diff --git a/CHANGELOG.md b/CHANGELOG.md
index b60865d..d9892da 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -31,6 +31,7 @@ Improvements
- Allow changing the entire ui style for a single element
- Skip unnecessary area updates for elements with dirty parents
- Calculate panel scroll bar height based on content height
+- Remember the location that a scroll bar scroller was grabbed in when scrolling
Fixes
- Fixed VerticalSpace height parameter being an integer
diff --git a/MLEM.Ui/Elements/ScrollBar.cs b/MLEM.Ui/Elements/ScrollBar.cs
index 453361c..f97bec9 100644
--- a/MLEM.Ui/Elements/ScrollBar.cs
+++ b/MLEM.Ui/Elements/ScrollBar.cs
@@ -3,7 +3,6 @@ using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input.Touch;
-using MLEM.Extensions;
using MLEM.Input;
using MLEM.Misc;
using MLEM.Textures;
@@ -89,6 +88,13 @@ namespace MLEM.Ui.Elements {
///
public bool AutoHideWhenEmpty;
///
+ /// The position that this scroll bar's scroller is currently at.
+ /// This value takes the , as well as the into account.
+ ///
+ public Vector2 ScrollerPosition => this.DisplayArea.Location + new Vector2(
+ !this.Horizontal ? 0 : this.CurrentValue / this.maxValue * (this.DisplayArea.Width - this.ScrollerSize.X * this.Scale),
+ this.Horizontal ? 0 : this.CurrentValue / this.maxValue * (this.DisplayArea.Height - this.ScrollerSize.Y * this.Scale));
+ ///
/// Whether smooth scrolling should be enabled for this scroll bar.
/// Smooth scrolling causes the to change gradually rather than instantly when scrolling.
///
@@ -104,6 +110,7 @@ namespace MLEM.Ui.Elements {
private float maxValue;
private float scrollAdded;
private float currValue;
+ private Vector2 scrollStartOffset;
static ScrollBar() {
InputHandler.EnableGestures(GestureType.HorizontalDrag, GestureType.VerticalDrag);
@@ -130,13 +137,15 @@ namespace MLEM.Ui.Elements {
// MOUSE INPUT
var moused = this.Controls.MousedElement;
+ var mousedPos = Vector2.Transform(this.Input.MousePosition.ToVector2(), this.Root.InvTransform);
if (moused == this && this.Controls.Input.IsMouseButtonPressed(MouseButton.Left)) {
this.isMouseHeld = true;
+ this.scrollStartOffset = mousedPos - this.ScrollerPosition;
} else if (this.isMouseHeld && !this.Controls.Input.IsMouseButtonDown(MouseButton.Left)) {
this.isMouseHeld = false;
}
if (this.isMouseHeld)
- this.ScrollToPos(this.Input.MousePosition.Transform(this.Root.InvTransform));
+ this.ScrollToPos(mousedPos);
if (!this.Horizontal && moused != null && (moused == this.Parent || moused.GetParentTree().Contains(this.Parent))) {
var scroll = this.Input.LastScrollWheel - this.Input.ScrollWheel;
if (scroll != 0)
@@ -168,11 +177,12 @@ namespace MLEM.Ui.Elements {
// if we just started touching and are on top of the scroller, then we should start scrolling
if (this.DisplayArea.Contains(pos) && !loc.TryGetPreviousLocation(out _)) {
this.isTouchHeld = true;
+ this.scrollStartOffset = pos - this.ScrollerPosition;
break;
}
// scroll no matter if we're on the scroller right now
if (this.isTouchHeld)
- this.ScrollToPos(pos.ToPoint());
+ this.ScrollToPos(pos);
}
}
@@ -184,25 +194,22 @@ namespace MLEM.Ui.Elements {
}
}
- private void ScrollToPos(Point position) {
+ private void ScrollToPos(Vector2 position) {
+ var (width, height) = this.ScrollerSize * this.Scale;
if (this.Horizontal) {
- var internalX = position.X - this.Area.X - this.ScrollerSize.X * this.Scale / 2;
- this.CurrentValue = internalX / (this.Area.Width - this.ScrollerSize.X * this.Scale) * this.MaxValue;
+ var offset = this.scrollStartOffset.X >= 0 && this.scrollStartOffset.X <= width ? this.scrollStartOffset.X : width / 2;
+ this.CurrentValue = (position.X - this.Area.X - offset) / (this.Area.Width - width) * this.MaxValue;
} else {
- var internalY = position.Y - this.Area.Y - this.ScrollerSize.Y * this.Scale / 2;
- this.CurrentValue = internalY / (this.Area.Height - this.ScrollerSize.Y * this.Scale) * this.MaxValue;
+ var offset = this.scrollStartOffset.Y >= 0 && this.scrollStartOffset.Y <= height ? this.scrollStartOffset.Y : height / 2;
+ this.CurrentValue = (position.Y - this.Area.Y - offset) / (this.Area.Height - height) * this.MaxValue;
}
}
///
public override void Draw(GameTime time, SpriteBatch batch, float alpha, BlendState blendState, SamplerState samplerState, Matrix matrix) {
batch.Draw(this.Background, this.DisplayArea, Color.White * alpha, this.Scale);
-
if (this.MaxValue > 0) {
- var scrollerOffset = new Vector2(
- !this.Horizontal ? 0 : this.CurrentValue / this.maxValue * (this.DisplayArea.Width - this.ScrollerSize.X * this.Scale),
- this.Horizontal ? 0 : this.CurrentValue / this.maxValue * (this.DisplayArea.Height - this.ScrollerSize.Y * this.Scale));
- var scrollerRect = new RectangleF(this.DisplayArea.Location + scrollerOffset, this.ScrollerSize * this.Scale);
+ var scrollerRect = new RectangleF(this.ScrollerPosition, this.ScrollerSize * this.Scale);
batch.Draw(this.ScrollerTexture, scrollerRect, Color.White * alpha, this.Scale);
}
base.Draw(time, batch, alpha, blendState, samplerState, matrix);