From 3e7ddb8b1a60955795349d99e4aa145bf1e0a59f Mon Sep 17 00:00:00 2001
From: Ellpeck <megamaximal@gmail.com>
Date: Sun, 1 Sep 2019 19:53:52 +0200
Subject: [PATCH] add the ability for scroll bars to hide themselves when
 they're empty

---
 MLEM.Ui/Elements/Panel.cs     | 3 ++-
 MLEM.Ui/Elements/ScrollBar.cs | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/MLEM.Ui/Elements/Panel.cs b/MLEM.Ui/Elements/Panel.cs
index be9c330..4e9e832 100644
--- a/MLEM.Ui/Elements/Panel.cs
+++ b/MLEM.Ui/Elements/Panel.cs
@@ -27,7 +27,8 @@ namespace MLEM.Ui.Elements {
                 this.ScrollBar = new ScrollBar(Anchor.TopRight, new Vector2(scrollSize.X, 1), scrollSize.Y, 0) {
                     StepPerScroll = 10,
                     OnValueChanged = (element, value) => this.ForceChildrenScroll(),
-                    CanAutoAnchorsAttach = false
+                    CanAutoAnchorsAttach = false,
+                    AutoHideWhenEmpty = true
                 };
                 this.AddChild(this.ScrollBar);
 
diff --git a/MLEM.Ui/Elements/ScrollBar.cs b/MLEM.Ui/Elements/ScrollBar.cs
index 2fe5347..ee9e94d 100644
--- a/MLEM.Ui/Elements/ScrollBar.cs
+++ b/MLEM.Ui/Elements/ScrollBar.cs
@@ -22,6 +22,8 @@ namespace MLEM.Ui.Elements {
                 this.maxValue = Math.Max(0, value);
                 // force current value to be clamped
                 this.CurrentValue = this.currValue;
+                if (this.AutoHideWhenEmpty)
+                    this.IsHidden = this.maxValue <= 0;
             }
         }
         private float currValue;
@@ -41,6 +43,7 @@ namespace MLEM.Ui.Elements {
         private bool isMouseHeld;
         private bool isDragging;
         private bool isTouchHeld;
+        public bool AutoHideWhenEmpty;
 
         static ScrollBar() {
             InputHandler.EnableGestures(GestureType.HorizontalDrag, GestureType.VerticalDrag);