added sliders (horizontal scroll bars)

Demos/UiDemo.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using Coroutine;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
+using MLEM.Extensions;
 using MLEM.Font;
 using MLEM.Input;
 using MLEM.Startup;
@@ -121,6 +122,10 @@ namespace Demos {
                         tooltip.IsHidden = !tooltip.IsHidden;
                 }
             });
+
+            var slider = new Slider(Anchor.AutoLeft, new Vector2(1, 10), 5, 1);
+            root.AddChild(new Paragraph(Anchor.AutoLeft, 1, paragraph => "Slider is at " + (slider.CurrentValue * 100).Floor() + "%") {PositionOffset = new Vector2(0, 1)});
+            root.AddChild(slider);
         }
 
         protected override void DoDraw(GameTime gameTime) {

MLEM.Ui/Elements/Paragraph.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
@@ -25,11 +26,20 @@ namespace MLEM.Ui.Elements {
         public string Text {
             get => this.text;
             set {
-                this.text = value;
+                if (this.text != value) {
-                this.SetAreaDirty();
+                    this.text = value;
+                    this.SetAreaDirty();
+                }
             }
         }
         public bool AutoAdjustWidth;
+        public TextCallback GetTextCallback;
+
+        public Paragraph(Anchor anchor, float width, TextCallback textCallback, bool centerText = false, IGenericFont font = null)
+            : this(anchor, width, "", centerText, font) {
+            this.GetTextCallback = textCallback;
+            this.Text = textCallback(this);
+        }
 
         public Paragraph(Anchor anchor, float width, string text, bool centerText = false, IGenericFont font = null) : base(anchor, new Vector2(width, 0)) {
             this.text = text;
@@ -54,6 +64,12 @@ namespace MLEM.Ui.Elements {
             return new Point(this.AutoAdjustWidth ? this.longestLineLength.Ceil() + this.ScaledPadding.X * 2 : size.X, (this.lineHeight * this.splitText.Length).Ceil() + this.ScaledPadding.Y * 2);
         }
 
+        public override void Update(GameTime time) {
+            base.Update(time);
+            if (this.GetTextCallback != null)
+                this.Text = this.GetTextCallback(this);
+        }
+
         public override void Draw(GameTime time, SpriteBatch batch, float alpha, Point offset) {
             if (this.Background != null)
                 batch.Draw(this.Background, this.Area.OffsetCopy(offset), this.BackgroundColor * alpha);
@@ -77,6 +93,8 @@ namespace MLEM.Ui.Elements {
             this.font = style.Font;
         }
 
+        public delegate string TextCallback(Paragraph paragraph);
+
     }
 
 }

MLEM.Ui/Elements/ScrollBar.cs

@@ -33,30 +33,37 @@ namespace MLEM.Ui.Elements {
                 }
             }
         }
+        public readonly bool Horizontal;
         public float StepPerScroll = 1;
         public ValueChanged OnValueChanged;
         private bool isMouseHeld;
 
-        public ScrollBar(Anchor anchor, Vector2 size, int scrollerHeight, float maxValue) : base(anchor, size) {
+        public ScrollBar(Anchor anchor, Vector2 size, int scrollerSize, float maxValue, bool horizontal = false) : base(anchor, size) {
             this.maxValue = maxValue;
-            this.ScrollerSize = new Point(size.X.Floor(), scrollerHeight);
+            this.Horizontal = horizontal;
+            this.ScrollerSize = new Point(horizontal ? scrollerSize : size.X.Floor(), !horizontal ? scrollerSize : size.Y.Floor());
         }
 
         public override void Update(GameTime time) {
             base.Update(time);
             var moused = this.System.MousedElement;
-            if (moused == this && this.Input.IsMouseButtonDown(MouseButton.Left)) {
+            if (moused == this && this.Input.IsMouseButtonPressed(MouseButton.Left)) {
                 this.isMouseHeld = true;
             } else if (this.isMouseHeld && this.Input.IsMouseButtonUp(MouseButton.Left)) {
                 this.isMouseHeld = false;
             }
-            
+
             if (this.isMouseHeld) {
-                var internalY = this.MousePos.Y - this.Area.Y;
+                if (this.Horizontal) {
-                this.CurrentValue = internalY / (float) this.Area.Height * this.MaxValue;
+                    var internalX = this.MousePos.X - this.Area.X;
+                    this.CurrentValue = internalX / (float) this.Area.Width * this.MaxValue;
+                } else {
+                    var internalY = this.MousePos.Y - this.Area.Y;
+                    this.CurrentValue = internalY / (float) this.Area.Height * this.MaxValue;
+                }
             }
-            
+
-            if (moused == this.Parent || moused?.Parent == this.Parent) {
+            if (!this.Horizontal && (moused == this.Parent || moused?.Parent == this.Parent)) {
                 var scroll = this.Input.LastScrollWheel - this.Input.ScrollWheel;
                 if (scroll != 0)
                     this.CurrentValue += this.StepPerScroll * Math.Sign(scroll);
@@ -67,8 +74,10 @@ namespace MLEM.Ui.Elements {
             batch.Draw(this.Background, this.DisplayArea.OffsetCopy(offset), Color.White * alpha, this.Scale);
 
             var scrollerPos = new Point(this.DisplayArea.X + offset.X + this.ScrollerOffset.X, this.DisplayArea.Y + offset.Y + this.ScrollerOffset.Y);
-            var scrollerYOffset = (this.currValue / this.maxValue * (this.DisplayArea.Height - this.ScrollerSize.Y * this.Scale)).Floor();
+            var scrollerOffset = new Point(
-            var scrollerRect = new Rectangle(scrollerPos + new Point(0, scrollerYOffset), this.ScrollerSize.Multiply(this.Scale));
+                !this.Horizontal ? 0 : (this.currValue / this.maxValue * (this.DisplayArea.Width - this.ScrollerSize.X * this.Scale)).Floor(),
+                this.Horizontal ? 0 : (this.currValue / this.maxValue * (this.DisplayArea.Height - this.ScrollerSize.Y * this.Scale)).Floor());
+            var scrollerRect = new Rectangle(scrollerPos + scrollerOffset, this.ScrollerSize.Multiply(this.Scale));
             batch.Draw(this.ScrollerTexture, scrollerRect, Color.White * alpha, this.Scale);
             base.Draw(time, batch, alpha, offset);
         }

MLEM.Ui/Elements/Slider.cs

@@ -0,0 +1,11 @@
+using Microsoft.Xna.Framework;
+
+namespace MLEM.Ui.Elements {
+    public class Slider : ScrollBar {
+
+        public Slider(Anchor anchor, Vector2 size, int scrollerSize, float maxValue) :
+            base(anchor, size, scrollerSize, maxValue, true) {
+        }
+
+    }
+}