WebPCompressor Class Reference

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

#include <WebPCompressor.h>

Inheritance diagram for WebPCompressor:

Public Member Functions
	WebPCompressor (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 WebP 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.
void	injectMetadata (RawTile &r)
	Inject metadata into raw WebP bitstream.
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.

Additional Inherited Members
Protected Member Functions inherited from Compressor
virtual void	writeMetadata ()
	Write metadata.
virtual void	writeResolution ()
	Write DPI.
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 WebP library: Handles 8 and 16 bit PNG as well as alpha transparency.

Constructor & Destructor Documentation

WebPCompressor()

WebPCompressor::WebPCompressor ( int  compressionLevel )

inline

Constructor.

Parameters

compressionLevel

WebP compression level (range 0-100)

References Compressor::Q.

Member Function Documentation

Compress()

unsigned int WebPCompressor::Compress ( RawTile &  t )

virtual

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

Compress a single tile of data.

Parameters

t	tile of image data

Returns

size of compressed data

Reimplemented from Compressor.

References RawTile::capacity, RawTile::channels, RawTile::compressionType, RawTile::data, RawTile::dataLength, Compressor::exif, RawTile::height, Compressor::icc, RawTile::memoryManaged, Compressor::Q, RawTile::quality, RawTile::triplicate(), RawTile::width, and Compressor::xmp.

Referenced by InitCompression().

CompressStrip()

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

virtual

Compress a strip of image data.

libwebp cannot handle line or region-based encoding, so simulate strip-based output using byte chunks

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 RawTile::data, RawTile::dataLength, and RawTile::height.

Finish()

unsigned int WebPCompressor::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 RawTile::data, and RawTile::dataLength.

getImageEncoding()

ImageEncoding WebPCompressor::getImageEncoding ( ) const

inlinevirtual

Get compression type.

Reimplemented from Compressor.

getMimeType()

const char * WebPCompressor::getMimeType ( ) const

inlinevirtual

Return the WebP mime type.

Reimplemented from Compressor.

getSuffix()

const char * WebPCompressor::getSuffix ( ) const

inlinevirtual

Return the image filename suffix.

Reimplemented from Compressor.

InitCompression()

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

virtual

Initialize strip based compression.

Initialize chunk-based encoding for the CVT handler.

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, RawTile::channels, Compress(), RawTile::data, RawTile::dataLength, RawTile::height, RawTile::memoryManaged, and RawTile::width.

injectMetadata()

void WebPCompressor::injectMetadata ( RawTile &  r )

virtual

Inject metadata into raw WebP bitstream.

Parameters

r	image tile

Reimplemented from Compressor.

References RawTile::capacity, RawTile::data, RawTile::dataLength, Compressor::embedEXIF, Compressor::embedICC, Compressor::embedXMP, Compressor::exif, Compressor::icc, RawTile::memoryManaged, and Compressor::xmp.

setQuality()

void WebPCompressor::setQuality ( int  quality )

inlinevirtual

Set the compression level.

Parameters

quality

compression level: 0-100 with (0 = highest 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:

• WebPCompressor.h
• WebPCompressor.cc