merged previous stuffs on master

crates/ui/src/element_ext.rs

@@ -0,0 +1,27 @@
+use gpui::{canvas, App, Bounds, ParentElement, Pixels, Styled as _, Window};
+
+/// A trait to extend [`gpui::Element`] with additional functionality.
+pub trait ElementExt: ParentElement + Sized {
+    /// Add a prepaint callback to the element.
+    ///
+    /// This is a helper method to get the bounds of the element after paint.
+    ///
+    /// The first argument is the bounds of the element in pixels.
+    ///
+    /// See also [`gpui::canvas`].
+    fn on_prepaint<F>(self, f: F) -> Self
+    where
+        F: FnOnce(Bounds<Pixels>, &mut Window, &mut App) + 'static,
+    {
+        self.child(
+            canvas(
+                move |bounds, window, cx| f(bounds, window, cx),
+                |_, _, _, _| {},
+            )
+            .absolute()
+            .size_full(),
+        )
+    }
+}
+
+impl<T: ParentElement> ElementExt for T {}