Merge pull request #3554 from Taha-Mahmoodi/fix/3443-layers-scrollbar

Fix #3443: the Layers list's scroll bar no longer covers the rows' selection marks

crates/ui-egui/src/dock.rs

@@ -723,6 +723,49 @@ mod tests {
         assert!(covered.is_empty(), "under the scroll bar at {bar:?}: {covered:#?}");
     }
 
+    /// #3443: the Layers list's scroll bar sits beside the rows, not over the target and selection
+    /// marks at their right edge.
+    #[test]
+    fn the_layers_scroll_bar_covers_no_row() {
+        use egui::accesskit::Role;
+        let mut app = VectorcraftApp::new(Session::new(), Default::default());
+        app.run("file.new", json!({"width": 300, "height": 300})).unwrap();
+        for k in 0..40 {
+            app.run("shape.rectangle", json!({"x": k, "y": k, "width": 20, "height": 20})).unwrap();
+        }
+        app.run("window.panel", json!({"panel": "layers"})).unwrap();
+        let ctx = egui::Context::default();
+        ctx.enable_accesskit();
+        theme::install_fonts(&ctx);
+        let screen = egui::Rect::from_min_size(egui::Pos2::ZERO, vec2(1440.0, 600.0));
+        let mut nodes = vec![];
+        for k in 0..4 {
+            let input = egui::RawInput { time: Some(f64::from(k) * 0.1), screen_rect: Some(screen), ..Default::default() };
+            let mut out = ctx.run_ui(input, |ui| show(&mut app, ui));
+            out.textures_delta.clear();
+            nodes = out.platform_output.accesskit_update.unwrap().nodes;
+        }
+        let rect = |n: &egui::accesskit::Node| {
+            n.bounds().map(|b| egui::Rect::from_min_max(egui::pos2(b.x0 as f32, b.y0 as f32), egui::pos2(b.x1 as f32, b.y1 as f32)))
+        };
+        let bar = nodes
+            .iter()
+            .filter(|(_, n)| n.role() == Role::ScrollBar)
+            .filter_map(|(_, n)| rect(n))
+            .max_by(|a, b| a.left().total_cmp(&b.left()))
+            .filter(|bar| bar.left() > screen.right() - DOCK_WIDTH)
+            .expect("40 layers scroll in a 600 pt window");
+        let rows: Vec<egui::Rect> = nodes
+            .iter()
+            .filter(|(_, n)| n.role() != Role::ScrollBar)
+            .filter_map(|(_, n)| rect(n))
+            .filter(|r| r.top() >= bar.top() && r.bottom() <= bar.bottom() && r.right() > bar.left() - 40.0)
+            .collect();
+        assert!(!rows.is_empty(), "the rows beside the bar are in the tree");
+        let covered: Vec<_> = rows.iter().filter(|r| r.intersect(bar).is_positive()).collect();
+        assert!(covered.is_empty(), "under the scroll bar at {bar:?}: {covered:#?}");
+    }
+
     const SCREEN: egui::Vec2 = vec2(1600.0, 1000.0);
 
     /// A frame of the dock and its flyout on a 1600 × 1000 window.

crates/ui-egui/src/panels/layers.rs

@@ -613,15 +613,27 @@ pub fn show(app: &mut VectorcraftApp, ui: &mut Ui) {
     let revealed = reveal.and_then(|id| list.iter().position(|r| r.node.id == id));
     let scrolled = ui.scope(|ui| {
         ui.spacing_mut().item_spacing.y = 0.0;
-        egui::ScrollArea::vertical().max_height(list_h).auto_shrink([false, false]).show_rows(ui, view.h, list.len(), |ui, range| {
-            if let Some(i) = revealed.filter(|i| !range.contains(i)) {
-                let top = ui.max_rect().top() + (i as f32 - range.start as f32) * view.h;
-                ui.scroll_to_rect(egui::Rect::from_min_size(egui::pos2(ui.max_rect().left(), top), vec2(ui.max_rect().width(), view.h)), None);
-            }
-            for r in list.get(range).unwrap_or_default() {
-                row(ui, &view, r, &mut out);
-            }
-        })
+        // The bar takes a column of its own, so it never covers the target and selection marks at
+        // the rows' right edge (#3443). Whether the rows overflow is known before they are laid
+        // out, so the bar is decided up front and the rows never shift when it appears.
+        ui.spacing_mut().scroll = crate::widgets::list_scroll_style();
+        let overflows = view.h * list.len() as f32 > list_h;
+        let bar =
+            if overflows { egui::scroll_area::ScrollBarVisibility::AlwaysVisible } else { egui::scroll_area::ScrollBarVisibility::AlwaysHidden };
+        egui::ScrollArea::vertical().max_height(list_h).auto_shrink([false, false]).scroll_bar_visibility(bar).show_rows(
+            ui,
+            view.h,
+            list.len(),
+            |ui, range| {
+                if let Some(i) = revealed.filter(|i| !range.contains(i)) {
+                    let top = ui.max_rect().top() + (i as f32 - range.start as f32) * view.h;
+                    ui.scroll_to_rect(egui::Rect::from_min_size(egui::pos2(ui.max_rect().left(), top), vec2(ui.max_rect().width(), view.h)), None);
+                }
+                for r in list.get(range).unwrap_or_default() {
+                    row(ui, &view, r, &mut out);
+                }
+            },
+        )
     });
     let list_rect = scrolled.inner.inner_rect;
     resolve_click(ui, &view, &list, &mut out);