i guess there is some reasonable and an easy solution. So for instance i have:
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
time(2)
// anything else in the about class....
//return code
}
The problem is that the whole application almost freezes and i cannot do anything but "wait for the timer".
How can i make the timer runs irrespectively to any other operation? 10x!
You want to do a SetTimer call and either give it a pointer to a callback function, or respond to the WM_TIMER message that comes back.
Related
In order to hook a wndproc, I write a wndprochook and use SetWindowLong:
wndproc=(WNDPROC)GetWindowLong(hwnd_1,GWL_WNDPROC);
SetWindowLong(hwnd_1,GWL_WNDPROC,(LONG)wndprochook);
Now I have to do something in wndproc and at the end of the function, I call the original wndproc:
return wndproc(hwnd, uMsg, wParam, lParam);
It fails, but thank god I find CallWindowProc:
return CallWindowProc(wndproc, hwnd, uMsg, wParam, lParam);
Now it's working. So Question1: Why do we have to use CallWindowProc? What's missing when simply calling wndproc?
The hook is working good, but when I quit the program, it crashes. Of course, everything is done and the crash doesn't actually affect anything. But it's still bad to see a crash.
So Question2: What may happened here and how to fix it?
I'm sorry that I have no information about how the original program closes itself, since all that I do is just hooking the wndproc to capture some messages. So I'm just hoping someone experienced enough who have ever encountered similar situations before could help.
From the documentation of CallWindowProc:
“If this value is obtained by calling the GetWindowLong function with the nIndex parameter set to GWL_WNDPROC or DWL_DLGPROC, it is actually either the address of a window or dialog box procedure, or a special internal value meaningful only to CallWindowProc”
You can't call the “special internal value“ except by doing the same as CallWindowProc does, and the easiest way to do that is to call CalLWindowProc…
By the way, have a look at SetWindowSubclass, it may ease things for you.
Regarding Question 2:
From comments on another answer, it sounds like your subclass wndprochook is in a DLL that's injected into a process. If that's the case, then during exit, your DLL may be unloaded while there are still messages pending for the window. So the Window's class still points to your wndproc, but that code is unloaded, so it crashes.
The safest thing to do is probably to restore the original wndproc before you shut down. For example, when your subclass sees WM_DESTROY or perhaps WM_NCDESTROY, you essentially reverse the steps you did when you subclassed the window: restore the original wndproc field in the window class, before doing your CallWindowProc with that message. Your code will no longer be called, even if a few more messages trickle in for that window.
thx to Adrian McCarthy.
Private Function WndProc(ByVal hWnd As Long, ByVal MSG As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Select Case MSG
Case WM_CUT, WM_PASTE, WM_CLEAR
WndProc= 1
Case WM_DESTROY, WM_NCDESTROY
Call UnHookRKey(hWnd)
Case Else
WndProc= CallWindowProc(lngPrevWndProc, hWnd, MSG, wParam, lParam)
End Select
End Function
If I have a console application with a handle to it set up like so;
HWND hWnd = GetConsoleWindow();
Then how do I set up a new wndProc for the window?
I tried using
SetWindowLong(hWnd, GWL_WNDPROC, (LONG)conProc);
With conProc being defined as
LRESULT CALLBACK conProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch(msg)
{
case WM_NCHITTEST:
return HTCAPTION;
}
return DefWindowProc(hWnd, msg, wParam, lParam );
}
But it doesn't work and says "Error code: 5 - Access is denied" on GetLastError()
I understand that it's pretty difficult to modify the console application like this, since it's a csrss.exe application and all, but I'd still like to try..
Thanks.
While the impression is that console window belongs to your process (like other window), it is in fact hosted by CSRSS system process and its WndProc is there. This makes you unable to subclass the window and provide your own WndProc living in your process.
Some related reading:
The process that is in charge of displaying the GUI windows in which consoles are presented is... CSRSS
SetWindowsHookEx with WH_KEYBOARD doesn't work for me, what do I wrong?
Subclassing XP Console Window
First of all SetWindowLong is superseded by SetWindowLongPtr, you should use that function.
Are you trying to change the WNDPROC of your own console window or another process?
From the MSDN docs :
GWL_WNDPROC
-4
Sets a new address for the window procedure.
You cannot change this attribute if the window does not belong to the same process as the calling thread.
Hello everyone I am new to windows32 programming and I have a couple of questions-:
When I use the following code in a program it works fine -:
while(GetMessage(&msg,NULL,0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
But when I replace null of GetMessage to hwnd(the handle of the window just created) the doesn't seem to close it still remains running in the background. Why does this happen when I replace NULL with hwnd means I am receiving messages for only one window then why doesn't it work????
while(GetMessage(&msg,hwnd,0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
By the way the windows function is-:
LRESULT CALLBACK WinProc(HWND hWnd, UINT message,
WPARAM wparam, LPARAM lparam){
switch(message){
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wparam, lparam);
}
return 0;
}
Secondly-:
Is there any way I can see all the messages sent to any particular window????
Thirdly-:
What is the reason behind writing __stdcall(WINAPI) when compiling my windows programs ????
A quick reply would be appreciated.Thank You.
GetMessage returns 0 (making the loop end) only when it receives a WM_QUIT, but a WM_QUIT is not associated to any particular window, so it is never received if you have a GetMessage that asks only messages for a certain hWnd.
If it's a window of yours, you already see them inside their window procedure; if you want to filter them before dispatching them to their window procedure, you can check the msg structure that is populated by GetMessage before calling DispatchMessage.
The whole Windows API uses the stdcall calling convention (I think because it is slightly faster/produces less boilerplate code than the usual cdecl), so also your callbacks must follow that calling convention. Notice that you must use WINAPI (i.e. stdcall) only on functions that are called by Windows API functions, for the other ones you are free to use whatever calling convention you like best.
PostQuitMessage generates WM_QUIT which is processed by the message queue, but not associated with a particular window. By filtering only hwnd messages in your call to GetMessage, you don't process WM_QUIT.
Regarding seeing all messages being sent to a window / thread / process, see https://stackoverflow.com/questions/4038730/i-am-looking-for-a-windows-spy-application
Finally, regarding __stdcall, see What does "WINAPI" in main function mean?
I'm calling the HtmlHelpA winapi method to display the .chm of my app. This method returns a HWND immediatelly, and the help window is shown as a separate window.
Along with the window, I set a timer for this hwnd. My problem is that I need to know when this window gets closed to kill the timer.
My first approach was trying to register the WndProc callback, but I couldn't do that because I'm not creating the window, I only have a reference to the hwnd.
Then I tried with a hook (SetWindowsHookEx) but the HOOKPROC won't bring the HWND as a parameter to the callback. Besides, I need to know the thread for this hwnd.
Is there any way to register a callback when a HWND gets closed or having a WndProc to wait for the WM_CLOSE message?
If required you can register a new window procedure for an existing window. Check out the documentation on SetWindowLongPtr().
Invoking it like this:
SetWindowLongPtr(hwnd, GWLP_WNDPROC, &MyCustomHelpWindowProc);
Just remember that window subclassing is very delicate. You might want to store the old window procedure somewhere and invoke that rather than DefWindowProc() for messages you are not interested in.
You want to subclass the help window. Subclassing gives you a chance to spy on all the messages going to the window proc. You do whatever additional work you need when you see a message of interest, and then pass the message on to the original window procedure for normal processing.
LRESULT CALLBACK MyWndProc(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp);
WNDPROC fnOldProc = reinterpret_cast<WNDPROC>(::SetWindowLongPtr(hwndHelp, GWLP_WNDPROC, &MyWndProc));
LRESULT CALLBACK MyWndProc(HWND hwnd, UINT msg, WPARAM wp, LPARAM lp) {
if (msg == WM_CLOSE) {
// Kill your timer here.
}
return CallWindowProc(fnOldProc, hwnd, msg, wp, lp);
}
I'm trying to send a keystroke to another application. I can successfully find the window handle since using SendMessage worked exactly as intended.
However, when I switched the SendMessage over to PostMessage, the application no longer received the messages.
I did, however, find a workaround by using HWND_BROADCAST as the window handle, and it works fine, but isn't the ideal way to go about it.
What I'm asking is, I have a valid hWnd, how can I send it messages using PostMessage and not SendMessage?
Edit
This is what I'm trying to do.
HWND Target = FindWindow(0, "Window Title Goes Here");
LPARAM lParam = (1 | (57<<16)); // OEM Code and Repeat for WM_KEYDOWN
WPARAM wParam = VK_SPACE;
PostMessage(HWND_BROADCAST, WM_KEYDOWN, wParam, lParam); // Works
PostMessage(Target, WM_KEYDOWN, wParam, lParam); // Doesn't Work
SendMessage(Target, WM_KEYDOWN, wParam, lParam); // Works, but I need Post
The PostMessage function does not work when the message numbers between 0 and WM_USER-1. Use RegisterWindowMessage function to register your own messages.
Sent messages and posted messages take completely different routeres. Target is recieving your posted message, it's just either filtering or dispatching it to another window. It gets to do what ever it wants with it. When you send the messages, it goes directly to the window procedure without filtering, so is most likely that cause of that issue.
I don't know why HWND_BROADCAST is working; my best guess is that a window other than Target is processing the message. Or maybe its even being sent to a different window than Target. (You do realize that HWND_BROADCAST sends the messages to every top level window)
There is a Win32 API function designed to send input, SendInput(), that places the messages on the input queue just like a user keypress. However this doesn't let you specify a window, it sends its input to the active window. To use it you would have to activate and switch focus to Target, which means the user would see that window move to the top (just like you Alt-Tabbed to it). Along that same route VBScript has a SendKeys() function that does the same thing, but is easier to use.
As a final alternative you could use SendMessageCallback() which will give you the behavior of an asynchronous SendMessage which is what I assume you want. (And is different than PostMessage. Posted messages go into the posted message queue, sent messages are delivered directly)
*For the lparam go here http://msdn.microsoft.com/en-us/library/ms646280%28v=vs.85%29.aspx, change the 32 bits (31...3 2 1 0) of lParam. Once you have the binary sentence you want for your paramaters (cRepeat, Scancode etc), convert it to hexadecimal.
try this :
void SendString(HWND h, char *text)
{
int len = strlen(text);
for(int i = 0; i < len; i++)
PostMessage(h, WM_CHAR, text[i], 0);
}
HWND Target = FindWindow(0, "Window Title Goes Here");
LPARAM lParam = //The hexadecimal value matching with the parameters you want* example 0x29A1.
WPARAM wParam = VK_SPACE;
PostMessage(HWND_BROADCAST, WM_KEYDOWN, wParam, lParam);
PostMessage(Target, WM_KEYDOWN, wParam, lParam);
SendString(Target, (char*)"themessageyouwant\n");