Custom Canvas Button and Focusing

Syntec

Now that canvas class has AllowFocusRing we can handle drawing our own custom focus rings this is great!

I am running into an issue where I want the canvas to behave exactly like a button. My issue is the canvas receives keyboard focus when you click it, this is not how buttons behave, so I am having hard time separating out the focus logic. Any Ideas? I have it sort of working with flags but you run into issues when the button does something that takes focus away (such as a messagebox) and then returns the focus.

Garry

Good catch. A Button does receive focus when clicked, but it only displays its focus indicator when focus arrived through keyboard navigation. The Canvas previously exposed focus itself, but not that distinction, which is why flags became unreliable when a message box restored focus.

I’ve added a read-only FocusVisible property to Control for the next release (https://feedback.objo.dev/feature/1216). It is:

True after Tab or directional-key navigation.
False after mouse clicks, programmatic focus, modal restoration, or focus loss.
Independent of AllowFocusRing.

A custom Canvas button can now do this:

Sub Canvas1_FocusReceived()
    Canvas1.Refresh()
End Sub

Sub Canvas1_FocusLost()
    Canvas1.Refresh()
End Sub

Sub Canvas1_Paint(g As Graphics)
    # Draw the button...

    If Canvas1.FocusVisible Then
        # Draw the custom focus ring...
    End If
End Sub

Set Canvas1.AllowFocusRing = False when drawing the ring yourself. This should now behave consistently with a native Button, including after closing a message box.

Syntec

Garry Thank you Garry! You are rapidly making UI controls easier and easier to program for me 🙂