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package java.awt;
import java.awt.image.ColorModel;
The Composite interface, along with CompositeContext, defines the methods to compose a draw primitive with the underlying graphics area. After the Composite is set in the Graphics2D context, it combines a shape, text, or an image being rendered with the colors that have already been rendered according to pre-defined rules. The classes implementing this interface provide the rules and a method to create the context for a particular operation. CompositeContext is an environment used by the compositing operation, which is created by the Graphics2D prior to the start of the operation. CompositeContext contains private information and resources needed for a compositing operation. When the CompositeContext is no longer needed, the Graphics2D object disposes of it in order to reclaim resources allocated for the operation. Instances of classes implementing Composite must be immutable because the Graphics2D does not clone these objects when they are set as an attribute with the setComposite method or when the Graphics2D object is cloned. This is to avoid undefined rendering behavior of Graphics2D, resulting from the modification of the Composite object after it has been set in the Graphics2D context.
Since this interface must expose the contents of pixels on the target device or image to potentially arbitrary code, the use of custom objects which implement this interface when rendering directly to a screen device is governed by the readDisplayPixels AWTPermission. The permission check will occur when such a custom object is passed to the setComposite method of a Graphics2D retrieved from a Component.
See Also:
/**
* The {@code Composite} interface, along with
* {@link CompositeContext}, defines the methods to compose a draw
* primitive with the underlying graphics area.
* After the {@code Composite} is set in the
* {@link Graphics2D} context, it combines a shape, text, or an image
* being rendered with the colors that have already been rendered
* according to pre-defined rules. The classes
* implementing this interface provide the rules and a method to create
* the context for a particular operation.
* {@code CompositeContext} is an environment used by the
* compositing operation, which is created by the {@code Graphics2D}
* prior to the start of the operation. {@code CompositeContext}
* contains private information and resources needed for a compositing
* operation. When the {@code CompositeContext} is no longer needed,
* the {@code Graphics2D} object disposes of it in order to reclaim
* resources allocated for the operation.
* <p>
* Instances of classes implementing {@code Composite} must be
* immutable because the {@code Graphics2D} does not clone
* these objects when they are set as an attribute with the
* {@code setComposite} method or when the {@code Graphics2D}
* object is cloned. This is to avoid undefined rendering behavior of
* {@code Graphics2D}, resulting from the modification of
* the {@code Composite} object after it has been set in the
* {@code Graphics2D} context.
* <p>
* Since this interface must expose the contents of pixels on the
* target device or image to potentially arbitrary code, the use of
* custom objects which implement this interface when rendering directly
* to a screen device is governed by the {@code readDisplayPixels}
* {@link AWTPermission}. The permission check will occur when such
* a custom object is passed to the {@code setComposite} method
* of a {@code Graphics2D} retrieved from a {@link Component}.
* @see AlphaComposite
* @see CompositeContext
* @see Graphics2D#setComposite
*/
public interface Composite {
Creates a context containing state that is used to perform the compositing operation. In a multi-threaded environment, several contexts can exist simultaneously for a single Composite object. Params: - srcColorModel – the
ColorModel of the source - dstColorModel – the
ColorModel of the destination - hints – the hint that the context object uses to choose between
rendering alternatives
Returns: the CompositeContext object used to perform the compositing operation.
/**
* Creates a context containing state that is used to perform
* the compositing operation. In a multi-threaded environment,
* several contexts can exist simultaneously for a single
* {@code Composite} object.
* @param srcColorModel the {@link ColorModel} of the source
* @param dstColorModel the {@code ColorModel} of the destination
* @param hints the hint that the context object uses to choose between
* rendering alternatives
* @return the {@code CompositeContext} object used to perform the
* compositing operation.
*/
public CompositeContext createContext(ColorModel srcColorModel,
ColorModel dstColorModel,
RenderingHints hints);
}