Some background
One of my current clients runs a chain of Internet points where customers an access the net through PC:s set up as "kiosks" (a custom-built application "locks" the computer until a user has signed in, and the running account is heavily restricted through the Windows group policy). Currently, each computer is running Windows XP and uses Active Desktop to display advertisements in the background. However, since my client has got problems with Active Desktop crashing on a daily basis (in addition to generally slowing down the computer) I have been asked to develop an application that replaces it.
The problem
I am trying to investigate whether it is possible to build a Windows forms application (using C#) that always stays in the background. The application should lie above the desktop (so that it covers any icons, files etc) but always behind all other running applications. I guess I'm really looking for a BottomMost property of the Form class (which doesn't exist, of course).
Any tips or pointers on how to achieve this would be highly appreciated.
This isn't directly supported by the .NET Form class, so you have two options:
1) Use the Win32 API SetWindowPos function.
pinvoke.net shows how to declare this for use in C#:
[DllImport("user32.dll")]
static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
static readonly IntPtr HWND_BOTTOM = new IntPtr(1);
const UInt32 SWP_NOSIZE = 0x0001;
const UInt32 SWP_NOMOVE = 0x0002;
const UInt32 SWP_NOACTIVATE = 0x0010;
So in your code, call:
SetWindowPos(Handle, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE);
As you commented, this moves the form to the bottom of the z-order but doesn't keep it there. The only workaround I can see for this is to call SetWindowPos from the Form_Load and Form_Activate events. If your application is maximized and the user is unable to move or minimise the form then you might get away with this approach, but it's still something of a hack. Also the user might see a slight "flicker" if the form gets brought to the front of the z-order before the SetWindowPos call gets made.
2) subclass the form, override the WndProc function and intercept the WM_WINDOWPOSCHANGING Windows message, setting the SWP_NOZORDER flag (taken from this page).
I think the best way to do so is using the activated event handler and SendToBack method, like so:
private void Form1_Activated(object sender, EventArgs e)
{
this.SendToBack();
}
Set your window to be a child window of the desktop (the "Program Manager" or "progman" process). I've succeeded with this method in Windows XP (x86) and Windows Vista (x64).
I stumbled on this method while searching for a way to make a screensaver display as if it were wallpaper. It turns out, this is sort of built in to the system's .scr handler. You use screensaver.scr /p PID, where PID is the process id of another program to attach to. So write a program to find progman's handle, then invoke the .scr with that as the /p argument, and you have screensaver wallpaper!
The project I'm playing with now is desktop status display (shows the time, some tasks, mounted disks, etc), and it's built on Strawberry Perl and plain Win32 APIS (mainly the Win32::GUI and Win32::API modules), so the code is easy to port to or understand any dynamic language with similar Win32 API bindings or access to Windows' Scripting Host (eg, ActivePerl, Python, JScript, VBScript). Here's a relevant portion of the class that produces the window:
do { Win32::API->Import(#$_) or die "Win32::API can't import #$_ ($^E)" } for
[user32 => 'HWND FindWindow(LPCTSTR lpClassName, LPCTSTR lpWindowName)'],
[user32 => 'HWND SetParent(HWND hWndChild, HWND hWndNewParent)'],
sub __screen_x {
Win32::GUI::GetSystemMetrics(SM_CXSCREEN)
}
sub __screen_y {
Win32::GUI::GetSystemMetrics(SM_CYSCREEN)
}
sub _create_window { # create window that covers desktop
my $self = shift;
my $wnd = $$self{_wnd} = Win32::GUI::Window->new(
-width => __screen_x(), -left => 0,
-height => __screen_y(), -top => 0,
) or die "can't create window ($^E)";
$wnd->SetWindowLong(GWL_STYLE,
WS_VISIBLE
| WS_POPUP # popup: no caption or border
);
$wnd->SetWindowLong(GWL_EXSTYLE,
WS_EX_NOACTIVATE # noactivate: doesn't activate when clicked
| WS_EX_NOPARENTNOTIFY # noparentnotify: doesn't notify parent window when created or destroyed
| WS_EX_TOOLWINDOW # toolwindow: hide from taskbar
);
SetParent($$wnd{-handle}, # pin window to desktop (bottommost)
(FindWindow('Progman', 'Program Manager') or die "can't find desktop window ($^E)")
) or die "can't pin to desktop ($^E)";
Win32::GUI::DoEvents; # allow sizing and styling to take effect (otherwise DC bitmaps are the wrong size)
}
This program buffers output to prevent flickering, which you'll probably want to do as well. I create a DC (device context) and PaintDesktop to it (you could use any bitmap with only a couple more lines -- CreateCompatibleBitmap, read in a file, and select the bitmap's handle as a brush), then create a holding buffer to keep a clean copy of that background and a working buffer to assemble the pieces -- on each loop, copy in background, then draw lines and brush bitmaps and use TextOut -- which is then copied to the original DC, at which time it appears on screen.
Yes, function SetWindowPos with flag HWND_BOTTOM should help you. But, from my experience: even after calling SetWindowPos as result of some user operations your window may bring to front.
subclass the form, override the WndProc function and intercept the Windows message(s) that are responsible for moving it up the z-order when it gets activated.
Create a Panel that cover your form, but what ever you want on that Panel, then in the Panel's Click-Event write this.sendback .
I've managed to get rid of the flickering when using setwindowpos...
const UInt32 SWP_NOSIZE = 0x0001;
const UInt32 SWP_NOMOVE = 0x0002;
const UInt32 SWP_NOACTIVATE = 0x0010;
const UInt32 SWP_NOZORDER = 0x0004;
const int WM_ACTIVATEAPP = 0x001C;
const int WM_ACTIVATE = 0x0006;
const int WM_SETFOCUS = 0x0007;
static readonly IntPtr HWND_BOTTOM = new IntPtr(1);
const int WM_WINDOWPOSCHANGING = 0x0046;
[DllImport("user32.dll")]
static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X,
int Y, int cx, int cy, uint uFlags);
[DllImport("user32.dll")]
static extern IntPtr DeferWindowPos(IntPtr hWinPosInfo, IntPtr hWnd,
IntPtr hWndInsertAfter, int x, int y, int cx, int cy, uint uFlags);
[DllImport("user32.dll")]
static extern IntPtr BeginDeferWindowPos(int nNumWindows);
[DllImport("user32.dll")]
static extern bool EndDeferWindowPos(IntPtr hWinPosInfo);
private void Window_Loaded(object sender, RoutedEventArgs e)
{
IntPtr hWnd = new WindowInteropHelper(this).Handle;
SetWindowPos(hWnd, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
IntPtr windowHandle = (new WindowInteropHelper(this)).Handle;
HwndSource src = HwndSource.FromHwnd(windowHandle);
src.AddHook(new HwndSourceHook(WndProc));
}
private IntPtr WndProc(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
if (msg == WM_SETFOCUS)
{
IntPtr hWnd = new WindowInteropHelper(this).Handle;
SetWindowPos(hWnd, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
handled = true;
}
return IntPtr.Zero;
}
private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
IntPtr windowHandle = (new WindowInteropHelper(this)).Handle;
HwndSource src = HwndSource.FromHwnd(windowHandle);
src.RemoveHook(new HwndSourceHook(this.WndProc));
}
Related
So I want to have something similar to an desktop overlay. So the thing is I tried to draw to the desktop wallpaper directly but this will get redrawn and from what I read there is really no good way around this. So I tried to go with a broderless completely transparent WinForm with text on it.
The Problem I have with is that hitting Windows+D will hide the application and I didn't found a way to prevent this or bring it up again. Also I read that setting the form as a Child of the Desktop can cause problems aswell.
What I did so far was setting the position of the Form directly above the Desktop:
[DllImport("user32.dll")]
static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
static readonly IntPtr HWND_BOTTOM = new IntPtr(1);
const UInt32 SWP_NOSIZE = 0x0001;
const UInt32 SWP_NOMOVE = 0x0002;
const UInt32 SWP_NOACTIVATE = 0x0010;
//By calling SetWindowPos(Handle, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE); it will move to the very back of all windows.
What I want in the end is a Win Form that is always ontop of the Desktop but under every other window.
You should run a thread which in fraction of time ( such as 100ms) call BringWindowToTop api and bring your window aplication to top, it will solve to Win+D issue.
[DllImport("user32.dll", SetLastError=true)]
static extern bool BringWindowToTop(IntPtr hWnd);
[DllImport("user32.dll", SetLastError=true)]
static extern bool BringWindowToTop(HandleRef hWnd);
In vb.net or c# WinForms, how would you make a form topmost over the other forms in the project, but not over the windows of other applications?
Using form.topmost = True puts the form above other applications.
EDIT
I am NOT looking for a splash screen.
Below is an example of the intended behavior of this form. It remains on top of everything else in the application, and you can interact with it and the form behind it.
The topmost=true should work fine for your application. There must be a user error occurring.
To bring a form on top of other forms withon an application, you can use the BringToFront method.
Application.OpenForms["MyForm"].BringToFront();
The other forms will be accessible to the user.
You can use the SetWindowPos method to bring a window to the front without activating it. You could call this in a timer to keep it on top (but that will probably put it in front of other apps, so you would only want to do that if you were the activate application) or you would have to detect when other forms fire the Activated event and then call this.
internal const int SWP_NOMOVE = 0x0002;
internal const int SWP_NOSIZE = 0x0001;
internal const int SWP_SHOWWINDOW = 0x0040;
internal const int SWP_NOACTIVATE = 0x0010;
internal const int SWP_NOOWNERZORDER = 0x0200;
[DllImport("user32.dll", EntryPoint = "SetWindowPos")]
private static extern IntPtr SetWindowPos(IntPtr hWnd, int hWndInsertAfter, int x, int Y, int cx, int cy, int wFlags);
Call it with:
SetWindowPos(form.Handle,0,0,0,0,0,SWP_NOMOVE|SWP_NOSIZE|SWP_SHOWWINDOW|SWP_NOACTIVATE);
I have a programm, which calls an extern application. The application is designed to run with 2 monitors. The first programm on monitor 1 and the second at monitor 2.
Now i have the problem that the extern application has no parameter I can give them to enforce raising on the second monitor.
Is there any possability to force another application to chance his position. Also good would be a possability to enforce changing his window state (always start as maximized).
See this instruction from MSDN.
http://msdn.microsoft.com/en-us/library/windows/desktop/dd162827(v=vs.85).aspx
Functions from WinAPI you'll need are
FindWindow - Find the window handle (HWND)
SetWindowPos - Sets the window position
ShowWindow - Change window state
EnumDisplayMonitors - Get monitor information
See pinvoke.net how to import these functions in C#
API can help you achieve same
so start by declaring
[DllImport("user32.dll")]
static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
[DllImport("user32.dll")]
static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);
const int SW_SHOWMAXIMIZED = 3;
const int SWP_FRAMECHANGED = 0x0020;
to use above simply invoke the target app and send it where you want it to and maximize
Process p = Process.Start(new ProcessStartInfo("notepad"));
Thread.Sleep(1000); //depends
IntPtr handle = p.MainWindowHandle;
SetWindowPos(handle, IntPtr.Zero, 200, 200, 500, 600, SWP_FRAMECHANGED);
ShowWindowAsync(handle, SW_SHOWMAXIMIZED);
above example is using notepad, you will choose your app here
I've an application which has a system tray icon. While uninstalling I'm killing the process if its running. So, as am not gracefully stopping the app, the icon remains in the system tray and will remove only if we hover the mouse on it. I wrote a code that would run the cursor along the tray and get the cursor back in its initial position. This is what I have done:
[DllImport("user32.dll")]
static extern IntPtr FindWindow(string className, string windowName);
[DllImport("user32.dll")]
static extern IntPtr FindWindowEx(IntPtr parent, IntPtr child, string className, string windowName);
[DllImport("user32.dll")]
static extern bool GetWindowRect(HandleRef handle, out RECT rct);
[StructLayout(LayoutKind.Sequential)]
struct RECT
{
public int Left;
public int Top;
public int Right;
public int Bottom;
}
void RefreshTray()
{
IntPtr taskbar_Handle = FindWindow("Shell_Traywnd", "");
IntPtr tray_Handle = FindWindowEx(taskbar_Handle, IntPtr.Zero, "TrayNotifyWnd", "");
RECT rct;
if (!(GetWindowRect(new HandleRef(null, tray_Handle), out rct)))
{
}
System.Drawing.Point init = Control.MousePosition;
for (int i = rct.Left; i < rct.Right-20; i++)
{
Cursor.Position = new System.Drawing.Point(i, (rct.Bottom + rct.Top) / 2);
}
Cursor.Position = init;
}
This works good in all the cases except when the option "do not show notification icons" is enabled. Is there some way I could refresh the tray in this case?
EDIT
As the comments suggested I changed my approach. Instead of killing the tray application, I established a communication between my application service (yeah, forgot to mention, I have a service too running along with the application) and tray application. While uninstalling, I stop the service, from the service stop method I would send a socket message of a particular format to the tray application and ask it to close and I would set the notify icon visibility to false. This would leave the Tray Application running in background so I am using "taskkill" to remove the application. It worked fine in Win7 and Vista, but is not working properly in Win XP. But I have not written any environment specific code. Any possible clue?
That's similar to what I use.
A simple floating Keyboard I added to a touch gallery interface. The user wanted to also have my keyboard as a standalone application on their desktop. So I did this, created a tray app for it. Now - what if its open and they launch my gallery?
They would have two keyboards.
Sure - the user could end the first - but its easier to just end it. There are no repercussions from me killing it, so I do. But the tray Icon remains, as its waiting for an event. To get around this, I refresh the Tray area.
Please note - This would only work on an English Locale Installation. To get this to work on another language, change "User Promoted Notification Area", and "Notification Area" to the translated / equivalent string.
[StructLayout(LayoutKind.Sequential)]
public struct RECT
{
public int left;
public int top;
public int right;
public int bottom;
}
[DllImport("user32.dll")]
public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
[DllImport("user32.dll")]
public static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass,
string lpszWindow);
[DllImport("user32.dll")]
public static extern bool GetClientRect(IntPtr hWnd, out RECT lpRect);
[DllImport("user32.dll")]
public static extern IntPtr SendMessage(IntPtr hWnd, uint msg, int wParam, int lParam);
public static void RefreshTrayArea()
{
IntPtr systemTrayContainerHandle = FindWindow("Shell_TrayWnd", null);
IntPtr systemTrayHandle = FindWindowEx(systemTrayContainerHandle, IntPtr.Zero, "TrayNotifyWnd", null);
IntPtr sysPagerHandle = FindWindowEx(systemTrayHandle, IntPtr.Zero, "SysPager", null);
IntPtr notificationAreaHandle = FindWindowEx(sysPagerHandle, IntPtr.Zero, "ToolbarWindow32", "Notification Area");
if (notificationAreaHandle == IntPtr.Zero)
{
notificationAreaHandle = FindWindowEx(sysPagerHandle, IntPtr.Zero, "ToolbarWindow32",
"User Promoted Notification Area");
IntPtr notifyIconOverflowWindowHandle = FindWindow("NotifyIconOverflowWindow", null);
IntPtr overflowNotificationAreaHandle = FindWindowEx(notifyIconOverflowWindowHandle, IntPtr.Zero,
"ToolbarWindow32", "Overflow Notification Area");
RefreshTrayArea(overflowNotificationAreaHandle);
}
RefreshTrayArea(notificationAreaHandle);
}
private static void RefreshTrayArea(IntPtr windowHandle)
{
const uint wmMousemove = 0x0200;
RECT rect;
GetClientRect(windowHandle, out rect);
for (var x = 0; x < rect.right; x += 5)
for (var y = 0; y < rect.bottom; y += 5)
SendMessage(windowHandle, wmMousemove, 0, (y << 16) + x);
}
Shouldn't be difficult to close the current instance using something like pipes, or TCP if you don't feel like doing that and aren't running .NET4.0.
As everyone is implying, the issue is that by killing your process it doesn't get a chance to unregister its tray icon instance, so it sticks around until Windows attempts to send an event to it (the next time you move the mouse over it) at which point Windows will remove it.
Depending on what installer you are using, this could be quite easy or more difficult. Most popular installer frameworks allow for plugins, and a few of them support Pipes, many more support TCP requests. Alternatively, write up a small executable that your installer can run before it begins the uninstall process, which communicates with your primary app and sends a close message.
As a final note, if you can use .NET4.0 then I'd suggest looking at the built in System.IO.Pipes namespace and the included classes.
Use this tool
http://www.codeproject.com/Articles/19620/LP-TrayIconBuster
It iterates through ToolBarButtons in TrayNotifyWnd & NotifyIconOverflowWindow and removes those with null file names.
I found this (http://maruf-dotnetdeveloper.blogspot.com/2012/08/c-refreshing-system-tray-icon.html) solution worked for me.
Is it possible to resize a running application's window size from within another application?
I want that when the application that I am building starts, another application (let's say itunes)'s width be reduced to its 2/3 so that the remaining 1/3 be occupied by my application. The two application should be running altogether and accessible by the user.
Please help if possible.
You can use SetWindowPos to resize another process's window.
[DllImport("user32.dll")]
private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter,
int x, int y, int width, int height, uint uFlags);
private const uint SHOWWINDOW = 0x0040;
private void resizeItunes()
{
System.Diagnostics.Process[] itunesProcesses =
System.Diagnostics.Process.GetProcessesByName("iTunes");
if (itunesProcesses.Length > 0)
{
SetWindowPos(itunesProcesses[0].MainWindowHandle, this.Handle,
0, 0, Screen.GetWorkingArea(this).Width * 2 / 3,
Screen.GetWorkingArea(this).Height, SHOWWINDOW);
}
}
You need to get the Windows' handle so use the FindWindow function at http://msdn.microsoft.com/en-us/library/ms633499(VS.85).aspx then pass the handle to the window using SendMessage.
You need to SendMessage at http://msdn.microsoft.com/en-us/library/ms644950.aspx or PostMessage at http://msdn.microsoft.com/en-us/library/ms644944(VS.85).aspx with WM_SIZE (0x0005) and specify the size.