Class VolatileImage

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.

Field Value:

2

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.

Field Value:

0

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.

Field Value:

1

protected int transparency

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

Since:

1.5

public VolatileImage()

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

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.

Returns:

true if the validate should be called, false otherwise

public abstract Graphics2D createGraphics()

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

Returns:

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

public void flush()

Releases the system resources taken by this image.

Overrides:

flush in interface Image

public abstract ImageCapabilities getCapabilities()

Returns the capabilities of this image buffer.

Returns:

the capabilities of this image buffer

public 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.

Overrides:

getGraphics in interface Image

Returns:

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

public abstract int getHeight()

Returns the height of this image buffer.

Returns:

the height of this VolatileImage

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.

Returns:

a BufferedImage representing this VolatileImage

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.

Overrides:

getSource in interface Image

Returns:

an ImageProducer for a static BufferedImage snapshot of this image buffer

public int getTransparency()

Returns the transparency type of this image.

Specified by:

getTransparency in interface Transparency

Returns:

Transparency.OPAQUE, Transparency.BITMASK or Transparency.TRANSLUCENT

public abstract int getWidth()

Returns the width of this image buffer.

Returns:

the width of this VolatileImage

public abstract int validate(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.

Parameters:

gc - graphics configuration against which to validate or NULL

Returns:

a code indicating the result of validation. One of:

• IMAGE_OK if the image did not need to be validated and didn't need to be restored
• IMAGE_RESTORED if the image may need to be re-rendered.
• IMAGE_INCOMPATIBLE if this image's requirements are not fulfilled by the graphics configuration parameter. This implies that you need to create a new VolatileImage for the different GraphicsConfiguration or Component. This return value implies nothing about whether the image is valid or needs to be re-rendered.