今天突然來了一個這樣的需求，需要在C#的編輯框上加入一個Hint水印效果，類似如下圖：
以前在手機上(wp)上做過類似的效果。參考silverlight toolkit 的searchTextBox。現在要在winform下制作，開始我還以為應該有啥啥屬性可以一鍵搞定，結果目測了一下,沒有什么屬性，於是乎百度了一下，網上說用win32API來做，這倒挺神奇的,參考別人做了如下列子。
申明一個Win32Utility類,靜態的,
代碼如下
--------------------------------------------------------------------------------------------------------------------------
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();
}
}
--------------------------------------------------------------------------------------------------------------------------
然后在程序里這樣調用即可。實現超簡單… （本文章無源碼，需要使用直接拷貝如上代碼即可）
-------------------------------------------------------
另外一直想研究一下Win32API，不知道誰有沒有好的資料推薦一下。
做了這么久程序猿對系統的內核還是未入門階段,真心慚愧！！！
大俠們有資料就推薦一下哦, 3Q
本人從事網站開發，WP/Win8開發。目前想和一些有志向的朋友一同研究
一下WP/Win8這些新事物，一起玩轉論壇,一起合作出軟件,一起學習,一起賺Money.
有意向者聯系QQ：61797528
-------------------------------------------------------