Introduce `Shell` type in `iced_native`

Widgets now can invalidate the current layout of the application on demand.

2 files changed, 12 insertions, 13 deletions

diff --git a/native/src/overlay/element.rs b/native/src/overlay/element.rs
index 24b39ced..70cb417e 100644
--- a/native/src/overlay/element.rs
+++ b/native/src/overlay/element.rs
@@ -4,7 +4,7 @@ use crate::event::{self, Event};
 use crate::layout;
 use crate::mouse;
 use crate::renderer;
-use crate::{Clipboard, Hasher, Layout, Point, Rectangle, Size, Vector};
+use crate::{Clipboard, Hasher, Layout, Point, Rectangle, Shell, Size, Vector};
 
 /// A generic [`Overlay`].
 #[allow(missing_debug_implementations)]
@@ -62,7 +62,7 @@ where
         cursor_position: Point,
         renderer: &Renderer,
         clipboard: &mut dyn Clipboard,
-        messages: &mut Vec<Message>,
+        shell: &mut Shell<'_, Message>,
     ) -> event::Status {
         self.overlay.on_event(
             event,
@@ -70,7 +70,7 @@ where
             cursor_position,
             renderer,
             clipboard,
-            messages,
+            shell,
         )
     }
 
@@ -136,9 +136,10 @@ where
         cursor_position: Point,
         renderer: &Renderer,
         clipboard: &mut dyn Clipboard,
-        messages: &mut Vec<B>,
+        shell: &mut Shell<'_, B>,
     ) -> event::Status {
-        let mut original_messages = Vec::new();
+        let mut local_messages = Vec::new();
+        let mut local_shell = Shell::new(&mut local_messages);
 
         let event_status = self.content.on_event(
             event,
@@ -146,12 +147,10 @@ where
             cursor_position,
             renderer,
             clipboard,
-            &mut original_messages,
+            &mut local_shell,
         );
 
-        original_messages
-            .drain(..)
-            .for_each(|message| messages.push((self.mapper)(message)));
+        shell.merge(local_shell, self.mapper);
 
         event_status
     }
diff --git a/native/src/overlay/menu.rs b/native/src/overlay/menu.rs
index ee3bee6e..6776a3ee 100644
--- a/native/src/overlay/menu.rs
+++ b/native/src/overlay/menu.rs
@@ -11,7 +11,7 @@ use crate::widget::scrollable::{self, Scrollable};
 use crate::widget::Container;
 use crate::{
     Clipboard, Color, Element, Hasher, Layout, Length, Padding, Point,
-    Rectangle, Size, Vector, Widget,
+    Rectangle, Shell, Size, Vector, Widget,
 };
 
 pub use iced_style::menu::Style;
@@ -222,7 +222,7 @@ where
         cursor_position: Point,
         renderer: &Renderer,
         clipboard: &mut dyn Clipboard,
-        messages: &mut Vec<Message>,
+        shell: &mut Shell<'_, Message>,
     ) -> event::Status {
         self.container.on_event(
             event.clone(),
@@ -230,7 +230,7 @@ where
             cursor_position,
             renderer,
             clipboard,
-            messages,
+            shell,
         )
     }
 
@@ -333,7 +333,7 @@ where
         cursor_position: Point,
         renderer: &Renderer,
         _clipboard: &mut dyn Clipboard,
-        _messages: &mut Vec<Message>,
+        _shell: &mut Shell<'_, Message>,
     ) -> event::Status {
         match event {
             Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left)) => {