FPS Overlay is only drawn when the area underneath is also redrawn

[Murmele]

Bug Description

When FPS Overlay is enabled and partial draw is used the overlay gets not updated unless the area under the FPS text changes.

Workaround add a changing area under the place where the FPS text is shown:

property <color> first: #FF000001;
    property <color> second: #00FF0001;
    rec:= Rectangle {
        background: first;
        x: 0px;
        y: 0px;
        width: 600px;
        height: 10px;
    }

    Timer {
        interval: 100ms;
        triggered => {
            if rec.background == first {
                rec.background = second;
            } else {
                rec.background = first;
            }
        }
    }

Reproducible Code (if applicable)

Environment Details

• Slint Version: 1.15
• Platform/OS: Embedded
• Programming Language: C++
• Backend/Renderer: Software Renderer

Product Impact

No response

[ogoffart]

I am aware of this. We could either force the region containing the overlay to always be dirty but that would have an impact on the performance.
We could also redraw the overlay without drawing the actual UI when not dirty but that's a bit more complicated and would look bad.