JDIMENSION get_output_scanline

(

mpo_decompress_struct *

mpoinfo

)

Next scanline to be read from jpeg_read_scanlines().

Application may use this to control its processing loop, e.g., "while (get_output_scanline(mpoinfo) < get_output_height(mpoinfo))".

void mpo_create_decompress

(

mpo_decompress_struct *

mpoinfo

)

Initializes the mpoinfo struct.

Call this before doing anything with the decompression struct. It will initialize and create all necessary stuff for the decompression.

Note

Please call mpo_destroy_decompress once done with the decompression struct

void mpo_decompress_error_exit	(	mpo_decompress_struct *	mpoinfo,
		void	exit_funcj_common_ptr
	)

Function called when an error occurs in libjpeg.

Defaults to stopping the application

bool mpo_finish_decompress

(

mpo_decompress_struct *

mpoinfo

)

Finish JPEG decompression.

This will also set currentImage to currentImage+1

int mpo_get_number_images

(

mpo_decompress_struct *

mpoinfo

)

Number of images of the file.

Note

Only works after reading the 1st image header

bool mpo_read_header

(

mpo_decompress_struct *

mpoinfo

)

Read the first image header.

This will load all the MPO header information of the first image. You need to call this once before starting any decompression

Note

Individual images headers for the other images will be retrieved by calling mpo_start_decompress

Returns

false if suspended due to lack of input data

true if found a valid header

size_t mpo_read_scanlines	(	mpo_decompress_struct *	mpoinfo,
		JSAMPARRAY	scanlines,
		size_t	max_lines
	)

Read some scanlines of data from the JPEG decompressor.

The return value will be the number of lines actually read. This may be less than the number requested in several cases, including bottom of image, data source suspension, and operating modes that emit multiple scanlines at a time.

void mpo_skip_to_image	(	mpo_decompress_struct *	mpoinfo,
		int	image
	)

Skips to the beggining of an image.

You can skip data by calling this function. You can then use mpo_start_decompress to resume decompression of the image passed in arguments.

Note

The skipped images header information retrieval will also be skipped.

void mpo_stdio_src	(	mpo_decompress_struct *	mpoinfo,
		FILE *	input
	)

Set the source as a stdio FILE.

The file has to be opened before calling.

Note

The file has to be closed by the caller once the decompression is finished.