java.awt.image

Класс BufferStrategy

java.lang. Объект

java.awt.image. BufferStrategy

Прямые Известные Подклассы:

Компонент. BltBufferStrategy, Компонент. FlipBufferStrategy

public abstract class BufferStrategy
extends Object

BufferStrategy класс представляет механизм, с которым можно организовать сложную память на детали Canvas или Window. Аппаратные и программные ограничения определяют, ли и как может быть реализована определенная буферная стратегия. Эти ограничения обнаружимы через возможности GraphicsConfiguration используемый, создавая Canvas или Window.

Это стоит отметить, что буфер сроков и поверхность предназначаются, чтобы быть синонимичными: область непрерывной памяти, или в видео памяти устройства или в системной памяти.

Есть несколько типов сложных буферных стратегий, включая последовательную кольцевую буферизацию и буферизацию копирования битового массива. Последовательная кольцевая буферизация (то есть, двойная или тройная буферизация) наиболее распространена; приложение тянет к единственному заднему буферу и затем перемещает содержание в переднюю сторону (дисплей) в единственном шаге, или копируя данные или перемещая видео указатель. Перемещение видео указателя обменивается буферами так, чтобы первый оттянутый буфер стал передним буфером, или что в настоящий момент выводится на экран на устройстве; это вызывают зеркальным отражением страницы.

Альтернативно, содержание заднего буфера может быть скопировано, или блитироваться вперед в цепочке вместо того, чтобы переместить видео указатель.

 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();
 

Since:

1.4

See Also:

Window, Canvas, GraphicsConfiguration, VolatileImage

Constructor Summary

Constructors

Constructor and Description
BufferStrategy()

Method Summary

Methods

Modifier and Type	Method and Description
abstract boolean	contentsLost() Returns whether the drawing buffer was lost since the last call to getDrawGraphics.
abstract boolean	contentsRestored() Returns whether the drawing buffer was recently restored from a lost state and reinitialized to the default background color (white).
void	dispose() Releases system resources currently consumed by this BufferStrategy and removes it from the associated Component.
abstract BufferCapabilities	getCapabilities() Returns the BufferCapabilities for this BufferStrategy.
abstract Graphics	getDrawGraphics() Creates a graphics context for the drawing buffer.
abstract void	show() Makes the next available buffer visible by either copying the memory (blitting) or changing the display pointer (flipping).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BufferStrategy

public BufferStrategy()

Method Detail

getCapabilities

public abstract BufferCapabilities getCapabilities()

Returns the BufferCapabilities for this BufferStrategy.

Returns:

the buffering capabilities of this strategy

getDrawGraphics

public abstract Graphics getDrawGraphics()

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.

Returns:

a graphics context for the drawing buffer

contentsLost

public abstract boolean contentsLost()

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.

Returns:

Whether or not the drawing buffer was lost since the last call to getDrawGraphics.

See Also:

VolatileImage

contentsRestored

public abstract boolean contentsRestored()

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.

Returns:

Whether or not the drawing buffer was restored since the last call to getDrawGraphics.

See Also:

VolatileImage

show

public abstract void show()

Makes the next available buffer visible by either copying the memory (blitting) or changing the display pointer (flipping).

dispose

public void dispose()

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.

Since:

1.6

See Also:

Window.createBufferStrategy(int), Canvas.createBufferStrategy(int), Window.getBufferStrategy(), Canvas.getBufferStrategy()