CheckedCombobox in winforms C#

In this article we are going to see how to create a checkbox in the combobox item, For this we have to create a template for the data .

C#:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Drawing;

using System.Windows.Forms.VisualStyles;

namespace CustomControl

{

      class CheckComboBox:ComboBox

    {               

        public class ComboboxData

        {            

             string TotalData;

            private bool _checked;

            public bool Checked

            {

                set { _checked = value; }

                get { return _checked;  }

            }

            private string _data;

            public string Data

            {

                set { _data = value; }

                get { return _data;  }

            }

            public ComboboxData(string value,bool ischeck)

            {

                Data = value;

                Checked = ischeck;              

            }

            public override string ToString()

            {               

                return Data;

            }

        }

        public event EventHandler Checkchanged;

        public CheckComboBox()

        {

            this.DrawMode = System.Windows.Forms.DrawMode.OwnerDrawFixed;

        }

        public List<ComboboxData> CheckItems

        {

            get

            {

                List<ComboboxData> newitems = new List<ComboboxData>();

                foreach (var item in Items)

                {

                    if (item is ComboboxData)

                    {

                        newitems.Add(item as ComboboxData);

                    }

                }

                return newitems;

            }

        }

        protected override void OnSelectedIndexChanged(EventArgs e)

        {

            base.OnSelectedIndexChanged(e);

            ComboboxData data = (ComboboxData)SelectedItem;

            data.Checked = !data.Checked;

            if (Checkchanged != null) {

                Checkchanged(data, e);

            }

        }

        protected override void OnDrawItem(DrawItemEventArgs e)

        {

            if (e.Index == -1)

            {

                return;

            }

            if (Items[e.Index] is ComboboxData)

            {

                ComboboxData data = Items[e.Index] as ComboboxData;

                CheckBoxRenderer.RenderMatchingApplicationState = true;

                CheckBoxRenderer.DrawCheckBox(e.Graphics, new Point(e.Bounds.X, e.Bounds.Y),                      e.Bounds, data.Data, this.Font,

                    (e.State & DrawItemState.Focus) == 0, data.Checked ?                                          CheckBoxState.CheckedNormal : CheckBoxState.UncheckedNormal);

            }

            else

            {

                e.Graphics.DrawString(Items[e.Index].ToString(), this.Font, Brushes.Black,                          new Point(e.Bounds.X, e.Bounds.Y));

                return;

            }

            base.OnDrawItem(e);

        }

   

    }

}

Form.cs:
************

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

namespace Testing

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

            checkComboBox1.Items.Add(new CheckComboBox.ComboboxData("Rajesh", true));

            checkComboBox1.Items.Add(new CheckComboBox.ComboboxData("Suresh", false));

            checkComboBox1.Items.Add(new CheckComboBox.ComboboxData("Ram", true));

            checkComboBox1.Items.Add(new CheckComboBox.ComboboxData("Ravi", true));

            checkComboBox2.Items.Add(new CheckComboBox.ComboboxData("1", true));

            checkComboBox2.Items.Add(new CheckComboBox.ComboboxData("2", false));

            checkComboBox2.Items.Add(new CheckComboBox.ComboboxData("3", true));

            checkComboBox2.Items.Add(new CheckComboBox.ComboboxData("4", true));

        }

        private void button1_Click(object sender, EventArgs e)

        {

            List<CheckComboBox.ComboboxData> dat1 = checkComboBox1.CheckItems;

            var data = new CheckComboBox.ComboboxData("bnm", true);           

            var sdata =data.ToString();

        }

    }

}

Output:

From this post you can learn how to create a Custom Combobox.