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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 ListBox()
{
Click += () =>
{
//loop through the list of items on the screen
for(int i = itemOffset; i < itemOffset + itemsPerPage && i < items.Count; i++)
{
int screeni = i - itemOffset;
int loc = 1+screeni * fontheight;
int height = 1+(screeni + 1) * fontheight;
if(MouseY >= loc && MouseY <= height)
{
SelectedIndex = i;
RecalculateItemsPerPage();
return;
}
}
};
}
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)
{
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 - 1)
{
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 && 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+2, width, height, UIManager.SkinTextures["ControlTextColor"]);
gfx.DrawString(items[i].ToString(), x, y+2, LoadedSkin.ControlColor.ToMonoColor(), LoadedSkin.MainFont);
}
else
{
gfx.DrawRectangle(x, y+2, width, height, UIManager.SkinTextures["ControlColor"]);
gfx.DrawString(items[i].ToString(), x, y+2, LoadedSkin.ControlTextColor.ToMonoColor(), LoadedSkin.MainFont);
}
}
}
protected override void OnLayout(GameTime gameTime)
{
if(fontheight != LoadedSkin.MainFont.Height)
{
fontheight = LoadedSkin.MainFont.Height;
Invalidate();
}
base.OnLayout(gameTime);
}
public event Action SelectedIndexChanged;
}
}
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