Interactive Ui:s: add UiBuilder::sense and Ui::response

crates/egui/src/containers/area.rs

@@ -462,14 +462,17 @@ impl Area {
                 }
             });
 
-            let move_response = ctx.create_widget(WidgetRect {
-                id: interact_id,
-                layer_id,
-                rect: state.rect(),
-                interact_rect: state.rect(),
-                sense,
-                enabled,
-            });
+            let move_response = ctx.create_widget(
+                WidgetRect {
+                    id: interact_id,
+                    layer_id,
+                    rect: state.rect(),
+                    interact_rect: state.rect(),
+                    sense,
+                    enabled,
+                },
+                true,
+            );
 
             if movable && move_response.dragged() {
                 if let Some(pivot_pos) = &mut state.pivot_pos {

crates/egui/src/containers/window.rs

@@ -833,14 +833,17 @@ fn resize_interaction(
     }
 
     let is_dragging = |rect, id| {
-        let response = ctx.create_widget(WidgetRect {
-            layer_id,
-            id,
-            rect,
-            interact_rect: rect,
-            sense: Sense::drag(),
-            enabled: true,
-        });
+        let response = ctx.create_widget(
+            WidgetRect {
+                layer_id,
+                id,
+                rect,
+                interact_rect: rect,
+                sense: Sense::drag(),
+                enabled: true,
+            },
+            true,
+        );
         SideResponse {
             hover: response.hovered(),
             drag: response.dragged(),

crates/egui/src/context.rs

@@ -1049,8 +1049,11 @@ impl Context {
     /// You should use [`Ui::interact`] instead.
     ///
     /// If the widget already exists, its state (sense, Rect, etc) will be updated.
+    ///
+    /// `allow_focus` should usually be true, unless you call this function multiple times with the
+    /// same widget, then `allow_focus` should only be true once (like in [`Ui::new`] (true) and [`Ui::interact_bg`] (false)).
     #[allow(clippy::too_many_arguments)]
-    pub(crate) fn create_widget(&self, w: WidgetRect) -> Response {
+    pub(crate) fn create_widget(&self, w: WidgetRect, allow_focus: bool) -> Response {
         // Remember this widget
         self.write(|ctx| {
             let viewport = ctx.viewport();
@@ -1060,12 +1063,12 @@ impl Context {
             // but also to know when we have reached the widget we are checking for cover.
             viewport.this_frame.widgets.insert(w.layer_id, w);
 
-            if w.sense.focusable {
+            if allow_focus && w.sense.focusable {
                 ctx.memory.interested_in_focus(w.id);
             }
         });
 
-        if !w.enabled || !w.sense.focusable || !w.layer_id.allow_interaction() {
+        if allow_focus && (!w.enabled || !w.sense.focusable || !w.layer_id.allow_interaction()) {
             // Not interested or allowed input:
             self.memory_mut(|mem| mem.surrender_focus(w.id));
         }
@@ -1078,7 +1081,7 @@ impl Context {
         let res = self.get_response(w);
 
         #[cfg(feature = "accesskit")]
-        if w.sense.focusable {
+        if allow_focus && w.sense.focusable {
             // Make sure anything that can receive focus has an AccessKit node.
             // TODO(mwcampbell): For nodes that are filled from widget info,
             // some information is written to the node twice.
@@ -1114,7 +1117,7 @@ impl Context {
     }
 
     /// Do all interaction for an existing widget, without (re-)registering it.
-    fn get_response(&self, widget_rect: WidgetRect) -> Response {
+    pub(crate) fn get_response(&self, widget_rect: WidgetRect) -> Response {
         let WidgetRect {
             id,
             layer_id,

crates/egui/src/menu.rs

@@ -706,7 +706,7 @@ impl MenuState {
 
             self.open_submenu(sub_id, pos);
         } else if open
-            && ui.interact_bg(Sense::hover()).contains_pointer()
+            && ui.read_response().contains_pointer()
             && !button.hovered()
             && !self.hovering_current_submenu(&pointer)
         {

crates/egui/src/response.rs

@@ -857,14 +857,17 @@ impl Response {
             return self.clone();
         }
 
-        self.ctx.create_widget(WidgetRect {
-            layer_id: self.layer_id,
-            id: self.id,
-            rect: self.rect,
-            interact_rect: self.interact_rect,
-            sense: self.sense | sense,
-            enabled: self.enabled,
-        })
+        self.ctx.create_widget(
+            WidgetRect {
+                layer_id: self.layer_id,
+                id: self.id,
+                rect: self.rect,
+                interact_rect: self.interact_rect,
+                sense: self.sense | sense,
+                enabled: self.enabled,
+            },
+            true,
+        )
     }
 
     /// Adjust the scroll position until this UI becomes visible.

crates/egui/src/ui.rs

@@ -89,6 +89,13 @@ pub struct Ui {
 
     /// The [`UiStack`] for this [`Ui`].
     stack: Arc<UiStack>,
+
+    /// The sense for the ui background.
+    /// It will be used for [Ui::interact_bg].
+    sense: Sense,
+
+    /// Whether [`Ui::interact_bg`] should be called when the [`Ui`] is dropped.
+    should_interact_bg_on_drop: bool,
 }
 
 impl Ui {
@@ -109,6 +116,7 @@ impl Ui {
             invisible,
             sizing_pass,
             style,
+            sense,
         } = ui_builder;
 
         debug_assert!(
@@ -122,6 +130,7 @@ impl Ui {
         let invisible = invisible || sizing_pass;
         let disabled = disabled || invisible || sizing_pass;
         let style = style.unwrap_or_else(|| ctx.style());
+        let sense = sense.unwrap_or(Sense::hover());
 
         let placer = Placer::new(max_rect, layout);
         let ui_stack = UiStack {
@@ -142,18 +151,23 @@ impl Ui {
             sizing_pass: false,
             menu_state: None,
             stack: Arc::new(ui_stack),
+            sense,
+            should_interact_bg_on_drop: true,
         };
 
         // Register in the widget stack early, to ensure we are behind all widgets we contain:
         let start_rect = Rect::NOTHING; // This will be overwritten when/if `interact_bg` is called
-        ui.ctx().create_widget(WidgetRect {
-            id: ui.id,
-            layer_id: ui.layer_id(),
-            rect: start_rect,
-            interact_rect: start_rect,
-            sense: Sense::hover(),
-            enabled: ui.enabled,
-        });
+        ui.ctx().create_widget(
+            WidgetRect {
+                id: ui.id,
+                layer_id: ui.layer_id(),
+                rect: start_rect,
+                interact_rect: start_rect,
+                sense,
+                enabled: ui.enabled,
+            },
+            true,
+        );
 
         if disabled {
             ui.disable();
@@ -220,6 +234,7 @@ impl Ui {
             invisible,
             sizing_pass,
             style,
+            sense,
         } = ui_builder;
 
         let mut painter = self.painter.clone();
@@ -234,6 +249,7 @@ impl Ui {
         }
         let sizing_pass = self.sizing_pass || sizing_pass;
         let style = style.unwrap_or_else(|| self.style.clone());
+        let sense = sense.unwrap_or(Sense::hover());
 
         if self.sizing_pass {
             // During the sizing pass we want widgets to use up as little space as possible,
@@ -269,18 +285,23 @@ impl Ui {
             sizing_pass,
             menu_state: self.menu_state.clone(),
             stack: Arc::new(ui_stack),
+            sense,
+            should_interact_bg_on_drop: true,
         };
 
         // Register in the widget stack early, to ensure we are behind all widgets we contain:
         let start_rect = Rect::NOTHING; // This will be overwritten when/if `interact_bg` is called
-        child_ui.ctx().create_widget(WidgetRect {
-            id: child_ui.id,
-            layer_id: child_ui.layer_id(),
-            rect: start_rect,
-            interact_rect: start_rect,
-            sense: Sense::hover(),
-            enabled: child_ui.enabled,
-        });
+        child_ui.ctx().create_widget(
+            WidgetRect {
+                id: child_ui.id,
+                layer_id: child_ui.layer_id(),
+                rect: start_rect,
+                interact_rect: start_rect,
+                sense,
+                enabled: child_ui.enabled,
+            },
+            true,
+        );
 
         child_ui
     }
@@ -948,14 +969,17 @@ impl Ui {
 impl Ui {
     /// Check for clicks, drags and/or hover on a specific region of this [`Ui`].
     pub fn interact(&self, rect: Rect, id: Id, sense: Sense) -> Response {
-        self.ctx().create_widget(WidgetRect {
-            id,
-            layer_id: self.layer_id(),
-            rect,
-            interact_rect: self.clip_rect().intersect(rect),
-            sense,
-            enabled: self.enabled,
-        })
+        self.ctx().create_widget(
+            WidgetRect {
+                id,
+                layer_id: self.layer_id(),
+                rect,
+                interact_rect: self.clip_rect().intersect(rect),
+                sense,
+                enabled: self.enabled,
+            },
+            true,
+        )
     }
 
     /// Deprecated: use [`Self::interact`] instead.
@@ -970,13 +994,59 @@ impl Ui {
         self.interact(rect, id, sense)
     }
 
+    /// Read the [`Ui`]s background [`Response`].
+    /// It's [`Sense`] will be based on the [`UiBuilder::sense`] used to create this [`Ui`].
+    ///
+    /// The rectangle of the [`Response`] (and interactive area) will be [`Self::min_rect`]
+    /// of the last frame.
+    ///
+    /// On the first frame, when the [`Ui`] is created, this will return a [`Response`] with a
+    /// [`Rect`] of [`Rect::NOTHING`].
+    pub fn read_response(&self) -> Response {
+        // This is the inverse of Context::read_response. We prefer a response
+        // based on last frame's widget rect since the one from this frame is Rect::NOTHING until
+        // Ui::interact_bg is called or the Ui is dropped.
+        self.ctx()
+            .viewport(|viewport| {
+                viewport
+                    .prev_frame
+                    .widgets
+                    .get(self.id)
+                    .or_else(|| viewport.this_frame.widgets.get(self.id))
+                    .copied()
+            })
+            .map(|widget_rect| self.ctx().get_response(widget_rect))
+            .expect(
+                "Since we always call Context::create_widget in Ui::new, this should never be None",
+            )
+    }
+
     /// Interact with the background of this [`Ui`],
     /// i.e. behind all the widgets.
     ///
     /// The rectangle of the [`Response`] (and interactive area) will be [`Self::min_rect`].
-    pub fn interact_bg(&self, sense: Sense) -> Response {
+    /// You can customize the [`Sense`] via [`UiBuilder::sense`].
+    // This is marked as deprecated for public use but still makes sense to use internally.
+    #[deprecated = "Use Ui::read_response instead"]
+    pub fn interact_bg(&self) -> Response {
+        // We remove the id from used_ids to prevent a duplicate id warning from showing
+        // when the ui was created with `UiBuilder::sense`.
+        // This is a bit hacky, is there a better way?
+        self.ctx().frame_state_mut(|fs| {
+            fs.used_ids.remove(&self.id);
+        });
         // This will update the WidgetRect that was first created in `Ui::new`.
-        self.interact(self.min_rect(), self.id, sense)
+        self.ctx().create_widget(
+            WidgetRect {
+                id: self.id,
+                layer_id: self.layer_id(),
+                rect: self.min_rect(),
+                interact_rect: self.clip_rect().intersect(self.min_rect()),
+                sense: self.sense,
+                enabled: self.enabled,
+            },
+            false,
+        )
     }
 
     /// Is the pointer (mouse/touch) above this rectangle in this [`Ui`]?
@@ -2142,7 +2212,10 @@ impl Ui {
         let mut child_ui = self.new_child(ui_builder);
         self.next_auto_id_salt = next_auto_id_salt; // HACK: we want `scope` to only increment this once, so that `ui.scope` is equivalent to `ui.allocate_space`.
         let ret = add_contents(&mut child_ui);
-        let response = self.allocate_rect(child_ui.min_rect(), Sense::hover());
+        #[allow(deprecated)]
+        let response = child_ui.interact_bg();
+        child_ui.should_interact_bg_on_drop = false;
+        self.allocate_rect(child_ui.min_rect(), Sense::hover());
         InnerResponse::new(ret, response)
     }
 
@@ -2811,6 +2884,10 @@ impl Ui {
 #[cfg(debug_assertions)]
 impl Drop for Ui {
     fn drop(&mut self) {
+        if self.should_interact_bg_on_drop {
+            #[allow(deprecated)]
+            self.interact_bg();
+        }
         register_rect(self, self.min_rect());
     }
 }

crates/egui/src/ui_builder.rs

@@ -1,6 +1,6 @@
 use std::{hash::Hash, sync::Arc};
 
-use crate::{Id, Layout, Rect, Style, UiStackInfo};
+use crate::{Id, Layout, Rect, Sense, Style, UiStackInfo};
 
 #[allow(unused_imports)] // Used for doclinks
 use crate::Ui;
@@ -21,6 +21,7 @@ pub struct UiBuilder {
     pub invisible: bool,
     pub sizing_pass: bool,
     pub style: Option<Arc<Style>>,
+    pub sense: Option<Sense>,
 }
 
 impl UiBuilder {
@@ -116,4 +117,11 @@ impl UiBuilder {
         self.style = Some(style.into());
         self
     }
+
+    /// Sense of the Ui. Should be the same as the one passed to [`Ui::interact_bg`]
+    #[inline]
+    pub fn sense(mut self, sense: Sense) -> Self {
+        self.sense = Some(sense);
+        self
+    }
 }

crates/egui/src/widget_rect.rs

@@ -44,8 +44,8 @@ pub struct WidgetRect {
 
 /// Stores the [`WidgetRect`]s of all widgets generated during a single egui update/frame.
 ///
-/// All [`crate::Ui`]s have a [`WidgetRects`], but whether or not their rects are correct
-/// depends on if [`crate::Ui::interact_bg`] was ever called.
+/// All [`crate::Ui`]s have a [`WidgetRect`]. It is created in [`crate::Ui::new`] with [`Rect::NOTHING`]
+/// and updated with the correct [`Rect`] when the [`crate::Ui`] is dropped.
 #[derive(Default, Clone)]
 pub struct WidgetRects {
     /// All widgets, in painting order.