Radiobuttons are invisible inside of Array of Panels - arrays

Question

In the Form constructor I generate an array of panels (pnl_ in the code below), that include radiobuttons.
When I visualize the Form, only panels are visible, NOT radiobuttons inside.
Curiously, everything is OK, when I generate only one panel (pnl in the code below).
public partial class Radiobuttons_on_Panel : Form
{
private Panel pnl = new Panel();
private RadioButton rbtn1 = new RadioButton();
private RadioButton rbtn2 = new RadioButton();
private Panel[] pnl_ = new Panel[7];
private RadioButton[] rbtn1_ = new RadioButton[7];
private RadioButton[] rbtn2_ = new RadioButton[7];
public Radiobuttons_on_Panel()
{
InitializeComponent();
pnl.Location = new Point(10, 10);
pnl.Size = new Size(100, 100);
pnl.BorderStyle = BorderStyle.FixedSingle;
rbtn1.Location = pnl.Location;
rbtn1.Text = "AAA";
rbtn2.Location = new Point(pnl.Location.X, pnl.Location.Y + rbtn1.Height);
rbtn2.Text = "BBB";
pnl.Controls.Add(rbtn1);
pnl.Controls.Add(rbtn2);
this.Controls.Add(pnl);
for (int i = 0; i < pnl_.Length; i++)
{
pnl_[i] = new Panel();
pnl_[i].BorderStyle = BorderStyle.FixedSingle;
pnl_[i].Size = new Size(100, 100);
pnl_[i].Location = new Point(10 + i * 110, 200);
rbtn1_[i] = new RadioButton();
rbtn1_[i].Location = pnl_[i].Location;
rbtn1_[i].Text = "AAA";
rbtn2_[i] = new RadioButton();
rbtn2_[i].Location = new Point(pnl_[i].Location.X, pnl_[i].Location.Y + rbtn1_[i].Height);
rbtn2_[i].Text = "BBB";
pnl_[i].Controls.Add(rbtn1_[i]);
pnl_[i].Controls.Add(rbtn2_[i]);
this.Controls.Add(pnl_[i]);
}
}
}
Where is the problem?

Answer 1

Your problem with this is that your calculation of location is wrong. The location of the radio buttons are relative to their container - in this case, the panels. If you just set your locations to
rbtn1_[i] = new RadioButton();
rbtn1_[i].Location = new Point(10, 10);
rbtn1_[i].Text = "AAA";
rbtn2_[i] = new RadioButton();
rbtn2_[i].Location = new Point(rbtn1_[i].Location.X, rbtn1_[i].Location.Y + rbtn1_[i].Height);
rbtn2_[i].Text = "BBB";
the buttons will lay out like you want them to.
Thing work out in your first one because your radio button locations values are small enough to be visible in the panel. For those others, well, they are outside the bounds of their parent panels.
The long and short of it is that the Location property is always relative to the container, whether that is a Panel or a Form - the Location values for your panels are relative to the Form but the the Location values for your radio buttons are relative to whatever panel they are in.
MSDN Reference: http://msdn.microsoft.com/en-us/library/system.windows.forms.control.location.aspx