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Added in API level 1

SurfaceHolder

public interface SurfaceHolder

android.view.SurfaceHolder


Abstract interface to someone holding a display surface. Allows you to control the surface size and format, edit the pixels in the surface, and monitor changes to the surface. This interface is typically available through the SurfaceView class.

When using this interface from a thread other than the one running its SurfaceView, you will want to carefully read the methods lockCanvas() and Callback.surfaceCreated().

Summary

Nested classes

class SurfaceHolder.BadSurfaceTypeException

Exception that is thrown from lockCanvas() when called on a Surface whose type is SURFACE_TYPE_PUSH_BUFFERS. 

interface SurfaceHolder.Callback

A client may implement this interface to receive information about changes to the surface. 

interface SurfaceHolder.Callback2

Additional callbacks that can be received for SurfaceHolder.Callback

Constants

int SURFACE_TYPE_GPU

This constant was deprecated in API level 5. this is ignored, this value is set automatically when needed.

int SURFACE_TYPE_HARDWARE

This constant was deprecated in API level 5. this is ignored, this value is set automatically when needed.

int SURFACE_TYPE_NORMAL

This constant was deprecated in API level 11. this is ignored, this value is set automatically when needed.

int SURFACE_TYPE_PUSH_BUFFERS

This constant was deprecated in API level 11. this is ignored, this value is set automatically when needed.

Public methods

abstract void addCallback(SurfaceHolder.Callback callback)

Add a Callback interface for this holder.

abstract Surface getSurface()

Direct access to the surface object.

abstract Rect getSurfaceFrame()

Retrieve the current size of the surface.

abstract boolean isCreating()

Use this method to find out if the surface is in the process of being created from Callback methods.

abstract Canvas lockCanvas(Rect dirty)

Just like lockCanvas() but allows specification of a dirty rectangle.

abstract Canvas lockCanvas()

Start editing the pixels in the surface.

abstract void removeCallback(SurfaceHolder.Callback callback)

Removes a previously added Callback interface from this holder.

abstract void setFixedSize(int width, int height)

Make the surface a fixed size.

abstract void setFormat(int format)

Set the desired PixelFormat of the surface.

abstract void setKeepScreenOn(boolean screenOn)

Enable or disable option to keep the screen turned on while this surface is displayed.

abstract void setSizeFromLayout()

Allow the surface to resized based on layout of its container (this is the default).

abstract void setType(int type)

This method was deprecated in API level 11. this is ignored, this value is set automatically when needed.

abstract void unlockCanvasAndPost(Canvas canvas)

Finish editing pixels in the surface.

Constants

SURFACE_TYPE_GPU

Added in API level 1
int SURFACE_TYPE_GPU

This constant was deprecated in API level 5.
this is ignored, this value is set automatically when needed.

Constant Value: 2 (0x00000002)

SURFACE_TYPE_HARDWARE

Added in API level 1
int SURFACE_TYPE_HARDWARE

This constant was deprecated in API level 5.
this is ignored, this value is set automatically when needed.

Constant Value: 1 (0x00000001)

SURFACE_TYPE_NORMAL

Added in API level 1
int SURFACE_TYPE_NORMAL

This constant was deprecated in API level 11.
this is ignored, this value is set automatically when needed.

Constant Value: 0 (0x00000000)

SURFACE_TYPE_PUSH_BUFFERS

Added in API level 1
int SURFACE_TYPE_PUSH_BUFFERS

This constant was deprecated in API level 11.
this is ignored, this value is set automatically when needed.

Constant Value: 3 (0x00000003)

Public methods

addCallback

Added in API level 1
void addCallback (SurfaceHolder.Callback callback)

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

Parameters
callback SurfaceHolder.Callback: The new Callback interface.

getSurface

Added in API level 1
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).

Returns
Surface Surface The surface.

getSurfaceFrame

Added in API level 1
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 Rect The surface's dimensions. The left and top are always 0.

isCreating

Added in API level 1
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 surfaceChanged(SurfaceHolder, int, int, int).

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

lockCanvas

Added in API level 1
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 Rect: Area of the Surface that will be modified.
Returns
Canvas Canvas Use to draw into the surface.

See also:

lockCanvas

Added in API level 1
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(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 Canvas Use to draw into the surface.

removeCallback

Added in API level 1
void removeCallback (SurfaceHolder.Callback callback)

Removes a previously added Callback interface from this holder.

Parameters
callback SurfaceHolder.Callback: The Callback interface to remove.

setFixedSize

Added in API level 1
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 int: The surface's width.
height int: The surface's height.

setFormat

Added in API level 1
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 int: A constant from PixelFormat.

See also:

setKeepScreenOn

Added in API level 1
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 boolean: Set to true to force the screen to stay on, false to allow it to turn off.

setSizeFromLayout

Added in API level 1
void setSizeFromLayout ()

Allow the surface to resized based on layout of its container (this is the default). When this is enabled, you should monitor surfaceChanged(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.

setType

Added in API level 1
void setType (int type)

This method was deprecated in API level 11.
this is ignored, this value is set automatically when needed.

Sets the surface's type.

Parameters
type int

unlockCanvasAndPost

Added in API level 1
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 Canvas: The Canvas previously returned by lockCanvas().

See also:

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