Question

In this user control the designer adds items to this control on the form and it dynamically places them on the form. Unfortunately once these controls are shown on the form in designer I can then grab one and pull it right outside of the custom control.

How do I prevent this?

EDIT

Please note that I am not looking for a solution or alternative to handling radio buttons, that is just the control of choice in this scenario. If it helps insert any type of control you want here (Button, Label, TextBox, CustomControl1), this problem is about handling a property with a collection/array type. The bottom line is that the user shouldn’t be able to grab any of these controls in designer where an instance of this control has been defined and move it elsewhere. Just like a DataGridView or ListView albeit different types of objects, the user must use properties to change the contents of these controls. That is the beharior I am looking for.

RBLTest.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WFCL_Library
{
    public partial class RBLTest : UserControl
    {
        private RadioButton[] _items;

        private int leftSpacing = 100;
        private int topSpacing = 25;

        public RBLTest()
        {
            InitializeComponent();
        }

        private void RadioButtonList_Load(object sender, EventArgs e)
        {
            int curLeftPos = 0;
            int curTopPos = 0;
            foreach (RadioButton rb in _items)
            {
                rb.Location = new Point(curLeftPos, curTopPos);
                rb.Size = new Size(85, 17);

                curLeftPos += leftSpacing;

                if (curLeftPos > this.Width)
                {
                    curLeftPos = 0;
                    curTopPos += topSpacing;
                }

                this.Controls.Add(rb);                
            }
        }

        [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
        public RadioButton[] Items
        {
            get
            {
                return _items;
            }
            set
            {
                _items = value;
            }
        }
    }       
}

RBLTest.Designer.cs

namespace WFCL_Library
{
    partial class RBLTest
    {
        /// <summary> 
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary> 
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Component Designer generated code

        /// <summary> 
        /// Required method for Designer support - do not modify 
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.SuspendLayout();
            // 
            // RBLTest
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.Name = "RBLTest";
            this.Size = new System.Drawing.Size(407, 44);
            this.Load += new System.EventHandler(this.RadioButtonList_Load);
            this.ResumeLayout(false);

        }

        #endregion

    }
}

Answer 1

Well, it depends on how you want to do it. First off, I’m not a big fan of allowing direct access to controls on my user controls. For this reason, I make sure none of the controls are publically accessable. What I do is make everything private (or sometimes protected since it’s nice for derived classes to have some flexibility) then I create properties to access the controls’ properties that must be accessible and events to be handled by parent containers.

If all that really doesn’t matter to you, then I believe the property you are looking for is the Control.Locked property. In your code above once you’ve added the dynamic control to the Controls collection, set the Locked to true. So:

            this.Controls.Add(rb);
            rb.Locked = true;

Try something like this:

    public class RadioButtonProperties
    {
        private RadioButton _realtedRadioButton = new RadioButton();

        public RadioButtonProperties(RadioButton radio)
        {
            _realtedRadioButton = radio;

            Name = radio.Name;
            Checked = radio.Checked;
            //add other properties
        }

        public string Name
        {
            get
            {
                //logic to to handle if checkbox is null here

                return _realtedRadioButton.Name;
            }

            set
            {
                //logic to to handle if checkbox is null here

                _realtedRadioButton.Name = value;
            }
        }

        public bool Checked
        {
            get
            {
                //logic to to handle if checkbox is null here

                return _realtedRadioButton.Checked;
            }

            set
            {
                //logic to to handle if checkbox is null here

                _realtedRadioButton.Checked = value;
            }
        }
    }

Now in your custom control, instead of giving public access to your entire radiobox array, you give access to a representation of the array, exposing only the radiobox properties that you want. For example:

    [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]  
    public List<RadioButtonProperties> Items { get; set; }