/// <summary>
/// Validate if the provided routed event args are relevant for the given element according to the active captures
/// </summary>
/// <param name="element">The target element for which the args are validated</param>
/// <param name="args">The pending pointer event args that is under test</param>
/// <param name="autoRelease">A flag that allows to automatically release any pending out-dated capture (for PointerDown only)</param>
/// <returns>A boolean which indicates if the args are valid or not for the given element</returns>
public bool ValidateAndUpdate(UIElement element, PointerRoutedEventArgs args, bool autoRelease)
{
if ((autoRelease && MostRecentDispatchedEventFrameId < args.FrameId) ||
_nativeCaptureElement.GetHitTestVisibility() == HitTestability.Collapsed)
{
// If 'autoRelease' we want to release any previous capture that was not release properly no matter the reason.
// BUT we don't want to release a capture that was made by a child control (so MostRecentDispatchedEventFrameId should already be equals to current FrameId).
// We also do not allow a control that is not loaded to keep a capture (they should all have been release on unload).
// ** This is an IMPORTANT safety catch to prevent the application to become unresponsive **
Clear();
return(true);
}
else if (_targets.TryGetValue(element, out var target))
{
Update(target, args);
return(true);
}
else if (IsImplicitOnly)
{
// If the capture is implicit, we should not filter out events for children elements.
return(true);
}
else
{
// We should dispatch the event only if the control which has captured the pointer has already dispatched the event
// (Which actually means that the current control is a parent of the control which has captured the pointer)
// Remarks: This is not enough to determine parent-child relationship when we dispatch multiple events base on the same native event,
// (as they will all have the same FrameId), however in that case we dispatch events layer per layer
// instead of bubbling a single event before raising the next one, so we are safe.
// The only limitation would be when mixing native vs. managed bubbling, but this check only prevents
// the leaf of the tree to raise the event, so we cannot mix bubbling mode in that case.
return(MostRecentDispatchedEventFrameId >= args.FrameId);
}
}
