From a0f67ef3bc1bab4ae0d07115d6df97ef23bb88d8 Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Tue, 18 May 2021 18:57:52 +0900
Subject: [PATCH] Move scaling logic out of `OsuSelectionHandler` for reuse

---
 .../Edit/OsuSelectionHandler.cs               | 18 +----------------
 .../Compose/Components/SelectionHandler.cs    | 20 +++++++++++++++++++
 2 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/osu.Game.Rulesets.Osu/Edit/OsuSelectionHandler.cs b/osu.Game.Rulesets.Osu/Edit/OsuSelectionHandler.cs
index aaf3517c9c..8cb86bc108 100644
--- a/osu.Game.Rulesets.Osu/Edit/OsuSelectionHandler.cs
+++ b/osu.Game.Rulesets.Osu/Edit/OsuSelectionHandler.cs
@@ -225,26 +225,10 @@ namespace osu.Game.Rulesets.Osu.Edit
         private void scaleHitObjects(OsuHitObject[] hitObjects, Anchor reference, Vector2 scale)
         {
             scale = getClampedScale(hitObjects, reference, scale);
-
-            // move the selection before scaling if dragging from top or left anchors.
-            float xOffset = ((reference & Anchor.x0) > 0) ? -scale.X : 0;
-            float yOffset = ((reference & Anchor.y0) > 0) ? -scale.Y : 0;
-
             Quad selectionQuad = getSurroundingQuad(hitObjects);
 
             foreach (var h in hitObjects)
-            {
-                var newPosition = h.Position;
-
-                // guard against no-ops and NaN.
-                if (scale.X != 0 && selectionQuad.Width > 0)
-                    newPosition.X = selectionQuad.TopLeft.X + xOffset + (h.X - selectionQuad.TopLeft.X) / selectionQuad.Width * (selectionQuad.Width + scale.X);
-
-                if (scale.Y != 0 && selectionQuad.Height > 0)
-                    newPosition.Y = selectionQuad.TopLeft.Y + yOffset + (h.Y - selectionQuad.TopLeft.Y) / selectionQuad.Height * (selectionQuad.Height + scale.Y);
-
-                h.Position = newPosition;
-            }
+                h.Position = GetScaledPosition(reference, scale, selectionQuad, h.Position);
         }
 
         private (bool X, bool Y) isQuadInBounds(Quad quad)
diff --git a/osu.Game/Screens/Edit/Compose/Components/SelectionHandler.cs b/osu.Game/Screens/Edit/Compose/Components/SelectionHandler.cs
index bfd5ab7afa..26328b4dc7 100644
--- a/osu.Game/Screens/Edit/Compose/Components/SelectionHandler.cs
+++ b/osu.Game/Screens/Edit/Compose/Components/SelectionHandler.cs
@@ -375,6 +375,26 @@ namespace osu.Game.Screens.Edit.Compose.Components
             return position;
         }
 
+        /// <summary>
+        /// Given a scale vector, a surrounding quad for all selected objects, and a position,
+        /// will return the scaled position in screen space coordinates.
+        /// </summary>
+        protected static Vector2 GetScaledPosition(Anchor reference, Vector2 scale, Quad selectionQuad, Vector2 position)
+        {
+            // adjust the direction of scale depending on which side the user is dragging.
+            float xOffset = ((reference & Anchor.x0) > 0) ? -scale.X : 0;
+            float yOffset = ((reference & Anchor.y0) > 0) ? -scale.Y : 0;
+
+            // guard against no-ops and NaN.
+            if (scale.X != 0 && selectionQuad.Width > 0)
+                position.X = selectionQuad.TopLeft.X + xOffset + (position.X - selectionQuad.TopLeft.X) / selectionQuad.Width * (selectionQuad.Width + scale.X);
+
+            if (scale.Y != 0 && selectionQuad.Height > 0)
+                position.Y = selectionQuad.TopLeft.Y + yOffset + (position.Y - selectionQuad.TopLeft.Y) / selectionQuad.Height * (selectionQuad.Height + scale.Y);
+
+            return position;
+        }
+
         /// <summary>
         /// Returns a quad surrounding the provided points.
         /// </summary>