org.eclipse.swt.graphics
Class ImageLoader

java.lang.Object
  |
  +--org.eclipse.swt.graphics.ImageLoader

public class ImageLoader

extends Object

Instances of this class are used to load images from, and save images to, a file or stream.

Currently supported image formats are:

• BMP (Windows Bitmap)
• ICO (Windows Icon)
• JPEG
• GIF
• PNG

ImageLoaders can be used to:

• load/save single images in all formats
• load/save multiple images (GIF/ICO)
• load/save animated GIF images
• load interlaced GIF/PNG images
• load progressive JPEG images

Field Summary

int	backgroundPixel the background pixel for the logical screen (this corresponds to the GIF89a Background Color Index value).
ImageData[]	data the array of ImageData objects in this ImageLoader.
int	logicalScreenHeight the height of the logical screen on which the images reside, in pixels (this corresponds to the GIF89a Logical Screen Height value)
int	logicalScreenWidth the width of the logical screen on which the images reside, in pixels (this corresponds to the GIF89a Logical Screen Width value)
int	repeatCount the number of times to repeat the display of a sequence of animated images (this corresponds to the commonly-used GIF application extension for "NETSCAPE 2.0 01")

Constructor Summary

ImageLoader()
Construct a new empty ImageLoader.

Method Summary

void	addImageLoaderListener(ImageLoaderListener listener) Adds a listener to receive image loader events.
boolean	hasListeners() Returns true if the receiver has image loader listeners, and false otherwise.
ImageData[]	load(InputStream stream) Loads an array of ImageData objects from the specified input stream.
ImageData[]	load(String filename) Loads an array of ImageData objects from the file with the specified name.
void	notifyListeners(ImageLoaderEvent event) Notifies all image loader listeners that an image loader event has occurred.
void	removeImageLoaderListener(ImageLoaderListener listener) Removes a listener that was receiving image loader events.
void	save(OutputStream stream, int format) Saves the image data in this ImageLoader to the specified stream.
void	save(String filename, int format) Saves the image data in this ImageLoader to a file with the specified name.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

data

public ImageData[] data

the array of ImageData objects in this ImageLoader. This array is read in when the load method is called, and it is written out when the save method is called

logicalScreenWidth

public int logicalScreenWidth

the width of the logical screen on which the images reside, in pixels (this corresponds to the GIF89a Logical Screen Width value)

logicalScreenHeight

public int logicalScreenHeight

the height of the logical screen on which the images reside, in pixels (this corresponds to the GIF89a Logical Screen Height value)

backgroundPixel

public int backgroundPixel

the background pixel for the logical screen (this corresponds to the GIF89a Background Color Index value). The default is -1 which means 'unspecified background'

repeatCount

public int repeatCount

the number of times to repeat the display of a sequence of animated images (this corresponds to the commonly-used GIF application extension for "NETSCAPE 2.0 01")

Constructor Detail

ImageLoader

public ImageLoader()

Construct a new empty ImageLoader.

Method Detail

load

public ImageData[] load(InputStream stream)

Loads an array of ImageData objects from the specified input stream. Throws an error if either an error occurs while loading the images, or if the images are not of a supported type. Returns the loaded image data array.

Parameters:

stream - the input stream to load the images from

Returns:

an array of ImageData objects loaded from the specified input stream

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the stream is null

SWTException -

• ERROR_INVALID_IMAGE - if the image file contains invalid data
• ERROR_IO - if an input/output error occurs while reading data

load

public ImageData[] load(String filename)

Loads an array of ImageData objects from the file with the specified name. Throws an error if either an error occurs while loading the images, or if the images are not of a supported type. Returns the loaded image data array.

Parameters:

filename - the name of the file to load the images from

Returns:

an array of ImageData objects loaded from the specified file

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the file name is null

SWTException -

• ERROR_INVALID_IMAGE - if the image file contains invalid data
• ERROR_IO - if an IO error occurs while reading data

save

public void save(OutputStream stream,
                 int format)

Saves the image data in this ImageLoader to the specified stream. The format parameter can have one of the following values:

IMAGE_BMP

Windows BMP file format, no compression

IMAGE_BMP_RLE

Windows BMP file format, RLE compression if appropriate

IMAGE_GIF

GIF file format

IMAGE_ICO

Windows ICO file format

IMAGE_JPEG

JPEG file format

IMAGE_PNG

PNG file format

Parameters:

stream - the output stream to write the images to

format - the format to write the images in

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the stream is null

SWTException -

• ERROR_INVALID_IMAGE if the image data contains invalid data
• ERROR_IO if an IO error occurs while writing to the stream

save

public void save(String filename,
                 int format)

Saves the image data in this ImageLoader to a file with the specified name. The format parameter can have one of the following values:

IMAGE_BMP

Windows BMP file format, no compression

IMAGE_BMP_RLE

Windows BMP file format, RLE compression if appropriate

IMAGE_GIF

GIF file format

IMAGE_ICO

Windows ICO file format

IMAGE_JPEG

JPEG file format

IMAGE_PNG

PNG file format

Parameters:

filename - the name of the file to write the images to

format - the format to write the images in

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the file name is null

SWTException -

• ERROR_INVALID_IMAGE if the image data contains invalid data
• ERROR_IO if an IO error occurs while writing to the file

addImageLoaderListener

public void addImageLoaderListener(ImageLoaderListener listener)

Adds a listener to receive image loader events.

An ImageLoaderListener should be added before invoking one of the receiver's load methods. The listener's imageDataLoaded method is called when image data has been partially loaded, as is supported by interlaced GIF/PNG or progressive JPEG images.

Parameters:

listener - the ImageLoaderListener to add

See Also:

ImageLoaderListener, ImageLoaderEvent

removeImageLoaderListener

public void removeImageLoaderListener(ImageLoaderListener listener)

Removes a listener that was receiving image loader events.

Parameters:

listener - the ImageLoaderListener to remove

See Also:

addImageLoaderListener(org.eclipse.swt.graphics.ImageLoaderListener)

hasListeners

public boolean hasListeners()

Returns true if the receiver has image loader listeners, and false otherwise.

Returns:

true if there are ImageLoaderListeners, and false otherwise

See Also:

addImageLoaderListener(org.eclipse.swt.graphics.ImageLoaderListener), removeImageLoaderListener(org.eclipse.swt.graphics.ImageLoaderListener)

notifyListeners

public void notifyListeners(ImageLoaderEvent event)

Notifies all image loader listeners that an image loader event has occurred. Pass the specified event object to each listener.

Parameters:

event - the ImageLoaderEvent to send to each ImageLoaderListener