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org.eclipse.jface.resource
Class ImageDescriptor  

java.lang.Object
  org.eclipse.jface.resource.ImageDescriptor

Direct Known Subclasses:

CompositeImageDescriptor, FileImageDescriptor, MissingImageDescriptor, URLImageDescriptor

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public abstract class ImageDescriptor

extends java.lang.Object

An image descriptor is an object that knows how to create an SWT image. It does not hold onto images or cache them, but rather just creates them on demand. An image descriptor is intended to be a lightweight representation of an image that can be manipulated even when no SWT display exists.

This package defines a concrete image descriptor implementation which reads an image from a file (FileImageDescriptor). It also provides abstract framework classes (this one and CompositeImageDescriptor) which may be subclassed to define news kinds of image descriptors.

Using this abstract class involves defining a concrete subclass and providing an implementation for the getImageData method.

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Field Summary
protected static org.eclipse.swt.graphics.ImageData	DEFAULT_IMAGE_DATA           A small red square used to warn that an image cannot be created.

 

Constructor Summary
protected	ImageDescriptor()           Constructs an image descriptor.

 

Method Summary
static ImageDescriptor	createFromFile(java.lang.Class location, java.lang.String filename)           Creates and returns a new image descriptor from a file.
static ImageDescriptor	createFromURL(java.net.URL url)           Creates and returns a new image descriptor from a URL.
org.eclipse.swt.graphics.Image	createImage()           Creates and returns a new SWT image for this image descriptor.
org.eclipse.swt.graphics.Image	createImage(boolean returnMissingImageOnError)           Creates and returns a new SWT image for this image descriptor.
org.eclipse.swt.graphics.Image	createImage(boolean returnMissingImageOnError, org.eclipse.swt.graphics.Device device)           Creates and returns a new SWT image for this image descriptor.
org.eclipse.swt.graphics.Image	createImage(org.eclipse.swt.graphics.Device device)           Creates and returns a new SWT image for this image descriptor.
abstract  org.eclipse.swt.graphics.ImageData	getImageData()           Creates and returns a new SWT ImageData object for this image descriptor.
static ImageDescriptor	getMissingImageDescriptor()           Returns the shared image descriptor for a missing image.

 

Methods inherited from class java.lang.Object

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

 

Field Detail

DEFAULT_IMAGE_DATA

protected static final org.eclipse.swt.graphics.ImageData DEFAULT_IMAGE_DATA

A small red square used to warn that an image cannot be created.

Constructor Detail

ImageDescriptor

protected ImageDescriptor()

Constructs an image descriptor.

Method Detail

createFromFile

public static ImageDescriptor createFromFile(java.lang.Class location,
                                             java.lang.String filename)

Creates and returns a new image descriptor from a file. Convenience method for new FileImageDescriptor(location,filename).

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createFromURL

public static ImageDescriptor createFromURL(java.net.URL url)

Creates and returns a new image descriptor from a URL.

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createImage

public org.eclipse.swt.graphics.Image createImage()

Creates and returns a new SWT image for this image descriptor. Note that each call returns a new SWT image object. A default image is returned in the event of an error.

Note: it is still possible for this method to return null in extreme cases, for example if SWT runs out of image handles.

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createImage

public org.eclipse.swt.graphics.Image createImage(boolean returnMissingImageOnError)

Creates and returns a new SWT image for this image descriptor. In the even of an error, a default image is returned if returnMissingImageOnError is true, otherwise null is returned.

Note: Even if returnMissingImageOnError is true, it is still possible for this method to return null in extreme cases, for example if SWT runs out of image handles.

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createImage

public org.eclipse.swt.graphics.Image createImage(org.eclipse.swt.graphics.Device device)

Creates and returns a new SWT image for this image descriptor. A default image is returned in the event of an error.

Note: it is still possible for this method to return null in extreme cases, for example if SWT runs out of image handles.

Since:

2.0

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createImage

public org.eclipse.swt.graphics.Image createImage(boolean returnMissingImageOnError,
                                                  org.eclipse.swt.graphics.Device device)

Creates and returns a new SWT image for this image descriptor. In the even of an error, a default image is returned if returnMissingImageOnError is true, otherwise null is returned.

Note: Even if returnMissingImageOnError is true, it is still possible for this method to return null in extreme cases, for example if SWT runs out of image handles.

Since:

2.0

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getImageData

public abstract org.eclipse.swt.graphics.ImageData getImageData()

Creates and returns a new SWT ImageData object for this image descriptor. Note that each call returns a new SWT image data object.

This framework method is declared public so that it is possible to request an image descriptor's image data without creating an SWT image object.

Returns null if the image data could not be created.

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getMissingImageDescriptor

public static ImageDescriptor getMissingImageDescriptor()

Returns the shared image descriptor for a missing image.

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