如何在C＃应用程序中将焦点设置到桌面

Question

Winforms App. .Net 3.5.

I need to set the focus from my C# application to the user's desktop (almost like simulating a mouse click on the desktop).

Can someone please show me how to do this with C#? I just want to set focus on the desktop so the focus is no longer on my application but I want to do this from within my application.

Edit: An answer below works by setting the focus to the desktop, but it minimizes all the open windows on the user's desktop.

Is there a way I can maybe set the focus to the next open window on the desktop instead? I just want to get the focus off of my application (without minimizing my application or hiding it). I just want to move focus to somewhere else. Maybe the desktop was not the best choice if it will minimize all the user's open windows/applications.

Answer 1

This should do it for you.

using System; 
using System.Runtime.InteropServices; 

namespace ConsoleApplication1 { 
class Program { 
    [DllImport("user32.dll", EntryPoint = "FindWindow", SetLastError = true)] 
    static extern IntPtr FindWindow(string lpClassName, string lpWindowName); 
    [DllImport("user32.dll", EntryPoint = "SendMessage", SetLastError = true)] 
    static extern IntPtr SendMessage(IntPtr hWnd, Int32 Msg, IntPtr wParam, IntPtr lParam); 

    const int WM_COMMAND = 0x111; 
    const int MIN_ALL = 419; 
    const int MIN_ALL_UNDO = 416; 

    static void Main(string[] args) { 
        IntPtr lHwnd = FindWindow("Shell_TrayWnd", null); 
        SendMessage(lHwnd, WM_COMMAND, (IntPtr)MIN_ALL, IntPtr.Zero);  
        System.Threading.Thread.Sleep(2000); 
        SendMessage(lHwnd, WM_COMMAND, (IntPtr)MIN_ALL_UNDO, IntPtr.Zero); 
    } 
} 
} 

Get Next Window

I don't have a code example ready for these two but I'm going to give you the links to both. The first think you need to do is call GetWindow . After doing that you'll want to call SwitchToThisWindow passing in the pointer you received from GetWindow .

Answer 2

You can add this COM object in your project:

Microsoft Shell Controls And Automation

And then just call:

Shell32.ShellClass shell = new Shell32.ShellClass();
shell.MinimizeAll();

This will minimize all the windows and then focus the desktop. Otherwise, if you have your window non-full screen then you can simulate the mouse click using:

//This is a replacement for Cursor.Position in WinForms
[System.Runtime.InteropServices.DllImport("user32.dll")]
static extern bool SetCursorPos(int x, int y);

[System.Runtime.InteropServices.DllImport("user32.dll")]
public static extern void mouse_event(int dwFlags, int dx, int dy, int cButtons, int dwExtraInfo);

public const int MOUSEEVENTF_LEFTDOWN = 0x02;
public const int MOUSEEVENTF_LEFTUP = 0x04;

//This simulates a left mouse click
public static void LeftMouseClick(int xpos, int ypos)
{
    SetCursorPos(xpos, ypos);
    mouse_event(MOUSEEVENTF_LEFTDOWN, xpos, ypos, 0, 0);
    mouse_event(MOUSEEVENTF_LEFTUP, xpos, ypos, 0, 0);
}

You can calculate coordinates by looking at your window startup location plus height/width and select a available space (that will be the desktop indeed).