BufferStrategy class represents the mechanism with which
+ * to organize complex memory on a particular Canvas or
+ * Window. Hardware and software limitations determine whether and
+ * how a particular buffer strategy can be implemented. These limitations
+ * are detectible through the capabilities of the
+ * GraphicsConfiguration used when creating the
+ * Canvas or Window.
+ * + * It is worth noting that the terms buffer and surface are meant + * to be synonymous: an area of contiguous memory, either in video device + * memory or in system memory. + *
+ * There are several types of complex buffer strategies, including + * sequential ring buffering and blit buffering. + * Sequential ring buffering (i.e., double or triple + * buffering) is the most common; an application draws to a single back + * buffer and then moves the contents to the front (display) in a single + * step, either by copying the data or moving the video pointer. + * Moving the video pointer exchanges the buffers so that the first buffer + * drawn becomes the front buffer, or what is currently displayed on the + * device; this is called page flipping. + *
+ * Alternatively, the contents of the back buffer can be copied, or + * blitted forward in a chain instead of moving the video pointer. + *
+ *
+ * Double buffering: + * + * *********** *********** + * * * ------> * * + * [To display] <---- * Front B * Show * Back B. * <---- Rendering + * * * <------ * * + * *********** *********** + * + * Triple buffering: + * + * [To *********** *********** *********** + * display] * * --------+---------+------> * * + * <---- * Front B * Show * Mid. B. * * Back B. * <---- Rendering + * * * <------ * * <----- * * + * *********** *********** *********** + * + *+ *
+ * Here is an example of how buffer strategies can be created and used: + *
+ *
+ * // Check the capabilities of the GraphicsConfiguration
+ * ...
+ *
+ * // Create our component
+ * Window w = new Window(gc);
+ *
+ * // Show our window
+ * w.setVisible(true);
+ *
+ * // Create a general double-buffering strategy
+ * w.createBufferStrategy(2);
+ * BufferStrategy strategy = w.getBufferStrategy();
+ *
+ * // Main loop
+ * while (!done) {
+ * // Prepare for rendering the next frame
+ * // ...
+ *
+ * // Render single frame
+ * do {
+ * // The following loop ensures that the contents of the drawing buffer
+ * // are consistent in case the underlying surface was recreated
+ * do {
+ * // Get a new graphics context every time through the loop
+ * // to make sure the strategy is validated
+ * Graphics graphics = strategy.getDrawGraphics();
+ *
+ * // Render to graphics
+ * // ...
+ *
+ * // Dispose the graphics
+ * graphics.dispose();
+ *
+ * // Repeat the rendering if the drawing buffer contents
+ * // were restored
+ * } while (strategy.contentsRestored());
+ *
+ * // Display the buffer
+ * strategy.show();
+ *
+ * // Repeat the rendering if the drawing buffer was lost
+ * } while (strategy.contentsLost());
+ * }
+ *
+ * // Dispose the window
+ * w.setVisible(false);
+ * w.dispose();
+ * BufferCapabilities for this
+ * BufferStrategy.
+ *
+ * @return the buffering capabilities of this strategy
+ */
+ public abstract BufferCapabilities getCapabilities();
+
+ /**
+ * Creates a graphics context for the drawing buffer. This method may not
+ * be synchronized for performance reasons; use of this method by multiple
+ * threads should be handled at the application level. Disposal of the
+ * graphics object obtained must be handled by the application.
+ *
+ * @return a graphics context for the drawing buffer
+ */
+ public abstract Graphics getDrawGraphics();
+
+ /**
+ * Returns whether the drawing buffer was lost since the last call to
+ * getDrawGraphics. Since the buffers in a buffer strategy
+ * are usually type VolatileImage, they may become lost.
+ * For a discussion on lost buffers, see VolatileImage.
+ *
+ * @return Whether or not the drawing buffer was lost since the last call
+ * to getDrawGraphics.
+ * @see java.awt.image.VolatileImage
+ */
+ public abstract boolean contentsLost();
+
+ /**
+ * Returns whether the drawing buffer was recently restored from a lost
+ * state and reinitialized to the default background color (white).
+ * Since the buffers in a buffer strategy are usually type
+ * VolatileImage, they may become lost. If a surface has
+ * been recently restored from a lost state since the last call to
+ * getDrawGraphics, it may require repainting.
+ * For a discussion on lost buffers, see VolatileImage.
+ *
+ * @return Whether or not the drawing buffer was restored since the last
+ * call to getDrawGraphics.
+ * @see java.awt.image.VolatileImage
+ */
+ public abstract boolean contentsRestored();
+
+ /**
+ * Makes the next available buffer visible by either copying the memory
+ * (blitting) or changing the display pointer (flipping).
+ */
+ public abstract void show();
+
+ /**
+ * Releases system resources currently consumed by this
+ * BufferStrategy and
+ * removes it from the associated Component. After invoking this
+ * method, getBufferStrategy will return null. Trying
+ * to use a BufferStrategy after it has been disposed will
+ * result in undefined behavior.
+ *
+ * @see java.awt.Window#createBufferStrategy
+ * @see java.awt.Canvas#createBufferStrategy
+ * @see java.awt.Window#getBufferStrategy
+ * @see java.awt.Canvas#getBufferStrategy
+ * @since 1.6
+ */
+ public void dispose() {
+ }
+}