WM_POWERBROADCAST handler for CMainDlg in ATL app not invoked - winapi

I have an ATL app where I want to handle WM_POWERBROADCAST. I have a CMainDlg (CAxDialogImpl) in whose MSG_MAP I defined the handler.
BEGIN_MSG_MAP(CMainDlg)
...
MESSAGE_HANDLER(WM_POWERBROADCAST, OnPowerChange)
...
END_MSG_MAP()
However, the handler isn't invoked when I do things that should invoke it, for instance change power settings or put the machine to sleep.
Any ideas about what might be going on, and how to fix this? Does CMainDlg not get notified of power events, for some reason?

I suspect your dialog not being a top level window (WS_POPUP styled).
Just tested with a WTL AppWizard non modal dialog app that WM_POWERBROADCAST is received (without any registration) on AC plugged/unplugged.

Did you register to receive the power events?

To add to answers above, you might want to use Spy++ tool to make sure the messages of interest are posted to your application in first place. You will also see which windows they are posted to, and if it is your window where you are waiting for this message.

Related

How to intercept a window message in a shell extension

I have a shell extension that needs to reload its configuration when a specific window message (custom message registered with RegisterWindowMessage) is broadcasted by another application.
I tried several approaches to intercept the message:
Installing a window subclass callback on a window of Windows Explorer, using SetWindowSubclass. This works on Window 7, but not on Windows 8, because apparently DllMain is not called on the main thread, and SetWindowSubclass doesn't work from another thread. This is mentioned in the documentation:
You cannot use the subclassing helper functions to subclass a window across threads
Installing a hook for CALLWNDPROC, using SetWindowsHookEx. Because I don't want to slow down the whole system, I install the hook for a specific thread only (the explorer's main thread). This works on Windows 8, but not on Windows 7... I suspect this is because I'm hooking on the wrong thread, but I'm not sure. And anyway, this approach seems overly intrusive.
Creating a message-only window to handle the message. This doesn't work at all, because message-only windows don't receive broadcasted messages.
Is there a reliable way to receive a window message in a shell extension?
A window message initially seemed to be the easiest way to notify the shell extension, but if you think another mechanism would be more appropriate, I'm open to suggestions.
Create a hidden window and listen for the message in its window procedure.
Register a window class that has default values for all the fields apart from the window procedure and class name. You don't need to specify anything else in the window class since the window will never be visible.
When you create the window, pass 0 for the window style. Specifically exclude WS_VISIBLE.
Pass 0 for the WndParent when you create the window. This will make it a top level window and so eligible to receive broadcast messages.

Preventing WM_SETCURSOR and WM_NCHITTEST messages from being generated

I'm making an application that hooks itself in to a target application and, when activated by the user, prevents all keyboard and mouse window messages from reaching the target application's window proc. My application does this by translating the incoming input messages, such as WM_MOUSEMOVE, to WM_NULL, so that the window proc is unaware input happened.
The problem is that Windows also automatically sends WM_SETCURSOR and WM_NCHITTEST to the window proc (e.g. when the application calls PeekMessage) when mouse input occurs. These messages aren't posted to the window's message queue, so I can't change them to WM_NULL.
I initially worked around this by subclassing the window proc and simply ignoring WM_SETCURSOR and WM_NCHITTEST there, but subclassing seems to have compatibility issues with some of the applications I'm hooked in to.
My question is: How do I prevent WM_SETCURSOR and WM_NCHITTEST from being generated in the first place OR how do I prevent them from reaching the application's window proc.
Some Ideas to Try
I just finished implementing a global/system wide CallWndRetProc with a WH_CALLWNDPROCRET Windows Hook (like it describes in the past post of the link below).
http://help.lockergnome.com/windows2/Igor-SetCursor-SetWindowsHookEx--ftopict285504.html
Using that in combination with hiding all the system cursors using SetSystemCursor has effectively hidden the cursor for most applications.
If you wanted to continue hacking at this target application, you could try using API Monitor to diagnosis what is going on: http://www.rohitab.com/apimonitor
The guy at rohitab hints at releasing his source code eventually; his site seems to have some of the better forums about Hooking, Subclassing, Injecting, etc.
It sounds like you successfully used SetWindowLongPtr(), but there are a few different ways to get into the address space of the program you are working on...
Have you tried SetCapture()?
Other Links
Here are a few other links that may be useful:
http://support.microsoft.com/kb/31747
http://msdn.microsoft.com/en-us/library/windows/desktop/ms646262(v=vs.85).aspx
http://msdn.microsoft.com/en-us/library/windows/desktop/ms633569%28v=vs.85%29.aspx#winproc_subclassing
http://msdn.microsoft.com/en-us/library/windows/desktop/ms648395(v=vs.85).aspx
Hope that helps. Good luck.

OnMouseWheel event with MFC

I am having some problems with the ON_WM_MOUSEWHEEL event and MFC. The function handling the event does get called, but not when scrolling, just when "pinching" the touchpad. Is it supposed to behave like this?
I am using Visual Studio 2010 and Windows 7.
I've noticed that some touchpad drivers implement scrolling using the WM_VSCROLL message, however since the java AWT's mouseWheelListener is working, my recommendation would be:
Open Spy++ and verify whether or not WM_MOUSEWHEEL messages are being posted.
If messages are not being posted the control might not have focus.
If messages are being posted, it might be a problem with the way the control is attempting to receive the message. In this case, showing us the message map might help.
Take a look at the WM_TOUCH message.

Qt::X11BypassWindowManagerHint functionality on Windows

I'm currently developing a cross-plataform virtual keyboard. In linux i was able to do whatever i want, but in Windows i'm having problems to prevent the widget to obtain the keyboard focus.
In linux, using the window flag
Qt::X11BypassWindowManagerHint
the widget never gets the keyboard input, but of course, that flag does not work on Windows
Is there something equivalent to that flag or some method i can use instead?
any ideas would be appreciated
thanks in advance
I posted an answer to a similar question over in Make a floating QDockWidget unfocusable. On Win32 you don't really have the choice of bypassing the window manager completely, but you should be able to get most of the behavior you want by intercepting nativeEvent to handle WM_MOUSEACTIVATE.
I would try to ignore the event. I believe you need to ignore FocusIn on the main application window - not sure about the actual event, you might need to prototype it. You can do ignore events by either installing an event filter or manually re-implementing one of the event methods (possibly event itself). I don't know which is the preferred way though but I'd attempt the event filter first for this task: http://doc.trolltech.com/4.6/qobject.html#eventFilter
I've never tried to capture the keyboard focus event, but I have been able to successfully ignore escape keys in a QDialog to prevent users from accidentally closing the window. I believe it should be possible.

Receive screensaver notification

I want to receive a notification in my C++ application when a screensaver is about to start. I tried listening to WM_SYSCOMMAND messages with wParam == SC_SCREENSAVE which some people think should do the trick.
That didn't work. Spy++ even showed that my window didn't receive any WM_SYSCOMMAND message. Interesting thing is when I turned off the monitor I did receive the message with wParam == SC_MONITORPOWER. Am I understanding it wrong? Or did I just miss something?
Edit: For testing I used the default windows screensaver (the one with windows logo).
It appears that I will receive the SC_SCREENSAVE message only when my window has focus. The way around this is to set global hook. That would require me to put the callback function in a separate DLL and there is also this scary message about hooks slowing down the system so I decided to drop the idea of responding to screensaver start.
This is a relatively complex task (although it would be nice if it were easy).
Some of these tests you'll find online only work if your window is in focus. If it's running in the background it may not receive such messages.
Other tests rely on a screensaver program running (check the currently set screensaver, and then watch the process list to see if it's active) but don't work if you go into powersave mode, or if your screensaver is a black screen (ie, no program, just monitor off).
I don't believe there's an ideal way to do this. You might want to go back to the beginning and think more carefully about why you need to detect this state, and what you are trying to accomplish. You might need a different solution.
Probably my answer comes too late.
The MSDN handles screensavers under "Legacy".
On a notebook they waste battery and on a PC they are also useless.
It is better to turn the monitor off than letting it show a screensaver.
As you don't explain exactly what you want to do I don't know if you really need the notification BEFORE the saver starts or if it is enough to get notified when it already has just started.
In the latter case it is easy.
Write a thread that periodically checks:
BOOL b_SaverRunning;
SystemParametersInfo(SPI_GETSCREENSAVERRUNNING, 0, &b_SaverRunning, 0);

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