125 lines
4.7 KiB
Java
125 lines
4.7 KiB
Java
/* BufferStrategy.java -- describes image buffering resources
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Copyright (C) 2002, 2005 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.awt.image;
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import java.awt.BufferCapabilities;
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import java.awt.Graphics;
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/**
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* This class describes a strategy for managing image buffering
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* resources on a Canvas or Window. A given buffer strategy may make
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* use of hardware acceleration or take advantage of features of the
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* native graphics system. Examples of buffering strategies are
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* double or triple buffering using either flipping or blitting. For
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* the details of these algorithms see BufferCapabilities.
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*
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* To use a buffer strategy, you retrieve it from either the current
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* GraphicsConfiguration or from the Component on which you'd like to
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* draw. Then you can query the strategy's capabilities to make sure
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* they're suitable.
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*
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* If the strategy's capabilities are suitable, you can obtain a
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* graphics object and use it to draw with this strategy. Drawing
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* with a buffer strategy requires extra care, however. You'll need
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* to manually cause the next buffer to be shown on the output device.
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* And since buffer strategies are usually implemented with a
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* VolatileImage, you must frequently check that the contents of the
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* buffer are valid and that the buffer still exists.
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*
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* A buffer strategy is usually implemented using a VolatileImage.
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*
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* @see VolatileImage
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* @since 1.4
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*/
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public abstract class BufferStrategy
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{
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/**
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* Creates a new buffer strategy.
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*/
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public BufferStrategy()
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{
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}
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/**
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* Retrieves the capabilities of this buffer strategy.
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*
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* @return this buffer strategy's capabilities
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*/
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public abstract BufferCapabilities getCapabilities();
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/**
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* Retrieves a graphics object that can be used to draw using this
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* buffer strategy. This method may not be synchronized so be
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* careful when calling it from multiple threads. You also must
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* manually dispose of this graphics object.
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*
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* @return a graphics object that can be used to draw using this
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* buffer strategy
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*/
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public abstract Graphics getDrawGraphics();
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/**
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* Returns whether or not the buffer's resources have been reclaimed
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* by the native graphics system. If the buffer resources have been
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* lost then you'll need to obtain new resources before drawing
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* again. For details, see the documentation for VolatileImage.
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*
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* @return true if the contents were lost, false otherwise
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*/
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public abstract boolean contentsLost();
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/**
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* Returns whether or not the buffer's resources were re-created and
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* cleared to the default background color. If the buffer's
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* resources have recently been re-created and initialized then the
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* buffer's image may need to be re-rendered. For details, see the
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* documentation for VolatileImage.
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*
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* @return true if the contents were restored, false otherwise
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*/
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public abstract boolean contentsRestored();
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/**
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* Applies this buffer strategy. In other words, this method brings
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* the contents of the back or intermediate buffers to the front
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* buffer.
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*/
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public abstract void show();
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}
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