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package java.awt;
import java.awt.image.ColorModel;
/**
* The <code>Composite</code> interface, along with
* {@link CompositeContext}, defines the methods to compose a draw
* primitive with the underlying graphics area.
* After the <code>Composite</code> 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</code> is an environment used by the
* compositing operation, which is created by the <code>Graphics2D</code>
* prior to the start of the operation. <code>CompositeContext</code>
* contains private information and resources needed for a compositing
* operation. When the <code>CompositeContext</code> is no longer needed,
* the <code>Graphics2D</code> object disposes of it in order to reclaim
* resources allocated for the operation.
* <p>
* Instances of classes implementing <code>Composite</code> must be
* immutable because the <code>Graphics2D</code> does not clone
* these objects when they are set as an attribute with the
* <code>setComposite</code> method or when the <code>Graphics2D</code>
* object is cloned. This is to avoid undefined rendering behavior of
* <code>Graphics2D</code>, resulting from the modification of
* the <code>Composite</code> object after it has been set in the
* <code>Graphics2D</code> 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</code>
* {@link AWTPermission}. The permission check will occur when such
* a custom object is passed to the <code>setComposite</code> method
* of a <code>Graphics2D</code> 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
* <code>Composite</code> object.
* @param srcColorModel the {@link ColorModel} of the source
* @param dstColorModel the <code>ColorModel</code> of the destination
* @param hints the hint that the context object uses to choose between
* rendering alternatives
* @return the <code>CompositeContext</code> object used to perform the
* compositing operation.
*/
public CompositeContext createContext(ColorModel srcColorModel,
ColorModel dstColorModel,
RenderingHints hints);
}