LT-22691: Answer the allomorph, variant and relation menus natively

DistFiles/Language Explorer/Configuration/Lexicon/DataTreeInclude.xml

@@ -56,21 +56,9 @@
 		<!--
 	  AlternateForms
 	   -->
-		<command id="CmdDataTree-MoveUp-AlternateForm" label="Move Form _Up" message="MoveUpObjectInSequence" icon="MoveUp">
-			<parameters field="AlternateForms" className="MoForm"/>
-		</command>
-		<command id="CmdDataTree-MoveDown-AlternateForm" label="Move Form _Down" message="MoveDownObjectInSequence" icon="MoveDown">
-			<parameters field="AlternateForms" className="MoForm"/>
-		</command>
 		<command id="CmdDataTree-Insert-AlternateForm" label="Insert Allomorph" message="DataTreeInsert">
 			<parameters field="AlternateForms" className="MoForm"/>
 		</command>
-		<command id="CmdDataTree-Delete-AlternateForm" label="Delete AlternateForm" message="DataTreeDelete" icon="Delete">
-			<parameters field="AlternateForms" className="MoForm"/>
-		</command>
-		<command id="CmdDataTree-Merge-AlternateForm" label="Merge AlternateForm into..." message="DataTreeMerge">
-			<parameters field="AlternateForms" className="MoForm"/>
-		</command>
 		<command id="CmdDataTree-Swap-Allomorph" label="Swap Allomorph with Lexeme Form" message="SwapAllomorphWithLexeme">
 			<parameters field="AlternateForms" className="MoForm"/>
 		</command>
@@ -335,13 +323,6 @@
 			<item label="-" translate="do not translate"/>
 			<item command="CmdDataTree-Delete-Picture"/>
 		</menu>
-		<menu id="mnuDataTree-AlternateForm">
-			<item command="CmdDataTree-MoveUp-AlternateForm"/>
-			<item command="CmdDataTree-MoveDown-AlternateForm"/>
-			<item label="-" translate="do not translate"/>
-			<item command="CmdDataTree-Merge-AlternateForm"/>
-			<item command="CmdDataTree-Delete-AlternateForm"/>
-		</menu>
 		<menu id="mnuDataTree-Sense">
 			<item command="CmdDataTree-Insert-Example"/>
 			<item command="CmdFindExampleSentence"/>

DistFiles/Language Explorer/Configuration/Parts/LexEntryParts.xml

@@ -116,7 +116,7 @@
 				   header="true" helpTopicID="khtpField-LexEntry-AlternateFormsSection"/>
 		</part>
 		<part id="LexEntry-Detail-AlternateForms" type="Detail">
-			<seq field="AlternateForms" menu="mnuDataTree-AlternateForm" />
+			<seq field="AlternateForms" />
 		</part>
 		<part id="LexEntry-Jt-HeadWordInPara" type="jtview">
 			<para>

Src/Common/Controls/DetailControls/Resources/DetailControlsStrings.resx

@@ -230,12 +230,6 @@
   <data name="ksRootNoComponentsMessage" xml:space="preserve">
     <value>An entry that has components cannot have a morph type of root, since by definition a root is indivisible. Would you like Language Explorer to delete the references to components in this entry?</value>
   </data>
-  <data name="ksRedoDeleteRef" xml:space="preserve">
-    <value>Redo Delete Reference</value>
-  </data>
-  <data name="ksUndoDeleteRef" xml:space="preserve">
-    <value>Undo Delete Reference</value>
-  </data>
   <data name="ksRedoUpdatePicture" xml:space="preserve">
     <value>Redo Update Picture</value>
   </data>

Src/Common/Controls/DetailControls/Slice.cs

@@ -2320,24 +2320,9 @@ public virtual bool CanDeleteReferenceNow(Command cmd)
 		public virtual void HandleDeleteReferenceCommand(Command cmd)
 		{
 			CheckDisposed();
-			if (NextSlice != null && NextSlice.Object != null)
+			if (NextSlice?.Object is ILexEntryRef ler && ContainingDataTree.Root is ILexEntry root)
 			{
-				var ler = NextSlice.Object as ILexEntryRef;
-				if (ler != null)
-				{
-					UndoableUnitOfWorkHelper.Do(DetailControlsStrings.ksUndoDeleteRef, DetailControlsStrings.ksRedoDeleteRef, ler, () =>
-					{
-						ler.ComponentLexemesRS.Remove(ContainingDataTree.Root);
-						// probably not needed, but safe...
-						if (ler.PrimaryLexemesRS.Contains(ContainingDataTree.Root))
-							ler.PrimaryLexemesRS.Remove(ContainingDataTree.Root);
-
-						ILexEntry entry;
-						entry = (ILexEntry)m_cache.ServiceLocator.GetObject(ler.OwningEntry.Hvo);
-						if (entry.EntryRefsOS.Contains(ler))
-							entry.EntryRefsOS.Remove(ler);
-					});
-				}
+				VariantBackReferences.DeleteReference(root, ler);
 			}
 		}
 
@@ -2385,38 +2370,9 @@ public virtual int Flid
 			}
 		}
 
-		private bool FromVariantBackRefField
-		{
-			get
-			{
-				var rootObj = ContainingDataTree.Root;
-				int clidRoot = rootObj.ClassID;
-				return clidRoot == LexEntryTags.kClassId &&
-					Object != null && Object != rootObj &&
-					Object.Owner != null && Object.Owner != rootObj &&
-					(Object.ClassID == clidRoot || Object.Owner.ClassID == clidRoot);
-			}
-		}
+		private bool FromVariantBackRefField => BackRefObject != null;
 
-		private ICmObject BackRefObject
-		{
-			get
-			{
-				var rootObj = ContainingDataTree.Root;
-				int clidRoot = rootObj.ClassID;
-				if (clidRoot == LexEntryTags.kClassId &&
-					Object != null && Object != rootObj &&
-					Object.Owner != null && Object.Owner != rootObj)
-				{
-					if (Object.ClassID == clidRoot)
-						return Object;
-
-					if (Object.Owner.ClassID == clidRoot)
-						return Object.Owner;
-				}
-				return null;
-			}
-		}
+		private ICmObject BackRefObject => VariantBackReferences.BackReferencedEntry(ContainingDataTree.Root, Object);
 
 		/// <summary>
 		/// is it possible to do a deletion menu command on this slice right now?
@@ -2435,53 +2391,7 @@ public bool GetCanMergeNow()
 		{
 			CheckDisposed();
 
-			var obj = GetObjectForMenusToOperateOn();
-			if (obj == null)
-				return false;
-
-			var owner = obj.Owner;
-			int flid = obj.OwningFlid;
-			// No support yet for atomic properties.
-			if (!Cache.IsVectorProperty(flid))
-				return false;
-
-			// Special handling for allomorphs, as they can be merged into the lexeme form.
-			int clsid = obj.ClassID;
-			if (flid == LexEntryTags.kflidAlternateForms)
-			{
-				// We can merge an alternate with the lexeme form,
-				// if it is the same class.
-				if (clsid == ((ILexEntry) owner).LexemeFormOA.ClassID)
-					return true;
-			}
-			// A subsense can always merge into its owning sense.
-			if (flid == LexSenseTags.kflidSenses)
-				return true;
-
-			int vectorSize = Cache.DomainDataByFlid.get_VecSize(owner.Hvo, flid);
-			if (owner.IsFieldRequired(flid)
-				&& vectorSize < 2)
-				return false;
-
-			// Check now to see if there are any other objects of the same class in the flid,
-			// since only objects of the same class can be merged.
-			int[] contents;
-			int chvoMax = Cache.DomainDataByFlid.get_VecSize(owner.Hvo, flid);
-			using (ArrayPtr arrayPtr = MarshalEx.ArrayToNative<int>(chvoMax))
-			{
-				Cache.DomainDataByFlid.VecProp(owner.Hvo, flid, chvoMax, out chvoMax, arrayPtr);
-				contents = MarshalEx.NativeToArray<int>(arrayPtr, chvoMax);
-			}
-			foreach (int hvoInner in contents)
-			{
-				var innerObj = m_cache.ServiceLocator.GetInstance<ICmObjectRepository>().GetObject(hvoInner);
-				if (innerObj != obj && clsid == innerObj.ClassID)
-				{
-					return true;
-				}
-			}
-
-			return false;
+			return DetailObjectMerge.CanMergeNow(GetObjectForMenusToOperateOn());
 		}
 
 		/// <summary></summary>

Src/Common/FwAvalonia/Detail/DetailFocusMemory.cs

@@ -231,7 +231,8 @@ public static bool TryRestoreScroll(Control root, Memento memento)
 		/// current item when the memento asks for it (a move or removal made from the row keeps
 		/// the keyboard in the row); else the first surviving row the outgoing view asked for
 		/// (a gesture removed the focused row), which comes before the remembered editor only
-		/// when that is a row's menu button. Safe to call before the view is attached.
+		/// when that is a row's menu button. The scroll offset yields to the row of the object
+		/// asked for. Safe to call before the view is attached.
 		/// </summary>
 		public static void RestoreAfterLayout(Control root, Memento memento)
 		{
@@ -263,12 +264,18 @@ public static void RestoreAfterLayout(Control root, Memento memento)
 					else
 						RestoreRequestedFocus(root, memento);
 				}
-				// A bring-into-view request queued by a focus change is applied by the next
-				// arrange; the remembered offset is re-asserted after it.
+				// After the next arrange: re-assert the remembered offset, or bring the row
+				// of the object the gesture chose into view wherever it sits.
 				if (needsScroll)
 				{
-					Avalonia.Threading.Dispatcher.UIThread.Post(() => TryRestoreScroll(root, memento),
-						Avalonia.Threading.DispatcherPriority.Background);
+					var showsRequestedObject = focused && memento.ObjectHvo != 0;
+					Avalonia.Threading.Dispatcher.UIThread.Post(() =>
+					{
+						if (showsRequestedObject)
+							(TopLevel.GetTopLevel(root)?.FocusManager?.GetFocusedElement() as Control)?.BringIntoView();
+						else
+							TryRestoreScroll(root, memento);
+					}, Avalonia.Threading.DispatcherPriority.Background);
 				}
 			};
 			root.LayoutUpdated += onLayout;

Src/Common/FwAvalonia/FwAvaloniaTests/DetailFocusMemoryTests.cs

@@ -135,6 +135,35 @@ public void RequestedObjectFocus_FocusesTheFirstRowShowingTheObject()
 				"the new form's editor takes focus");
 		}
 
+		// A gesture replaced an object whose row sits far from where the user had scrolled (a
+		// merge into the lexeme form from an allomorph near the bottom): the focused row shows
+		// instead of the remembered offset.
+		[AvaloniaTest]
+		public void RequestedObjectFocus_ScrollsToTheObjectsRow_InsteadOfKeepingTheOffset()
+		{
+			var first = NewLongViewOfForm(8);
+			var window = new Window { Content = first, Width = 420, Height = 200 };
+			window.Show();
+			Dispatcher.UIThread.RunJobs();
+			FindScroller(first).Offset = new Avalonia.Vector(0, 400);
+			Dispatcher.UIThread.RunJobs();
+			Assert.That(FindScroller(first).Offset.Y, Is.EqualTo(400).Within(0.5), "precondition: scrolled well down");
+
+			first.RequestObjectFocusOnRebuild(9);
+			var memento = DetailFocusMemory.Capture(first);
+			var second = NewLongViewOfForm(9);
+			DetailFocusMemory.RestoreAfterLayout(second, memento);
+			window.Content = second;
+			Dispatcher.UIThread.RunJobs();
+			second.UpdateLayout();
+			Dispatcher.UIThread.RunJobs();
+
+			Assert.That(FindEditor(second, "LexEntry/identity/#0@9.vern").IsFocused, Is.True, "the new form's editor takes focus");
+			// The editor, not the row, is brought into view: a few pixels of row padding stay
+			// above.
+			Assert.That(FindScroller(second).Offset.Y, Is.LessThan(10), "the view scrolled up to the editor's row");
+		}
+
 		// A gesture made from a header's hotlinks link added an object: the link survives the
 		// re-show and is remembered, but the object asked for takes focus over it.
 		[AvaloniaTest]
@@ -228,6 +257,21 @@ private static DataTree NewViewOfForm(int formHvo, bool withHotlinks = false)
 				menuRequested: withHotlinks ? request => { } : (Action<DetailMenuRequest>)null);
 		}
 
+		// A long view whose first row shows the form with the given hvo; the rest show object 3.
+		private static DataTree NewLongViewOfForm(int formHvo)
+		{
+			var values = new List<DetailWsValue> { new DetailWsValue("vern", "casa") };
+			var fields = new List<DetailField>();
+			fields.Add(new DetailField("LexEntry/identity/#0@" + formHvo, "Lexeme Form", "Form", "vernacular", DetailFieldKind.Text,
+				EditorClassification.Known, null, null, HostRouting.Product, values, null, null, objectHvo: formHvo));
+			for (var i = 1; i < 60; i++)
+			{
+				fields.Add(new DetailField("LexEntry/identity/#" + i + "@3", "Field " + i, "Gloss", "analysis", DetailFieldKind.Text,
+					EditorClassification.Known, null, null, HostRouting.Product, values, null, null, objectHvo: 3));
+			}
+			return new DataTree(new DetailModel("LexEntry", "identity", fields, new List<ViewDiagnostic>()));
+		}
+
 		private static DataTree NewLongView()
 		{
 			var roots = new List<ViewNode>();

Src/FdoUi/DetailRules/DetailObjectMerge.cs

@@ -0,0 +1,69 @@
+// Copyright (c) 2026 SIL International
+// This software is licensed under the LGPL, version 2.1 or later
+// (http://www.gnu.org/licenses/lgpl-2.1.html)
+
+using SIL.FieldWorks.Common.FwUtils;
+using SIL.LCModel;
+
+// Rules both detail views share. Nothing here may depend on WinForms, Avalonia, or a slice
+// or control type, so the rules outlive WinForms. DetailRulesBoundaryTests enforces this.
+namespace SIL.FieldWorks.Common.DetailRules
+{
+	/// <summary>
+	/// The Merge command of a detail row (message DataTreeMerge): whether the row's object
+	/// has something to merge into now, and the menu text that says so. Execution stays with
+	/// <c>CmObjectUi.MergeUnderlyingObject</c>, which asks for the survivor.
+	/// </summary>
+	public static class DetailObjectMerge
+	{
+		/// <summary>The strings-table key of the text appended to a disabled Merge
+		/// item.</summary>
+		public const string CannotMergeKey = "(cannot merge this)";
+
+		/// <summary>
+		/// Whether <paramref name="target"/> can merge into another object now: it sits in an
+		/// owning vector that holds another object of its class, or an allomorph of the lexeme
+		/// form's class, or a subsense (which merges into its sense). A required vector keeps
+		/// its last item.
+		/// </summary>
+		public static bool CanMergeNow(ICmObject target)
+		{
+			if (target == null || !target.IsValidObject)
+				return false;
+			var owner = target.Owner;
+			var flid = target.OwningFlid;
+			var cache = target.Cache;
+			if (owner == null || !cache.IsVectorProperty(flid))
+				return false;
+			var classId = target.ClassID;
+			if (flid == LexEntryTags.kflidAlternateForms)
+			{
+				var lexemeForm = ((ILexEntry)owner).LexemeFormOA;
+				if (lexemeForm != null && lexemeForm.ClassID == classId)
+					return true;
+			}
+			if (flid == LexSenseTags.kflidSenses)
+				return true;
+			var sda = cache.DomainDataByFlid;
+			var count = sda.get_VecSize(owner.Hvo, flid);
+			if (owner.IsFieldRequired(flid) && count < 2)
+				return false;
+			var repository = cache.ServiceLocator.ObjectRepository;
+			for (var i = 0; i < count; i++)
+			{
+				var hvo = sda.get_VecItem(owner.Hvo, flid, i);
+				if (hvo != target.Hvo && repository.GetObject(hvo).ClassID == classId)
+					return true;
+			}
+			return false;
+		}
+
+		/// <summary>The Merge item's text: the configured label, with the cannot-merge note
+		/// appended when <paramref name="canMerge"/> is false.</summary>
+		public static string MergeLabel(string label, bool canMerge)
+		{
+			var text = label ?? string.Empty;
+			return canMerge ? text : text + StringTable.Table.GetString(CannotMergeKey);
+		}
+	}
+}