SetWindowPos函数

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有一天，用户突然对我说，你这个窗口能不能放到最顶端，这样操作和打开文件就很不方便了。这个功能就需要改变窗口的属性了。比如大家使用QQ时，就有一个功能，设置QQ的窗口在最顶端，不管你选择了什么窗口，QQ的界面永远都在最前面。又像FlashGet的状态查看窗口，一直保持在窗口的最前端，让你看到当前下载的流量程况。现在股票那么火爆，很多人一边工作，一边查看股票，如果错失了机会，又少了很多钱的啊！面对这样的需求，就需要把一些窗口永远摆在最前面，这样起到提示用户的作用。因此，学会使用SetWindowPos函数，就成为能否让软件满足客户需求的关键了。与MoveWindow函数相比，SetWindowPos函数的功能比较强大一点。

函数SetWindowPos声明如下：

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// C# Signature:

[DllImport("user32.dll", SetLastError=true)]
static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, SetWindowPosFlags uFlags);

// VB.NET Signature:

<DllImport("user32.dll", SetLastError:=True)> _
Private Shared Function SetWindowPos(ByVal hWnd As IntPtr, ByVal hWndInsertAfter As IntPtr, ByVal X As Integer, ByVal Y As Integer, ByVal cx As Integer, ByVal cy As Integer, ByVal uFlags As SetWindowPosFlags) As Boolean
End Function

// VB Signature

Public Declare Function SetWindowPos Lib "user32.dll" _
         (ByVal hWnd As Long, _
          ByVal hWndInsertAfter As Long, _
          ByVal X As Long, _
          ByVal Y As Long, _
          ByVal cx As Long, _
          ByVal cy As Long, _
          ByVal wFlags As Long) As Long

hWnd是窗口的句柄。

hWndInsertAfter是窗口Z顺序属性。

X是窗口在X轴的位置。

Y是窗口在Y辆的位置。

cx是窗口的宽度。

cy是窗口的高度。

uFlags是选择设置的标志。

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// C# Constants:

static readonly IntPtr HWND_TOPMOST = new IntPtr(-1);
static readonly IntPtr HWND_NOTOPMOST = new IntPtr(-2);
static readonly IntPtr HWND_TOP = new IntPtr(0);
static readonly IntPtr HWND_BOTTOM = new IntPtr(1);

public static class HWND
{
   public static IntPtr
   NoTopMost = new IntPtr(-2),
   TopMost = new IntPtr(-1),
   Top = new IntPtr(0),
   Bottom = new IntPtr(1);
}

public static class SWP
{
   public static readonly int
   NOSIZE = 0x0001,
   NOMOVE = 0x0002,
   NOZORDER = 0x0004,
   NOREDRAW = 0x0008,
   NOACTIVATE = 0x0010,
   DRAWFRAME = 0x0020,
   FRAMECHANGED = 0x0020,
   SHOWWINDOW = 0x0040,
   HIDEWINDOW = 0x0080,
   NOCOPYBITS = 0x0100,
   NOOWNERZORDER = 0x0200,
   NOREPOSITION = 0x0200,
   NOSENDCHANGING = 0x0400,
   DEFERERASE = 0x2000,
   ASYNCWINDOWPOS = 0x4000;
}

//VB.NET Constants:

Private ReadOnly HWND_BOTTOM As New IntPtr(1)
Private ReadOnly HWND_NOTOPMOST As New IntPtr(-2)
Private ReadOnly HWND_TOP As New IntPtr(0)
Private ReadOnly HWND_TOPMOST As New IntPtr(-1)

调用这个函数的例子如下：

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public static void MoveWindowToMonitor(int monitor)
    {
        var windowHandler = GetActiveWindowHandle();

        var windowRec = GetWindowRect(windowHandler);
        // When I move a window to a different monitor it subtracts 16 from the Width and 38 from the Height, Not sure if this is on my system or others.
        SetWindowPos(windowHandler, (IntPtr)SpecialWindowHandles.HWND_TOP, Screen.AllScreens[monitor].WorkingArea.Left,
             Screen.AllScreens[monitor].WorkingArea.Top, windowRec.Size.Width + 16, windowRec.Size.Height + 38,
             SetWindowPosFlags.SWP_SHOWWINDOW);
    }