Android APIs
public class

SurfaceView

extends View
java.lang.Object
   ↳ android.view.View
     ↳ android.view.SurfaceView
Known Direct Subclasses

Class Overview

Provides a dedicated drawing surface embedded inside of a view hierarchy. You can control the format of this surface and, if you like, its size; the SurfaceView takes care of placing the surface at the correct location on the screen

The surface is Z ordered so that it is behind the window holding its SurfaceView; the SurfaceView punches a hole in its window to allow its surface to be displayed. The view hierarchy will take care of correctly compositing with the Surface any siblings of the SurfaceView that would normally appear on top of it. This can be used to place overlays such as buttons on top of the Surface, though note however that it can have an impact on performance since a full alpha-blended composite will be performed each time the Surface changes.

The transparent region that makes the surface visible is based on the layout positions in the view hierarchy. If the post-layout transform properties are used to draw a sibling view on top of the SurfaceView, the view may not be properly composited with the surface.

Access to the underlying surface is provided via the SurfaceHolder interface, which can be retrieved by calling getHolder().

The Surface will be created for you while the SurfaceView's window is visible; you should implement surfaceCreated(SurfaceHolder) and surfaceDestroyed(SurfaceHolder) to discover when the Surface is created and destroyed as the window is shown and hidden.

One of the purposes of this class is to provide a surface in which a secondary thread can render into the screen. If you are going to use it this way, you need to be aware of some threading semantics:

Summary

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Inherited XML Attributes
From class android.view.View
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Inherited Constants
From class android.view.View
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Inherited Fields
From class android.view.View
Public Constructors
SurfaceView(Context context)
SurfaceView(Context context, AttributeSet attrs)
SurfaceView(Context context, AttributeSet attrs, int defStyleAttr)
SurfaceView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)
Public Methods
void draw(Canvas canvas)
Manually render this view (and all of its children) to the given Canvas.
boolean gatherTransparentRegion(Region region)
This is used by the RootView to perform an optimization when the view hierarchy contains one or several SurfaceView.
SurfaceHolder getHolder()
Return the SurfaceHolder providing access and control over this SurfaceView's underlying surface.
void setSecure(boolean isSecure)
Control whether the surface view's content should be treated as secure, preventing it from appearing in screenshots or from being viewed on non-secure displays.
void setVisibility(int visibility)
Set the enabled state of this view.
void setZOrderMediaOverlay(boolean isMediaOverlay)
Control whether the surface view's surface is placed on top of another regular surface view in the window (but still behind the window itself).
void setZOrderOnTop(boolean onTop)
Control whether the surface view's surface is placed on top of its window.
Protected Methods
void dispatchDraw(Canvas canvas)
Called by draw to draw the child views.
void onAttachedToWindow()
This is called when the view is attached to a window.
void onDetachedFromWindow()
This is called when the view is detached from a window.
void onMeasure(int widthMeasureSpec, int heightMeasureSpec)

Measure the view and its content to determine the measured width and the measured height.

void onWindowVisibilityChanged(int visibility)
Called when the window containing has change its visibility (between GONE, INVISIBLE, and VISIBLE).
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Inherited Methods
From class android.view.View
From class java.lang.Object
From interface android.graphics.drawable.Drawable.Callback
From interface android.view.KeyEvent.Callback
From interface android.view.accessibility.AccessibilityEventSource

Public Constructors

public SurfaceView (Context context)

Added in API level 1

Parameters
context Context

public SurfaceView (Context context, AttributeSet attrs)

Added in API level 1

Parameters
context Context
attrs AttributeSet

public SurfaceView (Context context, AttributeSet attrs, int defStyleAttr)

Added in API level 1

Parameters
context Context
attrs AttributeSet
defStyleAttr int

public SurfaceView (Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)

Added in API level 21

Parameters
context Context
attrs AttributeSet
defStyleAttr int
defStyleRes int

Public Methods

public void draw (Canvas canvas)

Added in API level 1

Manually render this view (and all of its children) to the given Canvas. The view must have already done a full layout before this function is called. When implementing a view, implement onDraw(android.graphics.Canvas) instead of overriding this method. If you do need to override this method, call the superclass version.

Parameters
canvas Canvas: The Canvas to which the View is rendered.

public boolean gatherTransparentRegion (Region region)

Added in API level 1

This is used by the RootView to perform an optimization when the view hierarchy contains one or several SurfaceView. SurfaceView is always considered transparent, but its children are not, therefore all View objects remove themselves from the global transparent region (passed as a parameter to this function).

Parameters
region Region: The transparent region for this ViewAncestor (window).
Returns
boolean Returns true if the effective visibility of the view at this point is opaque, regardless of the transparent region; returns false if it is possible for underlying windows to be seen behind the view.

public SurfaceHolder getHolder ()

Added in API level 1

Return the SurfaceHolder providing access and control over this SurfaceView's underlying surface.

Returns
SurfaceHolder SurfaceHolder The holder of the surface.

public void setSecure (boolean isSecure)

Added in API level 17

Control whether the surface view's content should be treated as secure, preventing it from appearing in screenshots or from being viewed on non-secure displays.

Note that this must be set before the surface view's containing window is attached to the window manager.

See FLAG_SECURE for details.

Parameters
isSecure boolean: True if the surface view is secure.

public void setVisibility (int visibility)

Added in API level 1

Set the enabled state of this view.

Parameters
visibility int: One of VISIBLE, INVISIBLE, or GONE.

public void setZOrderMediaOverlay (boolean isMediaOverlay)

Added in API level 5

Control whether the surface view's surface is placed on top of another regular surface view in the window (but still behind the window itself). This is typically used to place overlays on top of an underlying media surface view.

Note that this must be set before the surface view's containing window is attached to the window manager.

Calling this overrides any previous call to setZOrderOnTop(boolean).

Parameters
isMediaOverlay boolean

public void setZOrderOnTop (boolean onTop)

Added in API level 5

Control whether the surface view's surface is placed on top of its window. Normally it is placed behind the window, to allow it to (for the most part) appear to composite with the views in the hierarchy. By setting this, you cause it to be placed above the window. This means that none of the contents of the window this SurfaceView is in will be visible on top of its surface.

Note that this must be set before the surface view's containing window is attached to the window manager.

Calling this overrides any previous call to setZOrderMediaOverlay(boolean).

Parameters
onTop boolean

Protected Methods

protected void dispatchDraw (Canvas canvas)

Added in API level 1

Called by draw to draw the child views. This may be overridden by derived classes to gain control just before its children are drawn (but after its own view has been drawn).

Parameters
canvas Canvas: the canvas on which to draw the view

protected void onAttachedToWindow ()

Added in API level 1

This is called when the view is attached to a window. At this point it has a Surface and will start drawing. Note that this function is guaranteed to be called before onDraw(android.graphics.Canvas), however it may be called any time before the first onDraw -- including before or after onMeasure(int, int).

protected void onDetachedFromWindow ()

Added in API level 1

This is called when the view is detached from a window. At this point it no longer has a surface for drawing.

protected void onMeasure (int widthMeasureSpec, int heightMeasureSpec)

Added in API level 1

Measure the view and its content to determine the measured width and the measured height. This method is invoked by measure(int, int) and should be overridden by subclasses to provide accurate and efficient measurement of their contents.

CONTRACT: When overriding this method, you must call setMeasuredDimension(int, int) to store the measured width and height of this view. Failure to do so will trigger an IllegalStateException, thrown by measure(int, int). Calling the superclass' onMeasure(int, int) is a valid use.

The base class implementation of measure defaults to the background size, unless a larger size is allowed by the MeasureSpec. Subclasses should override onMeasure(int, int) to provide better measurements of their content.

If this method is overridden, it is the subclass's responsibility to make sure the measured height and width are at least the view's minimum height and width (getSuggestedMinimumHeight() and getSuggestedMinimumWidth()).

Parameters
widthMeasureSpec int: horizontal space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec.
heightMeasureSpec int: vertical space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec.

protected void onWindowVisibilityChanged (int visibility)

Added in API level 1

Called when the window containing has change its visibility (between GONE, INVISIBLE, and VISIBLE). Note that this tells you whether or not your window is being made visible to the window manager; this does not tell you whether or not your window is obscured by other windows on the screen, even if it is itself visible.

Parameters
visibility int: The new visibility of the window.