java::awt::Image Class Reference

Inheritance diagram for java::awt::Image:

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Collaboration diagram for java::awt::Image:

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List of all members.


Detailed Description

The abstract class Image is the superclass of all classes that represent graphical images.

The image must be obtained in a platform-specific manner.

Version:
1.33, 01/23/03
Author:
Sami Shaio

Arthur van Hoff

Since:
JDK1.0

Public Types

enum  IMAGE_SCALE_HINTS {
  SCALE_DEFAULT = 1, SCALE_FAST = 2, SCALE_SMOOTH = 4, SCALE_REPLICATE = 8,
  SCALE_AREA_AVERAGING = 16
}

Public Member Functions

virtual jint getWidth (const Ref< ImageObserver > &observer) const =0
 Determines the width of the image.
virtual jint getHeight (const Ref< ImageObserver > &observer) const =0
 Determines the height of the image.
virtual Ref
< ImageProducer
getSource () const =0
 Gets the object that produces the pixels for the image.
virtual Ref< GraphicsgetGraphics () const =0
 Creates a graphics context for drawing to an off-screen image.
virtual ObjectRef getProperty (const String &name, const Ref< ImageObserver > &observer) const =0
 Gets a property of this image by name.
virtual Ref< ImagegetScaledInstance (jint width, jint height, jint hints) const
 Creates a scaled version of this image.
virtual void flush ()=0
 Flushes all resources being used by this Image object.

Member Enumeration Documentation

enum java::awt::Image::IMAGE_SCALE_HINTS

Enumerator:
SCALE_DEFAULT  Use the default image-scaling algorithm.

Since:
JDK1.1
SCALE_FAST  Choose an image-scaling algorithm that gives higher priority to scaling speed than smoothness of the scaled image.

Since:
JDK1.1
SCALE_SMOOTH  Choose an image-scaling algorithm that gives higher priority to image smoothness than scaling speed.

Since:
JDK1.1
SCALE_REPLICATE  Use the image scaling algorithm embodied in the ReplicateScaleFilter class.

The Image object is free to substitute a different filter that performs the same algorithm yet integrates more efficiently into the imaging infrastructure supplied by the toolkit.

See also:
java.awt.image.ReplicateScaleFilter
Since:
JDK1.1
SCALE_AREA_AVERAGING  Use the Area Averaging image scaling algorithm.

The image object is free to substitute a different filter that performs the same algorithm yet integrates more efficiently into the image infrastructure supplied by the toolkit.

See also:
java.awt.image.AreaAveragingScaleFilter
Since:
JDK1.1


Member Function Documentation

virtual jint java::awt::Image::getWidth ( const Ref< ImageObserver > &  observer  )  const [pure virtual]

Determines the width of the image.

If the width is not yet known, this method returns -1 and the specified ImageObserver object is notified later.

Parameters:
observer an object waiting for the image to be loaded.
Returns:
the width of this image, or -1 if the width is not yet known.
See also:
java.awt.Image::getHeight

java.awt.image.ImageObserver

virtual jint java::awt::Image::getHeight ( const Ref< ImageObserver > &  observer  )  const [pure virtual]

Determines the height of the image.

If the height is not yet known, this method returns -1 and the specified ImageObserver object is notified later.

Parameters:
observer an object waiting for the image to be loaded.
Returns:
the height of this image, or -1 if the height is not yet known.
See also:
java.awt.Image::getWidth

java.awt.image.ImageObserver

virtual Ref<ImageProducer> java::awt::Image::getSource (  )  const [pure virtual]

Gets the object that produces the pixels for the image.

This method is called by the image filtering classes and by methods that perform image conversion and scaling.

Returns:
the image producer that produces the pixels for this image.
See also:
java.awt.image.ImageProducer

virtual Ref<Graphics> java::awt::Image::getGraphics (  )  const [pure virtual]

Creates a graphics context for drawing to an off-screen image.

This method can only be called for off-screen images.

Returns:
a graphics context to draw to the off-screen image.
See also:
java.awt.Graphics

java.awt.Component::createImage(int, int)

virtual ObjectRef java::awt::Image::getProperty ( const String name,
const Ref< ImageObserver > &  observer 
) const [pure virtual]

Gets a property of this image by name.

Individual property names are defined by the various image formats. If a property is not defined for a particular image, this method returns the UndefinedProperty object.

If the properties for this image are not yet known, this method returns null, and the ImageObserver object is notified later.

The property name "comment" should be used to store an optional comment which can be presented to the application as a description of the image, its source, or its author.

Parameters:
name a property name.
observer an object waiting for this image to be loaded.
Returns:
the value of the named property.
See also:
java.awt.image.ImageObserver

java.awt.Image::UndefinedProperty

virtual Ref<Image> java::awt::Image::getScaledInstance ( jint  width,
jint  height,
jint  hints 
) const [virtual]

Creates a scaled version of this image.

A new Image object is returned which will render the image at the specified width and height by default. The new Image object may be loaded asynchronously even if the original source image has already been loaded completely. If either the width or height is a negative number then a value is substituted to maintain the aspect ratio of the original image dimensions.

Parameters:
width the width to which to scale the image.
height the height to which to scale the image.
hints flags to indicate the type of algorithm to use for image resampling.
Returns:
a scaled version of the image.
See also:
java.awt.Image::SCALE_DEFAULT

java.awt.Image::SCALE_FAST

java.awt.Image::SCALE_SMOOTH

java.awt.Image::SCALE_REPLICATE

java.awt.Image::SCALE_AREA_AVERAGING

Since:
JDK1.1

virtual void java::awt::Image::flush (  )  [pure virtual]

Flushes all resources being used by this Image object.

This includes any pixel data that is being cached for rendering to the screen as well as any system resources that are being used to store data or pixels for the image. The image is reset to a state similar to when it was first created so that if it is again rendered, the image data will have to be recreated or fetched again from its source.

This method always leaves the image in a state such that it can be reconstructed. This means the method applies only to cached or other secondary representations of images such as those that have been generated from an ImageProducer (read from a file, for example). It does nothing for off-screen images that have only one copy of their data.


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