android.support.v4.view
Class ViewCompat

java.lang.Object
  android.support.v4.view.ViewCompat

public class ViewCompat
extends Object

Helper for accessing features in View introduced after API level 4 in a backwards compatible fashion.

Field Summary

static int	OVER_SCROLL_ALWAYS Always allow a user to over-scroll this view, provided it is a view that can scroll.
static int	OVER_SCROLL_IF_CONTENT_SCROLLS 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.
static int	OVER_SCROLL_NEVER Never allow a user to over-scroll this view.

Constructor Summary

ViewCompat()

Method Summary

static boolean	canScrollHorizontally(android.view.View v, int direction) Check if this view can be scrolled horizontally in a certain direction.
static boolean	canScrollVertically(android.view.View v, int direction) Check if this view can be scrolled vertically in a certain direction.
static int	getOverScrollMode(android.view.View v) Returns the over-scroll mode for this view.
static void	onInitializeAccessibilityEvent(android.view.View v, android.view.accessibility.AccessibilityEvent event) Initializes an AccessibilityEvent with information about this View which is the event source.
static void	onInitializeAccessibilityNodeInfo(android.view.View v, AccessibilityNodeInfoCompat info) Initializes an AccessibilityNodeInfo with information about this view.
static void	onPopulateAccessibilityEvent(android.view.View v, android.view.accessibility.AccessibilityEvent event) Called from View.dispatchPopulateAccessibilityEvent(AccessibilityEvent) giving a chance to this View to populate the accessibility event with its text content.
static void	setAccessibilityDelegate(android.view.View v, AccessibilityDelegateCompat delegate) Sets a delegate for implementing accessibility support via compositon as opposed to inheritance.
static void	setOverScrollMode(android.view.View v, int overScrollMode) Set the over-scroll mode for this view.

Methods inherited from class java.lang.Object

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

Field Detail

OVER_SCROLL_ALWAYS

public static final int OVER_SCROLL_ALWAYS

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

See Also:

Constant Field Values

OVER_SCROLL_IF_CONTENT_SCROLLS

public static final int OVER_SCROLL_IF_CONTENT_SCROLLS

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.

See Also:

Constant Field Values

OVER_SCROLL_NEVER

public static final int OVER_SCROLL_NEVER

Never allow a user to over-scroll this view.

See Also:

Constant Field Values

Constructor Detail

ViewCompat

public ViewCompat()

Method Detail

canScrollHorizontally

public static boolean canScrollHorizontally(android.view.View v,
                                            int direction)

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

Parameters:

v - The View against which to invoke the method.

direction - Negative to check scrolling left, positive to check scrolling right.

Returns:

true if this view can be scrolled in the specified direction, false otherwise.

canScrollVertically

public static boolean canScrollVertically(android.view.View v,
                                          int direction)

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

Parameters:

v - The View against which to invoke the method.

direction - Negative to check scrolling up, positive to check scrolling down.

Returns:

true if this view can be scrolled in the specified direction, false otherwise.

getOverScrollMode

public static int getOverScrollMode(android.view.View v)

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.

Parameters:

v - The View against which to invoke the method.

Returns:

This view's over-scroll mode.

setOverScrollMode

public static void setOverScrollMode(android.view.View v,
                                     int overScrollMode)

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.

Parameters:

v - The View against which to invoke the method.

overScrollMode - The new over-scroll mode for this view.

onPopulateAccessibilityEvent

public static void onPopulateAccessibilityEvent(android.view.View v,
                                                android.view.accessibility.AccessibilityEvent event)

Called from View.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 View.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 View.setAccessibilityDelegate(android.view.View.AccessibilityDelegate) its View.AccessibilityDelegate.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.

Parameters:

v - The View against which to invoke the method.

event - The accessibility event which to populate.

See Also:

View.sendAccessibilityEvent(int), View.dispatchPopulateAccessibilityEvent(AccessibilityEvent)

onInitializeAccessibilityEvent

public static void onInitializeAccessibilityEvent(android.view.View v,
                                                  android.view.accessibility.AccessibilityEvent event)

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 View.setAccessibilityDelegate(android.view.View.AccessibilityDelegate) its View.AccessibilityDelegate.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.

Parameters:

v - The View against which to invoke the method.

event - The event to initialize.

See Also:

View.sendAccessibilityEvent(int), View.dispatchPopulateAccessibilityEvent(AccessibilityEvent)

onInitializeAccessibilityNodeInfo

public static void onInitializeAccessibilityNodeInfo(android.view.View v,
                                                     AccessibilityNodeInfoCompat info)

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

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

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

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

Parameters:

v - The View against which to invoke the method.

info - The instance to initialize.

setAccessibilityDelegate

public static void setAccessibilityDelegate(android.view.View v,
                                            AccessibilityDelegateCompat delegate)

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.

Parameters:

v - The View against which to invoke the method.

delegate - The delegate instance.

See Also:

View.AccessibilityDelegate