ViewTreeObserver Class
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
A view tree observer is used to register listeners that can be notified of global changes in the view tree.
[Android.Runtime.Register("android/view/ViewTreeObserver", DoNotGenerateAcw=true)]
public sealed class ViewTreeObserver : Java.Lang.Object[<Android.Runtime.Register("android/view/ViewTreeObserver", DoNotGenerateAcw=true)>]
type ViewTreeObserver = class
inherit Object- Inheritance
- Attributes
Remarks
A view tree observer is used to register listeners that can be notified of global changes in the view tree. Such global events include, but are not limited to, layout of the whole tree, beginning of the drawing pass, touch mode change....
A ViewTreeObserver should never be instantiated by applications as it is provided by the views hierarchy. Refer to android.view.View#getViewTreeObserver() for more information.
Java documentation for android.view.ViewTreeObserver.
Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.
Properties
| Name | Description |
|---|---|
| Class |
Returns the runtime class of this |
| Handle |
The handle to the underlying Android instance. (Inherited from Object) |
| IsAlive |
Indicates whether this ViewTreeObserver is alive. |
| JniIdentityHashCode |
Gets the identity hash code assigned to this Java peer by the interop runtime. (Inherited from Object) |
| JniManagedPeerState | (Inherited from JavaObject) |
| JniPeerMembers |
Gets the JNI peer metadata used by the .NET for Android binding runtime. |
| PeerReference |
Gets the JNI object reference for this Java peer. (Inherited from Object) |
| ThresholdClass |
This API supports the Mono for Android infrastructure and is not intended to be used directly from your code. (Inherited from Object) |
| ThresholdType |
This API supports the Mono for Android infrastructure and is not intended to be used directly from your code. (Inherited from Object) |
Methods
| Name | Description |
|---|---|
| AddOnDrawListener(ViewTreeObserver+IOnDrawListener) |
Register a callback to be invoked when the view tree is about to be drawn. |
| AddOnGlobalFocusChangeListener(ViewTreeObserver+IOnGlobalFocusChangeListener) |
Register a callback to be invoked when the focus state within the view tree changes. |
| AddOnGlobalLayoutListener(ViewTreeObserver+IOnGlobalLayoutListener) |
Register a callback to be invoked when the global layout state or the visibility of views within the view tree changes |
| AddOnPreDrawListener(ViewTreeObserver+IOnPreDrawListener) |
Register a callback to be invoked when the view tree is about to be drawn |
| AddOnScrollChangedListener(ViewTreeObserver+IOnScrollChangedListener) |
Register a callback to be invoked when a view has been scrolled. |
| AddOnSystemGestureExclusionRectsChangedListener(IConsumer) |
Add a listener to be notified when the tree's <em>transformed</em> gesture exclusion rects change. |
| AddOnTouchModeChangeListener(ViewTreeObserver+IOnTouchModeChangeListener) |
Register a callback to be invoked when the invoked when the touch mode changes. |
| AddOnWindowAttachListener(ViewTreeObserver+IOnWindowAttachListener) |
Register a callback to be invoked when the view hierarchy is attached to a window. |
| AddOnWindowFocusChangeListener(ViewTreeObserver+IOnWindowFocusChangeListener) |
Register a callback to be invoked when the window focus state within the view tree changes. |
| AddOnWindowVisibilityChangeListener(ViewTreeObserver+IOnWindowVisibilityChangeListener) |
Register a callback to be invoked when the window visibility changes. |
| Clone() |
Creates and returns a copy of this object. (Inherited from Object) |
| Construct(JniObjectReference, JniObjectReferenceOptions) | (Inherited from JavaObject) |
| DispatchOnDraw() |
Notifies registered listeners that the drawing pass is about to start. |
| DispatchOnGlobalLayout() |
Notifies registered listeners that a global layout happened. |
| DispatchOnPreDraw() |
Notifies registered listeners that the drawing pass is about to start. |
| DispatchOnScrollChanged() |
Notifies registered listeners that something has scrolled. |
| Dispose() |
Releases the resources held by this Java peer. (Inherited from Object) |
| Dispose(Boolean) |
Releases the resources held by this Java peer. (Inherited from Object) |
| DisposeUnlessReferenced() | (Inherited from JavaObject) |
| Equals(Object) | (Inherited from JavaObject) |
| Equals(Object) |
Indicates whether some other object is "equal to" this one. (Inherited from Object) |
| GetHashCode() |
Returns a hash code value for the object. (Inherited from Object) |
| JavaFinalize() |
Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. (Inherited from Object) |
| Notify() |
Wakes up a single thread that is waiting on this object's monitor. (Inherited from Object) |
| NotifyAll() |
Wakes up all threads that are waiting on this object's monitor. (Inherited from Object) |
| RegisterFrameCommitCallback(IRunnable) |
Adds a frame commit callback. |
| RemoveGlobalOnLayoutListener(ViewTreeObserver+IOnGlobalLayoutListener) |
Obsolete.
Remove a previously installed global layout callback |
| RemoveOnDrawListener(ViewTreeObserver+IOnDrawListener) |
Remove a previously installed pre-draw callback. |
| RemoveOnGlobalFocusChangeListener(ViewTreeObserver+IOnGlobalFocusChangeListener) |
Remove a previously installed focus change callback. |
| RemoveOnGlobalLayoutListener(ViewTreeObserver+IOnGlobalLayoutListener) |
Remove a previously installed global layout callback |
| RemoveOnPreDrawListener(ViewTreeObserver+IOnPreDrawListener) |
Remove a previously installed pre-draw callback |
| RemoveOnScrollChangedListener(ViewTreeObserver+IOnScrollChangedListener) |
Remove a previously installed scroll-changed callback |
| RemoveOnSystemGestureExclusionRectsChangedListener(IConsumer) |
Unsubscribe the given listener from gesture exclusion rect changes. |
| RemoveOnTouchModeChangeListener(ViewTreeObserver+IOnTouchModeChangeListener) |
Remove a previously installed touch mode change callback |
| RemoveOnWindowAttachListener(ViewTreeObserver+IOnWindowAttachListener) |
Remove a previously installed window attach callback. |
| RemoveOnWindowFocusChangeListener(ViewTreeObserver+IOnWindowFocusChangeListener) |
Remove a previously installed window focus change callback. |
| RemoveOnWindowVisibilityChangeListener(ViewTreeObserver+IOnWindowVisibilityChangeListener) |
Remove a previously installed window visibility callback. |
| SetHandle(IntPtr, JniHandleOwnership) |
Sets the Handle property. (Inherited from Object) |
| SetPeerReference(JniObjectReference, JniObjectReferenceOptions) | (Inherited from JavaObject) |
| ToArray<T>() |
Creates a managed array from this Java array wrapper. (Inherited from Object) |
| ToString() |
Returns a string representation of the object. (Inherited from Object) |
| UnregisterFrameCommitCallback(IRunnable) |
Attempts to remove the given callback from the list of pending frame complete callbacks. |
| UnregisterFromRuntime() |
Unregisters this Java peer from the interop runtime. (Inherited from Object) |
| Wait() |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>. (Inherited from Object) |
| Wait(Int64, Int32) |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object) |
| Wait(Int64) |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object) |
Events
| Name | Description |
|---|---|
| Draw |
Occurs during a view-tree draw pass. |
| GlobalFocusChange |
Occurs when focus changes anywhere in the view tree. |
| GlobalLayout |
Occurs after the global layout state changes. |
| PreDraw |
Occurs immediately before the view tree is drawn. |
| ScrollChanged |
Occurs when a view-tree scroll position changes. |
| TouchModeChange |
Occurs when touch mode changes. |
| WindowAttached |
Occurs when the window is attached. |
| WindowDetached |
Occurs when the window is detached. |
| WindowFocusChange |
Occurs when the window gains or loses focus. |
| WindowVisibilityChange |
Occurs when the window visibility changes. |
Explicit Interface Implementations
| Name | Description |
|---|---|
| IJavaPeerable.Disposed() | (Inherited from JavaObject) |
| IJavaPeerable.Finalized() | (Inherited from JavaObject) |
| IJavaPeerable.JniObjectReferenceControlBlock | (Inherited from JavaObject) |
| IJavaPeerable.SetJniIdentityHashCode(Int32) | (Inherited from JavaObject) |
| IJavaPeerable.SetJniManagedPeerState(JniManagedPeerStates) | (Inherited from JavaObject) |
| IJavaPeerable.SetPeerReference(JniObjectReference) | (Inherited from JavaObject) |
Extension Methods
| Name | Description |
|---|---|
| GetJniTypeName(IJavaPeerable) |
Gets the JNI name of the type of the instance |
| JavaAs<TResult>(IJavaPeerable) |
Try to coerce |
| JavaCast<TResult>(IJavaObject) |
Performs an Android runtime-checked type conversion. |
| JavaCast<TResult>(IJavaObject) | |
| TryJavaCast<TResult>(IJavaPeerable, TResult) |
Try to coerce |