How to use enter key in textbox?

Quote:

Dave K. wrote: "By using ENTER to move from field to field, you are going against the standard functionality of Windows applications."

I respectfully disagree with this statement in the sense that I think it is too generalized, too absolute.

There are many scenarios where an application controls the focus of user interaction from Control to Control according to some set of rules, or, in sequential order. A "wizard" is a good example.

The designers of Windows Forms allow any Control to be removed from being a TabStop by simply setting a property. For TextBox and RichTextBox, both offer Control over whether Tabs are accepted, and the TextBox allows you to ignore Enter.

These options, I believe, are there for a reason: to enable developers to have flexibility for designing application behavior.

Now, let me show you a fairly complete sketch (that means it works in VS 2017) for a WinForm UserControl that manages the users data entry in sequence through six TextBoxes. This UserControl has two Buttons, 'btnSubmit, and 'btnCancel..

All Controls in the UserControl have their TabStop property set to 'false. The TextBoxes have both AcceptsTab, and AcceptsReturn properties set to false.

All key-entry on the UserControl is intercepted by over-riding ProcessCmdKey.

Validators are attached to the first three TextBoxes: the first requires at least one digit to complete; the second requires 2 digits and 2 punctuations to complete; the third requires some text entry of any type. The other three TextBoxes have a default validator defined that accepts anything, or no text.

When the user reaches the last TextBox, if there is no validation error, the Submit Button is enabled.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;

namespace MatrixTestForm
{
    public partial class DataEntryUserControl : UserControl
    {
        public DataEntryUserControl()
        {
            InitializeComponent();
        }

        public Action<List<string>> SendData;
        
        public Dictionary<TextBox,Func<TextBox, bool>>  TxtBxesToValidator = new Dictionary<TextBox, Func<TextBox, Boolean>>();

        private bool allValid = false;

        private List<TextBox> textBoxes = new List<TextBox>();
        private TextBox activeTextBox;
        private int lastTBoxIndex;
        
        private void DataEntryUserControl_Load(object sender, EventArgs e)
        {
            btnSubmit.Enabled = false;
            
            textBoxes.AddRange(new List<TextBox>()
            {
                textBox1, textBox2, textBox3, textBox4, textBox5, textBox6
            });

            lastTBoxIndex = textBoxes.Count - 1; // adjust for #0 offset

            foreach (var tbx in textBoxes)
            {   
                tbx.Enter += TbxOnEnter;
                tbx.Leave += TbxOnLeave;
            }
            
            activeTextBox = textBox1;
            textBox1.Capture = true;

            // no digits
            toolTip1.SetToolTip(textBox1, "no digits");
            TxtBxesToValidator[textBox1] = box =>
            {
                return box.Text != null && !box.Text.Any(char.IsDigit);
            };

            // must have 2 digit2 and 2 punctuation
            toolTip1.SetToolTip(textBox2,"2 digits, 2 ounctuation");
            TxtBxesToValidator[textBox2] = box =>
            {
                return box.Text != null
                       && box.Text.Any(char.IsDigit)
                       && box.Text.Where(char.IsDigit).Count() == 2
                       && box.Text.Any(char.IsPunctuation)
                       && box.Text.Where(char.IsPunctuation).Count() == 2;
            };

            // gotta have something
            toolTip1.SetToolTip(textBox3, "enter something");
            TxtBxesToValidator[textBox3] = box =>
            {
                return !String.IsNullOrWhiteSpace(box.Text);
            };
        }
        
        private void TbxOnEnter(Object sender, EventArgs eventArgs)
        {
            activeTextBox = sender as TextBox;
            activeTextBox.Capture = true;
        }

        private void TbxOnLeave(Object sender, EventArgs eventArgs)
        {
            activeTextBox.Capture = false;
            activeTextBox = null;
        }

        protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
        {
            if (keyData == Keys.Enter && activeTextBox != null)
            {
                activeTextBox.Capture = false;
                
                // validator

                if (TxtBxesToValidator.ContainsKey(activeTextBox))
                {
                    allValid = TxtBxesToValidator[activeTextBox](activeTextBox);      
                }

                if (! allValid)
                {
                    btnSubmit.Enabled = false;
                    MessageBox.Show("invalid");
                    return base.ProcessCmdKey(ref msg, keyData);
                }

                int ndx = textBoxes.IndexOf(activeTextBox);

                if (ndx == lastTBoxIndex)
                {
                    btnSubmit.Enabled = allValid;
                }
                else
                {
                    textBoxes[ndx + 1].Focus();
                    textBoxes[ndx + 1].Capture = true;
                }

                return true;
            }

            return base.ProcessCmdKey(ref msg, keyData);
        }

        private void btnCancel_Click(object sender, EventArgs e)
        {
            btnSubmit.Enabled = false;
            
            // whatever : hide the UserControl ?
        }

        private void btnSubmit_Click(object sender, EventArgs e)
        {
            // send the valid data back to wherever ?
            SendData?.Invoke(textBoxes.Select(tbx => tbx.Text).ToList());
            
            // clean-up
            // hide the UserControl ?
            // clear the TextBoxes ?
            // other ??
        }
    }
}

By using ENTER to move from field to field, you are going against the standard functionality of Windows applications. ENTER is considered as the Submit button for a form, not move to the next field.

But, it is possible with Control.SelectNextControl()[^].

I haven't used it but after looking at the documentation, I would probably make a custom TextBox control (create a new class and derive from TextBox) and override its OnKeyDown method for a start:

private override void OnKeyDown(KeyEventArgs e)
{
    if (e.KeyCode == Keys.Enter)
    {
        e.Handled = true;
        e.SuppressKeyPress = true;

        Parent.SelectNextControl(this, true, true, true, true);
    }
    else
    {
        base.OnKeyDown(e);
    }
}

WARNING!!
In order for this to work, the parent Form can NOT have it's AcceptButton property set. It must be "(none)".

Below code you use for this.

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == 13)
SendKeys.Send("{Tab}");
}

please set tab order in sequence for textboxes.