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java.awt.image
Class VolatileImage  

java.lang.Object
  java.awt.Image
      java.awt.image.VolatileImage

All Implemented Interfaces:

java.awt.Transparency

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public abstract class VolatileImage

extends java.awt.Image

implements java.awt.Transparency

VolatileImage represents a hardware-accelerated graphics buffer. The native graphics system may free or damage the resources occupied by a VolatileImage at any time. As such, one must frequently check the "validity" of the image buffer's resources. A volatile image's "validity" depends on multiple factors. Its resources may have become unavailble in which case you must reallocate them. If you move the image from one output device to another, you may need to recreate the image's resources if the new output device's capabilities don't match the old one's. Finally, if the contents of the image's buffer have been damaged you must re-render the image. VolatileImages should always be created using either Component.createVolatileImage or GraphicsConfiguration.createCompatibleVolatileImage.

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Field Summary
static int	IMAGE_INCOMPATIBLE           One of validate's possible return values.
static int	IMAGE_OK           One of validate's possible return values.
static int	IMAGE_RESTORED           One of validate's possible return values.
protected  int	transparency           This image's transparency type.

 

Fields inherited from class java.awt.Image

SCALE_AREA_AVERAGING, SCALE_DEFAULT, SCALE_FAST, SCALE_REPLICATE, SCALE_SMOOTH, UndefinedProperty

 

Fields inherited from interface java.awt.Transparency

BITMASK, OPAQUE, TRANSLUCENT

 

Constructor Summary

VolatileImage()           Default constructor.

 

Method Summary
abstract  boolean	contentsLost()           Returns true if the contents of the image buffer have been damaged or if the image buffer's resources have been reclaimed by the graphics system.
abstract  java.awt.Graphics2D	createGraphics()           Returns a Graphics2D object that can be used to draw onto this image.
void	flush()           Releases the system resources taken by this image.
abstract  java.awt.ImageCapabilities	getCapabilities()           Returns the capabilities of this image buffer.
java.awt.Graphics	getGraphics()           Returns a Graphics2D object that can be used to draw onto this image.
abstract  int	getHeight()           Returns the height of this image buffer.
abstract  BufferedImage	getSnapshot()           Returns an image representing the current state of the volatile image buffer.
ImageProducer	getSource()           Calling this method is equivalent to calling getSnapshot().getSource().
int	getTransparency()           Returns the transparency type of this image.
abstract  int	getWidth()           Returns the width of this image buffer.
abstract  int	validate(java.awt.GraphicsConfiguration gc)           Validates and restores this image.

 

Methods inherited from class java.awt.Image

getHeight, getProperty, getScaledInstance, getWidth

 

Methods inherited from class java.lang.Object

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

 

Field Detail

IMAGE_OK

public static final int IMAGE_OK

One of validate's possible return values. Indicates that the image buffer matches its graphics configuration's capabilities and that its resources are initialized and ready to be drawn into. Also implies that any existing image rendered to the buffer is intact and need not be re-rendered.

See Also:

Constant Field Values

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IMAGE_RESTORED

public static final int IMAGE_RESTORED

One of validate's possible return values. Indicates that the image buffer has been restored, meaning that it is valid and ready-to-use but that its previous contents have been lost. This return value implies that the image needs to be re-rendered.

See Also:

Constant Field Values

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IMAGE_INCOMPATIBLE

public static final int IMAGE_INCOMPATIBLE

One of validate's possible return values. Indicates that the image buffer type is unsupported by the current graphics configuration. The graphics configuration may have changed, for example if the image moved from one output device to another. This return value implies that the image buffer's resources should be re-acquired.

See Also:

Constant Field Values

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transparency

protected int transparency

This image's transparency type. One of Transparency.BITMASK, Transparency.OPAQUE or Transparency.TRANSLUCENT.

Since:

1.5

Constructor Detail

VolatileImage

public VolatileImage()

Default constructor. VolatileImages should not be created directly. Rather, you should use Component.createVolatileImage or GraphicsConfiguration.createCompatibleVolatileImage.

Method Detail

getSnapshot

public abstract BufferedImage getSnapshot()

Returns an image representing the current state of the volatile image buffer. The returned image is static meaning that it is not updated after being created. It is a snapshot of the volatile image buffer at the time getSnapshot is called. This method, which reads pixels from the volatile image buffer, may be less-performant than methods that write pixels since VolatileImages are typically optimized for writing.

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getWidth

public abstract int getWidth()

Returns the width of this image buffer.

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getHeight

public abstract int getHeight()

Returns the height of this image buffer.

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getSource

public ImageProducer getSource()

Calling this method is equivalent to calling getSnapshot().getSource(). The ImageProducer produces pixels from the BufferedImage snapshot and not from the VolatileImage itself. Thus, changes to the VolatileImage that occur after this ImageProducer has been retrieved will not be reflected in the produced pixels. This method, which reads pixels from the volatile image buffer, may be less-performant than methods that write pixels since VolatileImages are typically optimized for writing.

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flush

public void flush()

Releases the system resources taken by this image.

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getGraphics

public java.awt.Graphics getGraphics()

Returns a Graphics2D object that can be used to draw onto this image. This method is present for backwards-compatibility. It simply returns the result of createGraphics.

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createGraphics

public abstract java.awt.Graphics2D createGraphics()

Returns a Graphics2D object that can be used to draw onto this image.

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validate

public abstract int validate(java.awt.GraphicsConfiguration gc)

Validates and restores this image. If the image buffer has become unavailable for further use since the last call to validate, validate will allocate a new image buffer. The image is also "validated" against the GraphicsConfiguration parameter. "Validating" the image means checking that the capabilities it requires of the output device are indeed supported by the given output device. If the image's characteristics, which can be highly output device-specific, are not supported by the graphics configuration, then IMAGE_INCOMPATIBLE will be returned. This can happen, for example, if this image was created on one output device, then validated against a different output device with different capabilities. Calling validate with a NULL gc argument causes validate to skip the validation test.

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contentsLost

public abstract boolean contentsLost()

Returns true if the contents of the image buffer have been damaged or if the image buffer's resources have been reclaimed by the graphics system. You should call this method after a series of rendering operations to or from the image, to see if the image buffer needs to be revalidated or the image re-rendered.

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getCapabilities

public abstract java.awt.ImageCapabilities getCapabilities()

Returns the capabilities of this image buffer.

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getTransparency

public int getTransparency()

Returns the transparency type of this image.

Specified by:

getTransparency in interface java.awt.Transparency

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