Viewport3D Mouse Event doesn't fire when hitting background

Question

I set up a Viewport3D with a MouseEventHandler

[...]
Main3DWindow.MouseUp += new MouseButtonEventHandler(mainViewport_MouseUp);
[...]
void mainViewport_MouseUp (object sender, MouseButtonEventArgs e) {
    Point location = e.GetPosition(Main3DWindow);
    ModelVisual3D result = GetHitTestResult(location);
    if (result == null) {
        _CurrentData.Unselect();
        return;
    }
    _CurrentData.SelectItemFromObjectList(result);
}

And it works pretty fine when an object is clicked. My expectation was: If no object is clicked (because the user clicked at the background) the result is null. But in fact the mainViewport_MouseUp-method is not even called.

My question: how can i detect clicks on the background of the Viewport3D?

Answer 1

It is as you wrote, it wont be fired.

I solved that by defining events on border and put viewport into border. Sample is from XAML:

<Border
                MouseWheel="mainViewport_MouseWheel"
                MouseMove="mainViewport_MouseMove"
                MouseLeftButtonDown="mainViewport_MouseLeftButtonDown"
                Background="Black">
                <Viewport3D
                    Name="mainViewport"
                    ClipToBounds="True"
                    Grid.Row="0"
                    Grid.Column="0"
                    Grid.ColumnSpan="3"
                    Margin="0,0,0,0">
.....
                </Viewport3D>
            </Border>

And in the code:

private void mainViewport_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    Point location = e.GetPosition(mainViewport);
    try
    {
                ModelVisual3D result = (ModelVisual3D)GetHitTestResult(location);
        //some code.......
    }
    catch
    {
        //some code .......
    }
}