There's WM_ACTIVATEAPP message on "desktop Windows":
Sent when a window belonging to a different application than the
active window is about to be activated. The message is sent to the
application whose window is being activated and to the application
whose window is being deactivated.
Is there anything similar on Windows Mobile? WM_ACTIVATE cannot be used, as my application has multiple windows.
I need WM_ACTIVATEAPP (or something similar), because I'd like to request/release some power-consuming resources (GPS, backlight etc) when app gets activated/deactivated.
I think WM_ACTIVATEAPP is not supported on windows mobile. To detect when app is activated/deactivated you can capture WM_ACTIVATE message. As per MSDN documentation, hWndPrevious i.e. lParam will always be NULL when the window being activated and the window being deactivated are in separate processes.
Following post makes use of same concept to address this issue. Hope this helps you. http://social.msdn.microsoft.com/forums/en-US/vssmartdevicesnative/thread/3fbe52b6-a895-4470-8cfe-c3d86a58fd73/
Related
If I register a hook via SetWindowsHookEx(WH_SHELL, ShellProc, ...), what is the meaning of event HSHELL_WINDOWREPLACED? (My Google-fu fails me. I have searched high and low!)
Win32 Docs:
SetWindowsHookEx(): https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-setwindowshookexw
ShellProc (callback): https://learn.microsoft.com/en-us/windows/win32/winmsg/shellproc
The offical docs read: A top-level window is being replaced. Weirdly, they also say: Windows 2000: Not supported. Does that mean only supported before or after Win2K?
I created a test driver to watch a Microsoft Windows session, but I was never able to trigger this mysterious event.
I also found a similar event here:
RegisterShellHookWindow: https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-registershellhookwindow
... that says:
HSHELL_WINDOWREPLACING: A handle to the window replacing the top-level window.
HSHELL_WINDOWREPLACED: A handle to the window being replaced.
Related:
How can I be notified when a new window is created on Win32?
Why HSHELL_WINDOWDESTROYED, HSHELL_WINDOWCREATED?
In this instance, the term "replace" refers to the occasions when a window stops responding to messages ("hangs") and, after a certain period, Windows hides it and replaces it on-screen with a faded-out copy (called a "ghost window").
Windows does this so that, even when the app is not processing messages, the user can interact with the ghost window to move it around and try to close it.
The wParam value is the handle of the hung window (the one being replaced) and the lParam value is the handle of the ghost window (its replacement).
If the window starts responding again, the notification is sent again, with the window handles swapped around.
I was attempting to verify that messages were being sent to my window using Spy++ (running Windows 7), but I mistakingly tried to spy on a console window that my program was using for debug output. Spy++ promptly notified me that "The specified window cannot be spied upon. Windows will not allow access to the message stream for this window."
While Spy++ does correctly gather other information about the window (e.x. name, style, class name), it cannot process the message queue. Why is this? And, out of morbid curiosity, is there a way to prevent Spy++ from accessing the message queue of my own custom window using the Windows API?
While Spy++ does correctly gather other information about the window (e.x. name, style, class name), it cannot process the message queue. Why is this?
The console window belongs to the CSRSS process, not the CMD.EXE process. CSRSS is a critical system service that is protected and cannot be hooked without special debug privileges.
"When a user-mode process calls a function involving console windows, process/thread creation, or side-by-side support, instead of issuing a system call, the Win32 libraries (kernel32.dll, user32.dll, gdi32.dll) send an inter-process call to the CSRSS process which does most of the actual work without compromising the kernel."
And, out of morbid curiosity, is there a way to prevent Spy++ from accessing the message queue of my own custom window using the Windows API?
Typically, no. Unless you manage to run your window in a protected system process.
So, I discovered this myself recently, I created a console .NET application which launches a process using CMD.EXE and I ran into an issue with some Win32 interop around the keyboard. So I broke out the previously trusty Spy++ utility to see what was happening to find that I was completely unable to monitor the message queue for my application from it.
So as per the op's question:
"Is there a way to prevent Spy++ from accessing the message queue of my own custom window using the Windows API?"
There is a list of restricted windows classes baked into Spy++:
SpyxxHk (presumably it's own hooking class),
#32768 (Context Menu),
#32769 (the Desktop),
ttyGrab ,
ConsoleWindowClass (Command Prompt)
So, if you in any way tie your app to these classes Spy++ will display that block message when attempting to watch their messages, of course this may not prove useful since it only restricts those classes.
Referring to MS documentation:
https://msdn.microsoft.com/en-us/library/windows/desktop/dd373640(v=vs.85).aspx
"For out-of-context events, the event is delivered on the same thread that called SetWinEventHook. In some situations, even if you request WINEVENT_INCONTEXT events, the events will still be delivered out-of-context. These scenarios include events from console windows and events from processes that have a different bit-depth (64 bit versus 32 bits)"
Suggests it is possible to get console window events.
My application is a fullscreen window which is rendering a designated other window (from dwm), for example Google Chrome. I would like to know if it's possible to send events (such as mouse keyboard events) to the specified window.
Of course the designated window has to stay in background, and my current application on the foreground.
My application is written in C++. I'm working on Windows 7/8.
Just to put it into an answer.
Based on this question Does any program/language/library that interacts with windows do it via the WIN32 API? you should be able to use the windows API to send a windows message to any window. All you need to get is that windows handle, or you could do a broadcast to all windows.
The specific function http://msdn.microsoft.com/en-us/library/windows/desktop/ms644950(v=vs.85).aspx
Though that function will block until the windows responds and processes the message, this could hurt GUI performance. If you notice issues try implementing http://msdn.microsoft.com/en-us/library/windows/desktop/ms644951(v=vs.85).aspx instead.
If I have a program running in the background and it needs the user to see it (like a dialog box) when it pops up, can I take the user out of Metro Mode (in Windows 8) for him to be able to see this notification?
I highly doubt it, such a capability would spawn a bunch of apps that would essentially try to take over and be very jarring for the user. Your desktop app though could generate a toast notification that would alert the user there is some action to take, see this MSDN topic for details.
I agree with Jim: switching context automatically from the desktop to Metro (or whatever they're calling it now) would be visually jarring and user-hostile. I realize the OS itself does this, like when you launch a desktop app from the Start screen. That doesn't make it good design.
Besides, when it does it, the user (presumably) wanted to interact with the newly-launched application. That's not necessarily the case when you're just showing a notification. There may not even be action required.
Instead, I recommend that you use Toast, the notification framework designed explicitly for this purpose. There's a sample application available for download: Sending toast notifications from desktop apps.
Note, however, that in order for Toast notifications to work from desktop applications, you must install a shortcut to your desktop application in the Start screen, with a System.AppUserModel.ID. This should be handled by your installer. More information is here.
Of course, the user can disable this by either turning off notifications or removing your app's shortcut from their Start screen. That's perfectly okay—if they take either of these actions, you can assume that they no longer want to receive notifications from your app.
Using JUCE with TUIO, I'm developing a multi-touch utility to send "hot keys" commands to other applications (I am using a usb touch frame that sends TUIO messages). For instance, I provide an interface through which users can touch-and-hold to program a key combo and then tap that button to send the programmed key combo to another app. They way I accomplish this on OSX is by running my utility as a "background only" application (NSApplicationActivationPolicyProhibited). I use [NSWindow setCanHide: NO] so the GUI of my utility is visible even though it runs as a background app.
It works well except in the case that a window from another application is on top of mine. What happens is that touches get passed through that other app into mine- causing unintentional button pushes in my app. Normally, I could have my app only listen to the TUIO touch callback whenever is is the active application, [NSApp isActive]. But, since my app is background only, it is never active and I have no way to tell if another window is covering it to prevent touches.
So, is there any way for a "background only" app to be able to tell if it is on top of all other windows? Or, is there a way from within my app to get a list of all Cocoa windows from other applications and be able to tell if they are appearing on top of my "background only" app?
Also, does anyone know how I would go about all of the above in Windows? In other words, what is the Windows equivalent of NSApplicationActivationPolicyProhibited and would I be able to tell if it is covered by other applications' windows?