jdk.awt.image.VolatileImage
VolatileImage is an image which can lose its contents at any time due to circumstances beyond the control of the application (e.g., situations caused by the operating system or by other applications). Because of the potential for hardware acceleration, a VolatileImage object can have significant performance benefits on some platforms.
The drawing surface of an image (the memory where the image contents actually reside) can be lost or invalidated, causing the contents of that memory to go away. The drawing surface thus needs to be restored or recreated and the contents of that surface need to be re-rendered. VolatileImage provides an interface for allowing the user to detect these problems and fix them when they occur.
When a VolatileImage object is created, limited system resources such as video memory (VRAM) may be allocated in order to support the image. When a VolatileImage object is no longer used, it may be garbage-collected and those system resources will be returned, but this process does not happen at guaranteed times. Applications that create many VolatileImage objects (for example, a resizing window may force recreation of its back buffer as the size changes) may run out of optimal system resources for new VolatileImage objects simply because the old objects have not yet been removed from the system. (New VolatileImage objects may still be created, but they may not perform as well as those created in accelerated memory). The flush method may be called at any time to proactively release the resources used by a VolatileImage so that it does not prevent subsequent VolatileImage objects from being accelerated. In this way, applications can have more control over the state of the resources taken up by obsolete VolatileImage objects.
This image should not be subclassed directly but should be created by using the Component.createVolatileImage or GraphicsConfiguration.createCompatibleVolatileImage(int, int) methods.
An example of using a VolatileImage object follows:
// image creation VolatileImage vImg = createVolatileImage(w, h);
// rendering to the image void renderOffscreen() { do { if (vImg.validate(getGraphicsConfiguration()) == VolatileImage.IMAGE_INCOMPATIBLE) { // old vImg doesn't work with new GraphicsConfig; re-create it vImg = createVolatileImage(w, h); } Graphics2D g = vImg.createGraphics(); // // miscellaneous rendering commands... // g.dispose(); } while (vImg.contentsLost()); }
// copying from the image (here, gScreen is the Graphics // object for the onscreen window) do { int returnCode = vImg.validate(getGraphicsConfiguration()); if (returnCode == VolatileImage.IMAGE_RESTORED) { // Contents need to be restored renderOffscreen(); // restore contents } else if (returnCode == VolatileImage.IMAGE_INCOMPATIBLE) { // old vImg doesn't work with new GraphicsConfig; re-create it vImg = createVolatileImage(w, h); renderOffscreen(); } gScreen.drawImage(vImg, 0, 0, this); } while (vImg.contentsLost());
Note that this class subclasses from the Image class, which includes methods that take an ImageObserver parameter for asynchronous notifications as information is received from a potential ImageProducer. Since this VolatileImage is not loaded from an asynchronous source, the various methods that take an ImageObserver parameter will behave as if the data has already been obtained from the ImageProducer. Specifically, this means that the return values from such methods will never indicate that the information is not yet available and the ImageObserver used in such methods will never need to be recorded for an asynchronous callback notification.
VolatileImage is an image which can lose its
contents at any time due to circumstances beyond the control of the
application (e.g., situations caused by the operating system or by
other applications). Because of the potential for hardware acceleration,
a VolatileImage object can have significant performance benefits on
some platforms.
The drawing surface of an image (the memory where the image contents
actually reside) can be lost or invalidated, causing the contents of that
memory to go away. The drawing surface thus needs to be restored
or recreated and the contents of that surface need to be
re-rendered. VolatileImage provides an interface for
allowing the user to detect these problems and fix them
when they occur.
When a VolatileImage object is created, limited system resources
such as video memory (VRAM) may be allocated in order to support
the image.
When a VolatileImage object is no longer used, it may be
garbage-collected and those system resources will be returned,
but this process does not happen at guaranteed times.
Applications that create many VolatileImage objects (for example,
a resizing window may force recreation of its back buffer as the
size changes) may run out of optimal system resources for new
VolatileImage objects simply because the old objects have not
yet been removed from the system.
(New VolatileImage objects may still be created, but they
may not perform as well as those created in accelerated
memory).
The flush method may be called at any time to proactively release
the resources used by a VolatileImage so that it does not prevent
subsequent VolatileImage objects from being accelerated.
In this way, applications can have more control over the state
of the resources taken up by obsolete VolatileImage objects.
This image should not be subclassed directly but should be created
by using the Component.createVolatileImage or
GraphicsConfiguration.createCompatibleVolatileImage(int, int) methods.
An example of using a VolatileImage object follows:
// image creation
VolatileImage vImg = createVolatileImage(w, h);
// rendering to the image
void renderOffscreen() {
do {
if (vImg.validate(getGraphicsConfiguration()) ==
VolatileImage.IMAGE_INCOMPATIBLE)
{
// old vImg doesn't work with new GraphicsConfig; re-create it
vImg = createVolatileImage(w, h);
}
Graphics2D g = vImg.createGraphics();
//
// miscellaneous rendering commands...
//
g.dispose();
} while (vImg.contentsLost());
}
// copying from the image (here, gScreen is the Graphics
// object for the onscreen window)
do {
int returnCode = vImg.validate(getGraphicsConfiguration());
if (returnCode == VolatileImage.IMAGE_RESTORED) {
// Contents need to be restored
renderOffscreen(); // restore contents
} else if (returnCode == VolatileImage.IMAGE_INCOMPATIBLE) {
// old vImg doesn't work with new GraphicsConfig; re-create it
vImg = createVolatileImage(w, h);
renderOffscreen();
}
gScreen.drawImage(vImg, 0, 0, this);
} while (vImg.contentsLost());
Note that this class subclasses from the Image class, which
includes methods that take an ImageObserver parameter for
asynchronous notifications as information is received from
a potential ImageProducer. Since this VolatileImage
is not loaded from an asynchronous source, the various methods that take
an ImageObserver parameter will behave as if the data has
already been obtained from the ImageProducer.
Specifically, this means that the return values from such methods
will never indicate that the information is not yet available and
the ImageObserver used in such methods will never
need to be recorded for an asynchronous callback notification.*-image-incompatibleclj
Static Constant.
Validated image is incompatible with supplied GraphicsConfiguration object and should be re-created as appropriate. Usage of the image as-is after receiving this return code from validate is undefined.
type: int
Static Constant. Validated image is incompatible with supplied GraphicsConfiguration object and should be re-created as appropriate. Usage of the image as-is after receiving this return code from validate is undefined. type: int
*-image-okclj
Static Constant.
Validated image is ready to use as-is.
type: int
Static Constant. Validated image is ready to use as-is. type: int
*-image-restoredclj
Static Constant.
Validated image has been restored and is now ready to use. Note that restoration causes contents of the image to be lost.
type: int
Static Constant. Validated image has been restored and is now ready to use. Note that restoration causes contents of the image to be lost. type: int
contents-lostclj
(contents-lost this)Returns true if rendering data was lost since last validate call. This method should be called by the application at the end of any series of rendering operations to or from the image to see whether the image needs to be validated and the rendering redone.
returns: true if the drawing surface needs to be restored;
false otherwise. - boolean
Returns true if rendering data was lost since last validate call. This method should be called by the application at the end of any series of rendering operations to or from the image to see whether the image needs to be validated and the rendering redone. returns: true if the drawing surface needs to be restored; false otherwise. - `boolean`
create-graphicsclj
(create-graphics this)Creates a Graphics2D, which can be used to draw into this VolatileImage.
returns: a Graphics2D, used for drawing into this
image. - java.awt.Graphics2D
Creates a Graphics2D, which can be used to draw into
this VolatileImage.
returns: a Graphics2D, used for drawing into this
image. - `java.awt.Graphics2D`get-capabilitiesclj
(get-capabilities this)Returns an ImageCapabilities object which can be inquired as to the specific capabilities of this VolatileImage. This would allow programmers to find out more runtime information on the specific VolatileImage object that they have created. For example, the user might create a VolatileImage but the system may have no video memory left for creating an image of that size, so although the object is a VolatileImage, it is not as accelerated as other VolatileImage objects on this platform might be. The user might want that information to find other solutions to their problem.
returns: an ImageCapabilities object that contains
the capabilities of this VolatileImage. - java.awt.ImageCapabilities
Returns an ImageCapabilities object which can be
inquired as to the specific capabilities of this
VolatileImage. This would allow programmers to find
out more runtime information on the specific VolatileImage
object that they have created. For example, the user
might create a VolatileImage but the system may have
no video memory left for creating an image of that
size, so although the object is a VolatileImage, it is
not as accelerated as other VolatileImage objects on
this platform might be. The user might want that
information to find other solutions to their problem.
returns: an ImageCapabilities object that contains
the capabilities of this VolatileImage. - `java.awt.ImageCapabilities`get-graphicsclj
(get-graphics this)This method returns a Graphics2D, but is here for backwards compatibility. createGraphics is more convenient, since it is declared to return a Graphics2D.
returns: a Graphics2D, which can be used to draw into
this image. - java.awt.Graphics
This method returns a Graphics2D, but is here
for backwards compatibility. createGraphics is more
convenient, since it is declared to return a
Graphics2D.
returns: a Graphics2D, which can be used to draw into
this image. - `java.awt.Graphics`get-heightclj
(get-height this)Returns the height of the VolatileImage.
returns: the height of this VolatileImage. - int
Returns the height of the VolatileImage. returns: the height of this VolatileImage. - `int`
get-snapshotclj
(get-snapshot this)Returns a static snapshot image of this object. The BufferedImage returned is only current with the VolatileImage at the time of the request and will not be updated with any future changes to the VolatileImage.
returns: a BufferedImage representation of this
VolatileImage - java.awt.image.BufferedImage
Returns a static snapshot image of this object. The
BufferedImage returned is only current with
the VolatileImage at the time of the request
and will not be updated with any future changes to the
VolatileImage.
returns: a BufferedImage representation of this
VolatileImage - `java.awt.image.BufferedImage`get-sourceclj
(get-source this)This returns an ImageProducer for this VolatileImage. Note that the VolatileImage object is optimized for rendering operations and blitting to the screen or other VolatileImage objects, as opposed to reading back the pixels of the image. Therefore, operations such as getSource may not perform as fast as operations that do not rely on reading the pixels. Note also that the pixel values read from the image are current with those in the image only at the time that they are retrieved. This method takes a snapshot of the image at the time the request is made and the ImageProducer object returned works with that static snapshot image, not the original VolatileImage. Calling getSource() is equivalent to calling getSnapshot().getSource().
returns: an ImageProducer that can be used to produce the
pixels for a BufferedImage representation of
this Image. - java.awt.image.ImageProducer
This returns an ImageProducer for this VolatileImage. Note that the VolatileImage object is optimized for rendering operations and blitting to the screen or other VolatileImage objects, as opposed to reading back the pixels of the image. Therefore, operations such as getSource may not perform as fast as operations that do not rely on reading the pixels. Note also that the pixel values read from the image are current with those in the image only at the time that they are retrieved. This method takes a snapshot of the image at the time the request is made and the ImageProducer object returned works with that static snapshot image, not the original VolatileImage. Calling getSource() is equivalent to calling getSnapshot().getSource(). returns: an ImageProducer that can be used to produce the pixels for a BufferedImage representation of this Image. - `java.awt.image.ImageProducer`
get-transparencyclj
(get-transparency this)Returns the transparency. Returns either OPAQUE, BITMASK, or TRANSLUCENT.
returns: the transparency of this VolatileImage. - int
Returns the transparency. Returns either OPAQUE, BITMASK, or TRANSLUCENT. returns: the transparency of this VolatileImage. - `int`
get-widthclj
(get-width this)Returns the width of the VolatileImage.
returns: the width of this VolatileImage. - int
Returns the width of the VolatileImage. returns: the width of this VolatileImage. - `int`
validateclj
(validate this gc)Attempts to restore the drawing surface of the image if the surface had been lost since the last validate call. Also validates this image against the given GraphicsConfiguration parameter to see whether operations from this image to the GraphicsConfiguration are compatible. An example of an incompatible combination might be a situation where a VolatileImage object was created on one graphics device and then was used to render to a different graphics device. Since VolatileImage objects tend to be very device-specific, this operation might not work as intended, so the return code from this validate call would note that incompatibility. A null or incorrect value for gc may cause incorrect values to be returned from validate and may cause later problems with rendering.
gc - a GraphicsConfiguration object for this image to be validated against. A null gc implies that the validate method should skip the compatibility test. - java.awt.GraphicsConfiguration
returns: IMAGE_OK if the image did not need validation
IMAGE_RESTORED if the image needed restoration.
Restoration implies that the contents of the image may have
been affected and the image may need to be re-rendered.
IMAGE_INCOMPATIBLE if the image is incompatible
with the GraphicsConfiguration object passed
into the validate method. Incompatibility
implies that the image may need to be recreated with a
new Component or
GraphicsConfiguration in order to get an image
that can be used successfully with this
GraphicsConfiguration.
An incompatible image is not checked for whether restoration
was necessary, so the state of the image is unchanged
after a return value of IMAGE_INCOMPATIBLE
and this return value implies nothing about whether the
image needs to be restored. - int
Attempts to restore the drawing surface of the image if the surface
had been lost since the last validate call. Also
validates this image against the given GraphicsConfiguration
parameter to see whether operations from this image to the
GraphicsConfiguration are compatible. An example of an
incompatible combination might be a situation where a VolatileImage
object was created on one graphics device and then was used
to render to a different graphics device. Since VolatileImage
objects tend to be very device-specific, this operation might
not work as intended, so the return code from this validate
call would note that incompatibility. A null or incorrect
value for gc may cause incorrect values to be returned from
validate and may cause later problems with rendering.
gc - a GraphicsConfiguration object for this image to be validated against. A null gc implies that the validate method should skip the compatibility test. - `java.awt.GraphicsConfiguration`
returns: IMAGE_OK if the image did not need validation
IMAGE_RESTORED if the image needed restoration.
Restoration implies that the contents of the image may have
been affected and the image may need to be re-rendered.
IMAGE_INCOMPATIBLE if the image is incompatible
with the GraphicsConfiguration object passed
into the validate method. Incompatibility
implies that the image may need to be recreated with a
new Component or
GraphicsConfiguration in order to get an image
that can be used successfully with this
GraphicsConfiguration.
An incompatible image is not checked for whether restoration
was necessary, so the state of the image is unchanged
after a return value of IMAGE_INCOMPATIBLE
and this return value implies nothing about whether the
image needs to be restored. - `int`cljdoc is a website building & hosting documentation for Clojure/Script libraries
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