Question

I need your help in following question (using .Net 3.5 and Windows Forms):

I just simply want to draw a line on a middle of a combobox (Windows Forms) that is situated on a form.
The code I use is:

void comboBox1_Paint(object sender, PaintEventArgs e)
{
  e.Graphics.DrawLine(new Pen(Brushes.DarkBlue),
                      this.comboBox1.Location.X,
                      this.comboBox1.Location.Y + (this.comboBox1.Size.Height / 2),
                      this.comboBox1.Location.X + this.comboBox1.Size.Width,
                      this.comboBox1.Location.Y + (this.comboBox1.Size.Height / 2));
}

To fire a paint event:

private void button1_Click(object sender, EventArgs e)
{
  comboBox1.Refresh();
}

When I execute the code and press button the line isn’t drawn. In debug the breakpoint at the paint handler isn’t being hit. The strange thing is that on MSDN there is a paint event in ComBox’s events list, but in VS 2010 IntelliSense doesn’t find such event in ComboBox’s members

Thanks.

Answer 1

public Form1() 
{
  InitializeComponent();
  comboBox1.DrawMode = DrawMode.OwnerDrawFixed;
  comboBox1.DrawItem += new DrawItemEventHandler(comboBox1_DrawItem);
}

void comboBox1_DrawItem(object sender, DrawItemEventArgs e) {
  e.DrawBackground();
  e.Graphics.DrawLine(Pens.Black, new Point(e.Bounds.Left, e.Bounds.Bottom-1),
    new Point(e.Bounds.Right, e.Bounds.Bottom-1));
  TextRenderer.DrawText(e.Graphics, comboBox1.Items[e.Index].ToString(), 
    comboBox1.Font, e.Bounds, comboBox1.ForeColor, TextFormatFlags.Left);
  e.DrawFocusRectangle();
}