Public Member Functions | Static Public Member Functions | Protected Member Functions | List of all members
ImageFileFormat Class Referenceabstract

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

Inheritance diagram for ImageFileFormat:

Public Member Functions

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

Static Public Member Functions

static ImageFileFormatfindImageFormatForStream (InputStream &input)
 Tries the built-in formats to see if it can find one to read this stream. More...
 
static ImageFileFormatfindImageFormatForFileExtension (const File &file)
 Looks for a format that can handle the given file extension. More...
 
static Image loadFrom (InputStream &input)
 Tries to load an image from a stream. More...
 
static Image loadFrom (const File &file)
 Tries to load an image from a file. More...
 
static Image loadFrom (const void *rawData, size_t numBytesOfData)
 Tries to load an image from a block of raw image data. More...
 

Protected Member Functions

 ImageFileFormat ()
 Creates an ImageFormat. More...
 

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

Constructor & Destructor Documentation

◆ ImageFileFormat()

ImageFileFormat::ImageFileFormat ( )
protected

Creates an ImageFormat.

◆ ~ImageFileFormat()

virtual ImageFileFormat::~ImageFileFormat ( )
virtual

Destructor.

Member Function Documentation

◆ getFormatName()

virtual String ImageFileFormat::getFormatName ( )
pure virtual

Returns a description of this file format.

E.g. "JPEG", "PNG"

Implemented in GIFImageFormat, JPEGImageFormat, and PNGImageFormat.

◆ canUnderstand()

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.

Note that this will advance the stream and leave it in a new position, so if you're planning on re-using it, you may want to rewind it after calling this method.

See also
decodeImage

Implemented in GIFImageFormat, JPEGImageFormat, and PNGImageFormat.

◆ usesFileExtension()

virtual bool ImageFileFormat::usesFileExtension ( const File possibleFile)
pure virtual

Returns true if this format uses the file extension of the given file.

Implemented in GIFImageFormat, JPEGImageFormat, and PNGImageFormat.

◆ decodeImage()

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
inputthe 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 an invalid image if it fails.
See also
loadFrom

Implemented in GIFImageFormat, JPEGImageFormat, and PNGImageFormat.

◆ writeImageToStream()

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 GIFImageFormat, JPEGImageFormat, and PNGImageFormat.

◆ findImageFormatForStream()

static ImageFileFormat* ImageFileFormat::findImageFormatForStream ( InputStream input)
static

Tries the built-in formats 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

◆ findImageFormatForFileExtension()

static ImageFileFormat* ImageFileFormat::findImageFormatForFileExtension ( const File file)
static

Looks for a format that can handle the given file extension.

There are currently built-in formats for PNG, JPEG and GIF formats. The object that is returned should not be deleted by the caller.

◆ loadFrom() [1/3]

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 an invalid image if it fails.

◆ loadFrom() [2/3]

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 an invalid image if it fails.

◆ loadFrom() [3/3]

static Image ImageFileFormat::loadFrom ( const void *  rawData,
size_t  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 an invalid image if it fails.

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