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Remember the location that a scroll bar scroller was grabbed in when scrolling

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Ell 2021-11-14 21:32:13 +01:00
parent 2a7dc119eb
commit 91d34c0a83
2 changed files with 21 additions and 13 deletions
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1
CHANGELOG.md
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@ -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

33
MLEM.Ui/Elements/ScrollBar.cs
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@ -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 {
/// </summary>
public bool AutoHideWhenEmpty;
/// <summary>
/// The position that this scroll bar's scroller is currently at.
/// This value takes the <see cref="Element.DisplayArea"/>, as well as the <see cref="Element.Scale"/> into account.
/// </summary>
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));
/// <summary>
/// Whether smooth scrolling should be enabled for this scroll bar.
/// Smooth scrolling causes the <see cref="CurrentValue"/> to change gradually rather than instantly when scrolling.
/// </summary>
@ -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;
}
}
/// <inheritdoc />
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);