VisualCpp.org Collection of Visual C++ Stuffs

Moving your window by dragging it by clicking on anywhere on the dialog?

For that you have to handle WM_NCHITTESTand returning HTCAPTION, which will instruct the Windows, that user is dragging through the Title-Bar and it have to move the window with it.

A small example :-

UINT CMyDialog::OnNcHitTest(CPoint point)
{
UINT nRet = CDialog::OnNcHitTest(point);
if(HTCLIENT == nRet)
{
nRet = HTCAPTION;
}

return nRet;
}

Tip Courtesy :Mr. Ovidiu Cucu

Clicking menu item remotely (on same computer) through another application (Part1)?

Virus??? No man no, I am trying to demonstrate the power on windows API /messages!. I will demonstrate same in two part,  first using keybd_event and another using raw Window Message Posting.

Let me demonstrate that by opening the FontDialog of Notepad application, for that you need handle to Main window of Notepad application. This tip will come handy for reterieving handle of windows. FontDialog menuitem is present in Format|Font menu, to reach there from accelerators key, you have to first press Alt+O followed by the F Key to open FontDialog. Now achieve same using code you have to rely on keybd_event api, which simulate the keyboard inputs. it is old api, this api isreplaced by SendInput api.

HWND hWnd = ::FindWindow(_T("Notepad"),NULL);

// Make the Notepad window on top
::SetForegroundWindow(hWnd);

// open Format menu item

--------1-----------------
keybd_event(VK_MENU,0,0,0);
keybd_event(VkKeyScan('O'),0,0,0);
keybd_event(VkKeyScan('O'),0,KEYEVENTF_KEYUP,0);
keybd_event(VK_MENU,0,KEYEVENTF_KEYUP,0);
----------2--------------
// will cick the Font menuitem
keybd_event(VkKeyScan('F'),0,0,0);

See screen shot for above, I have put some sleep at Task 2, so that I could see what happening visually.

After Completion of Task 1

 

After Completion of Task 2

Please note, for above to work, Notepad should be always in focus, for Keyboard input, otherwise the keyboard input would be delivered to some other application.

How to create Single Instance application on Window OS where multiple user session are running using Terminal services?

If you developing desktop application, one or other day your requirement would be to develop the application, which only one instance run on particular computer. There are many articles available on this, on internet. But, just today I have to create application which would run on that computer where many parallel sessions of windows are running using terminal services. Usually, I follow this technique for creating single instance application:-
 

// For handling Single Instance of Application
 HANDLE hSingleInstance = NULL;

hSingleInstance = CreateMutex(NULL,FALSE,_T("SINGLEINSTANCE_APP"));

DWORD dwLastError = GetLastError();
 if((dwLastError == ERROR_ALREADY_EXISTS) ||
  (dwLastError == ERROR_ACCESS_DENIED))
 {
  AfxMessageBox("Application already running");
  CloseHandle(hSingleInstance);
  return 0;
 }

// End handling Single Instance of Application
// Close the handle of hSingleInstance when application closes
CloseHandle(hSingleInstance);

Now making application, which have single instance for all session you have to include Global\ prefix before application mutex name or if you required that application restricted to single user session, you could use Local\ prefix (back slash included). Now let me change above for you:-

Global Single Instance:-

hSingleInstance = CreateMutex(NULL,FALSE,_T("Global\\SINGLEINSTANCE_APP"));

Local Single Instance:-

hSingleInstance = CreateMutex(NULL,FALSE,_T("Local\\SINGLEINSTANCE_APP"));

Note: Please don’t use another backslash when using Global and Local prefix and both Global and Local are case sensitive.