fix: 修复 PR #1457 的选择与拖拽评审问题

- 标签在选择边界外也参与收窄，Dev Mode 单击已选图层只选它
- 区分点击命中图层与描边空白处的拖拽回退目标
- 重排圆环按按下时的修饰键判断点击，画布外松手视为拖拽结束
- 修复 clippy unnecessary_get_then_check

crates/engine/src/canvas/tools/drag.rs

@@ -94,6 +94,10 @@ impl Session {
         let behind_sel = |t: Option<NodeId>| {
             t.is_none_or(|t| sel.iter().any(|s| *s != t && (doc.is_ancestor(t, *s) || (in_own_box(*s) && paints_below(&doc, t, *s)))))
         };
+        // What the press hit (a label or a painted layer): a click that doesn't become a drag
+        // selects just it. A press that reaches nothing above the selection uses the selection as
+        // its drag target instead; that fallback is not a clicked layer.
+        let clicked = target;
         let target = match sel.iter().copied().find(|s| !locked_in(&doc, *s)) {
             Some(first) if label.is_none() && !ev.shift && behind_sel(target) && selection_box(&doc, &sel).is_some_and(|q| in_quad(&q, ev.p())) => {
                 Some(first)
@@ -109,7 +113,10 @@ impl Session {
                 // drag; a drag moves the selection with it. Where no drag can start, it goes now.
                 let deselect = (ev.shift && sel.contains(&target)).then_some(target);
                 let without_target = || sel.iter().copied().filter(|x| *x != target).collect::<Vec<_>>();
-                let keep = (in_sel_box && !ev.cmd && (sel.contains(&target) || sel.iter().any(|s| doc.is_ancestor(*s, target)))).then_some(target);
+                // A release without a drag narrows the selection to the layer the press hit. A
+                // selected frame's name label sits outside the selection bounds, so it counts too.
+                let keep = clicked
+                    .filter(|c| (label.is_some() || in_sel_box) && !ev.cmd && (sel.contains(c) || sel.iter().any(|s| doc.is_ancestor(*s, *c))));
                 let new_sel = if keep.is_some() {
                     sel.clone()
                 } else if ev.shift && deselect.is_none() {
@@ -122,10 +129,13 @@ impl Session {
                     vec![target]
                 };
                 self.set_selection(new_sel.clone());
-                // Dev Mode only selects (Shift-click still deselects): nothing moves.
+                // Dev Mode only selects (Shift-click still deselects): nothing moves. No move
+                // gesture starts, so a click selects the layer it hit now instead of on release.
                 if !edits {
                     if deselect.is_some() {
                         self.set_selection(without_target());
+                    } else if let Some(k) = keep.filter(|_| sel.len() > 1) {
+                        self.set_selection(vec![k]);
                     }
                     return Ok(());
                 }
@@ -134,9 +144,9 @@ impl Session {
                 if new_sel.is_empty() || doc.node(target).is_some_and(|n| n.locked) || ids.is_empty() {
                     if deselect.is_some() {
                         self.set_selection(without_target());
-                    } else if keep.is_some() {
+                    } else if let Some(k) = keep {
                         // No drag can start here, so the click narrows the selection now.
-                        self.set_selection(vec![target]);
+                        self.set_selection(vec![k]);
                     }
                     return Ok(());
                 }

crates/engine/src/devmode_behaviour_tests.rs

@@ -38,6 +38,19 @@ fn status(s: &mut Session, ids: &[NodeId], st: &str) {
     ex(s, "node.set", json!({"ids": ids, "props": {"devStatus": st}}));
 }
 
+#[test]
+fn a_dev_mode_click_on_a_selected_layer_selects_just_it() {
+    let mut s = Session::new();
+    let a = idv(&ex(&mut s, "shape.rectangle", json!({"x": 0, "y": 0, "width": 40, "height": 40})));
+    let b = idv(&ex(&mut s, "shape.rectangle", json!({"x": 80, "y": 0, "width": 40, "height": 40})));
+    s.tool.dev_mode = true;
+    ex(&mut s, "select.set", json!({"ids": [a, b]}));
+    // Dev Mode starts no move gesture, so the click narrows the selection at the press itself.
+    s.pointer(&ev(PointerKind::Down, 20.0, 20.0)).unwrap();
+    s.pointer(&ev(PointerKind::Up, 20.0, 20.0)).unwrap();
+    assert_eq!(s.selection(), vec![a], "a click on one of several selected layers selects it");
+}
+
 #[test]
 fn the_dev_mode_canvas_selects_and_pans_but_never_edits() {
     let mut s = Session::new();

crates/engine/src/frame_label_tests.rs

@@ -62,6 +62,21 @@ fn pressing_a_rotated_frames_label_selects_and_drags_the_frame() {
     assert!(s.selection().is_empty());
 }
 
+#[test]
+fn a_click_on_a_selected_frames_label_selects_only_it() {
+    let (mut s, f, q) = setup();
+    let other = id_of(&ex(&mut s, "shape.rectangle", json!({"x": 500, "y": 500, "width": 40, "height": 40}))["id"]).unwrap();
+    ex(&mut s, "select.set", json!({"ids": [f, other]}));
+    // A point on the label's left edge, clear of the selection box's resize handles, lies outside
+    // the selection's bounds (the strip starts left of the frame's left edge there).
+    let p = q[0] + (q[3] - q[0]) * 0.2 + (q[1] - q[0]) * 0.02;
+    assert!(s.doc().unwrap().bounds_of(&[f, other]).is_some_and(|b| !b.contains(p)), "the label point is outside the selection bounds");
+    assert_eq!(label_at(s.doc().unwrap(), s.page().unwrap(), &s.tool.labels, p), Some(f), "the point is on the label");
+    s.pointer(&ev(PointerKind::Down, p)).unwrap();
+    s.pointer(&ev(PointerKind::Up, p)).unwrap();
+    assert_eq!(s.selection(), vec![f], "the label outside the bounds still narrows the selection to its frame");
+}
+
 #[test]
 fn labels_of_frames_that_cant_be_picked_do_nothing() {
     let (mut s, f, q) = setup();

crates/engine/src/property_copy_tests.rs

@@ -114,7 +114,7 @@ fn a_copied_image_fill_brings_its_image_to_another_file() {
     // Another file has no image under that key: the copy brings the data with it.
     ex(&mut s, "file.new", json!({}));
     let b = rect(&mut s);
-    assert!(s.doc().unwrap().images.get("img-key").is_none());
+    assert!(!s.doc().unwrap().images.contains_key("img-key"));
     ex(&mut s, "fill.paste", json!({"ids": [b], "index": 0}));
     assert_eq!(s.doc().unwrap().images.get("img-key"), Some(&data));
     assert!(matches!(node(&s, b).fills[0].kind, figcraft_color::PaintKind::Image(_)));

crates/engine/src/selection_behaviour_tests.rs

@@ -456,6 +456,21 @@ fn a_layer_stacked_below_the_selection_doesnt_take_a_drag_from_inside_it() {
     assert_eq!(at(&s, gap), Point::new(home.x + 10.0, home.y + 10.0));
 }
 
+#[test]
+fn a_click_where_nothing_is_hit_inside_a_multiple_selection_keeps_it() {
+    let mut s = Session::new();
+    let a = rect(&mut s, 100.0, 300.0, None);
+    let b = rect(&mut s, 220.0, 300.0, None);
+    for i in [a, b] {
+        ex(&mut s, "node.set", json!({"ids": [i], "props": {"fills": [], "strokes": ["#000000"], "strokeWeight": 1}}));
+    }
+    ex(&mut s, "select.set", json!({"ids": [a, b]}));
+    // The press is inside `a` but its unfilled inside hits nothing: `a` is only the drag fallback,
+    // not a clicked layer, so a click keeps the selection.
+    click(&mut s, 120.0, 320.0, NONE);
+    assert_eq!(sorted(s.selection()), sorted(vec![a, b]));
+}
+
 #[test]
 fn alt_shift_drag_on_a_selected_layer_duplicates_it() {
     let mut s = Session::new();