From bcc558f591455e14e95897e3e05bd029f76fbb22 Mon Sep 17 00:00:00 2001
From: Ellpeck <me@ellpeck.de>
Date: Fri, 14 Jun 2024 22:31:32 +0200
Subject: [PATCH] some panel improvements

- Added Panel.ScrollToTop and Panel.ScrollToBottom
- Fixed Panel.ScrollToElement not scrolling correctly when the panel's area is dirty
---
 CHANGELOG.md              |  2 ++
 MLEM.Ui/Elements/Panel.cs | 17 +++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 90d1cc0..2492978 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -28,6 +28,7 @@ Additions
 - Added the ability to set the anchor that should be used when a tooltip attaches to an element or the mouse
 - Added the ability to display tooltips using the auto-nav style even when using the mouse
 - Added the ScissorGroup element, which applies a scissor rectangle when drawing its content
+- Added Panel.ScrollToTop and Panel.ScrollToBottom
 
 Improvements
 - **Include the SpriteBatchContext in OnDrawn, OnElementDrawn and OnSelectedElementDrawn**
@@ -39,6 +40,7 @@ Fixes
 - Fixed hidden scroll bars inhibiting scrolling on their parent panel
 - Fixed scroll bars doing unnecessary calculations when hidden
 - Fixed auto-sized elements sometimes updating their location based on outdated parent positions
+- Fixed Panel.ScrollToElement not scrolling correctly when the panel's area is dirty
 
 ## 6.3.1
 
diff --git a/MLEM.Ui/Elements/Panel.cs b/MLEM.Ui/Elements/Panel.cs
index 4b85e1e..c07ae92 100644
--- a/MLEM.Ui/Elements/Panel.cs
+++ b/MLEM.Ui/Elements/Panel.cs
@@ -236,9 +236,26 @@ namespace MLEM.Ui.Elements {
             var highestValidChild = this.Children.FirstOrDefault(c => c != this.ScrollBar && !c.IsHidden);
             if (highestValidChild == null)
                 return;
+            this.UpdateAreaIfDirty();
             this.ScrollBar.CurrentValue = (elementY - this.Area.Height / 2 - highestValidChild.Area.Top) / this.Scale + this.ChildPadding.Value.Height / 2;
         }
 
+        /// <summary>
+        /// Scrolls this panel's <see cref="ScrollBar"/> to the top, causing the top of this panel to be shown.
+        /// </summary>
+        public void ScrollToTop() {
+            this.UpdateAreaIfDirty();
+            this.ScrollBar.CurrentValue = 0;
+        }
+
+        /// <summary>
+        /// Scrolls this panel's <see cref="ScrollBar"/> to the bottom, causing the bottom of this panel to be shown.
+        /// </summary>
+        public void ScrollToBottom() {
+            this.UpdateAreaIfDirty();
+            this.ScrollBar.CurrentValue = this.ScrollBar.MaxValue;
+        }
+
         /// <inheritdoc />
         protected override void InitStyle(UiStyle style) {
             base.InitStyle(style);