Sunday, 29 November 2015

Add Dynamic TextBox, Label and Button controls with TextChanged and Click event handlers in Windows Forms (WinForms) Application

In this article I will explain how to add dynamic controls like Label, TextBox, Button, etc. to Windows Forms Application on click of a Button.
I will here also explain how we can attach event handler to various dynamically added controls like TextBox, Button, etc.

Form Layout
The form layout consists of a Button and a Panel control to add dynamic controls within it.

You will need to import the following namespaces.
using System.Linq;
using System.Drawing;

Imports System.Linq
Imports System.Drawing

Dynamically adding Windows Label Control
Firstly we need to create a new object of the Label control and then count of the Label controls is determined, Count is useful to give number incremented unique Ids to the controls as well as for setting location of the controls on the Windows Form so that controls don’t overlap each other. After the location, the remaining properties like Size, Name and Text are set. Finally the Label control is added to the Windows Forms Panel control.
Label label = new Label();
int count = panel1.Controls.OfType<Label>().ToList().Count;
label.Location = new Point(10, (25 * count) + 2);
label.Size = new Size(40, 20);
label.Name = "label_" + (count + 1);
label.Text = "label " + (count + 1);

Dim label As New Label()
Dim count As Integer = panel1.Controls.OfType(Of Label)().ToList().Count
label.Location = New Point(10, (25 * count) + 2)
label.Size = New Size(40, 20)
label.Name = "label_" & (count + 1)
label.Text = "label " & (count + 1)

Dynamically adding Windows TextBox Control
Similar to Label the TextBox control is dynamically added, the only difference here is the Text property and the dynamic TextChaned event handler.
TextBox textbox = new TextBox();
count = panel1.Controls.OfType<TextBox>().ToList().Count;
textbox.Location = new System.Drawing.Point(60, 25 * count);
textbox.Size = new System.Drawing.Size(80, 20);
textbox.Name = "textbox_" + (count + 1);
textbox.TextChanged += new System.EventHandler(this.TextBox_Changed);

Dim textbox As New TextBox()
count = panel1.Controls.OfType(Of TextBox)().ToList().Count
textbox.Location = New System.Drawing.Point(60, 25 * count)
textbox.Size = New System.Drawing.Size(80, 20)
textbox.Name = "textbox_" & (count + 1)
AddHandler textbox.TextChanged, AddressOf TextBox_Changed

The following dynamic TextChanged event handler is raised when the text is changed inside the dynamic TextBox control.
private void TextBox_Changed(object sender, EventArgs e)
    TextBox textbox = (sender as TextBox);
    MessageBox.Show(textbox.Name + " text changed. Value " + textbox.Text);

Private Sub TextBox_Changed(sender As Object, e As EventArgs)
    Dim textbox As TextBox = TryCast(sender, TextBox)
    MessageBox.Show(textbox.Name + " text changed. Value " + textbox.Text)
End Sub

Dynamically adding Windows Button Control
Similar to the TextBox control, here a Button control is dynamically added. The only difference is that here we have a dynamic Click event handler.
Button button = new Button();
count = panel1.Controls.OfType<Button>().ToList().Count;
button.Location = new System.Drawing.Point(150, 25 * count);
button.Size = new System.Drawing.Size(60, 20);
button.Name = "button_" + (count + 1);
button.Text = "Button " + (count + 1);
button.Click += new System.EventHandler(this.Button_Click);

Dim button As New Button()
count = panel1.Controls.OfType(Of Button)().ToList().Count
button.Location = New System.Drawing.Point(150, 25 * count)
button.Size = New System.Drawing.Size(60, 20)
button.Name = "button_" & (count + 1)
button.Text = "Button " & (count + 1)
AddHandler button.Click, AddressOf Button_Click

The following dynamic Click event handler is raised when the dynamic TextBox control is clicked.
private void Button_Click(object sender, EventArgs e)
    Button button = (sender as Button);
    MessageBox.Show(button.Name + " clicked");

Private Sub Button_Click(sender As Object, e As EventArgs)
    Dim button As Button = TryCast(sender, Button)
    MessageBox.Show(button.Name + " clicked")
End Sub