Winforms dynamically add buttons and events

Lionsure 2020-08-29 Original by the website

Buttons need to be added dynamically in some cases in Winforms development. For example, when making a form, different input boxes need to be displayed according to the category selected by the user. If there is a category of file source, when the file comes from a remote server, you need to enter the user name and password to login to the remote server; when the file comes from the current computer, you only need to select the folder where the file is located.

If the default selection is from a remote server, when the user selects from the current computer, hide or delete the input box from the server, add a button to select the folder where the file is located, and when the user clicks the button, the dialog box for selecting a folder is opened, after the folder is selected, assign the path to the textbox.

Winforms dynamically add buttons and events

First drag a ComboBox to the Form, and then drag a Panel control to the Form, and start to dynamically add different input boxes, folder selection boxes, button and button click events based on user selections:

1. Double-click the Form, open the code behind file, add an option method for ComboBox, and call it in the initialization event(WinformsDynamicallyAddButtons_Load):

private void AddComboBox1Items()
       {
              comboBox1.Items.Add("Remote server");
              comboBox1.Items.Add("Current computer");
              comboBox1.SelectedIndex = 0;
       }

private void WinformsDynamicallyAddButtons_Load(object sender, EventArgs e)
       {
              AddComboBox1Items();
       }

2. Switch to the Form, double-click the ComboBox, and display different items in the comboBox1_SelectedIndexChanged event according to the user's selection:

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
       {
              switch (comboBox1.SelectedIndex)
              {
                     case 0:
                            AddServer();
                            break;
                     case 1:
                            AddLocal();
                            break;
                     default:
                            return;
              }
       }

//When selecting a remote server, the content displayed
       private void AddServer()
       {
              if(panel1.Controls.Count > 0)
                     panel1.Controls.Clear();

       Label label1 = new Label();
              label1.Width = 63;
              label1.Text = "Username: ";
              label1.Top = panel1.Top / 2;
              label1.Left = panel1.Left - 10;
              panel1.Controls.Add(label1);

       TextBox textbox1 = new TextBox();
              textbox1.Name = "txtUser";
              textbox1.Width = 150;
              textbox1.Top = label1.Top - 5;
              textbox1.Left = label1.Left + label1.Width;
              panel1.Controls.Add(textbox1);

       Label label2 = new Label();
              label2.Width = 63;
              label2.Text = "Password: ";
              label2.Top = label1.Top;
              label2.Left = 240;
              panel1.Controls.Add(label2);

       TextBox textbox2 = new TextBox();
              textbox2.Name = "txtPass";
              textbox2.Width = 150;
              textbox2.Top = label1.Top - 5;
              textbox2.Left = 303;
              panel1.Controls.Add(textbox2);
       }

//When selecting the current computer, the corresponding content displayed
       private void AddLocal()
       {
              if (panel1.Controls.Count > 0)
                     panel1.Controls.Clear();

       Label label1 = new Label();
              label1.Width = 102;
              label1.Text = "Files in the folder: ";
              label1.Top = panel1.Top / 8 + 6;
              label1.Left = panel1.Left - 10;
              panel1.Controls.Add(label1);

       TextBox textbox1 = new TextBox();
              textbox1.Name = "txtLocal";
              textbox1.Width = 250;
              textbox1.Top = label1.Top - 5;
              textbox1.Left = label1.Left + label1.Width;
              panel1.Controls.Add(textbox1);

       Button button1 = new Button(); //Add buttons dynamically
              button1.Text = " Browse ";
              button1.Top = label1.Top - 6;
              button1.Left = 370;
              button1.Click += new EventHandler(button1_Click); //Add button click event
              panel1.Controls.Add(button1);
       }

//Click the button to execute the method
       private void button1_Click(object sender, EventArgs e)
       {
              FolderBrowserDialog fbd = new FolderBrowserDialog();
              fbd.ShowDialog();
              foreach (Control c in panel1.Controls)
              {
                     if (c.Name.Equals("txtLocal"))
                            c.Text = fbd.SelectedPath; ;
              }
       }