From 3d42973764434fbfe5359996e9edb270a56c759d Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Wed, 5 Feb 2020 15:58:35 +0900
Subject: [PATCH] Allow scrolling via drag while dragging a hold note handle

---
 .../Timeline/TimelineBlueprintContainer.cs    | 40 ++++++++++++-------
 .../Timeline/TimelineHitObjectBlueprint.cs    | 16 +++++++-
 2 files changed, 41 insertions(+), 15 deletions(-)

diff --git a/osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineBlueprintContainer.cs b/osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineBlueprintContainer.cs
index 3b9cb1df24..9f3d776e5c 100644
--- a/osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineBlueprintContainer.cs
+++ b/osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineBlueprintContainer.cs
@@ -49,20 +49,9 @@ protected override void LoadComplete()
 
         protected override void OnDrag(DragEvent e)
         {
-            if (timeline != null)
-            {
-                var timelineQuad = timeline.ScreenSpaceDrawQuad;
-                var mouseX = e.ScreenSpaceMousePosition.X;
-
-                // scroll if in a drag and dragging outside visible extents
-                if (mouseX > timelineQuad.TopRight.X)
-                    timeline.ScrollBy((float)((mouseX - timelineQuad.TopRight.X) / 10 * Clock.ElapsedFrameTime));
-                else if (mouseX < timelineQuad.TopLeft.X)
-                    timeline.ScrollBy((float)((mouseX - timelineQuad.TopLeft.X) / 10 * Clock.ElapsedFrameTime));
-            }
+            handleScrollViaDrag(e);
 
             base.OnDrag(e);
-            lastDragEvent = e;
         }
 
         protected override void OnDragEnd(DragEndEvent e)
@@ -74,7 +63,7 @@ protected override void OnDragEnd(DragEndEvent e)
         protected override void Update()
         {
             // trigger every frame so drags continue to update selection while playback is scrolling the timeline.
-            if (IsDragged)
+            if (lastDragEvent != null)
                 OnDrag(lastDragEvent);
 
             base.Update();
@@ -82,10 +71,33 @@ protected override void Update()
 
         protected override SelectionHandler CreateSelectionHandler() => new TimelineSelectionHandler();
 
-        protected override SelectionBlueprint CreateBlueprintFor(HitObject hitObject) => new TimelineHitObjectBlueprint(hitObject);
+        protected override SelectionBlueprint CreateBlueprintFor(HitObject hitObject) => new TimelineHitObjectBlueprint(hitObject)
+        {
+            OnDragHandled = handleScrollViaDrag
+        };
 
         protected override DragBox CreateDragBox(Action<RectangleF> performSelect) => new TimelineDragBox(performSelect);
 
+        private void handleScrollViaDrag(DragEvent e)
+        {
+            lastDragEvent = e;
+
+            if (lastDragEvent == null)
+                return;
+
+            if (timeline != null)
+            {
+                var timelineQuad = timeline.ScreenSpaceDrawQuad;
+                var mouseX = e.ScreenSpaceMousePosition.X;
+
+                // scroll if in a drag and dragging outside visible extents
+                if (mouseX > timelineQuad.TopRight.X)
+                    timeline.ScrollBy((float)((mouseX - timelineQuad.TopRight.X) / 10 * Clock.ElapsedFrameTime));
+                else if (mouseX < timelineQuad.TopLeft.X)
+                    timeline.ScrollBy((float)((mouseX - timelineQuad.TopLeft.X) / 10 * Clock.ElapsedFrameTime));
+            }
+        }
+
         internal class TimelineSelectionHandler : SelectionHandler
         {
             // for now we always allow movement. snapping is provided by the Timeline's "distance" snap implementation
diff --git a/osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineHitObjectBlueprint.cs b/osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineHitObjectBlueprint.cs
index 8a6dd40bde..3de1cd3a4c 100644
--- a/osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineHitObjectBlueprint.cs
+++ b/osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineHitObjectBlueprint.cs
@@ -1,6 +1,7 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System;
 using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
@@ -28,6 +29,8 @@ public class TimelineHitObjectBlueprint : SelectionBlueprint
         [UsedImplicitly]
         private readonly Bindable<double> startTime;
 
+        public Action<DragEvent> OnDragHandled;
+
         public const float THICKNESS = 5;
 
         private const float circle_size = 16;
@@ -78,7 +81,7 @@ public TimelineHitObjectBlueprint(HitObject hitObject)
                             RelativeSizeAxes = Axes.Both,
                         }
                     },
-                    new DragBar(hitObject),
+                    new DragBar(hitObject) { OnDragHandled = e => OnDragHandled?.Invoke(e) }
                 });
             }
         }
@@ -90,6 +93,8 @@ public class DragBar : CompositeDrawable
             [Resolved]
             private Timeline timeline { get; set; }
 
+            public Action<DragEvent> OnDragHandled;
+
             public DragBar(HitObject hitObject)
             {
                 this.hitObject = hitObject;
@@ -155,6 +160,8 @@ protected override void OnDrag(DragEvent e)
             {
                 base.OnDrag(e);
 
+                OnDragHandled?.Invoke(e);
+
                 var time = timeline.GetTimeFromScreenSpacePosition(e.ScreenSpaceMousePosition);
 
                 switch (hitObject)
@@ -177,6 +184,13 @@ protected override void OnDrag(DragEvent e)
 
                 beatmap.UpdateHitObject(hitObject);
             }
+
+            protected override void OnDragEnd(DragEndEvent e)
+            {
+                base.OnDragEnd(e);
+
+                OnDragHandled?.Invoke(null);
+            }
         }
 
         protected override void Update()