AI: Add 2D translation gizmo for axis-constrained node moves

ZeroSpace/ZeroSpace.MapEditor/Views/MapEditorPage.xaml.cs

@@ -19,6 +19,8 @@ public partial class MapEditorPage : ContentPage
     private readonly Dictionary<MapNode, (double X, double Y)> _dragStartWorldPositions = new();
     private readonly HashSet<MapNode> _preMarqueeSelected = new();
     private bool _draggingNode;
+    private GizmoPart _gizmoPart = GizmoPart.None;
+    private bool _draggingGizmo;
     private bool _marqueeSelecting;
     private bool _panning;
     private bool _panModeEnabled;
@@ -266,6 +268,37 @@ public partial class MapEditorPage : ContentPage
             return;
         }
 
+        // The translation gizmo wins over node hit-testing: grabbing an axis
+        // handle moves the active node's selection along that axis.
+        _gizmoPart = GizmoPart.None;
+        _draggingGizmo = false;
+        _drawable.ActiveGizmoPart = GizmoPart.None;
+        if (_selected is not null)
+        {
+            _gizmoPart = HitTestGizmo(position.Value, _selected);
+        }
+
+        if (_gizmoPart != GizmoPart.None)
+        {
+            _drawable.ActiveGizmoPart = _gizmoPart;
+            _pressNode = null;
+            _dragStartWorldPositions.Clear();
+            var (clickWorldX, clickWorldY) = ToWorld(position.Value);
+            _dragStartWorldPoint = new Point(clickWorldX, clickWorldY);
+            foreach (var node in _selectedNodes)
+            {
+                _dragStartWorldPositions[node] = (node.X, node.Y);
+            }
+
+            if (_selected is not null && !_dragStartWorldPositions.ContainsKey(_selected))
+            {
+                _dragStartWorldPositions[_selected] = (_selected.X, _selected.Y);
+            }
+
+            MapView.Invalidate();
+            return;
+        }
+
         _pressNode = HitTest(position.Value);
 
         if (_pressNode is not null)
@@ -276,7 +309,7 @@ public partial class MapEditorPage : ContentPage
                 {
                     _selectedNodes.Remove(_pressNode);
                     _pressNode.IsSelected = false;
-                    _selected = _selectedNodes.FirstOrDefault();
+                    SetActiveNode(_selectedNodes.FirstOrDefault());
                     if (_selected is not null)
                     {
                         PopulateInspector(_selected);
@@ -290,7 +323,7 @@ public partial class MapEditorPage : ContentPage
                 {
                     _selectedNodes.Add(_pressNode);
                     _pressNode.IsSelected = true;
-                    _selected = _pressNode;
+                    SetActiveNode(_pressNode);
                     InspectorScroll.IsVisible = true;
                     PopulateInspector(_selected);
                 }
@@ -302,7 +335,7 @@ public partial class MapEditorPage : ContentPage
                 if (_selectedNodes.Contains(_pressNode))
                 {
                     _wasAlreadySelectedInGroup = _selectedNodes.Count > 1;
-                    _selected = _pressNode;
+                    SetActiveNode(_pressNode);
                     PopulateInspector(_selected);
                 }
                 else
@@ -352,6 +385,26 @@ public partial class MapEditorPage : ContentPage
             return;
         }
 
+        if (_gizmoPart != GizmoPart.None)
+        {
+            if (!_draggingGizmo && Distance(position.Value, _pressPoint) > 4)
+            {
+                _draggingGizmo = true;
+            }
+
+            if (_draggingGizmo)
+            {
+                var (currentWorldX, currentWorldY) = ToWorld(position.Value);
+                var deltaX = currentWorldX - _dragStartWorldPoint.X;
+                var deltaY = currentWorldY - _dragStartWorldPoint.Y;
+                MoveSelectedNodes(deltaX, deltaY,
+                    lockX: _gizmoPart == GizmoPart.YAxis,
+                    lockY: _gizmoPart == GizmoPart.XAxis);
+            }
+
+            return;
+        }
+
         if (_pressNode is not null)
         {
             if (!_draggingNode && Distance(position.Value, _pressPoint) > 4)
@@ -365,19 +418,7 @@ public partial class MapEditorPage : ContentPage
                 var deltaX = currentWorldX - _dragStartWorldPoint.X;
                 var deltaY = currentWorldY - _dragStartWorldPoint.Y;
 
-                foreach (var node in _selectedNodes)
+                MoveSelectedNodes(deltaX, deltaY, lockX: false, lockY: false);
-                {
-                    if (_dragStartWorldPositions.TryGetValue(node, out var startPos))
-                    {
-                        node.X = startPos.X + deltaX;
-                        node.Y = startPos.Y + deltaY;
-                        node.Doc.IsDirty = true;
-                    }
-                }
-
-                UpdateDirtyState();
-                SyncPositionEntries();
-                MapView.Invalidate();
             }
         }
         else if (_marqueeSelecting)
@@ -401,13 +442,37 @@ public partial class MapEditorPage : ContentPage
 
             MapView.Invalidate();
         }
+
+        // Hover highlight for the gizmo when idle (no drag, pan, or marquee).
+        if (_selected is not null && _pressNode is null && !_marqueeSelecting)
+        {
+            var hover = HitTestGizmo(position.Value, _selected);
+            if (hover != _drawable.ActiveGizmoPart)
+            {
+                _drawable.ActiveGizmoPart = hover;
+                MapView.Invalidate();
+            }
+        }
     }
 
     private void OnPointerReleased(object? sender, PointerEventArgs e)
     {
         var position = e.GetPosition(MapView);
 
-        if (_panning)
+        if (_gizmoPart != GizmoPart.None)
+        {
+            var wasDragging = _draggingGizmo;
+            _gizmoPart = GizmoPart.None;
+            _draggingGizmo = false;
+            _drawable.ActiveGizmoPart = GizmoPart.None;
+            MapView.Invalidate();
+
+            if (wasDragging)
+            {
+                _ = AutoSaveAsync();
+            }
+        }
+        else if (_panning)
         {
             if (_panModeEnabled && position is not null && Distance(position.Value, _pressPoint) <= 4)
             {
@@ -458,8 +523,89 @@ public partial class MapEditorPage : ContentPage
         MapView.Invalidate();
     }
 
+    // ----- translation gizmo -----
+
+    /// <summary>
+    /// Moves every node captured at drag start by the given world delta.
+    /// Used by both free node dragging and gizmo axis-constrained dragging.
+    /// </summary>
+    private void MoveSelectedNodes(double deltaX, double deltaY, bool lockX, bool lockY)
+    {
+        foreach (var node in _dragStartWorldPositions.Keys.ToList())
+        {
+            var startPos = _dragStartWorldPositions[node];
+            if (!lockX)
+            {
+                node.X = startPos.X + deltaX;
+            }
+
+            if (!lockY)
+            {
+                node.Y = startPos.Y + deltaY;
+            }
+
+            node.Doc.IsDirty = true;
+        }
+
+        UpdateDirtyState();
+        SyncPositionEntries();
+        MapView.Invalidate();
+    }
+
+    /// <summary>
+    /// Hit-tests the translation gizmo arms of the given node in screen space.
+    /// </summary>
+    private GizmoPart HitTestGizmo(Point screen, MapNode node)
+    {
+        var cx = node.X * _drawable.Scale + _drawable.OffsetX;
+        var cy = node.Y * _drawable.Scale + _drawable.OffsetY;
+        const double arm = MapDrawable.GizmoArmLength;
+        const double tolerance = 10;
+
+        if (Math.Abs(screen.X - cx) <= tolerance && Math.Abs(screen.Y - cy) <= tolerance)
+        {
+            return GizmoPart.Center;
+        }
+
+        if (DistanceToSegment(screen.X, screen.Y, cx, cy, cx + arm, cy) <= tolerance)
+        {
+            return GizmoPart.XAxis;
+        }
+
+        if (DistanceToSegment(screen.X, screen.Y, cx, cy, cx, cy + arm) <= tolerance)
+        {
+            return GizmoPart.YAxis;
+        }
+
+        return GizmoPart.None;
+    }
+
+    private static double DistanceToSegment(double px, double py,
+        double x1, double y1, double x2, double y2)
+    {
+        var dx = x2 - x1;
+        var dy = y2 - y1;
+        var lenSq = dx * dx + dy * dy;
+        var t = lenSq > 0 ? ((px - x1) * dx + (py - y1) * dy) / lenSq : 0;
+        t = Math.Clamp(t, 0, 1);
+        var qx = x1 + t * dx;
+        var qy = y1 + t * dy;
+        return Math.Sqrt((px - qx) * (px - qx) + (py - qy) * (py - qy));
+    }
+
     // ----- selection + inspector -----
 
+    /// <summary>
+    /// Sets the active (inspector) node and keeps the translation gizmo
+    /// in sync with it.
+    /// </summary>
+    private void SetActiveNode(MapNode? node)
+    {
+        _selected = node;
+        _drawable.GizmoNode = node;
+        _drawable.ActiveGizmoPart = GizmoPart.None;
+    }
+
     private void Select(MapNode? node)
     {
         foreach (var n in _nodes)
@@ -468,7 +614,7 @@ public partial class MapEditorPage : ContentPage
         }
 
         _selectedNodes.Clear();
-        _selected = node;
+        SetActiveNode(node);
 
         if (_selected is not null)
         {
@@ -501,14 +647,14 @@ public partial class MapEditorPage : ContentPage
 
         if (_selectedNodes.Count == 0)
         {
-            _selected = null;
+            SetActiveNode(null);
             InspectorScroll.IsVisible = false;
         }
         else
         {
-            _selected = primary ?? (_selected is not null && _selectedNodes.Contains(_selected)
+            SetActiveNode(primary ?? (_selected is not null && _selectedNodes.Contains(_selected)
                 ? _selected
-                : _selectedNodes.First());
+                : _selectedNodes.First()));
             InspectorScroll.IsVisible = true;
             PopulateInspector(_selected);
             if (_selectedNodes.Count > 1)