Make Overlay aware of viewport

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

core/src/element.rs

@@ -368,12 +368,13 @@ where
         tree: &'b mut Tree,
         layout: Layout<'_>,
         renderer: &Renderer,
+        viewport: &Rectangle,
         translation: Vector,
     ) -> Option<overlay::Element<'b, B, Theme, Renderer>> {
         let mapper = &self.mapper;
 
         self.widget
-            .overlay(tree, layout, renderer, translation)
+            .overlay(tree, layout, renderer, viewport, translation)
             .map(move |overlay| overlay.map(mapper))
     }
 }
@@ -519,10 +520,15 @@ where
         state: &'b mut Tree,
         layout: Layout<'_>,
         renderer: &Renderer,
+        viewport: &Rectangle,
         translation: Vector,
     ) -> Option<overlay::Element<'b, Message, Theme, Renderer>> {
-        self.element
-            .widget
-            .overlay(state, layout, renderer, translation)
+        self.element.widget.overlay(
+            state,
+            layout,
+            renderer,
+            viewport,
+            translation,
+        )
     }
 }

core/src/overlay.rs

@@ -122,6 +122,7 @@ pub fn from_children<'a, Message, Theme, Renderer>(
     tree: &'a mut Tree,
     layout: Layout<'_>,
     renderer: &Renderer,
+    viewport: &Rectangle,
     translation: Vector,
 ) -> Option<Element<'a, Message, Theme, Renderer>>
 where
@@ -132,9 +133,13 @@ where
         .zip(&mut tree.children)
         .zip(layout.children())
         .filter_map(|((child, state), layout)| {
-            child
-                .as_widget_mut()
-                .overlay(state, layout, renderer, translation)
+            child.as_widget_mut().overlay(
+                state,
+                layout,
+                renderer,
+                viewport,
+                translation,
+            )
         })
         .collect::<Vec<_>>();
 

core/src/widget.rs

@@ -146,6 +146,7 @@ where
         _state: &'a mut Tree,
         _layout: Layout<'_>,
         _renderer: &Renderer,
+        _viewport: &Rectangle,
         _translation: Vector,
     ) -> Option<overlay::Element<'a, Message, Theme, Renderer>> {
         None