ImageFileFormat Class Reference

Inheritance diagram for ImageFileFormat:

JPEGImageFormat PNGImageFormat List of all members.

Detailed Description

Base-class for codecs that can read and write image file formats such as PNG, JPEG, etc.

This class also contains static methods to make it easy to load images from files, streams or from memory.

See also:
Image, ImageCache


Public Member Functions

virtual ~ImageFileFormat () throw ()
 Destructor.
virtual const String getFormatName ()=0
 Returns a description of this file format.
virtual bool canUnderstand (InputStream &input)=0
 Returns true if the given stream seems to contain data that this format understands.
virtual Image * decodeImage (InputStream &input)=0
 Tries to decode and return an image from the given stream.
virtual bool writeImageToStream (const Image &sourceImage, OutputStream &destStream)=0
 Attempts to write an image to a stream.

Static Public Member Functions

static ImageFileFormat * findImageFormatForStream (InputStream &input)
 Tries the built-in decoders to see if it can find one to read this stream.
static Image * loadFrom (InputStream &input)
 Tries to load an image from a stream.
static Image * loadFrom (const File &file)
 Tries to load an image from a file.
static Image * loadFrom (const void *rawData, const int numBytesOfData)
 Tries to load an image from a block of raw image data.

Protected Member Functions

 ImageFileFormat () throw ()
 Creates an ImageFormat.

Constructor & Destructor Documentation

ImageFileFormat::ImageFileFormat (   )  throw () [protected]
 

Creates an ImageFormat.

virtual ImageFileFormat::~ImageFileFormat (   )  throw () [virtual]
 

Destructor.

Member Function Documentation

virtual const String ImageFileFormat::getFormatName (   )  [pure virtual]
 

Returns a description of this file format.

E.g. "JPEG", "PNG"

Implemented in PNGImageFormat, and JPEGImageFormat.

virtual bool ImageFileFormat::canUnderstand (  InputStream &  input  )  [pure virtual]
 

Returns true if the given stream seems to contain data that this format understands.

The format class should only read the first few bytes of the stream and sniff for header bytes that it understands.

See also:
decodeImage

Implemented in PNGImageFormat, and JPEGImageFormat.

virtual Image* ImageFileFormat::decodeImage (  InputStream &  input  )  [pure virtual]
 

Tries to decode and return an image from the given stream.

This will be called for an image format after calling its canUnderStand() method to see if it can handle the stream.

Parameters:
input the stream to read the data from. The stream will be positioned at the start of the image data (but this may not necessarily be position 0)
Returns:
the image that was decoded, or 0 if it fails. It's the caller's responsibility to delete this image when no longer needed.
See also:
loadFrom

Implemented in PNGImageFormat, and JPEGImageFormat.

virtual bool ImageFileFormat::writeImageToStream (  const Image &  sourceImage,
OutputStream &  destStream
)  [pure virtual]
 

Attempts to write an image to a stream.

To specify extra information like encoding quality, there will be appropriate parameters in the subclasses of the specific file types.

Returns:
true if it nothing went wrong.

Implemented in PNGImageFormat, and JPEGImageFormat.

static ImageFileFormat* ImageFileFormat::findImageFormatForStream (  InputStream &  input  )  [static]
 

Tries the built-in decoders to see if it can find one to read this stream.

There are currently built-in decoders for PNG, JPEG and GIF formats.

The object that is returned should not be deleted by the caller.

See also:
canUnderstand, decodeImage, loadFrom

static Image* ImageFileFormat::loadFrom (  InputStream &  input  )  [static]
 

Tries to load an image from a stream.

This will use the findImageFormatForStream() method to locate a suitable codec, and use that to load the image.

Returns:
the image that was decoded, or 0 if it fails to load one. It's the caller's responsibility to delete this image when no longer needed.

static Image* ImageFileFormat::loadFrom (  const File &  file  )  [static]
 

Tries to load an image from a file.

This will use the findImageFormatForStream() method to locate a suitable codec, and use that to load the image.

Returns:
the image that was decoded, or 0 if it fails to load one. It's the caller's responsibility to delete this image when no longer needed.

static Image* ImageFileFormat::loadFrom (  const void *  rawData,
const int  numBytesOfData
)  [static]
 

Tries to load an image from a block of raw image data.

This will use the findImageFormatForStream() method to locate a suitable codec, and use that to load the image.

Returns:
the image that was decoded, or 0 if it fails to load one. It's the caller's responsibility to delete this image when no longer needed.

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