fix(ui): traverse nested active controls when restoring focus

OpenNest.WinForms.Tests/Forms/EditNestFocusTraversalTests.cs

@@ -0,0 +1,162 @@
+using System.Reflection;
+using System.Runtime.ExceptionServices;
+using System.Windows.Forms;
+using OpenNest.Forms;
+
+namespace OpenNest.WinForms.Tests.Forms;
+
+[Collection("Fill operation lifetime")]
+public class EditNestFocusTraversalTests
+{
+    [Fact]
+    public void NestedActiveContainersReturnTheirLeaf() => RunSta(() =>
+    {
+        using var form = CreateForm();
+        var outer = new UserControl();
+        var inner = new UserControl();
+        var leaf = new TextBox();
+        form.Controls.Add(outer);
+        outer.Controls.Add(inner);
+        inner.Controls.Add(leaf);
+        inner.ActiveControl = leaf;
+        outer.ActiveControl = inner;
+        form.ActiveControl = outer;
+
+        Assert.Same(outer, form.ActiveControl);
+        Assert.Same(inner, outer.ActiveControl);
+        Assert.Same(leaf, inner.ActiveControl);
+        Assert.Same(leaf, GetFocusedControl(form));
+    });
+
+    [Fact]
+    public void OrdinaryActiveControlIsReturnedUnchanged() => RunSta(() =>
+    {
+        using var form = CreateForm();
+        var leaf = new TextBox();
+        form.Controls.Add(leaf);
+        form.ActiveControl = leaf;
+
+        Assert.Same(leaf, form.ActiveControl);
+        Assert.Same(leaf, GetFocusedControl(form));
+    });
+
+    [Fact]
+    public void NoActiveControlReturnsTheForm() => RunSta(() =>
+    {
+        using var form = CreateForm();
+        form.ActiveControl = null;
+
+        Assert.Null(form.ActiveControl);
+        Assert.Same(form, GetFocusedControl(form));
+    });
+
+    [Fact]
+    public void NestedContainerWithoutActiveControlIsReturned() => RunSta(() =>
+    {
+        using var form = CreateForm();
+        var outer = new UserControl();
+        var inner = new UserControl();
+        form.Controls.Add(outer);
+        outer.Controls.Add(inner);
+        inner.ActiveControl = null;
+        outer.ActiveControl = inner;
+        form.ActiveControl = outer;
+
+        Assert.Same(outer, form.ActiveControl);
+        Assert.Same(inner, outer.ActiveControl);
+        Assert.Null(inner.ActiveControl);
+        Assert.Same(inner, GetFocusedControl(form));
+    });
+
+    [Fact]
+    public void PlateListRefreshRestoresTheOriginalNestedLeaf() => RunSta(() =>
+    {
+        using var form = CreateForm();
+        form.Width = 1100;
+        form.Height = 600;
+        form.Show();
+        var outer = new UserControl();
+        var inner = new UserControl { Dock = DockStyle.Fill };
+        var original = new TextBox { Top = 10 };
+        var replacement = new TextBox { Top = 50 };
+        inner.Controls.AddRange(new Control[] { original, replacement });
+        outer.Controls.Add(inner);
+        form.ShowSidePanel(outer, "Focus regression");
+        var plates = PlateList(form);
+        Assert.True(original.Focus());
+        Assert.True(form.ContainsFocus);
+        Assert.Same(original, inner.ActiveControl);
+
+        // Force a different leaf to become active during the real refresh. Merely
+        // focusing the old outer container would now restore this replacement.
+        var focusWasDisplaced = false;
+        plates.SelectedIndexChanged += (_, _) =>
+        {
+            Assert.True(replacement.Focus());
+            focusWasDisplaced = true;
+        };
+
+        form.UpdatePlateList();
+
+        Assert.True(focusWasDisplaced);
+        Assert.True(original.Focused);
+        Assert.False(replacement.Focused);
+        Assert.Same(original, GetFocusedControl(form));
+        Assert.Equal(form.Nest.Plates.Count, plates.Items.Count);
+        Assert.Equal(form.PlateManager.CurrentIndex, Assert.Single(plates.SelectedIndices.Cast<int>()));
+    });
+
+    [Fact]
+    public void PlateListRefreshKeepsFocusOnThePlateList() => RunSta(() =>
+    {
+        using var form = CreateForm();
+        form.Show();
+        var plates = PlateList(form);
+        Assert.True(plates.Focus());
+
+        form.UpdatePlateList();
+
+        Assert.True(plates.Focused);
+        Assert.Same(plates, GetFocusedControl(form));
+        Assert.Equal(form.Nest.Plates.Count, plates.Items.Count);
+    });
+
+    private static EditNestForm CreateForm()
+    {
+        var form = new EditNestForm(new Nest("focus traversal"));
+        form.PlateView.SetOverlapAutoCheck(null);
+        return form;
+    }
+
+    private static Control GetFocusedControl(EditNestForm form)
+    {
+        var method = typeof(EditNestForm).GetMethod("GetFocusedControl", BindingFlags.Instance | BindingFlags.NonPublic);
+        Assert.NotNull(method);
+        return Assert.IsAssignableFrom<Control>(method.Invoke(form, null));
+    }
+
+    private static ListView PlateList(EditNestForm form) =>
+        Assert.IsType<ListView>(Assert.Single(form.Controls.Find("platesListView", true)));
+
+    private static void RunSta(System.Action testBody)
+    {
+        Exception? testFailure = null;
+        var staThread = new Thread(() =>
+        {
+            try
+            {
+                testBody();
+            }
+            catch (Exception error)
+            {
+                testFailure = error;
+            }
+        })
+        { IsBackground = true };
+        staThread.SetApartmentState(ApartmentState.STA);
+        staThread.Start();
+        Assert.True(staThread.Join(TimeSpan.FromSeconds(60)), "The focus traversal STA test did not complete.");
+        if (testFailure != null)
+            ExceptionDispatchInfo.Capture(testFailure).Throw();
+    }
+}

OpenNest/Forms/EditNestForm.cs

@@ -317,9 +317,9 @@ namespace OpenNest.Forms
 
         private Control GetFocusedControl()
         {
-            var ctrl = this;
+            Control ctrl = this;
             while (ctrl is ContainerControl container && container.ActiveControl != null)
-                return container.ActiveControl;
+                ctrl = container.ActiveControl;
             return ctrl;
         }