private void Focus(DependencyObject focus, bool askOld, bool askNew, bool forceToNullIfFailed)
{
// Make sure that the element is valid for receiving focus.
bool isValid = true;
if (focus != null)
{
isValid = Keyboard.IsFocusable(focus);
if (!isValid && forceToNullIfFailed)
{
focus = null;
isValid = true;
}
}
if (isValid)
{
// Get the keyboard input provider that provides input for the active source.
IKeyboardInputProvider keyboardInputProvider = null;
DependencyObject containingVisual = InputElement.GetContainingVisual(focus);
if (containingVisual != null)
{
PresentationSource source = PresentationSource.CriticalFromVisual(containingVisual);
if (source != null)
{
keyboardInputProvider = (IKeyboardInputProvider)source.GetInputProvider(typeof(KeyboardDevice));
}
}
// Start the focus-change operation.
TryChangeFocus(focus, keyboardInputProvider, askOld, askNew, forceToNullIfFailed);
}
}
public static int GetIntermediatePoints(IInputElement relativeTo, Point[] points)
{
// Security Mitigation: do not give out input state if the device is not active.
if (Mouse.PrimaryDevice.IsActive)
{
if (relativeTo != null)
{
PresentationSource inputSource = PresentationSource.FromDependencyObject(InputElement.GetContainingVisual(relativeTo as DependencyObject));
if (inputSource != null)
{
IMouseInputProvider mouseInputProvider = inputSource.GetInputProvider(typeof(MouseDevice)) as IMouseInputProvider;
if (null != mouseInputProvider)
{
return(mouseInputProvider.GetIntermediatePoints(relativeTo, points));
}
}
}
}
return(-1);
}
/// <summary>
/// Determines if we can remain focused on the element we think has focus
/// </summary>
/// <remarks>
/// Invoked asynchronously by ReevaluateFocusAsync.
/// Confirms that the element we think has focus is:
/// - still enabled
/// - still visible
/// - still in the tree
/// </remarks>
private object ReevaluateFocusCallback(object arg)
{
_reevaluateFocusOperation = null;
if (_focus == null)
{
return(null);
}
//
// Reevaluate the eligability of the focused element to actually
// have focus. If that element is no longer focusable, then search
// for an ancestor that is.
//
DependencyObject element = _focus;
while (element != null)
{
if (Keyboard.IsFocusable(element))
{
break;
}
// Walk the current tree structure.
element = DeferredElementTreeState.GetCoreParent(element, null);
}
// Get the PresentationSource that contains the element to be focused.
PresentationSource presentationSource = null;
DependencyObject visualContainer = InputElement.GetContainingVisual(element);
if (visualContainer != null)
{
presentationSource = PresentationSource.CriticalFromVisual(visualContainer);
}
// The default action is to reset focus to the root element
// of the active presentation source.
bool moveFocus = true;
DependencyObject moveFocusTo = null;
if (presentationSource != null)
{
IKeyboardInputProvider keyboardProvider = presentationSource.GetInputProvider(typeof(KeyboardDevice)) as IKeyboardInputProvider;
if (keyboardProvider != null)
{
// Confirm with the keyboard provider for this
// presentation source that it has acquired focus.
if (keyboardProvider.AcquireFocus(true))
{
if (element == _focus)
{
// The focus element is still good.
moveFocus = false;
}
else
{
// The focus element is no longer focusable, but we found
// an ancestor that is, so move focus there.
moveFocus = true;
moveFocusTo = element;
}
}
}
}
if (moveFocus)
{
if (moveFocusTo == null && _activeSource != null)
{
moveFocusTo = _activeSource.Value.RootVisual as DependencyObject;
}
Focus(moveFocusTo, /*askOld=*/ false, /*askNew=*/ true, /*forceToNullIfFailed=*/ true);
}
else
{
// Refresh FocusWithinProperty so that ReverseInherited Flags are updated.
//
// We only need to do this if there is any information about the old
// tree structure.
if (_focusTreeState != null && !_focusTreeState.IsEmpty)
{
UIElement.FocusWithinProperty.OnOriginValueChanged(_focus, _focus, ref _focusTreeState);
}
}
return(null);
}
