C#

arnold_w wrote:

I have a regular System.Windows.Forms.ComboBox. This control listens to OnDrawItem(DrawItemEventArgs ea) events.

private void CreateComboBox()
 {
     ComboBox cbox = new ComboBox();
     this.Controls.Add(cbox);

     cbox.DrawItem += new DrawItemEventHandler(cbox_DrawItem);
 }

 void cbox_DrawItem(object sender, DrawItemEventArgs e)
 {
     // Do your stuff here.
 }

public SpecialComboBox() : ComboBox
{
    protected override void OnDrawItem(DrawItemEventArgs ea)
    {
    }
}

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        CreateComboBox();
    }

    private void CreateComboBox()
    {
        MyCombo cbox = new MyCombo();
        cbox.DrawMode = DrawMode.OwnerDrawFixed;

        cbox.Items.Add("test1");
        cbox.Items.Add("test2");

        this.Controls.Add(cbox);
    }
}

public class MyCombo : ComboBox
{
    protected override void OnDrawItem(DrawItemEventArgs e)
    {
        e.DrawBackground();
        e.DrawFocusRectangle();


        String item = (String)this.Items[e.Index];

        Debug.WriteLine("drawing: " + item);
        e.Graphics.DrawString(item, e.Font, Brushes.Red, e.Bounds.Location);
        base.OnDrawItem(e);
    }
}

public SpecialComboBox() : ComboBox
{    
  protected override void OnDrawItem(DrawItemEventArgs ea)    
  {
  }


  // This method make Windows think it needs to draw the 
  // specified item. As a consequence, OnDrawItem above
  // will be automatically executed without us having to
  // call it. Anybody is allowed to call this method.
  private void MakeWindowsThinkItNeedsToDrawAnItem(int item)
  { 
    // What goes here?
  }
}

arnold_w wrote:

Can I somehow invalidate and/or refresh the individual items instead?