本文实例展示了WinForm实现为TextBox设置水印文字功能，非常实用的技巧，分享给大家供大家参考。
关键代码如下：
? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 using System; using System.Runtime.InteropServices; using System.Windows.Forms; namespace WinFormUtilHelpV2 { /// <summary> /// 基于.NET 2.0的TextBox工具类 /// </summary> public static class TextBoxToolV2 { private const int EM_SETCUEBANNER = 0x1501; [DllImport( "user32.dll" , CharSet = CharSet.Auto)] private static extern Int32 SendMessage (IntPtr hWnd, int msg, int wParam, [MarshalAs(UnmanagedType.LPWStr)] string lParam); /// <summary> /// 为TextBox设置水印文字 /// </summary> /// <param name="textBox">TextBox</param> /// <param name="watermark">水印文字</param> public static void SetWatermark( this TextBox textBox, string watermark) { SendMessage(textBox.Handle, EM_SETCUEBANNER, 0, watermark); } /// <summary> /// 清除水印文字 /// </summary> /// <param name="textBox">TextBox</param> public static void ClearWatermark( this TextBox textBox) { SendMessage(textBox.Handle, EM_SETCUEBANNER, 0, string .Empty); } } }测试代码如下：
? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 using System; using System.Windows.Forms; using WinFormUtilHelpV2; namespace WinFormUtilHelpV2Test { public partial class WinTextBoxToolV2Test : Form { public WinTextBoxToolV2Test() { InitializeComponent(); } private void WinTextBoxToolV2Test_Load( object sender, EventArgs e) { textBox1.SetWatermark( "请输入用户名称...." ); textBox2.SetWatermark( "请输入用户密码...." ); } private void button1_Click( object sender, EventArgs e) { textBox1.ClearWatermark(); textBox2.ClearWatermark(); } } }测试效果如下图所示：
希望本文所述的为TextBox设置水印文字功能示例对大家C#程序设计有所帮助！
