C#/WinForm给控件加入hint文字

[来源] 达内    [编辑] 达内   [时间]2012-10-16

今天突然来了一个这样的需求,需要在C#的编辑框上加入一个Hint水印效果

今天突然来了一个这样的需求,需要在C#的编辑框上加入一个Hint水印效果,类似如下图:

image

以前在手机上(wp)上做过类似的效果。参考silverlight toolkit 的searchTextBox。现在要在winform下制作,开始我还以为应该有啥啥属性可以一键搞定,结果目测了一下,没有什么属性,于是乎百度了一下,网上说用win32API来做,这倒挺神奇的,参考别人做了如下列子。

申明一个Win32Utility类,静态的,

代码如下

 

--------------------------------------------------------------------------------------------------------------------------

public static class Win32Utility 
    {

        [DllImport("user32.dll", CharSet = CharSet.Auto)] 
        private static extern Int32 SendMessage(IntPtr hWnd, int msg, 
            int wParam, [MarshalAs(UnmanagedType.LPWStr)] string lParam);

        [DllImport("user32.dll")] 
        private static extern bool SendMessage(IntPtr hwnd, int msg, int wParam, StringBuilder lParam);

        [DllImport("user32.dll")] 
        private static extern bool GetComboBoxInfo(IntPtr hwnd, ref COMBOBOXINFO pcbi);

        [StructLayout(LayoutKind.Sequential)] 
        private struct COMBOBOXINFO 
        { 
            public int cbSize; 
            public RECT rcItem; 
            public RECT rcButton; 
            public IntPtr stateButton; 
            public IntPtr hwndCombo; 
            public IntPtr hwndItem; 
            public IntPtr hwndList; 
        }

        [StructLayout(LayoutKind.Sequential)] 
        private struct RECT 
        { 
            public int left; 
            public int top; 
            public int right; 
            public int bottom; 
        }

        private const int EM_SETCUEBANNER = 0x1501; 
        private const int EM_GETCUEBANNER = 0x1502;

        public static void SetCueText(Control control, string text) 
        { 
            if (control is ComboBox) 
            { 
                COMBOBOXINFO info = GetComboBoxInfo(control); 
                SendMessage(info.hwndItem, EM_SETCUEBANNER, 0, text); 
            } 
            else 
            { 
                SendMessage(control.Handle, EM_SETCUEBANNER, 0, text); 
            } 
        }

        private static COMBOBOXINFO GetComboBoxInfo(Control control) 
        { 
            COMBOBOXINFO info = new COMBOBOXINFO(); 
            //a combobox is made up of three controls, a button, a list and textbox; 
            //we want the textbox 
            info.cbSize = Marshal.SizeOf(info); 
            GetComboBoxInfo(control.Handle, ref info); 
            return info; 
        }

        public static string GetCueText(Control control) 
        { 
            StringBuilder builder = new StringBuilder(); 
            if (control is ComboBox) 
            { 
                COMBOBOXINFO info = new COMBOBOXINFO(); 
                //a combobox is made up of two controls, a list and textbox; 
                //we want the textbox 
                info.cbSize = Marshal.SizeOf(info); 
                GetComboBoxInfo(control.Handle, ref info); 
                SendMessage(info.hwndItem, EM_GETCUEBANNER, 0, builder); 
            } 
            else 
            { 
                SendMessage(control.Handle, EM_GETCUEBANNER, 0, builder); 
            } 
            return builder.ToString(); 
        }

    }

--------------------------------------------------------------------------------------------------------------------------

然后在程序里这样调用即可。实现超简单… (本文章无源码,需要使用直接拷贝如上代码即可)

image

 

资源下载