Hit Testing
*Definován pro všechny kreslící elementy
*Bere transformace v úvahu
*Využívá směrování událostí (bublání)
<Ellipse x:Name="hlava" Fill="Yellow" Stroke="Black"
StrokeThickness="7" Width="100" Height="100" MouseLeftButtonDown="OnClick"/>
Hit testing for complex visuals has traditionally required a lot of work from the developer. When you have intricate imagery made up of multiple shapes, it can be difficult to work out which item, if any, the mouse is over. This becomes particularly complex if you have chains of transformations.

WPF does all the work for you. All of the drawing elements automatically support hit testing. (And if you eschew the FrameworkElement-level drawing elements, and instead drop down to the low-level drawing API, there is still support down there for making hit testing straightforward.)

All elements raise events for mouse activity including button, wheel, enter, and leave. The bubbling event model makes it easy to trap events for large chunks of your visual tree in a single place, and yet still be able to work out exactly which element was hit. (Events that bubble will propagate their way from the leaves of the UI tree up to the root until they hit a handler.)

As an example of how this works, consider a button with custom visuals. You can make a button any shape you like, and the hit testing works perfectly, even though the button doesn’t know much about its visuals. All it does is trap the relevant mouse events as they bubble out of its visual tree. This means that even the most complex of shapes will work in exactly the same way as the basic standard rectangular button shape.