The LibPNG API version 20201229. More...

#include "libpngapi.h"

Data Fields
int(*	png_sig_cmp )(png_const_bytep sig, size_t start, size_t num_to_check)
	Check PNG signature bytes to see if it's a PNG file. More...

jmp_buf (	png_set_longjmp_fn )(png_structrp png_ptr, png_longjmp_ptr longjmp_fn, size_t jmp_buf_size)
	Set a callback that will be used to catch unrecoverable errors. More...

void(*	png_longjmp )(png_const_structrp png_ptr, int val)
	Invoke the LibPNG error callback, with an error value . More...

void(*	png_error )(png_const_structrp png_ptr, png_const_charp error_message)
	Invoke a LibPNG error. More...

png_infop(*	png_create_info_struct )(png_const_structrp png_ptr)
	Create a PNG information structure. More...

png_structp(*	png_create_read_struct_2 )(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn)
	Create a structure handle for reading a PNG image. More...

void(*	png_destroy_read_struct )(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr)
	Destroy a PNG structure handle and associated information structures. More...

png_uint_32(*	png_get_IHDR )(png_const_structrp png_ptr, png_const_inforp info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth, int color_type, int interlace_method, int compression_method, int *filter_method)
	Get header information from a PNG image. More...

png_byte(*	png_get_color_type )(png_const_structrp png_ptr, png_const_inforp info_ptr)
	Get the color type from a PNG image. More...

png_uint_32(*	png_get_iCCP )(png_const_structrp png_ptr, png_inforp info_ptr, png_charpp name, int compression_type, png_bytepp profile, png_uint_32 proflen)
	Get the ICC profile information from a PNG image. More...

png_voidp(*	png_get_io_ptr )(png_const_structrp png_ptr)
	Get the reader/writer I/O data pointer. More...

png_uint_32(*	png_get_pHYs )(png_const_structrp png_ptr, png_const_inforp info_ptr, png_uint_32 res_x, png_uint_32 res_y, int *unit_type)
	Get the image resolution information from a PNG image. More...

size_t(*	png_get_rowbytes )(png_const_structrp png_ptr, png_const_inforp info_ptr)
	Get the number of bytes to store a transformed row of a PNG image. More...

png_uint_32(*	png_get_tRNS )(png_const_structrp png_ptr, png_inforp info_ptr, png_bytep trans_alpha, int num_trans, png_color_16p *trans_color)
	Get the transparency information from a PNG image. More...

png_uint_32(*	png_get_valid )(png_const_structrp png_ptr, png_const_inforp info_ptr, png_uint_32 flag)
	Determine if one or more information chunks are valid. More...

void(*	png_read_image )(png_structrp png_ptr, png_bytepp image)
	Read all of the data in an image. More...

void(*	png_read_info )(png_structrp png_ptr, png_inforp info_ptr)
	Read the information chunks from an image. More...

void(*	png_read_row )(png_structrp png_ptr, png_bytep row, png_bytep display_row)
	Read one row of data from an image. More...

void(*	png_read_update_info )(png_structrp png_ptr, png_inforp info_ptr)
	Update the PNG information structure after setting transformations. More...

int(*	png_set_interlace_handling )(png_structrp png_ptr)
	Request that LibPNG handles de-interlacing. More...

void(*	png_set_invert_alpha )(png_structrp png_ptr)
	Request that LibPNG invert opacity to transparency. More...

void(*	png_set_palette_to_rgb )(png_structrp png_ptr)
	Request that LibPNG expands palettized images to RGB. More...

void(*	png_set_read_fn )(png_structrp png_ptr, png_voidp io_ptr, png_rw_ptr read_data_fn)
	Set a callback function and data pointer to read PNG images. More...

void(*	png_set_strip_alpha )(png_structrp png_ptr)
	Request that LibPNG removes the alpha channel from transformed data. More...

void(*	png_set_swap_alpha )(png_structrp png_ptr)
	Request that LibPNG swaps the alpha channel in transformed data from RGBA to ARGB or vice-versa. More...

void(*	png_set_tRNS_to_alpha )(png_structrp png_ptr)
	Request that LibPNG expands tRNS chunk to a full alpha channel in transformed data. More...

png_structp(*	png_create_write_struct_2 )(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn)
	Create a structure handle for writing a PNG image. More...

void(*	png_destroy_write_struct )(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
	Destroy a PNG structure handle and associated information structures. More...

void(*	png_write_info )(png_structrp png_ptr, png_const_inforp info_ptr)
	Write information chunks to a PNG image. More...

void(*	png_write_row )(png_structrp png_ptr, png_const_bytep row)
	Write a row of data to a PNG image. More...

void(*	png_write_end )(png_structrp png_ptr, png_inforp info_ptr)
	Finish writing a PNG image, including any information comments. More...

void(*	png_set_write_fn )(png_structrp png_ptr, png_voidp io_ptr, png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)
	Set a callback function and data pointer to write PNG images. More...

void(*	png_set_IHDR )(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth, int color_type, int interlace_method, int compression_method, int filter_method)
	Set the header information for a PNG image. More...

void(*	png_set_compression_level )(png_structrp png_ptr, int level)
	Set the compression level of a PNG image. More...

void(*	png_set_text )(png_const_structrp png_ptr, png_inforp info_ptr, png_const_textp text_ptr, int num_text)
	Set a text comment for a PNG image. More...

Detailed Description

The LibPNG API version 20201229.

Field Documentation

◆ png_create_info_struct

png_infop( * sw_libpng_api_20201229::png_create_info_struct) (png_const_structrp png_ptr)

Create a PNG information structure.

Parameters

[in,out] png_ptr A PNG structure handle.

Returns: A pointer to the created information structure, or NULL on failure.

Both reading and writing PNGs need an information structure created. If creating the information structure fails, you should destroy the PNG structure handle and take suitable error actions.

See the LibPNG manual for more information.

◆ png_create_read_struct_2

png_structp( * sw_libpng_api_20201229::png_create_read_struct_2) (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn)

Create a structure handle for reading a PNG image.

Parameters

[in]	user_png_ver	Set this to `PNG_LIBPNG_VER_STRING`
[in]	error_ptr	A client data pointer that can be retrieved by error_fn or warn_fn.
[in]	error_fn	A function called when an unrecoverable error is encountered.
[in]	warn_fn	A function called when a warning is encountered.
[in]	mem_ptr	A client data pointer that can be retrieved by malloc_fn and free_fn.
[in]	malloc_fn	A function to allocate memory for LibPNG.
[in]	free_fn	A function to free memory allocated by alloc_fn.

Returns: A PNG structure handle, or NULL on failure.

Note: On Windows, you must align the PNG handle to 16 bytes for png_set_longjmp_fn() and png_longjmp() to work. This can be accomplished by passing malloc_fn and corresponding free_fn that align the returned pointers to a suitable boundary.; Global Graphics recommends using a malloc_fn and free_fn function that allocate from the RIP or Skin's memory pools, such as SwAlloc() and SwFree() for RIP pools, or MemAlloc() and MemFree() for skin pools.

See the LibPNG manual for more information.

◆ png_create_write_struct_2

png_structp( * sw_libpng_api_20201229::png_create_write_struct_2) (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn)

Create a structure handle for writing a PNG image.

Parameters

[in]	user_png_ver	Set this to `PNG_LIBPNG_VER_STRING`
[in]	error_ptr	A client data pointer that can be retrieved by error_fn or warn_fn.
[in]	error_fn	A function called when an unrecoverable error is encountered.
[in]	warn_fn	A function called when a warning is encountered.
[in]	mem_ptr	A client data pointer that can be retrieved by malloc_fn and free_fn.
[in]	malloc_fn	A function to allocate memory for LibPNG.
[in]	free_fn	A function to free memory allocated by alloc_fn.

Returns: A PNG structure handle, or NULL on failure.

Note: On Windows, you must align the PNG handle to 16 bytes for png_set_longjmp_fn() and png_longjmp() to work. This can be accomplished by passing malloc_fn and corresponding free_fn that align the returned pointers to a suitable boundary.; Global Graphics recommends using a malloc_fn and free_fn function that allocate from the RIP or Skin's memory pools, such as SwAlloc() and SwFree() for RIP pools, or MemAlloc() and MemFree() for skin pools.

See the LibPNG manual for more information.

◆ png_destroy_read_struct

void( * sw_libpng_api_20201229::png_destroy_read_struct) (png_structpp png_ptr_ptr, png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr)

Destroy a PNG structure handle and associated information structures.

Parameters

[out]	png_ptr_ptr	A pointer to a PNG structure handle created with png_create_read_struct_2().
[out]	info_ptr_ptr	A pointer to a PNG information structure handle created with png_create_info_struct().
[out]	end_info_ptr_ptr	A pointer to a PNG information structure handle, or NULL if no end information structure was created.

See the LibPNG manual for more information.

◆ png_destroy_write_struct

void( * sw_libpng_api_20201229::png_destroy_write_struct) (png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)

Destroy a PNG structure handle and associated information structures.

Parameters

[out]	png_ptr_ptr	A pointer to a PNG structure handle created with png_create_write_struct_2().
[out]	info_ptr_ptr	A pointer to a PNG information structure handle created with png_create_info_struct().
[out]	end_info_ptr_ptr	A pointer to a PNG information structure handle, or NULL if no end information structure was created.

◆ png_error

void( * sw_libpng_api_20201229::png_error) (png_const_structrp png_ptr, png_const_charp error_message)

Invoke a LibPNG error.

Parameters

[in,out]	png_ptr	A PNG structure handle.
[in]	error_message	An error message

This function calls the error function supplied to png_create_read_struct_2() or png_create_write_struct_2(), and then uses png_longjmp() to stop LibPNG processing.

See the LibPNG manual for more information.

◆ png_get_color_type

png_byte( * sw_libpng_api_20201229::png_get_color_type) (png_const_structrp png_ptr, png_const_inforp info_ptr)

Get the color type from a PNG image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.

Returns: The color and alpha channels (PNG_COLOR_TYPE_GRAY, PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB, or PNG_COLOR_TYPE_RGB_ALPHA).

This is the same as the color type returned by png_get_IHDR().

See the LibPNG manual for more information.

◆ png_get_iCCP

png_uint_32( * sw_libpng_api_20201229::png_get_iCCP) (png_const_structrp png_ptr, png_inforp info_ptr, png_charpp name, int *compression_type, png_bytepp profile, png_uint_32 *proflen)

Get the ICC profile information from a PNG image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.
[out]	name	A location to store the profile name.
[out]	compression_type	An optional location to store the compression type. The compression type is always `PNG_COMPRESSION_TYPE_BASE`.
[out]	profile	A location to store a pointer to the ICC profile data.
[out]	proflen	A location to store the length of the ICC profile data.

Returns: PNG_INFO_iCCP if a profile was successfully extracted, 0 otherwise.

See the LibPNG manual for more information.

◆ png_get_IHDR

png_uint_32( * sw_libpng_api_20201229::png_get_IHDR) (png_const_structrp png_ptr, png_const_inforp info_ptr, png_uint_32 *width, png_uint_32 *height, int *bit_depth, int *color_type, int *interlace_method, int *compression_method, int *filter_method)

Get header information from a PNG image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.
[out]	width	A location to store the image width.
[out]	height	A location to store the image height.
[out]	bit_depth	A location to store the image bit depth.
[out]	color_type	A location to store the color and alpha channels (`PNG_COLOR_TYPE_GRAY`, `PNG_COLOR_TYPE_GRAY_ALPHA`, `PNG_COLOR_TYPE_PALETTE`, `PNG_COLOR_TYPE_RGB`, or `PNG_COLOR_TYPE_RGB_ALPHA`).
[out]	interlace_method	A location to store the interlace type (`PNG_INTERLACE_NONE` or `PNG_INTERFACE_ADAM7`).
[out]	compression_method	A location to store the compression type (`PNG_COMPRESSION_TYPE_BASE` only).
[out]	filter_method	A location to store the filter method (`PNG_FILTER_TYPE_BASE` only).

Returns: FALSE if there was an error extracting data, TRUE if data was extracted successfully.

See the LibPNG manual for more information.

◆ png_get_io_ptr

png_voidp( * sw_libpng_api_20201229::png_get_io_ptr) (png_const_structrp png_ptr)

Get the reader/writer I/O data pointer.

Parameters

[in] png_ptr A pointer to a PNG structure handle.

Returns: The I/O data pointer set by calling png_set_read_fn() or png_set_write_fn()

See the LibPNG manual for more information.

◆ png_get_pHYs

png_uint_32( * sw_libpng_api_20201229::png_get_pHYs) (png_const_structrp png_ptr, png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type)

Get the image resolution information from a PNG image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.
[out]	res_x	A location to store the X resolution.
[out]	res_y	A location to store the Y resolution.
[out]	unit_type	A location to store the resolution unit (`PNG_RESOLUTION_METER` for pixels per meter, `PNG_RESOLUTION_UNKNOWN` for unknown units to set the aspect ratio).

Returns: PNG_INFO_pHYs if resolution data was successfully extracted, 0 otherwise.

See the LibPNG manual for more information.

◆ png_get_rowbytes

size_t( * sw_libpng_api_20201229::png_get_rowbytes) (png_const_structrp png_ptr, png_const_inforp info_ptr)

Get the number of bytes to store a transformed row of a PNG image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.

Returns: The number of bytes to store a row of transformed data.

See the LibPNG manual for more information.

◆ png_get_tRNS

png_uint_32( * sw_libpng_api_20201229::png_get_tRNS) (png_const_structrp png_ptr, png_inforp info_ptr, png_bytep *trans_alpha, int *num_trans, png_color_16p *trans_color)

Get the transparency information from a PNG image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.
[out]	trans_alpha	A location to store an array of alpha values for the palette, or store `NULL` if not a palettized image.
[out]	num_trans	A location to store the number of alpha or color values stored.
[out]	trans_color	A location to store an array of gray or color values of the transparent color for non palettized images, or store `NULL` if a palettized image.

Returns: PNG_INFO_tRNS if transparency data was successfully extracted, 0 otherwise.

See the LibPNG manual for more information.

◆ png_get_valid

png_uint_32( * sw_libpng_api_20201229::png_get_valid) (png_const_structrp png_ptr, png_const_inforp info_ptr, png_uint_32 flag)

Determine if one or more information chunks are valid.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.
[in]	flag	A bitmask of the information chunk IDs to test, e.g., `PNG_INFO_tRNS`, `PNG_INFO_iCCP`, `PNG_INFO_pHYs`, etc.

Returns: A bitmask of the information chunks present in the image. This will be flag if all requested chunks are valid, 0 if none are valid.

See the LibPNG manual for more information.

◆ png_longjmp

void( * sw_libpng_api_20201229::png_longjmp) (png_const_structrp png_ptr, int val)

Invoke the LibPNG error callback, with an error value .

Parameters

[in,out]	png_ptr	A PNG structure handle.
[in]	val	An error value to pass to the callback function set by png_set_longjmp_fn().

See the LibPNG manual for more information.

◆ png_read_image

void( * sw_libpng_api_20201229::png_read_image) (png_structrp png_ptr, png_bytepp image)

Read all of the data in an image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[out]	image	An array of row pointers to store the start location of each transformed image data row. The array should be at least as long as the image height.

The reader function set by png_set_read_fn() will be invoked to read the whole source image. The image data stored in the row pointers is owned by LibPNG.

See the LibPNG manual for more information.

◆ png_read_info

void( * sw_libpng_api_20201229::png_read_info) (png_structrp png_ptr, png_inforp info_ptr)

Read the information chunks from an image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.

The reader function set by png_set_read_fn() will be invoked to read all of the chunks up to the image data.

See the LibPNG manual for more information.

◆ png_read_row

void( * sw_libpng_api_20201229::png_read_row) (png_structrp png_ptr, png_bytep row, png_bytep display_row)

Read one row of data from an image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[out]	row	A location to store a single row of transformed image data.
[out]	display_row	This is used when handling interlaced images. It is simpler call png_read_image() to fully transform interlaced images, and to set this to `NULL` when reading non-interlaced images.

The reader function set by png_set_read_fn() will be invoked to read one row of the image.

See the LibPNG manual for more information.

◆ png_read_update_info

void( * sw_libpng_api_20201229::png_read_update_info) (png_structrp png_ptr, png_inforp info_ptr)

Update the PNG information structure after setting transformations.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.

See the LibPNG manual for more information.

◆ png_set_compression_level

void( * sw_libpng_api_20201229::png_set_compression_level) (png_structrp png_ptr, int level)

Set the compression level of a PNG image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	level	The compression level of the image, from 0 (no compression) to 9. A default compression level of `Z_DEFAULT_COMPRESSION` is a reasonable compromise between compression speed and size.

See the LibPNG manual for more information.

◆ png_set_IHDR

void( * sw_libpng_api_20201229::png_set_IHDR) (png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth, int color_type, int interlace_method, int compression_method, int filter_method)

Set the header information for a PNG image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.
[in]	width	The image width.
[in]	height	The image height.
[in]	bit_depth	The image bit depth.
[in]	color_type	The color and alpha channels (`PNG_COLOR_TYPE_GRAY`, `PNG_COLOR_TYPE_GRAY_ALPHA`, `PNG_COLOR_TYPE_PALETTE`, `PNG_COLOR_TYPE_RGB`, or `PNG_COLOR_TYPE_RGB_ALPHA`).
[in]	interlace_method	The interlace type (`PNG_INTERLACE_NONE` or `PNG_INTERFACE_ADAM7`).
[in]	compression_method	The compression type (`PNG_COMPRESSION_TYPE_BASE` only).
[in]	filter_method	The filter method (`PNG_FILTER_TYPE_BASE` only).

See the LibPNG manual for more information.

◆ png_set_interlace_handling

int( * sw_libpng_api_20201229::png_set_interlace_handling) (png_structrp png_ptr)

Request that LibPNG handles de-interlacing.

Parameters

[in] png_ptr A pointer to a PNG structure handle.

Returns: The number of passes that will be required to de-interlace. If you call png_read_image() to read the image data, you won't need to use this value.

See the LibPNG manual for more information.

◆ png_set_invert_alpha

void( * sw_libpng_api_20201229::png_set_invert_alpha) (png_structrp png_ptr)

Request that LibPNG invert opacity to transparency.

Parameters

[in] png_ptr A pointer to a PNG structure handle.

See the LibPNG manual for more information.

◆ png_set_longjmp_fn

jmp_buf*( * sw_libpng_api_20201229::png_set_longjmp_fn) (png_structrp png_ptr, png_longjmp_ptr longjmp_fn, size_t jmp_buf_size)

Set a callback that will be used to catch unrecoverable errors.

Parameters

[in,out]	png_ptr	A PNG structure handle.
[in]	longjmp_fn	A callback function that will invoke longjmp().
[in]	jmp_buf_size	The size of a setjmp()/longjmp() jump buffer, used to verify that the client and LibPNG are using compatible definitions.

Returns: The jump buffer built into png_ptr. This should be immediately passed to setjmp().

Note: On Windows, png_ptr must be 16-byte aligned. It is your responsibility to ensure this is the case, by suitably aligning the allocation used for png_create_read_struct_2() or png_create_write_struct_2().

See the LibPNG manual for more information.

◆ png_set_palette_to_rgb

void( * sw_libpng_api_20201229::png_set_palette_to_rgb) (png_structrp png_ptr)

Request that LibPNG expands palettized images to RGB.

Parameters

[in] png_ptr A pointer to a PNG structure handle.

See the LibPNG manual for more information.

◆ png_set_read_fn

void( * sw_libpng_api_20201229::png_set_read_fn) (png_structrp png_ptr, png_voidp io_ptr, png_rw_ptr read_data_fn)

Set a callback function and data pointer to read PNG images.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	io_ptr	A client data pointer that can be retrieved in read_data_fn by calling png_get_io_ptr().
[in]	read_data_fn	A callback function to read PNG source data. The callback function is passed png_ptr, a buffer to read data into, and the number of bytes to read. It may use png_get_io_ptr(png_ptr) to retrieve io_ptr. If the callback function cannot read the number of bytes specified, it should throw an error by calling png_error() or png_longjmp().

See the LibPNG manual for more information.

◆ png_set_strip_alpha

void( * sw_libpng_api_20201229::png_set_strip_alpha) (png_structrp png_ptr)

Request that LibPNG removes the alpha channel from transformed data.

Parameters

[in] png_ptr A pointer to a PNG structure handle.

See the LibPNG manual for more information.

◆ png_set_swap_alpha

void( * sw_libpng_api_20201229::png_set_swap_alpha) (png_structrp png_ptr)

Request that LibPNG swaps the alpha channel in transformed data from RGBA to ARGB or vice-versa.

Parameters

[in] png_ptr A pointer to a PNG structure handle.

See the LibPNG manual for more information.

◆ png_set_text

void( * sw_libpng_api_20201229::png_set_text) (png_const_structrp png_ptr, png_inforp info_ptr, png_const_textp text_ptr, int num_text)

Set a text comment for a PNG image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.
[in]	text_ptr	An array of text structures, each containing a compression type, keyword, the text, compressed text length, uncompressed text length, language of the comment, and UTF-8 keyword.
[in]	num_text	The number of comments in text_ptr.

See the LibPNG manual for more information.

◆ png_set_tRNS_to_alpha

void( * sw_libpng_api_20201229::png_set_tRNS_to_alpha) (png_structrp png_ptr)

Request that LibPNG expands tRNS chunk to a full alpha channel in transformed data.

Parameters

[in] png_ptr A pointer to a PNG structure handle.

See the LibPNG manual for more information.

◆ png_set_write_fn

void( * sw_libpng_api_20201229::png_set_write_fn) (png_structrp png_ptr, png_voidp io_ptr, png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)

Set a callback function and data pointer to write PNG images.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	io_ptr	A client data pointer that can be retrieved in write_data_fn and output_flush_fn by calling png_get_io_ptr().
[in]	write_data_fn	A callback function to write PNG output data. The callback function is passed png_ptr, a buffer to write data from, and the number of bytes to write. It may use png_get_io_ptr(png_ptr) to retrieve io_ptr. If the callback function cannot write the number of bytes specified, it should throw an error by calling png_error() or png_longjmp().
[in]	output_flush_fn	A callback function to flush PNG output data to storage. The callback function is passed png_ptr. It may use png_get_io_ptr(png_ptr) to retrieve io_ptr. If the callback function cannot flush any output data buffered, it should throw an error by calling png_error() or png_longjmp().

See the LibPNG manual for more information.

◆ png_sig_cmp

int( * sw_libpng_api_20201229::png_sig_cmp) (png_const_bytep sig, size_t start, size_t num_to_check)

Check PNG signature bytes to see if it's a PNG file.

Parameters

[in]	sig	Buffer of data containing the PNG file.
[in]	start	The start of the signature in sig.
[in]	num_to_check	The number of bytes remaining in the sig buffer after start.

Returns: 0 if a PNG signature is present, non-zero if not present.

See the LibPNG manual for more information.

◆ png_write_end

void( * sw_libpng_api_20201229::png_write_end) (png_structrp png_ptr, png_inforp info_ptr)

Finish writing a PNG image, including any information comments.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.

The writer function set by png_set_write_fn() will be invoked to write all of the chunks up to the image data.

See the LibPNG manual for more information.

◆ png_write_info

void( * sw_libpng_api_20201229::png_write_info) (png_structrp png_ptr, png_const_inforp info_ptr)

Write information chunks to a PNG image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	info_ptr	A pointer to a PNG information structure.

The writer function set by png_set_write_fn() will be invoked to write all of the chunks up to the image data.

See the LibPNG manual for more information.

◆ png_write_row

void( * sw_libpng_api_20201229::png_write_row) (png_structrp png_ptr, png_const_bytep row)

Write a row of data to a PNG image.

Parameters

[in]	png_ptr	A pointer to a PNG structure handle.
[in]	row	A pointer to a row of data to the image.

The writer function set by png_set_write_fn() may be invoked to write image data.

See the LibPNG manual for more information.

The documentation for this struct was generated from the following file:

lib/interface/libpngapi.h

Data Fields

Detailed Description

Field Documentation

◆ png_create_info_struct

◆ png_create_read_struct_2

◆ png_create_write_struct_2

◆ png_destroy_read_struct

◆ png_destroy_write_struct

◆ png_error

◆ png_get_color_type

◆ png_get_iCCP

◆ png_get_IHDR

◆ png_get_io_ptr

◆ png_get_pHYs

◆ png_get_rowbytes

◆ png_get_tRNS

◆ png_get_valid

◆ png_longjmp

◆ png_read_image

◆ png_read_info

◆ png_read_row

◆ png_read_update_info

◆ png_set_compression_level

◆ png_set_IHDR

◆ png_set_interlace_handling

◆ png_set_invert_alpha

◆ png_set_longjmp_fn

◆ png_set_palette_to_rgb

◆ png_set_read_fn

◆ png_set_strip_alpha

◆ png_set_swap_alpha

◆ png_set_text

◆ png_set_tRNS_to_alpha

◆ png_set_write_fn

◆ png_sig_cmp

◆ png_write_end

◆ png_write_info

◆ png_write_row