PNG format

Portable Network Graphics. More...

Collaboration diagram for PNG format:

Data Structures
struct	PNG_memory_buffer
	Private structure used in PNG_memory_read() and PNG_memory_write() More...

Functions
void	Test_PNG (T_IO_Context *context, FILE *file)
	Test for PNG format. More...
static int	PNG_read_unknown_chunk (png_structp ptr, png_unknown_chunkp chunk)
	Callback to handle our private chunks. More...
static void	PNG_memory_read (png_structp png_ptr, png_bytep p, png_size_t count)
	read from memory buffer More...
void	Load_PNG_Sub (T_IO_Context *context, FILE *file, const char *memory_buffer, unsigned long memory_buffer_size)
	Read PNG format file. More...
void	Load_PNG (T_IO_Context *context)
	Read PNG format files. More...
static void	PNG_memory_write (png_structp png_ptr, png_bytep p, png_size_t count)
	Write to memory buffer. More...
static void	PNG_memory_flush (png_structp png_ptr)
	do nothing More...
void	Save_PNG_Sub (T_IO_Context *context, FILE *file, char **buffer, unsigned long *buffer_size)
	Save a PNG to file or memory. More...
void	Save_PNG (T_IO_Context *context)
	Save a PNG file. More...

Detailed Description

Portable Network Graphics.

We make use of libpng : http://www.libpng.org/pub/png/libpng.html

Function Documentation

Test_PNG()

void Test_PNG	(	T_IO_Context *	context,
		FILE *	file
	)

Test for PNG format.

The 8 byte signature at the start of file is tested

References File_error, and Read_bytes().

PNG_read_unknown_chunk()

static int PNG_read_unknown_chunk ( png_structp  ptr, png_unknown_chunkp  chunk  )

static

Callback to handle our private chunks.

We have one private chunk at the moment :

• "crNg" which is similar to a CRNG chunk in an IFF file

References T_IO_Context::Color_cycles, T_IO_Context::Cycle_range, T_Color_cycle::End, flags, GFX2_DEBUG, GFX2_Log(), GFX2_LogHexDump(), T_Color_cycle::Inverse, T_Color_cycle::Speed, T_Color_cycle::Start, and SWAP_BYTES.

Referenced by Load_PNG_Sub().

PNG_memory_read()

static void PNG_memory_read ( png_structp  png_ptr, png_bytep  p, png_size_t  count  )

static

read from memory buffer

References PNG_memory_buffer::buffer, GFX2_DEBUG, GFX2_Log(), NULL, and PNG_memory_buffer::size.

Referenced by Load_PNG_Sub().

Load_PNG_Sub()

void Load_PNG_Sub	(	T_IO_Context *	context,
		FILE *	file,
		const char *	memory_buffer,
		unsigned long	memory_buffer_size
	)

Read PNG format file.

References PNG_memory_buffer::buffer, T_Config::Clear_palette, COMMENT_SIZE, Config, CONTEXT_BRUSH, CONTEXT_MAIN_IMAGE, CONTEXT_PALETTE, CONTEXT_PREVIEW, CONTEXT_PREVIEW_PALETTE, CONTEXT_SURFACE, File_error, File_length_file(), FORMAT_PNG, GFX2_DEBUG, GFX2_Log(), MIN, NULL, PIXEL_SIMPLE, PIXEL_TALL, PIXEL_WIDE, png_get_bit_depth, png_get_color_type, png_get_image_height, png_get_image_width, png_get_rowbytes, png_jmpbuf, PNG_memory_read(), PNG_read_unknown_chunk(), png_set_expand_gray_1_2_4_to_8, Pre_load(), Set_pixel(), Set_pixel_24b(), and PNG_memory_buffer::size.

Referenced by Load_BMP_Pixels(), Load_ClipBoard_Image(), Load_ICO(), and Load_PNG().

Load_PNG()

void Load_PNG

(

T_IO_Context *

context

)

Read PNG format files.

just read/test the header and call Load_PNG_Sub()

References File_error, Load_PNG_Sub(), NULL, Open_file_read(), and Read_bytes().

PNG_memory_write()

static void PNG_memory_write ( png_structp  png_ptr, png_bytep  p, png_size_t  count  )

static

Write to memory buffer.

References PNG_memory_buffer::buffer, File_error, GFX2_DEBUG, GFX2_ERROR, GFX2_Log(), and NULL.

Referenced by Save_PNG_Sub().

PNG_memory_flush()

static void PNG_memory_flush ( png_structp  png_ptr )

static

do nothing

References PNG_memory_buffer::buffer, GFX2_DEBUG, and GFX2_Log().

Referenced by Save_PNG_Sub().

Save_PNG_Sub()

void Save_PNG_Sub	(	T_IO_Context *	context,
		FILE *	file,
		char **	buffer,
		unsigned long *	buffer_size
	)

Save a PNG to file or memory.

Parameters

context	the IO context
file	the FILE to write to or NULL to write to memory
buffer	will receive a malloc'ed buffer if writting to memory
buffer_size	will receive the PNG size in memory

References T_IO_Context::Background_transparent, PNG_memory_buffer::buffer, memory_buffer::buffer, T_IO_Context::Color_cycles, T_IO_Context::Comment, T_IO_Context::Cycle_range, T_Color_cycle::End, File_error, flags, T_IO_Context::Height, T_Color_cycle::Inverse, NULL, memory_buffer::offset, T_IO_Context::Palette, T_IO_Context::Pitch, Pixel_ratio, PIXEL_TALL, PIXEL_TALL2, PIXEL_TALL3, PIXEL_WIDE, PIXEL_WIDE2, PNG_HAVE_PLTE, png_jmpbuf, PNG_memory_flush(), PNG_memory_write(), T_Color_cycle::Speed, T_Color_cycle::Start, T_IO_Context::Target_address, T_IO_Context::Transparent_color, and T_IO_Context::Width.

Referenced by Save_ClipBoard_Image(), and Save_PNG().

Save_PNG()

void Save_PNG

(

T_IO_Context *

context

)

Save a PNG file.

References File_error, NULL, Open_file_write(), Remove_file(), and Save_PNG_Sub().