1 files changed, 162 insertions, 0 deletions
diff --git a/ShiftOS.Frontend/GUI/ListBox.cs b/ShiftOS.Frontend/GUI/ListBox.cs
new file mode 100644
index 0000000..f9354e0
--- /dev/null
+++ b/ShiftOS.Frontend/GUI/ListBox.cs
@@ -0,0 +1,162 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.Xna.Framework;
+using ShiftOS.Frontend.GraphicsSubsystem;
+using static ShiftOS.Engine.SkinEngine;
+
+namespace ShiftOS.Frontend.GUI
+{
+    public class ListBox : GUI.Control
+    {
+        private int fontheight = 0;
+        private List<object> items = new List<object>();
+        private int selectedIndex = -1;
+        private int itemOffset = 0;
+        private int itemsPerPage = 1;
+
+        public int SelectedIndex
+        {
+            get
+            {
+                return MathHelper.Clamp(selectedIndex, 0, items.Count - 1);
+            }
+            set
+            {
+                selectedIndex = MathHelper.Clamp(value, 0, items.Count - 1);
+                RecalculateItemsPerPage();
+                SelectedIndexChanged?.Invoke();
+            }
+        }
+
+        public object SelectedItem
+        {
+            get
+            {
+                try
+                {
+                    return items[SelectedIndex];
+                }
+                catch
+                {
+                    return "";
+                }
+            }
+        }
+
+        public void ClearItems()
+        {
+            selectedIndex = -1;
+            items.Clear();
+            SelectedIndexChanged?.Invoke();
+            Invalidate();
+        }
+
+        public void AddItem(object item)
+        {
+            items.Add(item);
+            RecalculateItemsPerPage();
+            Invalidate();
+        }
+
+        public void RemoveItem(object item)
+        {
+            items.Remove(item);
+            selectedIndex = -1;
+            RecalculateItemsPerPage();
+            SelectedIndexChanged?.Invoke();
+            Invalidate();
+        }
+
+        public void RecalculateItemsPerPage()
+        {
+            itemsPerPage = 0;
+           while(itemsPerPage * fontheight < Height && itemsPerPage < items.Count - 1)
+            {
+                itemsPerPage++;
+            }
+           //We have the amount of items we can fit on screen.
+           //Now let's calculate the offset based on this, as well
+           //as the currently selected item.
+           //of course, if there IS one.
+           if(selectedIndex > -1)
+            {
+                if(selectedIndex >= items.Count)
+                {
+                    selectedIndex = items.Count - 1;
+                }
+                while(this.itemOffset > selectedIndex)
+                {
+                    itemOffset--;
+                }
+                while(this.itemOffset + itemsPerPage < selectedIndex)
+                {
+                    itemOffset++;
+                }
+            }
+        }
+
+        protected override void OnKeyEvent(KeyEvent e)
+        {
+            if(e.Key== Microsoft.Xna.Framework.Input.Keys.Down)
+            {
+                if(selectedIndex < items.Count - 2)
+                {
+                    selectedIndex++;
+                    RecalculateItemsPerPage();
+                    SelectedIndexChanged?.Invoke();
+                    Invalidate();
+                }
+            }
+            else if(e.Key == Microsoft.Xna.Framework.Input.Keys.Up)
+            {
+                if(selectedIndex > 0)
+                {
+                    selectedIndex--;
+                    RecalculateItemsPerPage();
+                    SelectedIndexChanged?.Invoke();
+                    Invalidate();
+                }
+            }
+        }
+
+        protected override void OnPaint(GraphicsContext gfx)
+        {
+            gfx.Clear(LoadedSkin.ControlTextColor.ToMonoColor());
+            gfx.DrawRectangle(1, 1, Width - 2, Height - 2, UIManager.SkinTextures["ControlColor"]);
+            for(int i = itemOffset; i < items.Count - 1 && i < itemsPerPage; i++)
+            {
+                int x = 1;
+                int y = fontheight * (i - itemOffset);
+                int width = Width - 2;
+                int height = fontheight;
+                if(i == selectedIndex)
+                {
+                    //draw the string as selected
+                    gfx.DrawRectangle(x, y, width, height, UIManager.SkinTextures["ControlTextColor"]);
+                    gfx.DrawString(items[i].ToString(), x, y, LoadedSkin.ControlColor.ToMonoColor(), LoadedSkin.MainFont);
+                }
+                else
+                {
+                    gfx.DrawRectangle(x, y, width, height, UIManager.SkinTextures["ControlColor"]);
+                    gfx.DrawString(items[i].ToString(), x, y, LoadedSkin.ControlTextColor.ToMonoColor(), LoadedSkin.MainFont);
+
+                }
+            }
+        }
+
+        protected override void OnLayout()
+        {
+            if(fontheight != LoadedSkin.MainFont.Height)
+            {
+                fontheight = LoadedSkin.MainFont.Height;
+                Invalidate();
+            }
+            base.OnLayout();
+        }
+
+        public event Action SelectedIndexChanged;
+    }
+}