IT. Expert System.

public interface SurfaceHolder

• Nested Class Summary

  Nested Classes

  Modifier and Type	Interface and Description
  static class	SurfaceHolder.BadSurfaceTypeException Exception that is thrown from lockCanvas() when called on a Surface whose type is SURFACE_TYPE_PUSH_BUFFERS.
  static interface	SurfaceHolder.Callback A client may implement this interface to receive information about changes to the surface.
  static interface	SurfaceHolder.Callback2 Additional callbacks that can be received for SurfaceHolder.Callback.

• Field Summary

  Fields

  Modifier and Type	Field and Description
  static int	SURFACE_TYPE_GPU Deprecated. this is ignored, this value is set automatically when needed.
  static int	SURFACE_TYPE_HARDWARE Deprecated. this is ignored, this value is set automatically when needed.
  static int	SURFACE_TYPE_NORMAL Deprecated. this is ignored, this value is set automatically when needed.
  static int	SURFACE_TYPE_PUSH_BUFFERS Deprecated. this is ignored, this value is set automatically when needed.

• Method Summary

  Methods

  Modifier and Type	Method and Description
  void	addCallback(SurfaceHolder.Callback callback) Add a Callback interface for this holder.
  Surface	getSurface() Direct access to the surface object.
  Rect	getSurfaceFrame() Retrieve the current size of the surface.
  boolean	isCreating() Use this method to find out if the surface is in the process of being created from Callback methods.
  Canvas	lockCanvas() Start editing the pixels in the surface.
  Canvas	lockCanvas(Rect dirty) Just like lockCanvas() but allows specification of a dirty rectangle.
  void	removeCallback(SurfaceHolder.Callback callback) Removes a previously added Callback interface from this holder.
  void	setFixedSize(int width, int height) Make the surface a fixed size.
  void	setFormat(int format) Set the desired PixelFormat of the surface.
  void	setKeepScreenOn(boolean screenOn) Enable or disable option to keep the screen turned on while this surface is displayed.
  void	setSizeFromLayout() Allow the surface to resized based on layout of its container (this is the default).
  void	setType(int type) Deprecated. this is ignored, this value is set automatically when needed.
  void	unlockCanvasAndPost(Canvas canvas) Finish editing pixels in the surface.

• Field Detail

  • SURFACE_TYPE_NORMAL

    @Deprecated
    static final int SURFACE_TYPE_NORMAL

    Deprecated. this is ignored, this value is set automatically when needed.

    See Also:

    Constant Field Values

  • SURFACE_TYPE_HARDWARE

    @Deprecated
    static final int SURFACE_TYPE_HARDWARE

    Deprecated. this is ignored, this value is set automatically when needed.

    See Also:

    Constant Field Values

  • SURFACE_TYPE_GPU

    @Deprecated
    static final int SURFACE_TYPE_GPU

    Deprecated. this is ignored, this value is set automatically when needed.

    See Also:

    Constant Field Values

  • SURFACE_TYPE_PUSH_BUFFERS

    @Deprecated
    static final int SURFACE_TYPE_PUSH_BUFFERS

    Deprecated. this is ignored, this value is set automatically when needed.

    See Also:

    Constant Field Values

• Method Detail

  • addCallback

    void addCallback(SurfaceHolder.Callback callback)

    Add a Callback interface for this holder. There can several Callback interfaces associated with a holder.

    Parameters:

    callback - The new Callback interface.

  • removeCallback

    void removeCallback(SurfaceHolder.Callback callback)

    Removes a previously added Callback interface from this holder.

    Parameters:

    callback - The Callback interface to remove.

  • isCreating

    boolean isCreating()

    Use this method to find out if the surface is in the process of being created from Callback methods. This is intended to be used with SurfaceHolder.Callback.surfaceChanged(android.view.SurfaceHolder, int, int, int).

    Returns:

    true if the surface is in the process of being created.

  • setType

    @Deprecated
    void setType(int type)

    Deprecated. this is ignored, this value is set automatically when needed.
    Sets the surface's type.

  • setFixedSize

    void setFixedSize(int width,
                    int height)

    Make the surface a fixed size. It will never change from this size. When working with a SurfaceView, this must be called from the same thread running the SurfaceView's window.

    Parameters:

    width - The surface's width.

    height - The surface's height.

  • setSizeFromLayout

    void setSizeFromLayout()

    Allow the surface to resized based on layout of its container (this is the default). When this is enabled, you should monitor SurfaceHolder.Callback.surfaceChanged(android.view.SurfaceHolder, int, int, int) for changes to the size of the surface. When working with a SurfaceView, this must be called from the same thread running the SurfaceView's window.

  • setFormat

    void setFormat(int format)

    Set the desired PixelFormat of the surface. The default is OPAQUE. When working with a SurfaceView, this must be called from the same thread running the SurfaceView's window.

    Parameters:

    format - A constant from PixelFormat.

    See Also:

    PixelFormat

  • setKeepScreenOn

    void setKeepScreenOn(boolean screenOn)

    Enable or disable option to keep the screen turned on while this surface is displayed. The default is false, allowing it to turn off. This is safe to call from any thread.

    Parameters:

    screenOn - Set to true to force the screen to stay on, false to allow it to turn off.

  • lockCanvas

    Canvas lockCanvas()

    Start editing the pixels in the surface. The returned Canvas can be used to draw into the surface's bitmap. A null is returned if the surface has not been created or otherwise cannot be edited. You will usually need to implement Callback.surfaceCreated to find out when the Surface is available for use.

    The content of the Surface is never preserved between unlockCanvas() and lockCanvas(), for this reason, every pixel within the Surface area must be written. The only exception to this rule is when a dirty rectangle is specified, in which case, non-dirty pixels will be preserved.

    If you call this repeatedly when the Surface is not ready (before Callback.surfaceCreated or after Callback.surfaceDestroyed), your calls will be throttled to a slow rate in order to avoid consuming CPU.

    If null is not returned, this function internally holds a lock until the corresponding unlockCanvasAndPost(android.graphics.Canvas) call, preventing SurfaceView from creating, destroying, or modifying the surface while it is being drawn. This can be more convenient than accessing the Surface directly, as you do not need to do special synchronization with a drawing thread in Callback.surfaceDestroyed.

    Returns:

    Canvas Use to draw into the surface.

  • lockCanvas

    Canvas lockCanvas(Rect dirty)

    Just like lockCanvas() but allows specification of a dirty rectangle. Every pixel within that rectangle must be written; however pixels outside the dirty rectangle will be preserved by the next call to lockCanvas().

    Parameters:

    dirty - Area of the Surface that will be modified.

    Returns:

    Canvas Use to draw into the surface.

    See Also:

    lockCanvas()

  • unlockCanvasAndPost

    void unlockCanvasAndPost(Canvas canvas)

    Finish editing pixels in the surface. After this call, the surface's current pixels will be shown on the screen, but its content is lost, in particular there is no guarantee that the content of the Surface will remain unchanged when lockCanvas() is called again.

    Parameters:

    canvas - The Canvas previously returned by lockCanvas().

    See Also:

    lockCanvas()

  • getSurfaceFrame

    Rect getSurfaceFrame()

    Retrieve the current size of the surface. Note: do not modify the returned Rect. This is only safe to call from the thread of SurfaceView's window, or while inside of lockCanvas().

    Returns:

    Rect The surface's dimensions. The left and top are always 0.

  • getSurface

    Surface getSurface()

    Direct access to the surface object. The Surface may not always be available -- for example when using a SurfaceView the holder's Surface is not created until the view has been attached to the window manager and performed a layout in order to determine the dimensions and screen position of the Surface. You will thus usually need to implement Callback.surfaceCreated to find out when the Surface is available for use.

    Note that if you directly access the Surface from another thread, it is critical that you correctly implement Callback.surfaceCreated and Callback.surfaceDestroyed to ensure that thread only accesses the Surface while it is valid, and that the Surface does not get destroyed while the thread is using it.

    This method is intended to be used by frameworks which often need direct access to the Surface object (usually to pass it to native code). When designing APIs always use SurfaceHolder to pass surfaces around as opposed to the Surface object itself. A rule of thumb is that application code should never have to call this method.

    Returns:

    Surface The surface.