fn apply_lightbox_zoom(
picture: &Picture,
viewer: &ScrolledWindow,
zoom: f64,
) -> Option<(f64, f64)>Expand description
Apply zoom to a lightbox Picture. Zoom is fit-relative: 1.0 = the size the
texture would occupy inside viewer under Contain layout. >1.0 overflows
the viewer for panning. Returns the computed content dimensions when zoomed.