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/* VolatileImage.java -- |
/* VolatileImage.java -- a hardware-accelerated image buffer |
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Copyright (C) 2002 Free Software Foundation, Inc. |
Copyright (C) 2002, 2005 Free Software Foundation, Inc. |
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This file is part of GNU Classpath. |
This file is part of GNU Classpath. |
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import java.awt.Graphics2D; |
import java.awt.Graphics2D; |
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import java.awt.GraphicsConfiguration; |
import java.awt.GraphicsConfiguration; |
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import java.awt.Image; |
import java.awt.Image; |
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import java.awt.Transparency; |
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import java.awt.ImageCapabilities; |
import java.awt.ImageCapabilities; |
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/** STUBS ONLY */ |
/** |
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* VolatileImage represents a hardware-accelerated graphics buffer. |
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* The native graphics system may free or damage the resources |
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* occupied by a VolatileImage at any time. As such, one must |
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* frequently check the "validity" of the image buffer's resources. |
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* |
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* A volatile image's "validity" depends on multiple factors. Its |
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* resources may have become unavailble in which case you must |
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* reallocate them. If you move the image from one output device to |
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* another, you may need to recreate the image's resources if the new |
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* output device's capabilities don't match the old one's. Finally, |
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* if the contents of the image's buffer have been damaged you must |
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* re-render the image. |
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* |
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* VolatileImages should always be created using either |
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* Component.createVolatileImage or |
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* GraphicsConfiguration.createCompatibleVolatileImage. |
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*/ |
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public abstract class VolatileImage extends Image |
public abstract class VolatileImage extends Image |
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implements Transparency |
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{ |
{ |
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/** |
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* One of validate's possible return values. Indicates that the |
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* image buffer matches its graphics configuration's capabilities |
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* and that its resources are initialized and ready to be drawn |
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* into. Also implies that any existing image rendered to the |
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* buffer is intact and need not be re-rendered. |
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*/ |
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public static final int IMAGE_OK = 0; |
public static final int IMAGE_OK = 0; |
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/** |
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* One of validate's possible return values. Indicates that the |
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* image buffer has been restored, meaning that it is valid and |
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* ready-to-use but that its previous contents have been lost. This |
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* return value implies that the image needs to be re-rendered. |
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*/ |
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public static final int IMAGE_RESTORED = 1; |
public static final int IMAGE_RESTORED = 1; |
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/** |
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* One of validate's possible return values. Indicates that the |
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* image buffer type is unsupported by the current graphics |
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* configuration. The graphics configuration may have changed, for |
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* example if the image moved from one output device to another. |
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* This return value implies that the image buffer's resources |
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* should be re-acquired. |
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*/ |
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public static final int IMAGE_INCOMPATIBLE = 2; |
public static final int IMAGE_INCOMPATIBLE = 2; |
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/** |
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* This image's transparency type. One of Transparency.BITMASK, |
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* Transparency.OPAQUE or Transparency.TRANSLUCENT. |
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* |
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* @since 1.5 |
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*/ |
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protected int transparency; |
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/** |
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* Default constructor. VolatileImages should not be created |
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* directly. Rather, you should use Component.createVolatileImage |
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* or GraphicsConfiguration.createCompatibleVolatileImage. |
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*/ |
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public VolatileImage() |
public VolatileImage() |
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{ |
{ |
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} |
} |
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/** |
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* Returns an image representing the current state of the volatile |
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* image buffer. The returned image is static meaning that it is |
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* not updated after being created. It is a snapshot of the |
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* volatile image buffer at the time getSnapshot is called. |
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* |
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* This method, which reads pixels from the volatile image buffer, |
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* may be less-performant than methods that write pixels since |
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* VolatileImages are typically optimized for writing. |
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* |
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* @return a BufferedImage representing this VolatileImage |
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*/ |
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public abstract BufferedImage getSnapshot(); |
public abstract BufferedImage getSnapshot(); |
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/** |
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* Returns the width of this image buffer. |
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* |
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* @return the width of this VolatileImage |
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*/ |
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public abstract int getWidth(); |
public abstract int getWidth(); |
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/** |
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* Returns the height of this image buffer. |
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* |
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* @return the height of this VolatileImage |
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*/ |
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public abstract int getHeight(); |
public abstract int getHeight(); |
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/** |
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* Calling this method is equivalent to calling |
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* getSnapshot().getSource(). The ImageProducer produces pixels |
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* from the BufferedImage snapshot and not from the VolatileImage |
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* itself. Thus, changes to the VolatileImage that occur after this |
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* ImageProducer has been retrieved will not be reflected in the |
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* produced pixels. |
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* |
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* This method, which reads pixels from the volatile image buffer, |
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* may be less-performant than methods that write pixels since |
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* VolatileImages are typically optimized for writing. |
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* |
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* @return an ImageProducer for a static BufferedImage snapshot of |
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* this image buffer |
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*/ |
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public ImageProducer getSource() |
public ImageProducer getSource() |
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{ |
{ |
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return getSnapshot().getSource(); |
return getSnapshot().getSource(); |
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} |
} |
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/** |
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* Releases the system resources taken by this image. |
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*/ |
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public void flush() |
public void flush() |
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{ |
{ |
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} |
} |
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/** |
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* Returns a Graphics2D object that can be used to draw onto this |
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* image. This method is present for backwards-compatibility. It |
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* simply returns the result of createGraphics. |
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* |
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* @return a Graphics2D object that can be used to draw onto this |
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* image |
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*/ |
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public Graphics getGraphics() |
public Graphics getGraphics() |
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{ |
{ |
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return createGraphics(); |
return createGraphics(); |
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} |
} |
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/** |
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* Returns a Graphics2D object that can be used to draw onto this |
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* image. |
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* |
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* @return a Graphics2D object that can be used to draw onto this |
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* image |
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*/ |
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public abstract Graphics2D createGraphics(); |
public abstract Graphics2D createGraphics(); |
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/** |
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* Validates and restores this image. If the image buffer has |
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* become unavailable for further use since the last call to |
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* validate, validate will allocate a new image buffer. The image |
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* is also "validated" against the GraphicsConfiguration parameter. |
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* |
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* "Validating" the image means checking that the capabilities it |
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* requires of the output device are indeed supported by the given |
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* output device. If the image's characteristics, which can be |
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* highly output device-specific, are not supported by the graphics |
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* configuration, then IMAGE_INCOMPATIBLE will be returned. This |
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* can happen, for example, if this image was created on one output |
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* device, then validated against a different output device with |
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* different capabilities. Calling validate with a NULL gc argument |
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* causes validate to skip the validation test. |
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* |
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* @param gc graphics configuration against which to validate or |
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* NULL |
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* |
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* @return a code indicating the result of validation. One of: |
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* <ul> |
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* <li><code>IMAGE_OK</code> if the image did not need to be |
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* validated and didn't need to be restored</li> |
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* <li><code>IMAGE_RESTORED</code> if the image may need to be |
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* re-rendered.</li> |
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* <li><code>IMAGE_INCOMPATIBLE</code> if this image's |
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* requirements are not fulfilled by the graphics configuration |
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* parameter. This implies that you need to create a new |
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* VolatileImage for the different GraphicsConfiguration or |
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* Component. This return value implies nothing about whether the |
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* image is valid or needs to be re-rendered.</li> |
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* </ul> |
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*/ |
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public abstract int validate(GraphicsConfiguration gc); |
public abstract int validate(GraphicsConfiguration gc); |
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/** |
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* Returns true if the contents of the image buffer have been |
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* damaged or if the image buffer's resources have been reclaimed by |
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* the graphics system. You should call this method after a series |
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* of rendering operations to or from the image, to see if the image |
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* buffer needs to be revalidated or the image re-rendered. |
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* |
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* @return true if the validate should be called, false otherwise |
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*/ |
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public abstract boolean contentsLost(); |
public abstract boolean contentsLost(); |
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/** |
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* Returns the capabilities of this image buffer. |
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* |
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* @return the capabilities of this image buffer |
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*/ |
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public abstract ImageCapabilities getCapabilities(); |
public abstract ImageCapabilities getCapabilities(); |
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} // class VolatileImage |
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/** |
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* Returns the transparency type of this image. |
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* |
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* @return Transparency.OPAQUE, Transparency.BITMASK or |
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* Transparency.TRANSLUCENT |
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*/ |
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public int getTransparency() |
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{ |
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return transparency; |
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} |
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} |