ImageDecoder Class Reference

An abstract base class for image decoders. More...

#include <ImageDecoder.hpp>

Inheritance diagram for ImageDecoder:

Public Member Functions
	ImageDecoder (ccxx::DataReader *reader)
	Construct a new ImageDecoder that will read an image from the given DataReader. More...
virtual	~ImageDecoder ()
	Destructor. More...
void	decodeMetadata ()
	Decode the metadata for the image. More...
void	decodeImage (Pixmap *pixmap)
	Decode the image itself. More...
Size	getSize () const
	Get the size of the image, in pixels. More...

Protected Member Functions
virtual void	readMetadata (ccxx::DataReader *reader)=0
	This method must be implemented to perform the image metadata decoding. More...
virtual void	readPixmap (ccxx::DataReader *reader, Pixmap *pixmap)=0
	This method must be implemented to perform the image data decoding. More...
void	setSize (const Size &size)
	This method should be called from readMetadata() to store the image size, once it has been determined. More...

Detailed Description

An abstract base class for image decoders.

An ImageDecoder decodes an image from a DataReader into a Pixmap. Thus it can be used to read images from files, from memory buffers, or from Android assets.

The steps to decode an image are as follows:

• call decodeMetadata() to decode the image metadata
• call getSize() to get the pixel dimensions of the image
• construct a Pixmap that is large enough to hold an image of that size
• call decodeImage() with the Pixmap to decode the image data

Author

Mark Lindner

Constructor & Destructor Documentation

ImageDecoder()

ImageDecoder

(

ccxx::DataReader *

reader

)

Construct a new ImageDecoder that will read an image from the given DataReader.

~ImageDecoder()

~ImageDecoder ( )

virtual

Destructor.

Member Function Documentation

decodeImage()

void decodeImage

(

Pixmap *

pixmap

)

Decode the image itself.

This method must be called after decodeMetadata().

Parameters

pixmap

The Pixmap in which to store the image data.

Exceptions

IOException

If an I/O error occurs, or if the supplied Pixmap is too small to accommodate the image.

decodeMetadata()

void decodeMetadata

(

)

Decode the metadata for the image.

This method must be called before decodeImage().

Exceptions

IOException

If an I/O error occurs.

getSize()

Size getSize ( ) const

inline

Get the size of the image, in pixels.

This method will return a size of 0x0 if decodeMetadata() has not yet been called.

readMetadata()

virtual void readMetadata ( ccxx::DataReader *  reader )

protectedpure virtual

This method must be implemented to perform the image metadata decoding.

Exceptions

IOException

If an I/O error occurs.

Implemented in PNGImageDecoder.

readPixmap()

virtual void readPixmap ( ccxx::DataReader *  reader, Pixmap *  pixmap  )

protectedpure virtual

This method must be implemented to perform the image data decoding.

Parameters

reader	The DataReader that the image is being read from.
pixmap	The Pixmap to store the image into.

Exceptions

IOException

If an I/O error occurs.

Implemented in PNGImageDecoder.

setSize()

void setSize ( const Size &  size )

inlineprotected

This method should be called from readMetadata() to store the image size, once it has been determined.

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

• ImageDecoder.hpp
• ImageDecoder.cpp