ViewCompat

Automatically determine whether a view is important for accessibility.

The view is not important for accessibility.

The view is important for accessibility.

Indicates that the view has a hardware layer. A hardware layer is backed by a hardware specific texture (generally Frame Buffer Objects or FBO on OpenGL hardware) and causes the view to be rendered using Android's hardware rendering pipeline, but only if hardware acceleration is turned on for the view hierarchy. When hardware acceleration is turned off, hardware layers behave exactly as software layers.

A hardware layer is useful to apply a specific color filter and/or blending mode and/or translucency to a view and all its children.

A hardware layer can be used to cache a complex view tree into a texture and reduce the complexity of drawing operations. For instance, when animating a complex view tree with a translation, a hardware layer can be used to render the view tree only once.

A hardware layer can also be used to increase the rendering quality when rotation transformations are applied on a view. It can also be used to prevent potential clipping issues when applying 3D transforms on a view.

Indicates that the view does not have a layer.

Indicates that the view has a software layer. A software layer is backed by a bitmap and causes the view to be rendered using Android's software rendering pipeline, even if hardware acceleration is enabled.

Software layers have various usages:

When the application is not using hardware acceleration, a software layer is useful to apply a specific color filter and/or blending mode and/or translucency to a view and all its children.

When the application is using hardware acceleration, a software layer is useful to render drawing primitives not supported by the hardware accelerated pipeline. It can also be used to cache a complex view tree into a texture and reduce the complexity of drawing operations. For instance, when animating a complex view tree with a translation, a software layer can be used to render the view tree only once.

Software layers should be avoided when the affected view tree updates often. Every update will require to re-render the software layer, which can potentially be slow (particularly when hardware acceleration is turned on since the layer will have to be uploaded into a hardware texture after every update.)

Always allow a user to over-scroll this view, provided it is a view that can scroll.

Allow a user to over-scroll this view only if the content is large enough to meaningfully scroll, provided it is a view that can scroll.

Never allow a user to over-scroll this view.

Check if this view can be scrolled horizontally in a certain direction.

Check if this view can be scrolled vertically in a certain direction.

Gets the provider for managing a virtual view hierarchy rooted at this View and reported to AccessibilityServices that explore the window content.

If this method returns an instance, this instance is responsible for managing AccessibilityNodeInfoCompats describing the virtual sub-tree rooted at this View including the one representing the View itself. Similarly the returned instance is responsible for performing accessibility actions on any virtual view or the root view itself.

If an AccessibilityDelegateCompat has been specified via calling its {@link AccessibilityDelegateCompat#getAccessibilityNodeProvider(View) is responsible for handling this call.

Gets the mode for determining whether this View is important for accessibility which is if it fires accessibility events and if it is reported to accessibility services that query the screen.

Gets the id of a view for which a given view serves as a label for accessibility purposes.

Indicates what type of layer is currently associated with this view. By default a view does not have a layer, and the layer type is LAYER_TYPE_NONE. Refer to the documentation of setLayerType(android.view.View, int, android.graphics.Paint) for more information on the different types of layers.

Returns the over-scroll mode for this view. The result will be one of OVER_SCROLL_ALWAYS (default), OVER_SCROLL_IF_CONTENT_SCROLLS (allow over-scrolling only if the view content is larger than the container), or OVER_SCROLL_NEVER.

Indicates whether the view is currently tracking transient state that the app should not need to concern itself with saving and restoring, but that the framework should take special note to preserve when possible.

Initializes an AccessibilityEvent with information about this View which is the event source. In other words, the source of an accessibility event is the view whose state change triggered firing the event.

Example: Setting the password property of an event in addition to properties set by the super implementation:

 public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
     super.onInitializeAccessibilityEvent(event);
     event.setPassword(true);
 }

If an View.AccessibilityDelegate has been specified via calling setAccessibilityDelegate(android.view.View.AccessibilityDelegate) its onInitializeAccessibilityEvent(View, AccessibilityEvent) is responsible for handling this call.

Note: Always call the super implementation before adding information to the event, in case the default implementation has basic information to add.

Initializes an AccessibilityNodeInfo with information about this view. The base implementation sets:

• setParent(View),
• setBoundsInParent(Rect),
• setBoundsInScreen(Rect),
• setPackageName(CharSequence),
• setClassName(CharSequence),
• setContentDescription(CharSequence),
• setEnabled(boolean),
• setClickable(boolean),
• setFocusable(boolean),
• setFocused(boolean),
• setLongClickable(boolean),
• setSelected(boolean),

Subclasses should override this method, call the super implementation, and set additional attributes.

If an View.AccessibilityDelegate has been specified via calling setAccessibilityDelegate(android.view.View.AccessibilityDelegate) its onInitializeAccessibilityNodeInfo(View, android.view.accessibility.AccessibilityNodeInfo) is responsible for handling this call.

Called from dispatchPopulateAccessibilityEvent(AccessibilityEvent) giving a chance to this View to populate the accessibility event with its text content. While this method is free to modify event attributes other than text content, doing so should normally be performed in onInitializeAccessibilityEvent(AccessibilityEvent).

Example: Adding formatted date string to an accessibility event in addition to the text added by the super implementation:

 public void onPopulateAccessibilityEvent(AccessibilityEvent event) {
     super.onPopulateAccessibilityEvent(event);
     final int flags = DateUtils.FORMAT_SHOW_DATE | DateUtils.FORMAT_SHOW_WEEKDAY;
     String selectedDateUtterance = DateUtils.formatDateTime(mContext,
         mCurrentDate.getTimeInMillis(), flags);
     event.getText().add(selectedDateUtterance);
 }

If an View.AccessibilityDelegate has been specified via calling setAccessibilityDelegate(android.view.View.AccessibilityDelegate) its onPopulateAccessibilityEvent(View, AccessibilityEvent) is responsible for handling this call.

Note: Always call the super implementation before adding information to the event, in case the default implementation has basic information to add.

Performs the specified accessibility action on the view. For possible accessibility actions look at AccessibilityNodeInfoCompat.

If an AccessibilityDelegateCompat has been specified via calling setAccessibilityDelegate(View, AccessibilityDelegateCompat) its performAccessibilityAction(View, int, Bundle) is responsible for handling this call.

Cause an invalidate to happen on the next animation time step, typically the next display frame.

This method can be invoked from outside of the UI thread only when this View is attached to a window.

Cause an invalidate of the specified area to happen on the next animation time step, typically the next display frame.

This method can be invoked from outside of the UI thread only when this View is attached to a window.

Causes the Runnable to execute on the next animation time step. The runnable will be run on the user interface thread.

This method can be invoked from outside of the UI thread only when this View is attached to a window.

Causes the Runnable to execute on the next animation time step, after the specified amount of time elapses. The runnable will be run on the user interface thread.

This method can be invoked from outside of the UI thread only when this View is attached to a window.

Sets a delegate for implementing accessibility support via compositon as opposed to inheritance. The delegate's primary use is for implementing backwards compatible widgets. For more details see View.AccessibilityDelegate.

Set whether this view is currently tracking transient state that the framework should attempt to preserve when possible.

Sets how to determine whether this view is important for accessibility which is if it fires accessibility events and if it is reported to accessibility services that query the screen.

Sets the id of a view for which a given view serves as a label for accessibility purposes.

Specifies the type of layer backing this view. The layer can be disabled, software or hardware.

A layer is associated with an optional Paint instance that controls how the layer is composed on screen. The following properties of the paint are taken into account when composing the layer:

• Translucency (alpha)
• Blending mode
• Color filter

If this view has an alpha value set to < 1.0 by calling setAlpha(float), the alpha value of the layer's paint is replaced by this view's alpha value. Calling setAlpha(float) is therefore equivalent to setting a hardware layer on this view and providing a paint with the desired alpha value.

Refer to the documentation of disabled, software and hardware for more information on when and how to use layers.

Set the over-scroll mode for this view. Valid over-scroll modes are OVER_SCROLL_ALWAYS (default), OVER_SCROLL_IF_CONTENT_SCROLLS (allow over-scrolling only if the view content is larger than the container), or OVER_SCROLL_NEVER. Setting the over-scroll mode of a view will have an effect only if the view is capable of scrolling.