1. 技术文章
  2. How to show form in front in C#

How to show form in front in C#

由 Deadly 提交于 2019-11-27 23:30:18

Simply

yourForm.TopMost = true;

There's an overload of Form.ShowDialog() which takes an IWin32Window object. That IWin32Window is treated as the parent window for the form.

If you have the parent window as a System.Windows.Forms.Form, go ahead and just pass it. If not, get the HWND (maybe by P/Invoking to FindWindow()), and create a dummy IWin32Window implementation that just returns the HWND (More details).

Esen

Form.Activate() worked in my case.

  1. You said that it works fine when you use Application.Run. Why don't you want to use Application.Run, then?
  2. Have you tried calling BringToFront() from OnLoad or OnShown?

This is the final solution I wrote after 20 different attempts:

/* A workaround for showing a form on the foreground and with focus,
 * even if it is run by a process other than the main one
 */
public static void ShowInForeground(this Form form, bool showDialog = false)
{
    if (showDialog)
    {
        //it's an hack, thanks to http://stackoverflow.com/a/1463479/505893
        form.WindowState = FormWindowState.Minimized;
        form.Shown += delegate(Object sender, EventArgs e) {
            ((Form)sender).WindowState = FormWindowState.Normal;
        };
        form.ShowDialog();
    }
    else
    {
        //it's an hack, thanks to http://stackoverflow.com/a/11941579/505893
        form.WindowState = FormWindowState.Minimized;
        form.Show();
        form.WindowState = FormWindowState.Normal;

        //set focus on the first control
        form.SelectNextControl(form.ActiveControl, true, true, true, true);
    }
}

I've hacked this from an application I've been working on. We have a large application that loads a series of modules written by different teams. We have written one of these modules, and needed to have a login dialog open during this initialization. It was set to '.TopMost=true', but that didn't work.

It uses the WindowsFormsSynchronizationContext to open a dialog box, and then get the result of the dialog box back.

I rarely do GUI coding, and suspect this may be overkill, but it might help someone if they get stuck. I had problems with understanding how state is passed to the SendOrPostCallback, as all the examples I could find didn't use it.

Also this is taken from a working application, but I've removed several bits of code, and changed some of the details. Apologies if it doesn't compile. 

public bool Dummy()
{

// create the login dialog
DummyDialogForm myDialog = new DummyDialogForm();

// How we show it depends on where we are. We might be in the main thread, or in a background thread
// (There may be better ways of doing this??)
if (SynchronizationContext.Current == null)
{
    // We are in the main thread. Just display the dialog
    DialogResult result = myDialog.ShowDialog();
    return result == DialogResult.OK;
}
else
{
    // Get the window handle of the main window of the calling process
    IntPtr windowHandle = Process.GetCurrentProcess().MainWindowHandle;

    if (windowHandle == IntPtr.Zero)
    {
        // No window displayed yet
        DialogResult result = myDialog.ShowDialog();
        return result == DialogResult.OK;
    }
    else
    {
        // Parent window exists on separate thread
        // We want the dialog box to appear in front of the main window in the calling program
        // We would like to be able to do 'myDialog.ShowDialog(windowHandleWrapper)', but that means doing something on the UI thread
        object resultState = null;
        WindowsFormsSynchronizationContext.Current.Send(
            new SendOrPostCallback(delegate(object state) { resultState = myDialog.ShowDialog(); }), resultState);

        if (resultState is DialogResult)
        {
            DialogResult result = (DialogResult) resultState;
            return result == DialogResult.OK;
        }
        else
            return false;

    }
}

}

user2162266

Activate() worked for me too.

BringToFront() did nothing in this case, I don't know why.

It would appear that is behaviour is specific to XP... Hence I can't reproduce it on Vista.

http://www.gamedev.net/community/forums/topic.asp?topic_id=218484

EDIT: PS: It's past my bedtime (2 AM;-).

Thanx all for your responses... there's a "few things" I can try... I might even go into the office tomorrow to try them... Yeah, yeah... I had a life once, but I traded it for a haircut and a job ;-)

Cheers all. Keith.

This did the job perfectly :

formxx.WindowState = FormWindowState.Normal;
formxx.BringToFront();
formxx.Topmost=true;
formxx.Focus();
phuong

I got a code in the project.

private static extern bool SetForegroundWindow(
IntPtr hWnd); 
public static void ShowToFront(Form form)
{
    FormWindowState oldState = form.WindowState;
    form.WindowState = FormWindowState.Minimized;
    form.Show();

    form.Activate();
    form.TopLevel = false;
    form.TopLevel = true;
    form.SelectNextControl(form.ActiveControl, true, true, true, true);
    SetForegroundWindow(form.Handle);
    form.Focus();
    form.WindowState = oldState;
}

This is what I use to bring an open form that is part of my application to the front. You can even use it with a button. But the form needs to be open or the application will break.

"YourOpenForm" has to be the name of your form from the properties window.

    private void button1_Click(object sender, EventArgs e)
    {
        Application.OpenForms["YourOpenForm"].BringToFront();
    }

Good Luck!

标签
c#
forms
z-order
易学教程内所有资源均来自网络或用户发布的内容，如有违反法律规定的内容欢迎反馈！
该文章没有解决你所遇到的问题?点击提问,说说你的问题,让更多的人一起探讨吧!