Simplify fn Events::handle_resize

crates/kas-core/src/core/events.rs

@@ -6,8 +6,8 @@
 //! Widget and Events traits
 
 use super::{Tile, Widget};
+use crate::ChildIndices;
 use crate::event::{ConfigCx, CursorIcon, Event, EventCx, IsUsed, Scroll, Unused};
-use crate::{ActionResize, ChildIndices};
 use crate::{Id, geom::Coord};
 #[allow(unused)] use crate::{Layout, event::EventState};
 #[allow(unused)] use kas_macros as macros;
@@ -308,26 +308,26 @@ pub trait Events: Widget + Sized {
     ///
     /// # Calling
     ///
-    /// This method may only be called after the widget is sized.
-    ///
-    /// This method is called during [event handling](crate::event) whenever a
-    /// resize action is required (see [`ConfigCx::resize`]).
+    /// This method may be called when processing an [update](Self#update) or
+    /// handling an event ([`Self::handle_event`]) or message
+    /// ([`Self::handle_messages`]) when a child widget requires resizing, but
+    /// only after the initial sizing of the widget.
     ///
     /// # Implementation
     ///
     /// Some widgets (for example, a scroll region) are able to handle resizes
-    /// locally and should implement this method to do so
-    /// (thus avoiding the need for a full-window resize).
+    /// locally and should implement this method to do so, avoiding the need for
+    /// a full-window resize.
     ///
-    /// Return `Some(ActionResize)` if further resizing is needed, or `None` if
-    /// resizing is complete.
+    /// Return `true` if resizing is complete, otherwise return `false` to
+    /// indicate that further resizing is required.
     ///
-    /// The default implementation simply returns `Some(ActionResize)`.
+    /// The default implementation simply returns `false`.
     #[inline]
     #[must_use]
-    fn handle_resize(&mut self, cx: &mut ConfigCx, data: &Self::Data) -> Option<ActionResize> {
-        let _ = (cx, data);
-        Some(ActionResize)
+    fn handle_resize(&mut self, cx: &mut ConfigCx) -> bool {
+        let _ = cx;
+        false
     }
 
     /// Handler for scrolling

crates/kas-core/src/core/impls.rs

@@ -42,8 +42,9 @@ pub fn _update<W: Events>(widget: &mut W, cx: &mut ConfigCx, data: &W::Data) {
         }
 
         if cx.needs_resize() && widget.status().is_sized() {
-            let opt_resize = widget.handle_resize(cx, data);
-            cx.set_resize(opt_resize);
+            if widget.handle_resize(cx) {
+                cx.set_resize(None);
+            }
         }
     }
 }
@@ -99,8 +100,9 @@ pub fn _send<W: Events>(
 
             if cx.needs_resize() {
                 debug_assert!(widget.status().is_sized());
-                let opt_resize = widget.handle_resize(cx, data);
-                cx.set_resize(opt_resize);
+                if widget.handle_resize(cx) {
+                    cx.set_resize(None);
+                }
             }
 
             if let Some(scroll) = cx.post_send(index) {
@@ -147,8 +149,9 @@ pub fn _replay<W: Events>(widget: &mut W, cx: &mut EventCx, data: &<W as Widget>
         }
 
         if cx.needs_resize() && widget.status().is_sized() {
-            let opt_resize = widget.handle_resize(cx, data);
-            cx.set_resize(opt_resize);
+            if widget.handle_resize(cx) {
+                cx.set_resize(None);
+            }
         }
 
         if let Some(scroll) = cx.post_send(index) {

crates/kas-view/src/grid_view.rs

@@ -462,8 +462,11 @@ mod GridView {
                 data_len = result.len();
                 if data_len != self.data_len {
                     self.data_len = data_len;
-                    cx.resize();
                     self.token_update = Update::Token;
+
+                    // TODO(opt): notify that content_size() has changed without
+                    // requiring re-evaluation of size_rules() or set_rect():
+                    cx.resize();
                 }
             } else {
                 data_len = self.data_len;

crates/kas-view/src/list_view.rs

@@ -567,6 +567,9 @@ mod ListView {
                 data_len = result.len();
                 if data_len != usize::conv(self.data_len) {
                     self.data_len = data_len.cast();
+
+                    // TODO(opt): notify that content_size() has changed without
+                    // requiring re-evaluation of size_rules() or set_rect():
                     cx.resize();
                 }
             } else {

crates/kas-widgets/src/edit/edit_box.rs

@@ -213,14 +213,10 @@ mod EditBox {
             }
         }
 
-        fn handle_resize(&mut self, cx: &mut ConfigCx, _: &Self::Data) -> Option<ActionResize> {
-            let size = self.inner.rect().size;
-            let axis = AxisInfo::new(false, Some(size.1));
-            let mut resize = self.inner.size_rules(&mut cx.size_cx(), axis).min_size() > size.0;
-            let axis = AxisInfo::new(true, Some(size.0));
-            resize |= self.inner.size_rules(&mut cx.size_cx(), axis).min_size() > size.1;
+        fn handle_resize(&mut self, cx: &mut ConfigCx) -> bool {
+            // Assumption: content does not require re-evaluation of size_rules() or set_rect()
             self.update_content_size(cx);
-            resize.then_some(ActionResize)
+            true
         }
 
         fn handle_scroll(&mut self, cx: &mut EventCx<'_>, _: &G::Data, scroll: Scroll) {

crates/kas-widgets/src/scroll.rs

@@ -456,12 +456,12 @@ mod ScrollRegion {
                 .update_offset(cx, data, self.inner.rect(), offset);
         }
 
-        fn handle_resize(&mut self, cx: &mut ConfigCx, _: &Self::Data) -> Option<ActionResize> {
+        fn handle_resize(&mut self, cx: &mut ConfigCx) -> bool {
             let _ = self.size_rules(&mut cx.size_cx(), AxisInfo::new(false, None));
             let width = self.rect().size.0;
             let _ = self.size_rules(&mut cx.size_cx(), AxisInfo::new(true, Some(width)));
             self.set_rect(&mut cx.size_cx(), self.rect(), self.hints);
-            None
+            true
         }
 
         fn handle_scroll(&mut self, cx: &mut EventCx, data: &Self::Data, scroll: Scroll) {

crates/kas-widgets/src/scroll_label.rs

@@ -547,7 +547,7 @@ mod ScrollText {
             }
         }
 
-        fn handle_resize(&mut self, cx: &mut ConfigCx, _: &Self::Data) -> Option<ActionResize> {
+        fn handle_resize(&mut self, cx: &mut ConfigCx) -> bool {
             let size = self.text.rect().size;
             let axis = AxisInfo::new(false, Some(size.1));
             let mut resize = self.text.size_rules(&mut cx.size_cx(), axis).min_size() > size.0;
@@ -556,7 +556,7 @@ mod ScrollText {
             self.text
                 .set_rect(&mut cx.size_cx(), self.text.rect(), Default::default());
             self.update_content_size(cx);
-            resize.then_some(ActionResize)
+            !resize
         }
 
         fn handle_scroll(&mut self, cx: &mut EventCx, _: &Self::Data, scroll: Scroll) {