WinForm中自定义搜索框（水印、清空按钮、加载中图标）

    public partial class CustomSearchBar : TextBox
     {
         private readonly Label lblwaterText = new Label();

         private readonly PictureBox clearButton = new PictureBox();

         private readonly int cancelImageSize = ;

         private int loadingCharsCount = ;

         public CustomSearchBar()
         {
             InitializeComponent();

             lblwaterText.BorderStyle = BorderStyle.None;
             lblwaterText.Enabled = false;
             lblwaterText.BackColor = Color.White;
             lblwaterText.AutoSize = false;
             lblwaterText.Top = ;
             lblwaterText.Left = ;
             lblwaterText.FlatStyle = FlatStyle.System;
             Controls.Add(lblwaterText);

             clearButton.Size = new Size(cancelImageSize, cancelImageSize);
             //clearButton.AutoSize = false;
             clearButton.SizeMode = PictureBoxSizeMode.StretchImage;
             //clearButton.Image = ResourceHandler.LoadImage("Loading");
             clearButton.Top = ;
             clearButton.Left = this.Width - cancelImageSize - ;
             clearButton.Click += new EventHandler(clearButton_Click);
             Controls.Add(clearButton);
         }

         public void AdjustClearButtonPosition(int width)
         {
             this.clearButton.Left = width - cancelImageSize - ;
         }

         public string WaterText
         {
             get { return lblwaterText.Text; }
             set { lblwaterText.Text = value; }
         }

         public override string Text
         {
             set
             {
                 lblwaterText.Visible = value == string.Empty;
                 base.Text = value;
             }
             get
             {
                 return base.Text;
             }
         }

         protected override void OnSizeChanged(EventArgs e)
         {
             if (Multiline && (ScrollBars == ScrollBars.Vertical || ScrollBars == ScrollBars.Both))
                 lblwaterText.Width = Width - ;
             else
                 lblwaterText.Width = Width;
             lblwaterText.Height = Height - ;
             base.OnSizeChanged(e);
         }

         protected override void OnTextChanged(EventArgs e)
         {
             lblwaterText.Visible = base.Text == string.Empty;
             base.OnTextChanged(e);
         }

         protected override void OnMouseDown(MouseEventArgs e)
         {
             lblwaterText.Visible = false;
             base.OnMouseDown(e);
         }

         protected override void OnMouseLeave(EventArgs e)
         {
             lblwaterText.Visible = base.Text == string.Empty;
             base.OnMouseLeave(e);
         }

         /// <summary>
         ///
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void clearButton_Click(object sender, EventArgs e)
         {
             this.Text = string.Empty;
             ClearSearchingTextHandler();
         }

         public void StartLoadSmartTip()
         {
             this.clearButton.Image = ResourceHandler.LoadImage("Loading");
             loadingCharsCount++;
         }

         public void EndLoadSmartTip()
         {
             loadingCharsCount--;
             if (loadingCharsCount <= )
             {
                 this.clearButton.Image = ResourceHandler.LoadImage("CloseButtonInactive");
             }
         }

         public delegate void ClearSearchingText();
         public event ClearSearchingText ClearSearchingTextHandler;
     }