PNGCompressor Class Reference

Wrapper class to PNG library: Handles 8 and 16 bit PNG as well as alpha transparency. More...

#include <PNGCompressor.h>

Inheritance diagram for PNGCompressor:

Public Member Functions
	PNGCompressor (int compressionLevel)
	Constructor.
void	InitCompression (const RawTile &rawtile, unsigned int strip_height)
	Initialize strip based compression.
unsigned int	CompressStrip (unsigned char *source, unsigned char *output, unsigned int tile_height)
	Compress a strip of image data.
unsigned int	Finish (unsigned char *output)
	Finish the strip based compression and free memory.
unsigned int	Compress (RawTile &t)
	Compress an entire buffer of image data at once in one command.
const char *	getMimeType () const
	Return the PNG mime type.
const char *	getSuffix () const
	Return the image filename suffix.
ImageEncoding	getImageEncoding () const
	Get compression type.
void	setQuality (int quality)
	Set the compression level.
Public Member Functions inherited from Compressor
	Compressor (int compressionLevel)
	Constructor.
unsigned int	getHeaderSize () const
	Return the image header size.
unsigned char *	getHeader ()
	Return a pointer to the image header itself.
int	getQuality () const
	Get the current quality level.
bool	defaultQuality () const
	Check whether we are using the default or whether user has requested a specific quality level.
void	setResolution (float x, float y, int units)
	Set the physical output resolution.
void	embedICCProfile (const bool embed)
	Embed ICC profile.
void	embedXMPMetadata (const bool embed)
	Embed XMP metadata.
void	embedExifMetadata (const bool embed)
	Embed EXIF metadata.
void	setMetadata (const std::map< const std::string, const std::string > &metadata)
	Set general metadata.
virtual void	injectMetadata (RawTile &t)
	Inject metadata into raw bitstream.

Additional Inherited Members
Protected Attributes inherited from Compressor
int	Q
	Quality or compression level for all image types.
bool	default_quality
	Whether compression level is default or has been set manually.
unsigned char *	header
	Pointer to the header data for the output image.
unsigned int	header_size
	Size of the header data.
int	dpi_units
	Physical resolution units: 0 for unknown, 1 for dots/inch or 2 for dots/cm.
float	dpi_x
	Physical resolution (pixels per physical unit) for X direction.
float	dpi_y
	Physical resolution (pixels per phyisical unit) in Y direction.
std::map< const std::string, const std::string >	metadata
	Metadata.
std::string	icc
	ICC Profile.
bool	embedICC
	Whether ICC profile should be embedded.
std::string	xmp
	XMP metadata.
bool	embedXMP
	Whether XMP metadata should be embedded.
std::string	exif
	EXIF metadata.
bool	embedEXIF
	Whether EXIF metadata should be embedded.

Detailed Description

Wrapper class to PNG library: Handles 8 and 16 bit PNG as well as alpha transparency.

Constructor & Destructor Documentation

PNGCompressor()

PNGCompressor::PNGCompressor ( int  compressionLevel )

inline

Constructor.

Parameters

compressionLevel

PNG compression level (zlib range is 0-9)

References png_destination_mgr::info_ptr, png_destination_mgr::output_size, and png_destination_mgr::png_ptr.

Member Function Documentation

Compress()

unsigned int PNGCompressor::Compress ( RawTile &  t )

virtual

Compress an entire buffer of image data at once in one command.

Parameters

t	tile of image data

Returns

size of compressed data

Reimplemented from Compressor.

References RawTile::bpc, png_destination_mgr::bytes_per_pixel, RawTile::capacity, RawTile::channels, RawTile::compressionType, RawTile::data, RawTile::dataLength, Compressor::exif, RawTile::height, Compressor::icc, png_destination_mgr::info_ptr, RawTile::memoryManaged, png_destination_mgr::output, png_destination_mgr::output_size, png_destination_mgr::png_ptr, Compressor::Q, RawTile::quality, RawTile::width, png_destination_mgr::written, and Compressor::xmp.

CompressStrip()

unsigned int PNGCompressor::CompressStrip ( unsigned char *  source, unsigned char *  output, unsigned int  tile_height  )

virtual

Compress a strip of image data.

Parameters

source	source image data
tile_height	pixel height of the tile we are compressing
output	output_buffer

Returns

size of compressed strip

Reimplemented from Compressor.

References png_destination_mgr::bytes_per_pixel, Compressor::header, Compressor::header_size, png_destination_mgr::output, png_destination_mgr::output_size, png_destination_mgr::png_ptr, and png_destination_mgr::written.

Finish()

unsigned int PNGCompressor::Finish ( unsigned char *  output )

virtual

Finish the strip based compression and free memory.

Parameters

output

Output buffer

Returns

size of output generated

Reimplemented from Compressor.

References png_destination_mgr::info_ptr, png_destination_mgr::output, png_destination_mgr::png_ptr, and png_destination_mgr::written.

getImageEncoding()

ImageEncoding PNGCompressor::getImageEncoding ( ) const

inlinevirtual

Get compression type.

Reimplemented from Compressor.

getMimeType()

const char * PNGCompressor::getMimeType ( ) const

inlinevirtual

Return the PNG mime type.

Reimplemented from Compressor.

getSuffix()

const char * PNGCompressor::getSuffix ( ) const

inlinevirtual

Return the image filename suffix.

Reimplemented from Compressor.

InitCompression()

void PNGCompressor::InitCompression ( const RawTile &  rawtile, unsigned int  strip_height  )

virtual

Initialize strip based compression.

For strip based encoding, we need to first initialize with InitCompression, then compress a single strip at a time using CompressStrip and finally clean up using Finish

Parameters

rawtile	RawTile object containing the image to be compressed
strip_height	height in pixels of the strip we want to compress

Reimplemented from Compressor.

References RawTile::bpc, png_destination_mgr::bytes_per_pixel, RawTile::channels, Compressor::exif, Compressor::header, Compressor::header_size, RawTile::height, Compressor::icc, png_destination_mgr::info_ptr, png_destination_mgr::output, png_destination_mgr::output_size, png_destination_mgr::png_ptr, Compressor::Q, RawTile::width, png_destination_mgr::written, and Compressor::xmp.

setQuality()

void PNGCompressor::setQuality ( int  quality )

inlinevirtual

Set the compression level.

Parameters

quality

Deflate compression level: 0-9 with (0 = no compression) Note that compression to 1 (Z_BEST_SPEED) results in a ~3x slowdown wrt to no compression

Reimplemented from Compressor.

References Compressor::default_quality, and Compressor::Q.

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The documentation for this class was generated from the following files:

• PNGCompressor.h
• PNGCompressor.cc