private static void EnsureValid(ref IInputElement element)
{
// We understand UIElements and ContentElements.
// If we are over something else (like a raw visual) find the containing element.
if ((element != null) && !InputElement.IsValid(element))
{
element = InputElement.GetContainingInputElement(element as DependencyObject);
}
}
private IInputElement CriticalHitTest(Point point, bool isSynchronize)
{
IInputElement over = null;
if (_activeSource != null)
{
switch (_captureMode)
{
case CaptureMode.None:
// No capture, do a regular hit-test.
if (_isDown)
{
if (isSynchronize)
{
// In a synchronize call, we need to hit-test the window in addition to the element
over = GlobalHitTest(point, _activeSource);
}
else
{
// Just hit-test the element
over = LocalHitTest(point, _activeSource);
}
EnsureValid(ref over);
}
break;
case CaptureMode.Element:
// Capture is to a specific element, so the device will always be over that element.
over = _captured;
break;
case CaptureMode.SubTree:
// Capture is set to an entire subtree. Hit-test to determine the element (and window)
// the device is over. If the element is within the captured sub-tree (which can span
// multiple windows), then the device is over that element. If the element is not within
// the sub-tree, then the device is over the captured element.
{
IInputElement capture = InputElement.GetContainingInputElement(_captured as DependencyObject);
if (capture != null)
{
// We need to re-hit-test to get the "real" UIElement we are over.
// This allows us to have our capture-to-subtree span multiple windows.
// GlobalHitTest always returns an IInputElement, so we are sure to have one.
over = GlobalHitTest(point, _activeSource);
}
EnsureValid(ref over);
// Make sure that the element we hit is acutally underneath
// our captured element. Because we did a global hit test, we
// could have hit an element in a completely different window.
//
// Note that we support the child being in a completely different window.
// So we use the GetUIParent method instead of just looking at
// visual/content parents.
if (over != null)
{
IInputElement ieTest = over;
while ((ieTest != null) && (ieTest != _captured))
{
UIElement eTest = ieTest as UIElement;
if (eTest != null)
{
ieTest = InputElement.GetContainingInputElement(eTest.GetUIParent(true));
}
else
{
ContentElement ceTest = ieTest as ContentElement;
if (ceTest != null)
{
ieTest = InputElement.GetContainingInputElement(ceTest.GetUIParent(true));
}
else
{
UIElement3D e3DTest = (UIElement3D)ieTest;
ieTest = InputElement.GetContainingInputElement(e3DTest.GetUIParent(true));
}
}
}
if (ieTest != _captured)
{
// If we missed the capture point, consider the device over the capture point.
over = _captured;
}
}
else
{
// If we didn't hit anything, consider the device over the capture point.
over = _captured;
}
}
break;
}
}
return(over);
}