Show `WidgetInfo` for each widget if `debug.show_interactive_widgets`

This was useful during debugging

crates/egui/src/context.rs

@@ -1202,6 +1202,19 @@ impl Context {
         res
     }
 
+    /// This is called by [`Response::widget_info`], but can also be called directly.
+    ///
+    /// With some debug flags it will store the widget info in [`WidgetRects`] for later display.
+    #[inline]
+    pub fn register_widget_info(&self, id: Id, make_info: impl Fn() -> crate::WidgetInfo) {
+        #[cfg(debug_assertions)]
+        self.write(|ctx| {
+            if ctx.memory.options.style.debug.show_interactive_widgets {
+                ctx.viewport().widgets_this_frame.set_info(id, make_info());
+            }
+        });
+    }
+
     /// Get a full-screen painter for a new or existing layer
     pub fn layer_painter(&self, layer_id: LayerId) -> Painter {
         let screen_rect = self.screen_rect();
@@ -1807,6 +1820,7 @@ impl Context {
         self.write(|ctx| ctx.end_frame())
     }
 
+    /// Called at the end of the frame.
     #[cfg(debug_assertions)]
     fn debug_painting(&self) {
         let paint_widget = |widget: &WidgetRect, text: &str, color: Color32| {
@@ -1839,8 +1853,8 @@ impl Context {
                         } else if rect.sense.drag {
                             (Color32::from_rgb(0, 0, 0x88), "drag")
                         } else {
-                            continue;
+                            // unreachable since we only show interactive
-                            // (Color32::from_rgb(0, 0, 0x88), "hover")
+                            (Color32::from_rgb(0, 0, 0x88), "hover")
                         };
                         painter.debug_rect(rect.interact_rect, color, text);
                     }
@@ -1860,10 +1874,32 @@ impl Context {
                     hovered,
                 } = interact_widgets;
 
-                if false {
+                if true {
-                    for widget in contains_pointer {
+                    for &id in &contains_pointer {
-                        paint_widget_id(widget, "contains_pointer", Color32::BLUE);
+                        paint_widget_id(id, "contains_pointer", Color32::BLUE);
                     }
+
+                    let widget_rects = self.write(|w| w.viewport().widgets_this_frame.clone());
+
+                    let mut contains_pointer: Vec<Id> = contains_pointer.iter().copied().collect();
+                    contains_pointer.sort_by_key(|&id| {
+                        widget_rects
+                            .order(id)
+                            .map(|(layer_id, order_in_layer)| (layer_id.order, order_in_layer))
+                    });
+
+                    let mut debug_text = "Widgets in order:\n".to_owned();
+                    for id in contains_pointer {
+                        let mut widget_text = format!("{id:?}");
+                        if let Some(rect) = widget_rects.get(id) {
+                            widget_text += &format!(" {:?} {:?}", rect.rect, rect.sense);
+                        }
+                        if let Some(info) = widget_rects.info(id) {
+                            widget_text += &format!(" {info:?}");
+                        }
+                        debug_text += &format!("{widget_text}\n");
+                    }
+                    self.debug_text(debug_text);
                 }
                 if true {
                     for widget in hovered {
@@ -1887,7 +1923,7 @@ impl Context {
                 drag,
             } = hits;
 
-            if false {
+            if true {
                 for widget in &contains_pointer {
                     paint_widget(widget, "contains_pointer", Color32::BLUE);
                 }

crates/egui/src/response.rs

@@ -745,6 +745,7 @@ impl Response {
     /// Call after interacting and potential calls to [`Self::mark_changed`].
     pub fn widget_info(&self, make_info: impl Fn() -> crate::WidgetInfo) {
         use crate::output::OutputEvent;
+
         let event = if self.clicked() {
             Some(OutputEvent::Clicked(make_info()))
         } else if self.double_clicked() {
@@ -758,6 +759,7 @@ impl Response {
         } else {
             None
         };
+
         if let Some(event) = event {
             self.output_event(event);
         } else {
@@ -765,6 +767,8 @@ impl Response {
             self.ctx.accesskit_node_builder(self.id, |builder| {
                 self.fill_accesskit_node_from_widget_info(builder, make_info());
             });
+
+            self.ctx.register_widget_info(self.id, make_info);
         }
     }
 
@@ -773,6 +777,10 @@ impl Response {
         self.ctx.accesskit_node_builder(self.id, |builder| {
             self.fill_accesskit_node_from_widget_info(builder, event.widget_info().clone());
         });
+
+        self.ctx
+            .register_widget_info(self.id, || event.widget_info().clone());
+
         self.ctx.output_mut(|o| o.events.push(event));
     }
 

crates/egui/src/widget_rect.rs

@@ -46,13 +46,25 @@ pub struct WidgetRect {
 ///
 /// All [`Ui`]s have a [`WidgetRects`], but whether or not their rects are correct
 /// depends on if [`Ui::interact_bg`] was ever called.
-#[derive(Default, Clone, PartialEq, Eq)]
+#[derive(Default, Clone)]
 pub struct WidgetRects {
     /// All widgets, in painting order.
     by_layer: HashMap<LayerId, Vec<WidgetRect>>,
 
     /// All widgets, by id, and their order in their respective layer
     by_id: IdMap<(usize, WidgetRect)>,
+
+    /// Info about some widgets.
+    ///
+    /// Only filled in if the widget is interacted with,
+    /// or if this is a debug build.
+    infos: IdMap<WidgetInfo>,
+}
+
+impl PartialEq for WidgetRects {
+    fn eq(&self, other: &Self) -> bool {
+        self.by_layer == other.by_layer
+    }
 }
 
 impl WidgetRects {
@@ -90,18 +102,28 @@ impl WidgetRects {
 
     /// Clear the contents while retaining allocated memory.
     pub fn clear(&mut self) {
-        let Self { by_layer, by_id } = self;
+        let Self {
+            by_layer,
+            by_id,
+            infos,
+        } = self;
 
         for rects in by_layer.values_mut() {
             rects.clear();
         }
 
         by_id.clear();
+
+        infos.clear();
     }
 
     /// Insert the given widget rect in the given layer.
     pub fn insert(&mut self, layer_id: LayerId, widget_rect: WidgetRect) {
-        let Self { by_layer, by_id } = self;
+        let Self {
+            by_layer,
+            by_id,
+            infos: _,
+        } = self;
 
         let layer_widgets = by_layer.entry(layer_id).or_default();
 
@@ -134,4 +156,12 @@ impl WidgetRects {
             }
         }
     }
+
+    pub fn set_info(&mut self, id: Id, info: WidgetInfo) {
+        self.infos.insert(id, info);
+    }
+
+    pub fn info(&self, id: Id) -> Option<&WidgetInfo> {
+        self.infos.get(&id)
+    }
 }