Changing the notification protocol for core_widgets.

crates/bevy_core_widgets/src/core_button.rs

@@ -2,6 +2,7 @@ use accesskit::Role;
 use bevy_a11y::AccessibilityNode;
 use bevy_app::{App, Plugin};
 use bevy_ecs::query::Has;
+use bevy_ecs::system::In;
 use bevy_ecs::{
     component::Component,
     entity::Entity,
@@ -15,7 +16,7 @@ use bevy_input_focus::FocusedInput;
 use bevy_picking::events::{Cancel, Click, DragEnd, Pointer, Press, Release};
 use bevy_ui::{InteractionDisabled, Pressed};
 
-use crate::{Callback, Notify};
+use crate::{Activate, Callback, Notify};
 
 /// Headless button widget. This widget maintains a "pressed" state, which is used to
 /// indicate whether the button is currently being pressed by the user. It emits a `ButtonClicked`
@@ -25,7 +26,7 @@ use crate::{Callback, Notify};
 pub struct CoreButton {
     /// Callback to invoke when the button is clicked, or when the `Enter` or `Space` key
     /// is pressed while the button is focused.
-    pub on_activate: Callback,
+    pub on_activate: Callback<In<Activate>>,
 }
 
 fn button_on_key_event(
@@ -41,7 +42,7 @@ fn button_on_key_event(
                 && (event.key_code == KeyCode::Enter || event.key_code == KeyCode::Space)
             {
                 trigger.propagate(false);
-                commands.notify(&bstate.on_activate);
+                commands.notify_with(&bstate.on_activate, Activate(trigger.target()));
             }
         }
     }
@@ -55,7 +56,7 @@ fn button_on_pointer_click(
     if let Ok((bstate, pressed, disabled)) = q_state.get_mut(trigger.target()) {
         trigger.propagate(false);
         if pressed && !disabled {
-            commands.notify(&bstate.on_activate);
+            commands.notify_with(&bstate.on_activate, Activate(trigger.target()));
         }
     }
 }

crates/bevy_core_widgets/src/core_checkbox.rs

@@ -15,7 +15,7 @@ use bevy_input_focus::{FocusedInput, InputFocus, InputFocusVisible};
 use bevy_picking::events::{Click, Pointer};
 use bevy_ui::{Checkable, Checked, InteractionDisabled};
 
-use crate::{Callback, Notify as _};
+use crate::{Callback, Notify as _, ValueChange};
 
 /// Headless widget implementation for checkboxes. The [`Checked`] component represents the current
 /// state of the checkbox. The `on_change` field is an optional system id that will be run when the
@@ -34,7 +34,7 @@ pub struct CoreCheckbox {
     /// One-shot system that is run when the checkbox state needs to be changed. If this value is
     /// `Callback::Ignore`, then the checkbox will update it's own internal [`Checked`] state
     /// without notification.
-    pub on_change: Callback<In<bool>>,
+    pub on_change: Callback<In<ValueChange<bool>>>,
 }
 
 fn checkbox_on_key_input(
@@ -162,7 +162,13 @@ fn set_checkbox_state(
     new_state: bool,
 ) {
     if !matches!(checkbox.on_change, Callback::Ignore) {
-        commands.notify_with(&checkbox.on_change, new_state);
+        commands.notify_with(
+            &checkbox.on_change,
+            ValueChange {
+                source: entity.into(),
+                value: new_state,
+            },
+        );
     } else if new_state {
         commands.entity(entity.into()).insert(Checked);
     } else {

crates/bevy_core_widgets/src/core_radio.rs

@@ -6,7 +6,6 @@ use bevy_ecs::query::Has;
 use bevy_ecs::system::In;
 use bevy_ecs::{
     component::Component,
-    entity::Entity,
     observer::On,
     query::With,
     system::{Commands, Query},
@@ -17,7 +16,7 @@ use bevy_input_focus::FocusedInput;
 use bevy_picking::events::{Click, Pointer};
 use bevy_ui::{Checkable, Checked, InteractionDisabled};
 
-use crate::{Callback, Notify};
+use crate::{Activate, Callback, Notify};
 
 /// Headless widget implementation for a "radio button group". This component is used to group
 /// multiple [`CoreRadio`] components together, allowing them to behave as a single unit. It
@@ -38,7 +37,7 @@ use crate::{Callback, Notify};
 #[require(AccessibilityNode(accesskit::Node::new(Role::RadioGroup)))]
 pub struct CoreRadioGroup {
     /// Callback which is called when the selected radio button changes.
-    pub on_change: Callback<In<Entity>>,
+    pub on_change: Callback<In<Activate>>,
 }
 
 /// Headless widget implementation for radio buttons. These should be enclosed within a
@@ -133,7 +132,7 @@ fn radio_group_on_key_input(
             let (next_id, _) = radio_buttons[next_index];
 
             // Trigger the on_change event for the newly checked radio button
-            commands.notify_with(on_change, next_id);
+            commands.notify_with(on_change, Activate(next_id));
         }
     }
 }
@@ -201,7 +200,7 @@ fn radio_group_on_button_click(
         }
 
         // Trigger the on_change event for the newly checked radio button
-        commands.notify_with(on_change, radio_id);
+        commands.notify_with(on_change, Activate(radio_id));
     }
 }
 

crates/bevy_core_widgets/src/core_slider.rs

@@ -23,7 +23,7 @@ use bevy_math::ops;
 use bevy_picking::events::{Drag, DragEnd, DragStart, Pointer, Press};
 use bevy_ui::{ComputedNode, ComputedNodeTarget, InteractionDisabled, UiGlobalTransform, UiScale};
 
-use crate::{Callback, Notify};
+use crate::{Callback, Notify, ValueChange};
 
 /// Defines how the slider should behave when you click on the track (not the thumb).
 #[derive(Debug, Default, PartialEq, Clone, Copy)]
@@ -78,7 +78,7 @@ pub struct CoreSlider {
     /// Callback which is called when the slider is dragged or the value is changed via other user
     /// interaction. If this value is `Callback::Ignore`, then the slider will update it's own
     /// internal [`SliderValue`] state without notification.
-    pub on_change: Callback<In<f32>>,
+    pub on_change: Callback<In<ValueChange<f32>>>,
     /// Set the track-clicking behavior for this slider.
     pub track_click: TrackClick,
     // TODO: Think about whether we want a "vertical" option.
@@ -298,7 +298,13 @@ pub(crate) fn slider_on_pointer_down(
                 .entity(trigger.target())
                 .insert(SliderValue(new_value));
         } else {
-            commands.notify_with(&slider.on_change, new_value);
+            commands.notify_with(
+                &slider.on_change,
+                ValueChange {
+                    source: trigger.target(),
+                    value: new_value,
+                },
+            );
         }
     }
 }
@@ -370,7 +376,13 @@ pub(crate) fn slider_on_drag(
                     .entity(trigger.target())
                     .insert(SliderValue(rounded_value));
             } else {
-                commands.notify_with(&slider.on_change, rounded_value);
+                commands.notify_with(
+                    &slider.on_change,
+                    ValueChange {
+                        source: trigger.target(),
+                        value: rounded_value,
+                    },
+                );
             }
         }
     }
@@ -417,7 +429,13 @@ fn slider_on_key_input(
                     .entity(trigger.target())
                     .insert(SliderValue(new_value));
             } else {
-                commands.notify_with(&slider.on_change, new_value);
+                commands.notify_with(
+                    &slider.on_change,
+                    ValueChange {
+                        source: trigger.target(),
+                        value: new_value,
+                    },
+                );
             }
         }
     }
@@ -509,7 +527,13 @@ fn slider_on_set_value(
                 .entity(trigger.target())
                 .insert(SliderValue(new_value));
         } else {
-            commands.notify_with(&slider.on_change, new_value);
+            commands.notify_with(
+                &slider.on_change,
+                ValueChange {
+                    source: trigger.target(),
+                    value: new_value,
+                },
+            );
         }
     }
 }

crates/bevy_core_widgets/src/lib.rs

@@ -23,6 +23,7 @@ mod core_slider;
 
 use bevy_app::{PluginGroup, PluginGroupBuilder};
 
+use bevy_ecs::entity::Entity;
 pub use callback::{Callback, Notify};
 pub use core_button::{CoreButton, CoreButtonPlugin};
 pub use core_checkbox::{CoreCheckbox, CoreCheckboxPlugin, SetChecked, ToggleChecked};
@@ -50,3 +51,16 @@ impl PluginGroup for CoreWidgetsPlugins {
             .add(CoreSliderPlugin)
     }
 }
+
+/// Notification sent by a button or menu item.
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub struct Activate(pub Entity);
+
+/// Notification sent by a widget that edits a scalar value.
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub struct ValueChange<T> {
+    /// The id of the widget that produced this value.
+    pub source: Entity,
+    /// The new value.
+    pub value: T,
+}

crates/bevy_feathers/src/controls/button.rs

@@ -1,5 +1,5 @@
 use bevy_app::{Plugin, PreUpdate};
-use bevy_core_widgets::{Callback, CoreButton};
+use bevy_core_widgets::{Activate, Callback, CoreButton};
 use bevy_ecs::{
     bundle::Bundle,
     component::Component,
@@ -9,7 +9,7 @@ use bevy_ecs::{
     query::{Added, Changed, Has, Or},
     schedule::IntoScheduleConfigs,
     spawn::{SpawnRelated, SpawnableList},
-    system::{Commands, Query},
+    system::{Commands, In, Query},
 };
 use bevy_input_focus::tab_navigation::TabIndex;
 use bevy_picking::{hover::Hovered, PickingSystems};
@@ -45,7 +45,7 @@ pub struct ButtonProps {
     /// Rounded corners options
     pub corners: RoundedCorners,
     /// Click handler
-    pub on_click: Callback,
+    pub on_click: Callback<In<Activate>>,
 }
 
 /// Template function to spawn a button.

crates/bevy_feathers/src/controls/checkbox.rs

@@ -1,5 +1,5 @@
 use bevy_app::{Plugin, PreUpdate};
-use bevy_core_widgets::{Callback, CoreCheckbox};
+use bevy_core_widgets::{Callback, CoreCheckbox, ValueChange};
 use bevy_ecs::{
     bundle::Bundle,
     children,
@@ -34,7 +34,7 @@ use crate::{
 #[derive(Default)]
 pub struct CheckboxProps {
     /// Change handler
-    pub on_change: Callback<In<bool>>,
+    pub on_change: Callback<In<ValueChange<bool>>>,
 }
 
 /// Marker for the checkbox frame (contains both checkbox and label)

crates/bevy_feathers/src/controls/slider.rs

@@ -2,7 +2,7 @@ use core::f32::consts::PI;
 
 use bevy_app::{Plugin, PreUpdate};
 use bevy_color::Color;
-use bevy_core_widgets::{Callback, CoreSlider, SliderRange, SliderValue, TrackClick};
+use bevy_core_widgets::{Callback, CoreSlider, SliderRange, SliderValue, TrackClick, ValueChange};
 use bevy_ecs::{
     bundle::Bundle,
     children,
@@ -42,7 +42,7 @@ pub struct SliderProps {
     /// Slider maximum value
     pub max: f32,
     /// On-change handler
-    pub on_change: Callback<In<f32>>,
+    pub on_change: Callback<In<ValueChange<f32>>>,
 }
 
 impl Default for SliderProps {

crates/bevy_feathers/src/controls/toggle_switch.rs

@@ -1,7 +1,7 @@
 use accesskit::Role;
 use bevy_a11y::AccessibilityNode;
 use bevy_app::{Plugin, PreUpdate};
-use bevy_core_widgets::{Callback, CoreCheckbox};
+use bevy_core_widgets::{Callback, CoreCheckbox, ValueChange};
 use bevy_ecs::{
     bundle::Bundle,
     children,
@@ -30,7 +30,7 @@ use crate::{
 #[derive(Default)]
 pub struct ToggleSwitchProps {
     /// Change handler
-    pub on_change: Callback<In<bool>>,
+    pub on_change: Callback<In<ValueChange<bool>>>,
 }
 
 /// Marker for the toggle switch outline

examples/ui/core_widgets.rs

@@ -3,9 +3,9 @@
 use bevy::{
     color::palettes::basic::*,
     core_widgets::{
-        Callback, CoreButton, CoreCheckbox, CoreRadio, CoreRadioGroup, CoreSlider,
+        Activate, Callback, CoreButton, CoreCheckbox, CoreRadio, CoreRadioGroup, CoreSlider,
         CoreSliderDragState, CoreSliderThumb, CoreWidgetsPlugins, SliderRange, SliderValue,
-        TrackClick,
+        TrackClick, ValueChange,
     },
     input_focus::{
         tab_navigation::{TabGroup, TabIndex, TabNavigationPlugin},
@@ -120,24 +120,24 @@ fn update_widget_values(
 
 fn setup(mut commands: Commands, assets: Res<AssetServer>) {
     // System to print a value when the button is clicked.
-    let on_click = commands.register_system(|| {
+    let on_click = commands.register_system(|_: In<Activate>| {
         info!("Button clicked!");
     });
 
     // System to update a resource when the slider value changes. Note that we could have
     // updated the slider value directly, but we want to demonstrate externalizing the state.
     let on_change_value = commands.register_system(
-        |value: In<f32>, mut widget_states: ResMut<DemoWidgetStates>| {
-            widget_states.slider_value = *value;
+        |value: In<ValueChange<f32>>, mut widget_states: ResMut<DemoWidgetStates>| {
+            widget_states.slider_value = value.0.value;
         },
     );
 
     // System to update a resource when the radio group changes.
     let on_change_radio = commands.register_system(
-        |value: In<Entity>,
+        |value: In<Activate>,
          mut widget_states: ResMut<DemoWidgetStates>,
          q_radios: Query<&DemoRadio>| {
-            if let Ok(radio) = q_radios.get(*value) {
+            if let Ok(radio) = q_radios.get(value.0 .0) {
                 widget_states.slider_click = radio.0;
             }
         },
@@ -155,9 +155,9 @@ fn setup(mut commands: Commands, assets: Res<AssetServer>) {
 
 fn demo_root(
     asset_server: &AssetServer,
-    on_click: Callback,
-    on_change_value: Callback<In<f32>>,
-    on_change_radio: Callback<In<Entity>>,
+    on_click: Callback<In<Activate>>,
+    on_change_value: Callback<In<ValueChange<f32>>>,
+    on_change_radio: Callback<In<Activate>>,
 ) -> impl Bundle {
     (
         Node {
@@ -181,7 +181,7 @@ fn demo_root(
     )
 }
 
-fn button(asset_server: &AssetServer, on_click: Callback) -> impl Bundle {
+fn button(asset_server: &AssetServer, on_click: Callback<In<Activate>>) -> impl Bundle {
     (
         Node {
             width: Val::Px(150.0),
@@ -324,7 +324,12 @@ fn set_button_style(
 }
 
 /// Create a demo slider
-fn slider(min: f32, max: f32, value: f32, on_change: Callback<In<f32>>) -> impl Bundle {
+fn slider(
+    min: f32,
+    max: f32,
+    value: f32,
+    on_change: Callback<In<ValueChange<f32>>>,
+) -> impl Bundle {
     (
         Node {
             display: Display::Flex,
@@ -469,7 +474,7 @@ fn thumb_color(disabled: bool, hovered: bool) -> Color {
 fn checkbox(
     asset_server: &AssetServer,
     caption: &str,
-    on_change: Callback<In<bool>>,
+    on_change: Callback<In<ValueChange<bool>>>,
 ) -> impl Bundle {
     (
         Node {
@@ -662,7 +667,7 @@ fn set_checkbox_or_radio_style(
 }
 
 /// Create a demo radio group
-fn radio_group(asset_server: &AssetServer, on_change: Callback<In<Entity>>) -> impl Bundle {
+fn radio_group(asset_server: &AssetServer, on_change: Callback<In<Activate>>) -> impl Bundle {
     (
         Node {
             display: Display::Flex,