Adjust layout in CommunityStructureCanvas by adding horizontal padding to positions and refining target position calculations for improved spacing and alignment. Enhance Stack widget behavior by allowing overflow clipping.

lib/pages/space_management_v2/main_module/widgets/community_structure_canvas.dart

@@ -257,6 +257,13 @@ class _CommunityStructureCanvasState extends State<CommunityStructureCanvas>
     final levelXOffset = <int, double>{};
     _calculateLayout(community.spaces, 0, levelXOffset);
 
+    const horizontalCanvasPadding = 100.0;
+    final originalPositions = Map.of(_positions);
+    _positions.clear();
+    for (final entry in originalPositions.entries) {
+      _positions[entry.key] = entry.value.translate(horizontalCanvasPadding, 0);
+    }
+
     final selectedSpace = widget.selectedSpace;
     final highlightedUuids = <String>{};
     if (selectedSpace != null) {
@@ -274,7 +281,7 @@ class _CommunityStructureCanvasState extends State<CommunityStructureCanvas>
       community: widget.community,
     );
 
-    final createButtonX = levelXOffset[0] ?? 0.0;
+    final createButtonX = (levelXOffset[0] ?? 0.0) + horizontalCanvasPadding;
     const createButtonY = 0.0;
 
     widgets.add(
@@ -306,10 +313,12 @@ class _CommunityStructureCanvasState extends State<CommunityStructureCanvas>
     CommunityModel? community,
     SpaceModel? parent,
   }) {
+    const targetWidth = 40.0;
+    final padding = (_horizontalSpacing - targetWidth) / 2;
     if (spaces.isNotEmpty) {
       final firstChildPos = _positions[spaces.first.uuid]!;
       final targetPos = Offset(
-        firstChildPos.dx - (_horizontalSpacing / 4),
+        firstChildPos.dx - padding - targetWidth,
         firstChildPos.dy,
       );
       widgets.add(_buildDropTarget(parent, community, 0, targetPos));
@@ -391,7 +400,7 @@ class _CommunityStructureCanvasState extends State<CommunityStructureCanvas>
       );
 
       final targetPos = Offset(
-        position.dx + cardWidth + (_horizontalSpacing / 4) - 20,
+        position.dx + cardWidth + padding,
         position.dy,
       );
       widgets.add(_buildDropTarget(parent, community, i + 1, targetPos));
@@ -426,24 +435,33 @@ class _CommunityStructureCanvasState extends State<CommunityStructureCanvas>
       child: DragTarget<SpaceReorderDataModel>(
         builder: (context, candidateData, rejectedData) {
           if (_draggedData == null) {
-            return const SizedBox();
+            return const SizedBox.shrink();
           }
 
-          final isTargetForDragged = (_draggedData?.parent?.uuid == parent?.uuid &&
-                  _draggedData?.community == null) ||
-              (_draggedData?.community?.uuid == community?.uuid &&
-                  _draggedData?.parent == null);
+          final children = parent?.children ?? community?.spaces ?? [];
+          final isSameParent = (_draggedData!.parent?.uuid == parent?.uuid &&
+                  _draggedData!.community == null) ||
+              (_draggedData!.community?.uuid == community?.uuid &&
+                  _draggedData!.parent == null);
 
-          if (!isTargetForDragged) {
-            return const SizedBox();
+          if (!isSameParent) {
+            return const SizedBox.shrink();
           }
 
-          return Container(
+          final oldIndex =
+              children.indexWhere((s) => s.uuid == _draggedData!.space.uuid);
+          if (oldIndex != -1 && (oldIndex == index || oldIndex == index - 1)) {
+            return const SizedBox.shrink();
+          }
+
+          return AnimatedContainer(
+            duration: const Duration(milliseconds: 150),
             width: 40,
+            alignment: Alignment.center,
             height: _cardHeight,
             decoration: BoxDecoration(
               color: context.theme.colorScheme.primary.withValues(
-                alpha: candidateData.isNotEmpty ? 0.7 : 0.3,
+                alpha: candidateData.isNotEmpty ? 0.9 : 0.3,
               ),
               borderRadius: BorderRadius.circular(8),
             ),
@@ -466,6 +484,9 @@ class _CommunityStructureCanvasState extends State<CommunityStructureCanvas>
 
           final oldIndex =
               children.indexWhere((s) => s.uuid == data.data.space.uuid);
+          if (oldIndex == -1) {
+            return true;
+          }
           if (oldIndex == index || oldIndex == index - 1) {
             return false;
           }
@@ -493,7 +514,7 @@ class _CommunityStructureCanvasState extends State<CommunityStructureCanvas>
         child: SizedBox(
           width: context.screenWidth * 5,
           height: context.screenHeight * 5,
-          child: Stack(children: treeWidgets),
+          child: Stack(clipBehavior: Clip.none, children: treeWidgets),
         ),
       ),
     );