Add to existing selection when dragging with control pressed

osu.Game.Tests/Visual/Editing/TestSceneComposerSelection.cs

@@ -215,6 +215,51 @@ public void TestMultiSelect()
             AddAssert("2 hitobjects selected", () => EditorBeatmap.SelectedHitObjects.Count == 2 && !EditorBeatmap.SelectedHitObjects.Contains(addedObjects[1]));
         }
 
+        [Test]
+        public void TestMultiSelectWithDragBox()
+        {
+            var addedObjects = new[]
+            {
+                new HitCircle { StartTime = 100 },
+                new HitCircle { StartTime = 200, Position = new Vector2(100) },
+                new HitCircle { StartTime = 300, Position = new Vector2(512, 0) },
+                new HitCircle { StartTime = 400, Position = new Vector2(412, 100) },
+            };
+            AddStep("add hitobjects", () => EditorBeatmap.AddRange(addedObjects));
+
+            AddStep("start dragging", () =>
+            {
+                InputManager.MoveMouseTo(blueprintContainer.ScreenSpaceDrawQuad.Centre);
+                InputManager.PressButton(MouseButton.Left);
+            });
+            AddStep("drag to left corner", () => InputManager.MoveMouseTo(blueprintContainer.ScreenSpaceDrawQuad.TopLeft - new Vector2(5)));
+            AddStep("end dragging", () => InputManager.ReleaseButton(MouseButton.Left));
+
+            AddAssert("2 hitobjects selected", () => EditorBeatmap.SelectedHitObjects, () => Has.Count.EqualTo(2));
+
+            AddStep("start dragging with control", () =>
+            {
+                InputManager.MoveMouseTo(blueprintContainer.ScreenSpaceDrawQuad.Centre);
+                InputManager.PressButton(MouseButton.Left);
+                InputManager.PressKey(Key.ControlLeft);
+            });
+            AddStep("drag to left corner", () => InputManager.MoveMouseTo(blueprintContainer.ScreenSpaceDrawQuad.TopRight + new Vector2(5, -5)));
+            AddStep("end dragging", () => InputManager.ReleaseButton(MouseButton.Left));
+            AddStep("release control", () => InputManager.ReleaseKey(Key.ControlLeft));
+
+            AddAssert("4 hitobjects selected", () => EditorBeatmap.SelectedHitObjects, () => Has.Count.EqualTo(4));
+
+            AddStep("start dragging without control", () =>
+            {
+                InputManager.MoveMouseTo(blueprintContainer.ScreenSpaceDrawQuad.Centre);
+                InputManager.PressButton(MouseButton.Left);
+            });
+            AddStep("drag to left corner", () => InputManager.MoveMouseTo(blueprintContainer.ScreenSpaceDrawQuad.TopRight + new Vector2(5, -5)));
+            AddStep("end dragging", () => InputManager.ReleaseButton(MouseButton.Left));
+
+            AddAssert("2 hitobjects selected", () => EditorBeatmap.SelectedHitObjects, () => Has.Count.EqualTo(2));
+        }
+
         [Test]
         public void TestNearestSelection()
         {

osu.Game/Screens/Edit/Compose/Components/BlueprintContainer.cs

@@ -196,6 +196,11 @@ protected override bool OnDragStart(DragStartEvent e)
 
             DragBox.HandleDrag(e);
             DragBox.Show();
+
+            selectionBeforeDrag.Clear();
+            if (e.ControlPressed)
+                selectionBeforeDrag.UnionWith(SelectedItems);
+
             return true;
         }
 
@@ -217,6 +222,7 @@ protected override void OnDragEnd(DragEndEvent e)
             }
 
             DragBox.Hide();
+            selectionBeforeDrag.Clear();
         }
 
         protected override void Update()
@@ -227,7 +233,7 @@ protected override void Update()
             {
                 lastDragEvent.Target = this;
                 DragBox.HandleDrag(lastDragEvent);
-                UpdateSelectionFromDragBox();
+                UpdateSelectionFromDragBox(selectionBeforeDrag);
             }
         }
 
@@ -426,7 +432,7 @@ bool runForBlueprint(SelectionBlueprint<T> blueprint)
         private bool endClickSelection(MouseButtonEvent e)
         {
             // If already handled a selection, double-click, or drag, we don't want to perform a mouse up / click action.
-            if (clickSelectionHandled || doubleClickHandled || isDraggingBlueprint) return true;
+            if (clickSelectionHandled || doubleClickHandled || isDraggingBlueprint || wasDragStarted) return true;
 
             if (e.Button != MouseButton.Left) return false;
 
@@ -442,7 +448,7 @@ private bool endClickSelection(MouseButtonEvent e)
                 return false;
             }
 
-            if (!wasDragStarted && selectedBlueprintAlreadySelectedOnMouseDown && SelectedItems.Count == 1)
+            if (selectedBlueprintAlreadySelectedOnMouseDown && SelectedItems.Count == 1)
             {
                 // If a click occurred and was handled by the currently selected blueprint but didn't result in a drag,
                 // cycle between other blueprints which are also under the cursor.
@@ -472,7 +478,7 @@ private bool endClickSelection(MouseButtonEvent e)
         /// <summary>
         /// Select all blueprints in a selection area specified by <see cref="DragBox"/>.
         /// </summary>
-        protected virtual void UpdateSelectionFromDragBox()
+        protected virtual void UpdateSelectionFromDragBox(HashSet<T> selectionBeforeDrag)
         {
             var quad = DragBox.Box.ScreenSpaceDrawQuad;
 
@@ -482,7 +488,7 @@ protected virtual void UpdateSelectionFromDragBox()
                 {
                     case SelectionState.Selected:
                         // Selection is preserved even after blueprint becomes dead.
-                        if (!quad.Contains(blueprint.ScreenSpaceSelectionPoint))
+                        if (!quad.Contains(blueprint.ScreenSpaceSelectionPoint) && !selectionBeforeDrag.Contains(blueprint.Item))
                             blueprint.Deselect();
                         break;
 
@@ -535,6 +541,8 @@ protected virtual void OnBlueprintDeselected(SelectionBlueprint<T> blueprint)
         /// </summary>
         private bool wasDragStarted;
 
+        private readonly HashSet<T> selectionBeforeDrag = new HashSet<T>();
+
         /// <summary>
         /// Attempts to begin the movement of any selected blueprints.
         /// </summary>

osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineBlueprintContainer.cs

@@ -173,7 +173,7 @@ protected override SelectionBlueprint<HitObject> CreateBlueprintFor(HitObject it
 
         protected sealed override DragBox CreateDragBox() => new TimelineDragBox();
 
-        protected override void UpdateSelectionFromDragBox()
+        protected override void UpdateSelectionFromDragBox(HashSet<HitObject> selectionBeforeDrag)
         {
             Composer.BlueprintContainer.CommitIfPlacementActive();
 
@@ -191,6 +191,9 @@ protected override void UpdateSelectionFromDragBox()
 
             bool shouldBeSelected(HitObject hitObject)
             {
+                if (selectionBeforeDrag.Contains(hitObject))
+                    return true;
+
                 double midTime = (hitObject.StartTime + hitObject.GetEndTime()) / 2;
                 return minTime <= midTime && midTime <= maxTime;
             }