Add OnLayoutView

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 - Add `Dialog::into_content`.
 - Add `Callback::from_fn_once` and `once1!` macro to wrap a `FnOnce` in a `FnMut`.
+- Add `FixedLayoutView` with manual placement of child views.
+- Add `OnLayoutView` to override `View::Layout`
 
 ### Bugfixes
 

cursive-core/src/views/mod.rs

@@ -79,6 +79,7 @@ mod menu_popup;
 mod menubar;
 mod named_view;
 mod on_event_view;
+mod on_layout_view;
 mod padded_view;
 mod panel;
 mod progress_bar;
@@ -114,6 +115,7 @@ pub use self::menu_popup::MenuPopup;
 pub use self::menubar::Menubar;
 pub use self::named_view::{NamedView, ViewRef};
 pub use self::on_event_view::OnEventView;
+pub use self::on_layout_view::OnLayoutView;
 pub use self::padded_view::PaddedView;
 pub use self::panel::Panel;
 pub use self::progress_bar::ProgressBar;

cursive-core/src/views/on_layout_view.rs

@@ -0,0 +1,59 @@
+use crate::{view::ViewWrapper, Vec2, View};
+
+/// View wrapper overriding the `View::layout` method.
+pub struct OnLayoutView<V> {
+    view: V,
+    on_layout: Box<dyn FnMut(&mut V, Vec2)>,
+}
+
+impl<V> OnLayoutView<V> {
+    /// Wraps a view in an `OnLayoutView`.
+    ///
+    /// Will run the given closure for layout _instead_ of the one from `view`.
+    ///
+    /// ```rust
+    /// use cursive_core::{View, views::{TextView, OnLayoutView}};
+    ///
+    /// let view = TextView::new("foo");
+    ///
+    /// // Here we just run the innver view's layout.
+    /// OnLayoutView::new(view, |v, s| v.layout(s));
+    /// ```
+    pub fn new<F>(view: V, on_layout: F) -> Self
+    where
+        F: FnMut(&mut V, Vec2) + 'static,
+    {
+        let on_layout = Box::new(on_layout);
+        OnLayoutView { view, on_layout }
+    }
+
+    /// Wraps a view in an `OnLayoutView`.
+    ///
+    /// This is a shortcut for `Self::new(view, V::layout)`
+    ///
+    /// You can change it later with `set_on_layout`.
+    pub fn wrap(view: V) -> Self
+    where
+        V: View,
+    {
+        Self::new(view, V::layout)
+    }
+
+    /// Replaces the callback to run.
+    pub fn set_on_layout<F>(&mut self, on_layout: F)
+    where
+        F: FnMut(&mut V, Vec2) + 'static,
+    {
+        self.on_layout = Box::new(on_layout);
+    }
+
+    inner_getters!(self.view: V);
+}
+
+impl<V: View> ViewWrapper for OnLayoutView<V> {
+    wrap_impl!(self.view: V);
+
+    fn wrap_layout(&mut self, size: Vec2) {
+        (self.on_layout)(&mut self.view, size);
+    }
+}