Implement horizontal scrolling and per-axis scroll control

bevyengine · Apr 18, 2023 · 29aa3a0 · 29aa3a0
1 parent 4033477
commit 29aa3a0
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Showing 4 changed files with 38 additions and 21 deletions.
diff --git a/crates/bevy_ui/src/layout/mod.rs b/crates/bevy_ui/src/layout/mod.rs
@@ -360,13 +360,12 @@ pub fn ui_layout_system(
             }
 
             // Adjust position by the scroll offset of the parent
-            let x_scroll_position = 0.0; // TODO: implement horizontal scrolling
-            new_position.x += x_scroll_position;
-            let y_scroll_position = scroll_position_query
+            let (x_scroll_position, y_scroll_position) = scroll_position_query
                 .get(**parent)
                 .ok()
-                .and_then(|(_, p)| p.map(|p| p.offset_y))
-                .unwrap_or(0.0);
+                .and_then(|(_, p)| p.map(|p| (p.offset_x, p.offset_y)))
+                .unwrap_or((0.0, 0.0));
+            new_position.x += x_scroll_position;
             new_position.y += y_scroll_position;
         }
         // only trigger change detection when the new value is different

diff --git a/crates/bevy_ui/src/ui_node.rs b/crates/bevy_ui/src/ui_node.rs
@@ -63,13 +63,16 @@ impl Default for Node {
 #[reflect(Component, Default)]
 pub struct ScrollPosition {
     pub is_hovered: bool,
+    /// How far accross the node is scrolled (0 = not scrolled / scrolled to right)
+    pub offset_x: f32,
     /// How far down the node is scrolled (0 = not scrolled / scrolled to top)
     pub offset_y: f32,
 }
 
 impl ScrollPosition {
     pub const DEFAULT: Self = Self {
         is_hovered: false,
+        offset_x: 0.0,
         offset_y: 0.0,
     };
 }

diff --git a/crates/bevy_ui/src/update.rs b/crates/bevy_ui/src/update.rs
@@ -114,22 +114,35 @@ pub fn update_scroll_position(
     query_node: Query<&Node>,
 ) {
     for mouse_wheel_event in mouse_wheel_events.iter() {
-        for (mut scroll_container, style, children, list_node) in &mut query_list {
-            if style.overflow.y == OverflowAxis::Scroll && scroll_container.is_hovered {
-                let container_height = list_node.size().y;
-                let items_height: f32 = children
-                    .iter()
-                    .map(|child| query_node.get(*child).unwrap().size().y)
-                    .sum();
+        let (dx, dy) = match mouse_wheel_event.unit {
+            MouseScrollUnit::Line => (mouse_wheel_event.x * 20., mouse_wheel_event.y * 20.),
+            MouseScrollUnit::Pixel => (mouse_wheel_event.x, mouse_wheel_event.y),
+        };
 
-                let max_scroll = (items_height - container_height).max(0.);
+        for (mut scroll_container, style, children, list_node) in &mut query_list {
+            if scroll_container.is_hovered {
+                if style.overflow.x == OverflowAxis::Scroll {
+                    let container_width = list_node.size().x;
+                    let items_width: f32 = children
+                        .iter()
+                        .map(|child| query_node.get(*child).unwrap().size().x)
+                        .sum();
 
-                let dy = match mouse_wheel_event.unit {
-                    MouseScrollUnit::Line => mouse_wheel_event.y * 20.,
-                    MouseScrollUnit::Pixel => mouse_wheel_event.y,
-                };
+                    let max_scroll_x = (items_width - container_width).max(0.);
+                    scroll_container.offset_x =
+                        (scroll_container.offset_x + dx).clamp(-max_scroll_x, 0.);
+                }
+                if style.overflow.y == OverflowAxis::Scroll {
+                    let container_height = list_node.size().y;
+                    let items_height: f32 = children
+                        .iter()
+                        .map(|child| query_node.get(*child).unwrap().size().y)
+                        .sum();
 
-                scroll_container.offset_y = (scroll_container.offset_y + dy).clamp(-max_scroll, 0.);
+                    let max_scroll_y = (items_height - container_height).max(0.);
+                    scroll_container.offset_y =
+                        (scroll_container.offset_y + dy).clamp(-max_scroll_y, 0.);
+                }
             }
         }
     }

diff --git a/examples/ui/ui.rs b/examples/ui/ui.rs
@@ -84,7 +84,8 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
                                         flex_direction: FlexDirection::Column,
                                         align_self: AlignSelf::Stretch,
                                         size: Size::height(Val::Percent(50.)),
-                                        overflow: Overflow::scroll_y(),
+                                        align_items: AlignItems::Start,
+                                        overflow: Overflow::scroll(),
                                         ..default()
                                     },
                                     background_color: Color::rgb(0.10, 0.10, 0.10).into(),
@@ -97,7 +98,8 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
                                             NodeBundle {
                                                 style: Style {
                                                     flex_direction: FlexDirection::Column,
-                                                    align_items: AlignItems::Center,
+                                                    align_items: AlignItems::Start,
+                                                    size: Size::width(Val::Px(600.)),
                                                     ..default()
                                                 },
                                                 ..default()
@@ -109,7 +111,7 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
                                             for i in 0..100 {
                                                 parent.spawn((
                                                     TextBundle::from_section(
-                                                        format!("Item {}", i + 1),
+                                                        format!("Item {} rhgiuherwiofhioewhfgioewhgioewhioghweioghiowhewiohgio", i + 1),
                                                         TextStyle {
                                                             font: asset_server
                                                                 .load("fonts/FiraSans-Bold.ttf"),