Provided by: libg2c-dev_2.1.0-1_amd64 
NAME
decenc_png.c - Decode/encode a PNG stream.
SYNOPSIS
#include 'grib2_int.h'
#include <png.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
Typedefs
typedef struct png_stream png_stream
Typedef for PNG stream.
Functions
int dec_png (unsigned char *pngbuf, g2int *width, g2int *height, unsigned char *cout)
Decode PNG.
int enc_png (unsigned char *data, g2int width, g2int height, g2int nbits, unsigned char *pngbuf)
Encode PNG.
int g2c_dec_png (unsigned char *pngbuf, int *width, int *height, unsigned char *cout)
Decode PNG.
int g2c_enc_png (unsigned char *data, int width, int height, int nbits, unsigned char *pngbuf)
Encode PNG.
void user_flush_data (png_structp png_ptr)
Dummy Custom flush function.
void user_read_data (png_structp png_ptr, png_bytep data, png_uint_32 length)
Custom read function used so that libpng will read a PNG stream from memory instead of a file on
disk.
void user_write_data (png_structp png_ptr, png_bytep data, png_uint_32 length)
Custom write function used to that libpng will write to memory location instead of a file on disk.
Detailed Description
Decode/encode a PNG stream.
Author
Alyson Stahl
Date
2024-13-08
Definition in file decenc_png.c.
Typedef Documentation
typedef struct png_stream png_stream
Typedef for PNG stream.
Definition at line 21 of file decenc_png.c.
Function Documentation
int dec_png (unsigned char * pngbuf, g2int * width, g2int * height, unsigned char * cout)
Decode PNG.
Parameters
pngbuf Pointer to PNG buffer.
width Pointer to width.
height Pointer to height.
cout Output buffer.
Returns
0 for success, error code otherwise.
Author
Stephen Gilbert
Definition at line 127 of file decenc_png.c.
References G2C_PNG_HEIGHT_MAX, G2C_PNG_WIDTH_MAX, and user_read_data().
Referenced by g2c_dec_png(), and pngunpack_int().
int enc_png (unsigned char * data, g2int width, g2int height, g2int nbits, unsigned char * pngbuf)
Encode PNG.
Parameters
data data.
width width.
height height.
nbits number of bits.
pngbuf PNG buffer.
Returns
PNG length, or negative number for error.
Author
Stephen Gilbert
Definition at line 259 of file decenc_png.c.
References user_flush_data(), and user_write_data().
Referenced by g2c_enc_png(), and pngpack_int().
int g2c_dec_png (unsigned char * pngbuf, int * width, int * height, unsigned char * cout)
Decode PNG.
Parameters
pngbuf Pointer to PNG buffer.
width Pointer to width.
height Pointer to height.
cout Output buffer.
Returns
0 for success, error code otherwise.
Author
Alyson Stahl
Definition at line 100 of file decenc_png.c.
References dec_png().
int g2c_enc_png (unsigned char * data, int width, int height, int nbits, unsigned char * pngbuf)
Encode PNG.
Parameters
data data.
width width.
height height.
nbits number of bits.
pngbuf PNG buffer.
Returns
PNG length, or negative number for error.
Author
Alyson Stahl
Definition at line 237 of file decenc_png.c.
References enc_png().
void user_flush_data (png_structp png_ptr)
Dummy Custom flush function.
Parameters
png_ptr Pointer to PNG struct.
Author
Stephen Gilbert
Definition at line 83 of file decenc_png.c.
Referenced by enc_png().
void user_read_data (png_structp png_ptr, png_bytep data, png_uint_32 length)
Custom read function used so that libpng will read a PNG stream from memory instead of a file on disk.
Parameters
png_ptr Pointer to PNG.
data Pointer to data.
length Length.
Author
Stephen Gilbert
Definition at line 38 of file decenc_png.c.
Referenced by dec_png().
void user_write_data (png_structp png_ptr, png_bytep data, png_uint_32 length)
Custom write function used to that libpng will write to memory location instead of a file on disk.
Parameters
png_ptr pointer
data data
length length
Author
Stephen Gilbert
Definition at line 62 of file decenc_png.c.
Referenced by enc_png().
Author
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