Component.FlipBufferStrategy (Java SE 21 & JDK 21)
Description: declaration: module: java.desktop, package: java.awt, class: Component, class: FlipBufferStrategy
Keywords: java.awt.Component.FlipBufferStrategy class

Module java.desktop
Package java.awt

# Class Component.FlipBufferStrategy

java.lang.Object
java.awt.image.BufferStrategy
java.awt.Component.FlipBufferStrategy

Enclosing class:
  `Component`

protected class Component.FlipBufferStrategy extends BufferStrategy
Inner class for flipping buffers on a component. That component must be a `Canvas` or `Window` or `Applet`.

Since:
  1.4
See Also:
  - `Canvas`
  - `Window`
  - `Applet`
  - `BufferStrategy`

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected BufferCapabilities`
  `caps`
  The buffering capabilities
  `protected Image`
  `drawBuffer`
  The drawing buffer
  `protected VolatileImage`
  `drawVBuffer`
  The drawing buffer as a volatile image
  `protected int`
  `numBuffers`
  The number of buffers
  `protected boolean`
  `validatedContents`
  Whether or not the drawing buffer has been recently restored from a lost state.

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  `protected`
  `FlipBufferStrategy(int numBuffers, BufferCapabilities caps)`
  Creates a new flipping buffer strategy for this component.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `boolean`
  `contentsLost()`
  Returns whether the drawing buffer was lost since the last call to `getDrawGraphics`.
  `boolean`
  `contentsRestored()`
  Returns whether the drawing buffer was recently restored from a lost state and reinitialized to the default background color (white).
  `protected void`
  `createBuffers(int numBuffers, BufferCapabilities caps)`
  Creates one or more complex, flipping buffers with the given capabilities.
  `protected void`
  `destroyBuffers()`
  Destroys the buffers created through this object
  `void`
  `dispose()`
  Releases system resources currently consumed by this `BufferStrategy` and removes it from the associated Component.
  `protected void`
  `flip(BufferCapabilities.FlipContents flipAction)`
  Flipping moves the contents of the back buffer to the front buffer, either by copying or by moving the video pointer.
  `protected Image`
  `getBackBuffer()`
  Provides direct access to the back buffer as an image.
  `BufferCapabilities`
  `getCapabilities()`
  Returns the `BufferCapabilities` for this `BufferStrategy`.
  `Graphics`
  `getDrawGraphics()`
  Creates a graphics context for the drawing buffer.
  `protected void`
  `revalidate()`
  Restore the drawing buffer if it has been lost
  `void`
  `show()`
  Makes the next available buffer visible by either blitting or flipping.

  ### Methods declared in class java.lang.Object

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

- ## Field Details

  - ### numBuffers

    protected int numBuffers
    The number of buffers

  - ### caps

    protected BufferCapabilities caps
    The buffering capabilities

  - ### drawBuffer

    protected Image drawBuffer
    The drawing buffer

  - ### drawVBuffer

    protected VolatileImage drawVBuffer
    The drawing buffer as a volatile image

  - ### validatedContents

    protected boolean validatedContents
    Whether or not the drawing buffer has been recently restored from a lost state.

- ## Constructor Details

  - ### FlipBufferStrategy

    protected FlipBufferStrategy(int numBuffers, BufferCapabilities caps) throws AWTException
    Creates a new flipping buffer strategy for this component. The component must be a `Canvas` or `Window` or `Applet`.
    Parameters:
      `numBuffers` - the number of buffers
      `caps` - the capabilities of the buffers
    Throws:
      `AWTException` - if the capabilities supplied could not be supported or met
      `ClassCastException` - if the component is not a canvas or window.
      `IllegalStateException` - if the component has no peer
      `IllegalArgumentException` - if `numBuffers` is less than two, or if `BufferCapabilities.isPageFlipping` is not `true`.
    See Also:
      - `Canvas`
      - `Window`
      - `Applet`
      - `createBuffers(int, BufferCapabilities)`

- ## Method Details

  - ### createBuffers

    protected void createBuffers(int numBuffers, BufferCapabilities caps) throws AWTException
    Creates one or more complex, flipping buffers with the given capabilities.
    Parameters:
      `numBuffers` - number of buffers to create; must be greater than one
      `caps` - the capabilities of the buffers. `BufferCapabilities.isPageFlipping` must be `true`.
    Throws:
      `AWTException` - if the capabilities supplied could not be supported or met
      `IllegalStateException` - if the component has no peer
      `IllegalArgumentException` - if numBuffers is less than two, or if `BufferCapabilities.isPageFlipping` is not `true`.
    See Also:
      - `BufferCapabilities.isPageFlipping()`

  - ### getBackBuffer

    protected Image getBackBuffer()
    Provides direct access to the back buffer as an image.
    Returns:
      the back buffer as an image
    Throws:
      `IllegalStateException` - if the buffers have not yet been created

  - ### flip

    protected void flip(BufferCapabilities.FlipContents flipAction)
    Flipping moves the contents of the back buffer to the front buffer, either by copying or by moving the video pointer.
    Parameters:
      `flipAction` - an integer value describing the flipping action for the contents of the back buffer. This should be one of the values of the `BufferCapabilities.FlipContents` property.
    Throws:
      `IllegalStateException` - if the buffers have not yet been created
    See Also:
      - `BufferCapabilities.getFlipContents()`

  - ### destroyBuffers

    protected void destroyBuffers()
    Destroys the buffers created through this object

  - ### getCapabilities

    public BufferCapabilities getCapabilities()
    Description copied from class: `BufferStrategy`
    Returns the `BufferCapabilities` for this `BufferStrategy`.
    Specified by:
      `getCapabilities` in class `BufferStrategy`
    Returns:
      the buffering capabilities of this strategy

  - ### getDrawGraphics

    public Graphics getDrawGraphics()
    Description copied from class: `BufferStrategy`
    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.
    Specified by:
      `getDrawGraphics` in class `BufferStrategy`
    Returns:
      the graphics on 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 must be handled by the application.

  - ### revalidate

    protected void revalidate()
    Restore the drawing buffer if it has been lost

  - ### contentsLost

    public boolean contentsLost()
    Description copied from class: `BufferStrategy`
    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`.
    Specified by:
      `contentsLost` in class `BufferStrategy`
    Returns:
      whether the drawing buffer was lost since the last call to `getDrawGraphics`
    See Also:
      - `VolatileImage`

  - ### contentsRestored

    public boolean contentsRestored()
    Description copied from class: `BufferStrategy`
    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`.
    Specified by:
      `contentsRestored` in class `BufferStrategy`
    Returns:
      whether the drawing buffer was recently restored from a lost state and reinitialized to the default background color (white)
    See Also:
      - `VolatileImage`

  - ### show

    public void show()
    Makes the next available buffer visible by either blitting or flipping.
    Specified by:
      `show` in class `BufferStrategy`

  - ### 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.
    Overrides:
      `dispose` in class `BufferStrategy`
    Since:
      1.6
    See Also:
      - `Window.createBufferStrategy(int)`
      - `Canvas.createBufferStrategy(int)`
      - `Window.getBufferStrategy()`
      - `Canvas.getBufferStrategy()`