Make Overlay aware of viewport

... and unify `Image::float` and `Image::translate`

examples/gallery/src/main.rs

@@ -212,11 +212,9 @@ fn card<'a>(
                     .scale(thumbnail.zoom.interpolate(1.0, 1.1, now))
                     .translate(move |bounds, viewport| {
                         let final_bounds = bounds.zoom(1.1);
-
                         final_bounds.offset(&viewport.shrink(10))
                             * thumbnail.zoom.interpolate(0.0, 1.0, now)
                     })
-                    .float(true)
                     .style(move |_theme| image::Style {
                         shadow: Shadow {
                             color: Color::BLACK.scale_alpha(

examples/toast/src/main.rs

@@ -425,6 +425,7 @@ mod toast {
             state: &'b mut Tree,
             layout: Layout<'_>,
             renderer: &Renderer,
+            viewport: &Rectangle,
             translation: Vector,
         ) -> Option<overlay::Element<'b, Message, Theme, Renderer>> {
             let instants = state.state.downcast_mut::<Vec<Option<Instant>>>();
@@ -435,6 +436,7 @@ mod toast {
                 &mut content_state[0],
                 layout,
                 renderer,
+                viewport,
                 translation,
             );