From 7f4cc773ec5eaa17138c05732c13bcc7f02152b9 Mon Sep 17 00:00:00 2001
From: Ellpeck <me@ellpeck.de>
Date: Sat, 30 Mar 2024 12:24:57 +0100
Subject: [PATCH] Fixed scrolling panels calculating their height incorrectly
 when their first child is hidden

---
 CHANGELOG.md              |  1 +
 MLEM.Ui/Elements/Panel.cs | 10 +++++-----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index bcf845d..4b36196 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -51,6 +51,7 @@ Improvements
 Fixes
 - Fixed panels updating their relevant children too much when the scroll bar is hidden
 - Fixed a stack overflow exception when a panel's scroll bar auto-hiding causes elements to gain height
+- Fixed scrolling panels calculating their height incorrectly when their first child is hidden
 
 ### MLEM.Extended
 Improvements
diff --git a/MLEM.Ui/Elements/Panel.cs b/MLEM.Ui/Elements/Panel.cs
index 65b974f..5c87a01 100644
--- a/MLEM.Ui/Elements/Panel.cs
+++ b/MLEM.Ui/Elements/Panel.cs
@@ -223,10 +223,10 @@ namespace MLEM.Ui.Elements {
         /// </summary>
         /// <param name="elementY">The y coordinate to scroll to, which should have this element's <see cref="Element.Scale"/> applied.</param>
         public void ScrollToElement(float elementY) {
-            var firstChild = this.Children.FirstOrDefault(c => c != this.ScrollBar);
-            if (firstChild == null)
+            var highestValidChild = this.Children.FirstOrDefault(c => c != this.ScrollBar && !c.IsHidden);
+            if (highestValidChild == null)
                 return;
-            this.ScrollBar.CurrentValue = (elementY - this.Area.Height / 2 - firstChild.Area.Top) / this.Scale + this.ChildPadding.Value.Height / 2;
+            this.ScrollBar.CurrentValue = (elementY - this.Area.Height / 2 - highestValidChild.Area.Top) / this.Scale + this.ChildPadding.Value.Height / 2;
         }
 
         /// <inheritdoc />
@@ -282,9 +282,9 @@ namespace MLEM.Ui.Elements {
 
             float childrenHeight;
             if (this.Children.Count > 1) {
-                var firstChild = this.Children.FirstOrDefault(c => c != this.ScrollBar);
+                var highestValidChild = this.Children.FirstOrDefault(c => c != this.ScrollBar && !c.IsHidden);
                 var lowestChild = this.GetLowestChild(c => c != this.ScrollBar && !c.IsHidden, true);
-                childrenHeight = lowestChild.GetTotalCoveredArea(false).Bottom - firstChild.Area.Top;
+                childrenHeight = lowestChild.GetTotalCoveredArea(false).Bottom - highestValidChild.Area.Top;
             } else {
                 // if we only have one child (the scroll bar), then the children take up no visual height
                 childrenHeight = 0;