From 740a72e16d07b380177c331096780043ded35da1 Mon Sep 17 00:00:00 2001
From: Salman Ahmed <frenzibyte@gmail.com>
Date: Mon, 14 Mar 2022 05:44:34 +0300
Subject: [PATCH] Share origin adjustment logic between storyboard sprite and
 animation

---
 .../Drawables/DrawableStoryboardAnimation.cs  | 30 +------------
 osu.Game/Storyboards/StoryboardExtensions.cs  | 43 +++++++++++++++++++
 2 files changed, 45 insertions(+), 28 deletions(-)
 create mode 100644 osu.Game/Storyboards/StoryboardExtensions.cs

diff --git a/osu.Game/Storyboards/Drawables/DrawableStoryboardAnimation.cs b/osu.Game/Storyboards/Drawables/DrawableStoryboardAnimation.cs
index 81623a9307..28ac83a25c 100644
--- a/osu.Game/Storyboards/Drawables/DrawableStoryboardAnimation.cs
+++ b/osu.Game/Storyboards/Drawables/DrawableStoryboardAnimation.cs
@@ -3,7 +3,6 @@
 
 using System;
 using osu.Framework.Allocation;
-using osu.Framework.Extensions.EnumExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Animations;
 using osu.Framework.Graphics.Textures;
@@ -70,34 +69,9 @@ public Vector2 VectorScale
 
         public override bool RemoveWhenNotAlive => false;
 
-        protected override Vector2 DrawScale
-            => new Vector2(FlipH ? -base.DrawScale.X : base.DrawScale.X, FlipV ? -base.DrawScale.Y : base.DrawScale.Y) * VectorScale;
+        protected override Vector2 DrawScale => new Vector2(FlipH ? -base.DrawScale.X : base.DrawScale.X, FlipV ? -base.DrawScale.Y : base.DrawScale.Y) * VectorScale;
 
-        public override Anchor Origin
-        {
-            get
-            {
-                var origin = base.Origin;
-
-                if (FlipH)
-                {
-                    if (origin.HasFlagFast(Anchor.x0))
-                        origin = Anchor.x2 | (origin & (Anchor.y0 | Anchor.y1 | Anchor.y2));
-                    else if (origin.HasFlagFast(Anchor.x2))
-                        origin = Anchor.x0 | (origin & (Anchor.y0 | Anchor.y1 | Anchor.y2));
-                }
-
-                if (FlipV)
-                {
-                    if (origin.HasFlagFast(Anchor.y0))
-                        origin = Anchor.y2 | (origin & (Anchor.x0 | Anchor.x1 | Anchor.x2));
-                    else if (origin.HasFlagFast(Anchor.y2))
-                        origin = Anchor.y0 | (origin & (Anchor.x0 | Anchor.x1 | Anchor.x2));
-                }
-
-                return origin;
-            }
-        }
+        public override Anchor Origin => StoryboardExtensions.AdjustOrigin(base.Origin, VectorScale, FlipH, FlipV);
 
         public override bool IsPresent
             => !float.IsNaN(DrawPosition.X) && !float.IsNaN(DrawPosition.Y) && base.IsPresent;
diff --git a/osu.Game/Storyboards/StoryboardExtensions.cs b/osu.Game/Storyboards/StoryboardExtensions.cs
new file mode 100644
index 0000000000..4e8251c9e7
--- /dev/null
+++ b/osu.Game/Storyboards/StoryboardExtensions.cs
@@ -0,0 +1,43 @@
+// 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 osu.Framework.Extensions.EnumExtensions;
+using osu.Framework.Graphics;
+using osuTK;
+
+namespace osu.Game.Storyboards
+{
+    public static class StoryboardExtensions
+    {
+        /// <summary>
+        /// Given an origin and a set of properties, adjust the origin to display the sprite/animation correctly.
+        /// </summary>
+        /// <param name="origin">The current origin.</param>
+        /// <param name="vectorScale">The vector scale.</param>
+        /// <param name="flipH">Whether the element is flipped horizontally.</param>
+        /// <param name="flipV">Whether the element is flipped vertically.</param>
+        /// <returns>The adjusted origin.</returns>
+        public static Anchor AdjustOrigin(Anchor origin, Vector2 vectorScale, bool flipH, bool flipV)
+        {
+            // Either flip horizontally or negative X scale, but not both.
+            if (flipH ^ (vectorScale.X < 0))
+            {
+                if (origin.HasFlagFast(Anchor.x0))
+                    origin = Anchor.x2 | (origin & (Anchor.y0 | Anchor.y1 | Anchor.y2));
+                else if (origin.HasFlagFast(Anchor.x2))
+                    origin = Anchor.x0 | (origin & (Anchor.y0 | Anchor.y1 | Anchor.y2));
+            }
+
+            // Either flip vertically or negative Y scale, but not both.
+            if (flipV ^ (vectorScale.Y < 0))
+            {
+                if (origin.HasFlagFast(Anchor.y0))
+                    origin = Anchor.y2 | (origin & (Anchor.x0 | Anchor.x1 | Anchor.x2));
+                else if (origin.HasFlagFast(Anchor.y2))
+                    origin = Anchor.y0 | (origin & (Anchor.x0 | Anchor.x1 | Anchor.x2));
+            }
+
+            return origin;
+        }
+    }
+}