c# - 我如何在我的文本框中进行这样的验证？

Question

public static Boolean TextBoxValidation(TextBox txt, String AdditionalMsg)
{
    if (txt.Text.Trim() == "")
    {
        MessageBox.Show("Please Enter " + AdditionalMsg); 
        return false;
    }
    
    return true;
}

这是我的代码；当用户未填写某些条目时，将显示一条消息。我想要一些更有创意的东西：当用户没有在文本框中填写一些条目时，我的文本框周围会闪烁一个红色边框，并向用户显示一条消息，就像工具提示一样。

参考我上传的图片：

Answer 1

我有一段时间想要这样的东西，这就是我想出的：

由于您无法为 TextBox 设置边框颜色，因此我制作了一个带有文本框的 UserControl：

 public partial class UCTextBoxCustomcs : UserControl
    {
        private ToolTip _errorToolTip;

        // keep original background color so you can change it when txet value is OK
        private Color _orgBgColor;
        public new Color BackColor
        {
            get { return _orgBgColor; }
            set 
            { 
                base.BackColor = value;
                _orgBgColor = value;

            }
        }

        public new string Text
        {
            get { return this.txbContent.Text; }
            set { this.txbContent.Text = value; }
        }

        public Color InvalidBgColor { get; set; }

        private bool _IsValid;
        public bool IsValid
        {
            get { return _IsValid; }
            set 
            {
                _IsValid = value;
                if (value)
                {
                    base.BackColor = _orgBgColor;
                    _errorToolTip.SetToolTip(this.txbContent, "");
                    _errorToolTip.ShowAlways = false;
                    _errorToolTip.Hide(this.txbContent);
                }
                else
                {
                    base.BackColor = InvalidBgColor;
                    _errorToolTip.ShowAlways = true;
                    this._errorToolTip.BackColor = InvalidBgColor;
                    _errorToolTip.Show(this.ErrorText, this.txbContent,this.txbContent.Width +3 ,0);
                }

            }
        }

        private string _ErrorText;

        public string ErrorText
        {
            get 
            { 
                return _ErrorText;
            }
            set 
            {
                _ErrorText = value;
                if (value == null || value.Length == 0) IsValid = true;
                else IsValid = false;
            }
        }


        public UCTextBoxCustomcs()
        {
            this._errorToolTip = new ToolTip();

            // BackColor in ToolTip is ignored, so if you want to change it,
            // you have to draw it yourself
            this._errorToolTip.OwnerDraw = true;
            _errorToolTip.Draw += new DrawToolTipEventHandler(_errorToolTip_Draw);
            _errorToolTip.Popup += new PopupEventHandler(_errorToolTip_Popup);

            // white background so it looks like TextBox
            this.BackColor = Color.White;

            InitializeComponent();

            this.txbContent.BorderStyle = BorderStyle.None;

            // Intelisense tells you this property isn't there, but it is
            // you have to set it to false so TextBox height can be changed
            // when MultiLine is set to false
            this.txbContent.AutoSize = false;
            this.txbContent.Multiline = false;

            // Leave 1 pixel around TextBox for pseudo-border
            this.Padding = new Padding(1);
            this.txbContent.Dock = DockStyle.Fill;

            this.InvalidBgColor = Color.Red;
            this.IsValid = true;
        }

        void _errorToolTip_Popup(object sender, PopupEventArgs e)
        {
            using (Font f = new Font("Calibri", 9))
            {
                Size ttSize = TextRenderer.MeasureText(
                    _errorToolTip.GetToolTip(e.AssociatedControl), f);
                e.ToolTipSize = new Size(ttSize.Width + 6, ttSize.Height + 6);
            }
        }

        void _errorToolTip_Draw(object sender, DrawToolTipEventArgs e)
        {
            // In this case a simple rectangle is drawn, but you can draw whatever you want
            // Draw the custom background.
            e.Graphics.FillRectangle(new SolidBrush(this.InvalidBgColor), e.Bounds);

            // Draw the standard border.
            e.DrawBorder();

            // Draw the custom text. 
            // The using block will dispose the StringFormat automatically. 
            using (StringFormat sf = new StringFormat())
            {
                sf.Alignment = StringAlignment.Center;
                sf.LineAlignment = StringAlignment.Center;
                sf.HotkeyPrefix = System.Drawing.Text.HotkeyPrefix.None;
                sf.FormatFlags = StringFormatFlags.NoWrap;
                using (Font f = new Font("Calibri", 9))
                {
                    Rectangle textBounds = new Rectangle(
                        e.Bounds.Left+3,
                        e.Bounds.Top+3,
                        e.Bounds.Width-6,
                        e.Bounds.Height-6);
                    e.Graphics.DrawString(e.ToolTipText, f,
                        SystemBrushes.ActiveCaptionText, e.Bounds, sf);
                }
            }
        }

        protected override void OnValidating(CancelEventArgs e)
        {
            this.ValidateChildren();
            base.OnValidating(e);
        }
    }

如何使用：

private void ucTextBoxCustomcs1_Validating(object sender, CancelEventArgs e)
        {
            if (ucTextBoxCustomcs1.Text.Length == 0)
            {
                ucTextBoxCustomcs1.ErrorText = "Cant be empty";
            }
            else ucTextBoxCustomcs1.ErrorText = null;
        }

它看起来像这样：