Use custom PopoverContainer instead of gtk4::MenuButton

src/popover_container.rs

@@ -0,0 +1,96 @@
+use cascade::cascade;
+use gtk4::{glib, prelude::*, subclass::prelude::*};
+
+use crate::deref_cell::DerefCell;
+
+/// Unlike gtk4's `MenuButton`, this supports a custom child.
+#[derive(Default)]
+pub struct PopoverContainerInner {
+    child: DerefCell<gtk4::Widget>,
+    popover: DerefCell<gtk4::Popover>,
+}
+
+#[glib::object_subclass]
+impl ObjectSubclass for PopoverContainerInner {
+    const NAME: &'static str = "S76PopoverContainer";
+    type ParentType = gtk4::Widget;
+    type Type = PopoverContainer;
+}
+
+impl ObjectImpl for PopoverContainerInner {
+    fn constructed(&self, obj: &PopoverContainer) {
+        let popover = cascade! {
+            gtk4::Popover::new();
+            ..set_parent(obj);
+        };
+
+        self.popover.set(popover);
+    }
+
+    fn dispose(&self, _obj: &PopoverContainer) {
+        self.child.unparent();
+        self.popover.unparent();
+    }
+}
+
+impl WidgetImpl for PopoverContainerInner {
+    fn measure(
+        &self,
+        _obj: &PopoverContainer,
+        orientation: gtk4::Orientation,
+        for_size: i32,
+    ) -> (i32, i32, i32, i32) {
+        self.child.measure(orientation, for_size)
+    }
+
+    fn size_allocate(&self, _obj: &PopoverContainer, width: i32, height: i32, baseline: i32) {
+        self.child.size_allocate(
+            &gtk4::Allocation {
+                x: 0,
+                y: 0,
+                width,
+                height,
+            },
+            baseline,
+        );
+        self.popover.present();
+    }
+
+    fn focus(&self, _obj: &PopoverContainer, direction: gtk4::DirectionType) -> bool {
+        if self.popover.is_visible() {
+            self.popover.child_focus(direction)
+        } else {
+            self.child.child_focus(direction)
+        }
+    }
+}
+
+glib::wrapper! {
+    pub struct PopoverContainer(ObjectSubclass<PopoverContainerInner>)
+        @extends gtk4::Widget;
+}
+
+impl PopoverContainer {
+    pub fn new<T: IsA<gtk4::Widget>>(child: &T) -> Self {
+        let obj = glib::Object::new::<Self>(&[]).unwrap();
+        child.set_parent(&obj);
+        obj.inner().child.set(child.clone().upcast());
+        obj
+    }
+
+    fn inner(&self) -> &PopoverContainerInner {
+        PopoverContainerInner::from_instance(self)
+    }
+
+    pub fn popover(&self) -> &gtk4::Popover {
+        &self.inner().popover
+    }
+
+    pub fn popup(&self) {
+        self.popover().popup();
+    }
+
+    pub fn popdown(&self) {
+        self.popover().popdown();
+    }
+}