wpfelementvisualtreehelpervisual-tree

WPF Get Element(s) under mouse

Is there a way with WPF to get an array of elements under the mouse on a MouseMove event?

Solution

  • From "WPF Unleashed", page 383:

    Visual hit testing can inform you about all Visuals that intersect a location, [...] you must use [...] the [VisualTreeHelper.]HitTest method that accepts a HitTestResultCallback delegate. Before this version of HitTest returns, the delegate is invoked once for each relevant Visual, starting from the topmost and ending at the bottommost.

    The signature of such a callback is

    HitTestResultBehavior Callback(HitTestResult result)

    and it has to return HitTestResultBehaviour.Continue to receive further hits, as shown below (from the linked page on MSDN):

    // Return the result of the hit test to the callback.
public HitTestResultBehavior MyHitTestResult(HitTestResult result)
{
    // Add the hit test result to the list that will be processed after the enumeration.
    hitResultsList.Add(result.VisualHit);

    // Set the behavior to return visuals at all z-order levels.
    return HitTestResultBehavior.Continue;
}

    For further information, please consult the MSDN documentation for VisualTreeHelper.HitTest.