WinForms TextBox的自定义插入

private void InsertText(string textToInsert)
{
    int cursorPosition = textBox1.SelectionStart;
    textBox1.Text = textBox1.Text.Insert(cursorPosition, textToInsert);
    textBox1.SelectionStart = cursorPosition + textToInsert.Length;
}

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (e.KeyChar != '\b') // 忽略退格键
    {
        int cursorPosition = textBox1.SelectionStart;
        textBox1.Text = textBox1.Text.Insert(cursorPosition, e.KeyChar.ToString());
        textBox1.SelectionStart = cursorPosition + 1;
        e.Handled = true;
    }
}