Added invert selection command

src/PixiEditor/Models/DocumentModels/Public/DocumentOperationsModule.cs

@@ -5,6 +5,7 @@ using PixiEditor.ChangeableDocument.Actions.Undo;
 using PixiEditor.ChangeableDocument.Enums;
 using PixiEditor.DrawingApi.Core.ColorsImpl;
 using PixiEditor.DrawingApi.Core.Numerics;
+using PixiEditor.DrawingApi.Core.Surface.Vector;
 using PixiEditor.Models.DocumentModels.UpdateableChangeExecutors;
 using PixiEditor.Models.DocumentPassthroughActions;
 using PixiEditor.Models.Enums;
@@ -549,4 +550,13 @@ internal class DocumentOperationsModule
         
         Internals.ActionAccumulator.AddFinishedActions(new SelectionToMask_Action(member.GuidValue, mode));
     }
+
+    public void InvertSelection()
+    {
+        var selection = Document.SelectionPathBindable;
+        var inverse = new VectorPath();
+        inverse.AddRect(new RectI(new(0, 0), Document.SizeBindable));
+
+        Internals.ActionAccumulator.AddFinishedActions(new SetSelection_Action(inverse.Op(selection, VectorPathOp.Difference)));
+    }
 }

src/PixiEditor/ViewModels/SubViewModels/Main/SelectionViewModel.cs

@@ -37,6 +37,12 @@ internal class SelectionViewModel : SubViewModel<ViewModelMain>
         return !Owner.DocumentManagerSubViewModel.ActiveDocument?.SelectionPathBindable?.IsEmpty ?? false;
     }
 
+    [Evaluator.CanExecute("PixiEditor.Selection.IsNotEmptyAndHasMask")]
+    public bool SelectionIsNotEmptyAndHasMask()
+    {
+        return SelectionIsNotEmpty() && (Owner.DocumentManagerSubViewModel.ActiveDocument?.SelectedStructureMember?.HasMaskBindable ?? false);
+    }
+
     [Command.Basic("PixiEditor.Selection.TransformArea", "Transform selected area", "Transform selected area", CanExecute = "PixiEditor.Selection.IsNotEmpty", Key = Key.T, Modifiers = ModifierKeys.Control)]
     public void TransformSelectedArea()
     {
@@ -53,16 +59,22 @@ internal class SelectionViewModel : SubViewModel<ViewModelMain>
         Owner.DocumentManagerSubViewModel.ActiveDocument?.Operations.NudgeSelectedObject(distance);
     }
 
-    [Command.Basic("PixiEditor.Selection.NewToMask", SelectionMode.New, "New mask from selection", "Selection to new mask")]
-    [Command.Basic("PixiEditor.Selection.AddToMask", SelectionMode.Add, "Add selection to mask", "Add selection to mask")]
-    [Command.Basic("PixiEditor.Selection.SubtractFromMask", SelectionMode.Subtract, "Subtract selection from mask", "Subtract selection from mask")]
-    [Command.Basic("PixiEditor.Selection.IntersectSelectionMask", SelectionMode.Intersect, "Intersect selection with mask", "Intersect selection with mask")]
+    [Command.Basic("PixiEditor.Selection.NewToMask", SelectionMode.New, "New mask from selection", "Selection to new mask", CanExecute = "PixiEditor.Selection.IsNotEmpty")]
+    [Command.Basic("PixiEditor.Selection.AddToMask", SelectionMode.Add, "Add selection to mask", "Add selection to mask", CanExecute = "PixiEditor.Selection.IsNotEmpty")]
+    [Command.Basic("PixiEditor.Selection.SubtractFromMask", SelectionMode.Subtract, "Subtract selection from mask", "Subtract selection from mask", CanExecute = "PixiEditor.Selection.IsNotEmptyAndHasMask")]
+    [Command.Basic("PixiEditor.Selection.IntersectSelectionMask", SelectionMode.Intersect, "Intersect selection with mask", "Intersect selection with mask", CanExecute = "PixiEditor.Selection.IsNotEmptyAndHasMask")]
     [Command.Filter("PixiEditor.Selection.ToMaskMenu", "Selection to mask", "Selection to mask", Key = Key.M, Modifiers = ModifierKeys.Control)]
     public void SelectionToMask(SelectionMode mode)
     {
         Owner.DocumentManagerSubViewModel.ActiveDocument?.Operations.SelectionToMask(mode);
     }
 
+    [Command.Basic("PixiEditor.Selection.InvertSelection", "Invert selection", "Invert the selected area", CanExecute = "PixiEditor.Selection.IsNotEmpty", Key = Key.I, Modifiers = ModifierKeys.Control)]
+    public void InvertSelection()
+    {
+        Owner.DocumentManagerSubViewModel.ActiveDocument?.Operations.InvertSelection();
+    }
+    
     [Evaluator.CanExecute("PixiEditor.Selection.CanNudgeSelectedObject")]
     public bool CanNudgeSelectedObject(int[] dist) => Owner.DocumentManagerSubViewModel.ActiveDocument?.UpdateableChangeActive == true;
 }

src/PixiEditor/Views/MainWindow.xaml

@@ -231,6 +231,9 @@
                         <MenuItem
                             Header="_Deselect"
                             cmds:Menu.Command="PixiEditor.Selection.Clear" />
+                        <MenuItem
+                            Header="_Invert"
+                            cmds:Menu.Command="PixiEditor.Selection.InvertSelection" />
                         <Separator/>
                         <MenuItem Header="Selection _to Mask">
                             <MenuItem