Boundaries

src/lib.rs

@@ -28,14 +28,14 @@ pub struct ScrollViewport {
 
 impl Default for ScrollViewport {
     fn default() -> Self {
-        Self {
-            scroll_speed: 500.0,
-        }
+        Self { scroll_speed: 500.0 }
     }
 }
 
 #[derive(Component, Debug, Reflect)]
-pub struct ScrollViewContent(pub Entity);
+pub struct ScrollViewContent {
+    pub pos_y: f32,
+}
 
 pub fn create_scroll_view(mut commands: Commands, q: Query<Entity, Added<ScrollView>>) {
     for e in q.iter() {
@@ -44,6 +44,9 @@ pub fn create_scroll_view(mut commands: Commands, q: Query<Entity, Added<ScrollV
                 NodeBundle {
                     style: Style {
                         overflow: Overflow::clip(),
+                        max_height: Val::Percent(100.0),
+                        max_width: Val::Percent(100.0),
+                        align_items: AlignItems::Start,
                         ..default()
                     },
                     ..Default::default()
@@ -60,7 +63,7 @@ pub fn create_scroll_view(mut commands: Commands, q: Query<Entity, Added<ScrollV
                         },
                         ..default()
                     },
-                    ScrollViewContent(e),
+                    ScrollViewContent { pos_y: 0.0 },
                 ));
             });
         });
@@ -69,21 +72,23 @@ pub fn create_scroll_view(mut commands: Commands, q: Query<Entity, Added<ScrollV
 
 fn input_mouse_pressed_move(
     mut motion_evr: EventReader<MouseMotion>,
-    mut q: Query<(&Children, &Interaction), With<ScrollViewport>>,
-    mut content_q: Query<&mut Style, With<ScrollViewContent>>,
+    mut q: Query<(&Children, &Interaction, &Node), With<ScrollViewport>>,
+    mut content_q: Query<(&mut Style, &mut ScrollViewContent, &Node)>,
 ) {
     for evt in motion_evr.read() {
-        info!("{:?}", evt);
-        for (children, &interaction) in q.iter_mut() {
+        for (children, &interaction, node) in q.iter_mut() {
             if interaction != Interaction::Pressed {
                 continue;
             }
+            let container_height = node.size().y;
             for &child in children.iter() {
-                if let Ok(mut style) = content_q.get_mut(child) {
-                    style.top = match style.top {
-                        Val::Px(px) => Val::Px(px + evt.delta.y),
-                        _ => Val::Px(0.0),
-                    }
+                if let Ok(item) = content_q.get_mut(child) {
+                    let mut style = item.0;
+                    let mut scroll = item.1;
+                    let max_scroll = (item.2.size().y - container_height).max(0.0);
+                    scroll.pos_y += evt.delta.y;
+                    scroll.pos_y = scroll.pos_y.clamp(-max_scroll, 0.);
+                    style.top = Val::Px(scroll.pos_y);
                 }
             }
         }
@@ -92,33 +97,33 @@ fn input_mouse_pressed_move(
 
 fn scroll_events(
     mut scroll_evr: EventReader<MouseWheel>,
-    mut q: Query<(&mut Style, &Interaction, &ScrollViewport), With<ScrollViewport>>,
+    mut q: Query<(&Children, &Interaction, &ScrollViewport, &Node), With<ScrollViewport>>,
     time: Res<Time>,
+    mut content_q: Query<(&mut Style, &mut ScrollViewContent, &Node)>,
 ) {
     use bevy::input::mouse::MouseScrollUnit;
     for ev in scroll_evr.read() {
-        let y = match ev.unit {
-            MouseScrollUnit::Line => {
-                println!(
-                    "Scroll (line units): vertical: {}, horizontal: {}",
-                    ev.y, ev.x
-                );
-                ev.y
+        for (children, &interaction, scroll_view, node) in q.iter_mut() {
+            let y = match ev.unit {
+                MouseScrollUnit::Line => {
+                    ev.y * time.delta().as_secs_f32() * scroll_view.scroll_speed
+                }
+                MouseScrollUnit::Pixel => ev.y,
+            };
+            if interaction != Interaction::Hovered {
+                continue;
             }
-            MouseScrollUnit::Pixel => {
-                println!(
-                    "Scroll (pixel units): vertical: {}, horizontal: {}",
-                    ev.y, ev.x
-                );
-                ev.y
-            }
-        };
-        for (mut style, &interaction, scroll_view) in q.iter_mut() {
-            if interaction == Interaction::Hovered {
-                let y = y * time.delta().as_secs_f32() * scroll_view.scroll_speed;
-                style.top = match style.top {
-                    Val::Px(px) => Val::Px(px + y),
-                    _ => Val::Px(0.0),
+            let container_height = node.size().y;
+
+            for &child in children.iter() {
+                if let Ok(item) = content_q.get_mut(child) {
+                    let y = y * time.delta().as_secs_f32() * scroll_view.scroll_speed;
+                    let mut style = item.0;
+                    let mut scroll = item.1;
+                    let max_scroll = (item.2.size().y - container_height).max(0.0);
+                    scroll.pos_y += y;
+                    scroll.pos_y = scroll.pos_y.clamp(-max_scroll, 0.);
+                    style.top = Val::Px(scroll.pos_y);
                 }
             }
         }