Function render_widget_png 

pub fn render_widget_png(
    widget: &mut dyn Widget,
    viewport: (u32, u32),
    theme: Theme,
    out: &Path,
) -> Result<(), WidgetLayoutError>

Render one frame of widget at viewport under theme and write it to out as a PNG: ShotFrame with its defaults, synced once, laid out once and drawn once with its top layer.

Errors

As ShotFrame::layout.