Question

I found that I can’t use the Image property for a PictureBox control in List<Control>.

I want to do something like this:

    List<Control> pictureboxes = new List<Control>();

    private void button1_Click(object sender, EventArgs e)
    {
        foreach (var picturebox in pictureboxes)
        {
             picturebox.Image = WindowsFormsApplication1.Properties.Resources.image;
        }
    }

Can I somehow do that?

Answer 1

The reason that you can’t access the Image property of your PictureBox controls when you place them in a List<Control> container is because the base type of the list (Control) doesn’t have an Image property.

The property didn’t disappear, though. You just have to cast the object from a Control to a more derived class, PictureBox. Then you can call whatever methods or access whatever properties you want. For example:

List<Control> MyList = new List<Control>();

private void button1_Click(object sender, EventArgs e)
{
    foreach (Control ctrl in MyList)
    {
        // Try to cast the Control object to a PictureBox
        PictureBox picBox = ctrl as PictureBox;
        if (picBox != null)
        {
            picBox.Image = WindowsFormsApplication1.Properties.Resources.image;
        }
    }
}