Default button material behavior

crates/bevy_ui/src/lib.rs

@@ -30,6 +30,7 @@ use bevy_math::{Rect, Size};
 use bevy_render::RenderStage;
 use bevy_transform::TransformSystem;
 use update::ui_z_system;
+use widget::DefaultButtonMaterials;
 
 #[derive(Default)]
 pub struct UiPlugin;
@@ -43,6 +44,7 @@ pub enum UiSystem {
 impl Plugin for UiPlugin {
     fn build(&self, app: &mut AppBuilder) {
         app.init_resource::<FlexSurface>()
+            .init_resource::<DefaultButtonMaterials>()
             .register_type::<AlignContent>()
             .register_type::<AlignItems>()
             .register_type::<AlignSelf>()
@@ -85,6 +87,14 @@ impl Plugin for UiPlugin {
                     .after(UiSystem::Flex)
                     .before(TransformSystem::TransformPropagate),
             )
+            .add_system_to_stage(
+                CoreStage::PostUpdate,
+                widget::button_default_materials_system.system(),
+            )
+            .add_system_to_stage(
+                CoreStage::PostUpdate,
+                widget::button_materials_system.system(),
+            )
             .add_system_to_stage(RenderStage::Draw, widget::draw_text_system.system());
 
         crate::render::add_ui_graph(app.world_mut());

crates/bevy_ui/src/widget/button.rs

@@ -1,2 +1,90 @@
+use bevy_asset::{Assets, Handle};
+use bevy_ecs::prelude::{Changed, FromWorld, Query, Res, With, Without, World};
+use bevy_render::prelude::Color;
+use bevy_sprite::ColorMaterial;
+
+use crate::Interaction;
+
 #[derive(Debug, Clone)]
 pub struct Button;
+
+#[derive(Debug, Clone)]
+pub struct DefaultButtonMaterials {
+    pub normal: Handle<ColorMaterial>,
+    pub hovered: Handle<ColorMaterial>,
+    pub pressed: Handle<ColorMaterial>,
+}
+
+impl FromWorld for DefaultButtonMaterials {
+    fn from_world(world: &mut World) -> Self {
+        let mut materials = world.get_resource_mut::<Assets<ColorMaterial>>().unwrap();
+
+        DefaultButtonMaterials {
+            normal: materials.add(Color::rgb(0.15, 0.15, 0.15).into()),
+            hovered: materials.add(Color::rgb(0.25, 0.25, 0.25).into()),
+            pressed: materials.add(Color::rgb(0.35, 0.75, 0.35).into()),
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct ButtonMaterials {
+    pub normal: Handle<ColorMaterial>,
+    pub hovered: Handle<ColorMaterial>,
+    pub pressed: Handle<ColorMaterial>,
+}
+
+#[derive(Debug, Clone)]
+pub struct CustomButtonMaterialBehavior;
+
+pub fn button_default_materials_system(
+    default_materials: Res<DefaultButtonMaterials>,
+    mut query: Query<
+        (&Interaction, &mut Handle<ColorMaterial>),
+        (
+            Changed<Interaction>,
+            With<Button>,
+            Without<ButtonMaterials>,
+            Without<CustomButtonMaterialBehavior>,
+        ),
+    >,
+) {
+    for (interaction, mut material) in query.iter_mut() {
+        match *interaction {
+            Interaction::None => {
+                *material = default_materials.normal.clone();
+            }
+            Interaction::Hovered => {
+                *material = default_materials.hovered.clone();
+            }
+            Interaction::Clicked => {
+                *material = default_materials.pressed.clone();
+            }
+        }
+    }
+}
+
+pub fn button_materials_system(
+    mut query: Query<
+        (&Interaction, &mut Handle<ColorMaterial>, &ButtonMaterials),
+        (
+            Changed<Interaction>,
+            With<Button>,
+            Without<CustomButtonMaterialBehavior>,
+        ),
+    >,
+) {
+    for (interaction, mut material, materials) in query.iter_mut() {
+        match *interaction {
+            Interaction::None => {
+                *material = materials.normal.clone();
+            }
+            Interaction::Hovered => {
+                *material = materials.hovered.clone();
+            }
+            Interaction::Clicked => {
+                *material = materials.pressed.clone();
+            }
+        }
+    }
+}

examples/ecs/state.rs

@@ -5,7 +5,6 @@ use bevy::prelude::*;
 fn main() {
     App::build()
         .add_plugins(DefaultPlugins)
-        .init_resource::<ButtonMaterials>()
         .add_state(AppState::Menu)
         .add_system_set(SystemSet::on_enter(AppState::Menu).with_system(setup_menu.system()))
         .add_system_set(SystemSet::on_update(AppState::Menu).with_system(menu.system()))
@@ -32,7 +31,7 @@ struct MenuData {
 fn setup_menu(
     mut commands: Commands,
     asset_server: Res<AssetServer>,
-    button_materials: Res<ButtonMaterials>,
+    mut materials: ResMut<Assets<ColorMaterial>>,
 ) {
     // ui camera
     commands.spawn_bundle(UiCameraBundle::default());
@@ -48,7 +47,7 @@ fn setup_menu(
                 align_items: AlignItems::Center,
                 ..Default::default()
             },
-            material: button_materials.normal.clone(),
+            material: materials.add(Color::WHITE.into()),
             ..Default::default()
         })
         .with_children(|parent| {
@@ -71,24 +70,11 @@ fn setup_menu(
 
 fn menu(
     mut state: ResMut<State<AppState>>,
-    button_materials: Res<ButtonMaterials>,
-    mut interaction_query: Query<
-        (&Interaction, &mut Handle<ColorMaterial>),
-        (Changed<Interaction>, With<Button>),
-    >,
+    mut interaction_query: Query<&Interaction, (Changed<Interaction>, With<Button>)>,
 ) {
-    for (interaction, mut material) in interaction_query.iter_mut() {
-        match *interaction {
-            Interaction::Clicked => {
-                *material = button_materials.pressed.clone();
-                state.set(AppState::InGame).unwrap();
-            }
-            Interaction::Hovered => {
-                *material = button_materials.hovered.clone();
-            }
-            Interaction::None => {
-                *material = button_materials.normal.clone();
-            }
+    for interaction in interaction_query.iter_mut() {
+        if *interaction == Interaction::Clicked {
+            state.set(AppState::InGame).unwrap();
         }
     }
 }
@@ -149,20 +135,3 @@ fn change_color(
             .set_b((time.seconds_since_startup() * 5.0).sin() as f32 + 2.0);
     }
 }
-
-struct ButtonMaterials {
-    normal: Handle<ColorMaterial>,
-    hovered: Handle<ColorMaterial>,
-    pressed: Handle<ColorMaterial>,
-}
-
-impl FromWorld for ButtonMaterials {
-    fn from_world(world: &mut World) -> Self {
-        let mut materials = world.get_resource_mut::<Assets<ColorMaterial>>().unwrap();
-        ButtonMaterials {
-            normal: materials.add(Color::rgb(0.15, 0.15, 0.15).into()),
-            hovered: materials.add(Color::rgb(0.25, 0.25, 0.25).into()),
-            pressed: materials.add(Color::rgb(0.35, 0.75, 0.35).into()),
-        }
-    }
-}