IT. Expert System.

public final class ViewTreeObserver
extends Object

• Nested Class Summary

  Nested Classes

  Modifier and Type	Class and Description
  static class	ViewTreeObserver.InternalInsetsInfo Parameters used with OnComputeInternalInsetsListener.
  static interface	ViewTreeObserver.OnComputeInternalInsetsListener Interface definition for a callback to be invoked when layout has completed and the client can compute its interior insets.
  static interface	ViewTreeObserver.OnDrawListener Interface definition for a callback to be invoked when the view tree is about to be drawn.
  static interface	ViewTreeObserver.OnGlobalFocusChangeListener Interface definition for a callback to be invoked when the focus state within the view tree changes.
  static interface	ViewTreeObserver.OnGlobalLayoutListener Interface definition for a callback to be invoked when the global layout state or the visibility of views within the view tree changes.
  static interface	ViewTreeObserver.OnPreDrawListener Interface definition for a callback to be invoked when the view tree is about to be drawn.
  static interface	ViewTreeObserver.OnScrollChangedListener Interface definition for a callback to be invoked when something in the view tree has been scrolled.
  static interface	ViewTreeObserver.OnTouchModeChangeListener Interface definition for a callback to be invoked when the touch mode changes.

• Method Summary

  Methods

  Modifier and Type	Method and Description
  void	addOnComputeInternalInsetsListener(ViewTreeObserver.OnComputeInternalInsetsListener listener) Register a callback to be invoked when the invoked when it is time to compute the window's internal insets.
  void	addOnDrawListener(ViewTreeObserver.OnDrawListener listener) Register a callback to be invoked when the view tree is about to be drawn.
  void	addOnGlobalFocusChangeListener(ViewTreeObserver.OnGlobalFocusChangeListener listener) Register a callback to be invoked when the focus state within the view tree changes.
  void	addOnGlobalLayoutListener(ViewTreeObserver.OnGlobalLayoutListener listener) Register a callback to be invoked when the global layout state or the visibility of views within the view tree changes
  void	addOnPreDrawListener(ViewTreeObserver.OnPreDrawListener listener) Register a callback to be invoked when the view tree is about to be drawn
  void	addOnScrollChangedListener(ViewTreeObserver.OnScrollChangedListener listener) Register a callback to be invoked when a view has been scrolled.
  void	addOnTouchModeChangeListener(ViewTreeObserver.OnTouchModeChangeListener listener) Register a callback to be invoked when the invoked when the touch mode changes.
  void	dispatchOnDraw() Notifies registered listeners that the drawing pass is about to start.
  void	dispatchOnGlobalLayout() Notifies registered listeners that a global layout happened.
  boolean	dispatchOnPreDraw() Notifies registered listeners that the drawing pass is about to start.
  boolean	isAlive() Indicates whether this ViewTreeObserver is alive.
  void	removeGlobalOnLayoutListener(ViewTreeObserver.OnGlobalLayoutListener victim) Deprecated. Use #removeOnGlobalLayoutListener instead
  void	removeOnComputeInternalInsetsListener(ViewTreeObserver.OnComputeInternalInsetsListener victim) Remove a previously installed internal insets computation callback
  void	removeOnDrawListener(ViewTreeObserver.OnDrawListener victim) Remove a previously installed pre-draw callback.
  void	removeOnGlobalFocusChangeListener(ViewTreeObserver.OnGlobalFocusChangeListener victim) Remove a previously installed focus change callback.
  void	removeOnGlobalLayoutListener(ViewTreeObserver.OnGlobalLayoutListener victim) Remove a previously installed global layout callback
  void	removeOnPreDrawListener(ViewTreeObserver.OnPreDrawListener victim) Remove a previously installed pre-draw callback
  void	removeOnScrollChangedListener(ViewTreeObserver.OnScrollChangedListener victim) Remove a previously installed scroll-changed callback
  void	removeOnTouchModeChangeListener(ViewTreeObserver.OnTouchModeChangeListener victim) Remove a previously installed touch mode change callback

  • Methods inherited from class java.lang.Object

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

• Method Detail

  • addOnGlobalFocusChangeListener

    public void addOnGlobalFocusChangeListener(ViewTreeObserver.OnGlobalFocusChangeListener listener)

    Register a callback to be invoked when the focus state within the view tree changes.

    Parameters:

    listener - The callback to add

    Throws:

    IllegalStateException - If isAlive() returns false

  • removeOnGlobalFocusChangeListener

    public void removeOnGlobalFocusChangeListener(ViewTreeObserver.OnGlobalFocusChangeListener victim)

    Remove a previously installed focus change callback.

    Parameters:

    victim - The callback to remove

    Throws:

    IllegalStateException - If isAlive() returns false

    See Also:

    addOnGlobalFocusChangeListener(OnGlobalFocusChangeListener)

  • addOnGlobalLayoutListener

    public void addOnGlobalLayoutListener(ViewTreeObserver.OnGlobalLayoutListener listener)

    Register a callback to be invoked when the global layout state or the visibility of views within the view tree changes

    Parameters:

    listener - The callback to add

    Throws:

    IllegalStateException - If isAlive() returns false

  • removeGlobalOnLayoutListener

    @Deprecated
    public void removeGlobalOnLayoutListener(ViewTreeObserver.OnGlobalLayoutListener victim)

    Deprecated. Use #removeOnGlobalLayoutListener instead
    Remove a previously installed global layout callback

    Parameters:

    victim - The callback to remove

    Throws:

    IllegalStateException - If isAlive() returns false

    See Also:

    addOnGlobalLayoutListener(OnGlobalLayoutListener)

  • removeOnGlobalLayoutListener

    public void removeOnGlobalLayoutListener(ViewTreeObserver.OnGlobalLayoutListener victim)

    Remove a previously installed global layout callback

    Parameters:

    victim - The callback to remove

    Throws:

    IllegalStateException - If isAlive() returns false

    See Also:

    addOnGlobalLayoutListener(OnGlobalLayoutListener)

  • addOnPreDrawListener

    public void addOnPreDrawListener(ViewTreeObserver.OnPreDrawListener listener)

    Register a callback to be invoked when the view tree is about to be drawn

    Parameters:

    listener - The callback to add

    Throws:

    IllegalStateException - If isAlive() returns false

  • removeOnPreDrawListener

    public void removeOnPreDrawListener(ViewTreeObserver.OnPreDrawListener victim)

    Remove a previously installed pre-draw callback

    Parameters:

    victim - The callback to remove

    Throws:

    IllegalStateException - If isAlive() returns false

    See Also:

    addOnPreDrawListener(OnPreDrawListener)

  • addOnDrawListener

    public void addOnDrawListener(ViewTreeObserver.OnDrawListener listener)

    Register a callback to be invoked when the view tree is about to be drawn.

    Note: this method cannot be invoked from ViewTreeObserver.OnDrawListener.onDraw().

    Parameters:

    listener - The callback to add

    Throws:

    IllegalStateException - If isAlive() returns false

  • removeOnDrawListener

    public void removeOnDrawListener(ViewTreeObserver.OnDrawListener victim)

    Remove a previously installed pre-draw callback.

    Note: this method cannot be invoked from ViewTreeObserver.OnDrawListener.onDraw().

    Parameters:

    victim - The callback to remove

    Throws:

    IllegalStateException - If isAlive() returns false

    See Also:

    addOnDrawListener(OnDrawListener)

  • addOnScrollChangedListener

    public void addOnScrollChangedListener(ViewTreeObserver.OnScrollChangedListener listener)

    Register a callback to be invoked when a view has been scrolled.

    Parameters:

    listener - The callback to add

    Throws:

    IllegalStateException - If isAlive() returns false

  • removeOnScrollChangedListener

    public void removeOnScrollChangedListener(ViewTreeObserver.OnScrollChangedListener victim)

    Remove a previously installed scroll-changed callback

    Parameters:

    victim - The callback to remove

    Throws:

    IllegalStateException - If isAlive() returns false

    See Also:

    addOnScrollChangedListener(OnScrollChangedListener)

  • addOnTouchModeChangeListener

    public void addOnTouchModeChangeListener(ViewTreeObserver.OnTouchModeChangeListener listener)

    Register a callback to be invoked when the invoked when the touch mode changes.

    Parameters:

    listener - The callback to add

    Throws:

    IllegalStateException - If isAlive() returns false

  • removeOnTouchModeChangeListener

    public void removeOnTouchModeChangeListener(ViewTreeObserver.OnTouchModeChangeListener victim)

    Remove a previously installed touch mode change callback

    Parameters:

    victim - The callback to remove

    Throws:

    IllegalStateException - If isAlive() returns false

    See Also:

    addOnTouchModeChangeListener(OnTouchModeChangeListener)

  • addOnComputeInternalInsetsListener

    public void addOnComputeInternalInsetsListener(ViewTreeObserver.OnComputeInternalInsetsListener listener)

    Register a callback to be invoked when the invoked when it is time to compute the window's internal insets.

    Parameters:

    listener - The callback to add

    Throws:

    IllegalStateException - If isAlive() returns false We are not yet ready to commit to this API and support it, so

  • removeOnComputeInternalInsetsListener

    public void removeOnComputeInternalInsetsListener(ViewTreeObserver.OnComputeInternalInsetsListener victim)

    Remove a previously installed internal insets computation callback

    Parameters:

    victim - The callback to remove

    Throws:

    IllegalStateException - If isAlive() returns false

    See Also:

    We are not yet ready to commit to this API and support it, so

  • isAlive

    public boolean isAlive()

    Indicates whether this ViewTreeObserver is alive. When an observer is not alive, any call to a method (except this one) will throw an exception. If an application keeps a long-lived reference to this ViewTreeObserver, it should always check for the result of this method before calling any other method.

    Returns:

    True if this object is alive and be used, false otherwise.

  • dispatchOnGlobalLayout

    public final void dispatchOnGlobalLayout()

    Notifies registered listeners that a global layout happened. This can be called manually if you are forcing a layout on a View or a hierarchy of Views that are not attached to a Window or in the GONE state.

  • dispatchOnPreDraw

    public final boolean dispatchOnPreDraw()

    Notifies registered listeners that the drawing pass is about to start. If a listener returns true, then the drawing pass is canceled and rescheduled. This can be called manually if you are forcing the drawing on a View or a hierarchy of Views that are not attached to a Window or in the GONE state.

    Returns:

    True if the current draw should be canceled and resceduled, false otherwise.

  • dispatchOnDraw

    public final void dispatchOnDraw()

    Notifies registered listeners that the drawing pass is about to start.