Gis C# Form 做一個ComboBox，只需要傳Map，即可顯示所有圖層

myComboBox1.Map = _map;

using ESRI.ArcGIS.Carto;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace MyGIS.Model
{
    public class MyLayerComboBox : System.Windows.Forms.ComboBox
    {
        List<string> layers = new List<string>();
        IMap map = null;
        public IMap Map
        {
            get
            {
                return map;
            }
            set
            {
                //////return;
                map = value;
                if (map == null) return;
                layers = new List<string>();
                for (int a = 0; a < map.LayerCount; a++)
                {
                    layers.Add(map.Layer[a].Name);
                }

                DataSource = layers;

            }
        }
        public ILayer Layer
        {
            get; set;
        }

        protected override void OnSelectedItemChanged(EventArgs e)
        {
            if (layers == null) return;
            if (layers.Count == 0) return;
            Layer = map.Layer[SelectedIndex];
            
        }
        protected override void OnSelectedValueChanged(EventArgs e)
        {
            if (layers == null) return;
            if (layers.Count == 0) return;
            Layer = map.Layer[SelectedIndex];
            
           
        }

        private void InitializeComponent()
        {
            this.SuspendLayout();
            // 
            // MyLayerComboBox
            // 
            this.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
            this.ResumeLayout(false);

        }
    }
}