Merge pull request #29020 from bdach/drag-selection-tolerance

Add tolerance when drag-scrolling editor timeline

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

@@ -3,6 +3,7 @@
 
 #nullable disable
 
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using osu.Framework.Allocation;
@@ -100,10 +101,14 @@ protected override bool OnDragStart(DragStartEvent e)
             return base.OnDragStart(e);
         }
 
+        private float dragTimeAccumulated;
+
         protected override void Update()
         {
             if (IsDragged || hitObjectDragged)
                 handleScrollViaDrag();
+            else
+                dragTimeAccumulated = 0;
 
             if (Composer != null && timeline != null)
             {
@@ -193,16 +198,42 @@ bool shouldBeSelected(HitObject hitObject)
 
         private void handleScrollViaDrag()
         {
+            // The amount of time dragging before we reach maximum drag speed.
+            const float time_ramp_multiplier = 5000;
+
+            // A maximum drag speed to ensure things don't get out of hand.
+            const float max_velocity = 10;
+
             if (timeline == null) return;
 
-            var timelineQuad = timeline.ScreenSpaceDrawQuad;
-            float mouseX = InputManager.CurrentState.Mouse.Position.X;
+            var mousePos = timeline.ToLocalSpace(InputManager.CurrentState.Mouse.Position);
+
+            // for better UX do not require the user to drag all the way to the edge and beyond to initiate a drag-scroll.
+            // this is especially important in scenarios like fullscreen, where mouse confine will usually be on
+            // and the user physically *won't be able to* drag beyond the edge of the timeline
+            // (since its left edge is co-incident with the window edge).
+            const float scroll_tolerance = 40;
+
+            float leftBound = timeline.BoundingBox.TopLeft.X + scroll_tolerance;
+            float rightBound = timeline.BoundingBox.TopRight.X - scroll_tolerance;
+
+            float amount = 0;
+
+            if (mousePos.X > rightBound)
+                amount = mousePos.X - rightBound;
+            else if (mousePos.X < leftBound)
+                amount = mousePos.X - leftBound;
+
+            if (amount == 0)
+            {
+                dragTimeAccumulated = 0;
+                return;
+            }
+
+            amount = Math.Sign(amount) * Math.Min(max_velocity, MathF.Pow(Math.Clamp(Math.Abs(amount), 0, scroll_tolerance), 2));
+            dragTimeAccumulated += (float)Clock.ElapsedFrameTime;
 
-            // 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));
+            timeline.ScrollBy(amount * (float)Clock.ElapsedFrameTime * Math.Min(1, dragTimeAccumulated / time_ramp_multiplier));
         }
 
         private partial class SelectableAreaBackground : CompositeDrawable