I'm looking through some Qt code and see that rather than just using QMessageBox, the program checks whether QAPPLICATION_H is defined. If it isn't, then it uses some default system message box. Here's what it looks like:
bool Connect()
{
...
{
#ifdef QAPPLICATION_H
QMessageBox::critical(0,QString("Error!"),QString("Cannot Connect To PS3"));
#else
MessageBoxA(0,"Error!","Cannot Connect To PS3",MB_ICONINFORMATION);
#endif
return false;
}
else
{
...
#ifdef QAPPLICATION_H
QMessageBox::information(0,QString("Sucess!"),QString("Connected To PS3!"));
#else
MessageBoxA(0,"Sucess!", "Connected To PS3", MB_ICONINFORMATION);
#endif
return true;
}
}
Basically, my question is: what's the compatibility of QMessageBox? If I released a program that only uses QMessageBox, will people without Qt not be able to see the message pop up? I just don't want to have to check for this every time in my own code, and also the standard non-Qt box looks worse.
Qt is cross platform QMessageBox will be available on any platform you compile your code. I don't know why in the listed code is that define and the call to MessageBoxA, maybe the developer wanted to be able to display a more windows look and feel message box, in case the target platform is windows.
Related
I am showing you my problem.
I'm creating an application in Qt Creator for a university project.
As you can see in the code below, I inserted two 'cout' inside a method just because they were useful to me to check that the program worked, this means that they have no real function.
After viewing it, the professor delegated me to do it in debug mode with #IFDEF so that that portion of the code containing the 'cout' is visible only to the programmer and not to a hypothetical client.
I hope I have explained my problem fairly well, I thank anyone who can help me.
Consider that in this type of thing I am quite novice.
Thanks
You have to use preprocessor macro. The correct one for qt creator is QT_DEBUG. Your code should look like this:
void BankAccount::addTransaction(Transaction* t){
if(t->getType()==0 && actualAccountBalance < t->getTransactionValue()) {
#ifdef QT_DEBUG
cout<<"Unable to add transaction: insufficient balance to make the requested withdrawal!"<<endl;
#endif
; // empty command, because of empty if
}
else if(find(transactions.begin(),transactions.end(),t) != transactions.end()) {
#ifdef QT_DEBUG
cout<<"This transaction has already been added!"<<endl;
#endif
; // empty command, because of empty if
}
else{
transactions.push_back(t);
assignID(t);
actualAccountBalance = calculateAccountBalance();
}
}
I'm working on an application for taking screenshots on Windows, OSX and Linux in C++/Qt. Now I need to set global hotkeys, so the user can take screenshots when the application is running in the background. I tried with Qxt and UGlobalHotkey, which are both Qt libraries, but neither of them seemed to work.
I tried to implement it for OSX with Carbon (tutorial), but I need to call a class member function, which just doesn't work. Could someone provide me with an example? You can find my code here. The function i need to call is new_screenshot().
Or is there any other way to achieve something like this? I really need my application to take a screenshot from the background, otherwise it's pretty useless (yes, I should probably have implemented it at the very beginning to see if it even works). Would it maybe be better to have a separate client for every platform (Cocoa Swift for OSX, GTK for Linux, C# client for Windows)? I have often thought about this the past few days.
Do I understand correctly that you want to call new_screenshot from the hot key event handler? If so, InstallApplicationEventHandler lets you pass a pointer to user data in 4th argument. Pass a pointer to your MainWindow instance (based on code from the tutorial):
MainWindow *mainWindow = ... // get main window somehow
InstallApplicationEventHandler(&MyHotKeyHandler,1,&eventType,mainWindow,NULL);
Then you can use it in the event handler.
OSStatus MyHotKeyHandler(EventHandlerCallRef nextHandler,EventRef theEvent, void *userData)
{
//Do something once the key is pressed
static_cast<MainWindow*>(userData)->new_screenshot();
return noErr;
}
I did something in the past with MFC and WIN32 API....so it only works on Windows...but pressing ALT+F10 was able to hide/show a window...
void CWinHideDlg::OnButtonActive()
{
CString tmp;
GetDlgItemText(IDC_BUTTON_ACTIVE,tmp);
if(0 == strcmp(tmp.GetBuffer(tmp.GetLength()),"Activate"))
{
m_myAtom=GlobalAddAtom("MY_GLOBAL_HOT_HIDE_KEY");
int err=RegisterHotKey(this->GetSafeHwnd(),m_myAtom,MOD_ALT,VK_F10);
SetDlgItemText(IDC_BUTTON_ACTIVE,"Stop");
CButton *pBtn = (CButton *)GetDlgItem(IDC_BUTTON_UNHIDE);
pBtn->EnableWindow(TRUE);
SetDlgItemText(IDC_STATIC_INFO,"Set the mouse over the window \nand press ALT + F10 to hide it...");
}
else
{
UnregisterHotKey(this->GetSafeHwnd(),m_myAtom);
GlobalDeleteAtom(m_myAtom);
CButton *pBtn = (CButton *)GetDlgItem(IDC_BUTTON_UNHIDE);
pBtn->EnableWindow(FALSE);
SetDlgItemText(IDC_BUTTON_ACTIVE,"Activate");
}
}
Basically this code activates/deactivates the hot key ALT+F10, once it activates you can hide/unhide a running window on the system by setting the mouse pointer over the window and press ALT+F10...
This is from the WindowProc function:
if(message == WM_HOTKEY)
{
CString tmp;
POINT pc;
GetCursorPos(&pc);
if(GetAsyncKeyState(VK_F10))
{
HWND hwnd=::WindowFromPoint(pc);
if(hwnd)
{
tmp.Format("%08Xh",hwnd);
m_HideWins.InsertString(m_HideWins.GetCount(),tmp);
::ShowWindow(hwnd,SW_HIDE);
}
}
}
You can use the code to register your own HOT Key and use it to take a screenshot...
Hope it helps...
Problem
I'm trying to open an MFC program that reads a Microsoft Access database (.mdb) and allows the user to view or modify the data. This is an existing program (and source code) given to me by a group in another lab where the program opens and works just fine.
In our lab, I have yet to see it load properly. When run, it pops up a dialog box that says, "Attempted an unsupported operation". Windows then offers me a chance to debug and such before it crashes.
Environment
In the other lab, they use Windows 7 and Microsoft Office 2010, and it works.
In our lab, I've tried Windows 7 with Office 2013 and Windows XP with Office 2010. The latter crashes without giving me the dialog box. I don't know if we have a Win7/MSO2010 machine.
The Function
I have the source code for the program. The solution file implies it was last developed in VS2010, which the computers I tested on had installed as well. Running it out of Visual Studio 2010 or straight from the executable yields the same results.
I have added additional debug dialog boxes to the code that narrow down the problem to this function call, which the code never gets past:
CwinApp:OpenDocumentFile(LPCTSTR lpszPathName)
The single string passed into the function is a path and filename for the MS Access database to be opened. It exists in a temporary directory created by another program. This is on a drive other than C, though I've tested some there, as well. Problems with programs related to this one often stem from files with "read only" status, but I continually check the temporary files created, and they are write-able.
Documentation
I found this information titled "Breaking Changes in Visual C++" for VS2010 through another SO question:
A new virtual function was added to the CDocTemplate class. This new virtual function is CDocTemplate::OpenDocumentFile. The previous version of OpenDocumentFile had two parameters. The new version has three parameters. To support the restart manager, any class derived from CDocTemplate must implement the version that has three parameters. For more information about the function, see CDocTemplate::OpenDocumentFile. The new parameter is bAddToMRU.
Code
I feel this might be the answer! But I don't have a strong idea of exactly what to change to get this to work. Here's where I stopped:
Program.cpp
CDocument* ProgramApp::OpenDocumentFile(LPCTSTR lpszFileName, BOOL bAddToLRU, BOOL bMakeVisible)
{
// Add specialized code here and/or call base class
// Debug messages added
CDocument* tempDoc;
AfxMessageBox(lpszFileName);
tempDoc = CWinApp::OpenDocumentFile(lpszFileName, bAddToMRU);
AfxMessageBox("Opened database!");
return tempDoc;
}
Program.h
class ProgramApp : public CWinApp
{
public:
...
virtual CDocument* OpenDocumentFile(LPCTSTR lpszFileName, BOOL bAddToMRU, BOOL bMakeVisible);
afxwin.h
class CWinApp : public CWinThread
{
...
virtual CDocument* OpenDocumentFile(LPCTSTR lpszFileName);
virtual CDocument* OpenDocumentFile(LPCTSTR lpszFileName, BOOL bAddToMRU);
Changing the Program.cpp call to be from a "Template" class caused errors, but I wouldn't be surprised if that's towards the answer. This solution looks similar, but I'm not sure exactly what to do.
My hope is that this problem has a simple solution that someone more knowledgeable can give me. I would be much appreciative, and additional context would help a lot.
Edit: Debugging
I drilled down into the Windows code to see what was precisely going wrong. It seemed too dense to understand, but a coworker and I may have clues based on it. The failure message happens here:
dlgdata.cpp
// Could be a windowless OCX
pSite = m_pDlgWnd->GetOldControlSite(nIDC);
if (pSite == NULL)
{
TRACE(traceAppMsg, 0, "Error: no data exchange control with ID 0x%04x.\n", nIDC);
ASSERT(FALSE);
AfxThrowNotSupportedException();
}
...Although we are seeing debugger issues here:
occcont.cpp
COleControlSiteOrWnd *pemp = new COleControlSiteOrWnd(hwndCtrl, pOccDlgInfo->m_pItemInfo[i].bAutoRadioButton);
ASSERT(IsWindow(pTemp->m_hWnd));
if (IsWindow(pTemp->m_hWnd))
{
hwndStart = pTemp->m_hWnd;
...
My coworker believes this could have little to do with the opening of this document as I suspected and more to do with objects/controls we don't have on our lab computers trying to be used for the program.
I have faced the same problem in opendocumentfile(), there was a control in CFormView class which i was not using so i commented it out but forget to delete from .rc file. Once i remove the control entry from .rc file the problem disappear.
there should be no control variable uninitialize , please check that also
I'm writing a library in QT which will take screenshots of arbitrary external windows. I know how to take the screenshot using QScreen::grabWindow(), but this takes as an argument a WId, and I would like to know if there is a way to get a list of WIds for all windows on the screen and/or desktop (or something similar, such as getting a WId for a specific window using a title name), via QT. I am aware that I can do this in a platform dependent way, such as EnumWindows in Windows, but I was hoping to keep it cross-platform within QT if possible.
This isn't possible with Qt. If you want your library to be platform independent, you need to write a code for each platform you want to support.
To make this platform independent, you have to write a (public) function in which you test for the platform using preprocessor #if:
#ifdef __unix__
// call unix specific code
#elseif ...
// other platforms
#else
#error Platform not supported!
#endif
For the unix specific code, you need to use xlib, which manages the windows in a tree. From the following code, you will get ALL windows, and in X11 there are a lot of invisible windows and windows which you don't think that they are separate windows. So you definitely have to filter the results, but this depends on which window types you want to have.
Take this code as a start:
#include <X11/Xlib.h>
// Window is a type in Xlib.h
QList<Window> listXWindowsRecursive(Display *disp, Window w)
{
Window root;
Window parent;
Window *children;
unsigned int childrenCount;
QList<Window> windows;
if(XQueryTree(disp, w, &root, &parent, &children, &childrenCount))
{
for(unsigned int i = 0; i < childrenCount; ++i)
{
windows << children[i];
windows << listXWindowsRecursive(disp, children[i]);
}
XFree(children);
}
return windows;
}
Display *disp = XOpenDisplay(":0.0");
Window rootWin = XDefaultRootWindow(disp);
QList<Window> windows = listXWindowsRecursive(disp, rootWin);
foreach(Window win, windows)
{
// Enumerate through all windows
}
My MFC application using the "ESRI MapObjects LT2" ActiveX plugin throws an ASSERT at me when closing it.
The error occurs in cmdtarg.cpp:
CCmdTarget::~CCmdTarget()
{
#ifndef _AFX_NO_OLE_SUPPORT
if (m_xDispatch.m_vtbl != 0)
((COleDispatchImpl*)&m_xDispatch)->Disconnect();
ASSERT(m_dwRef <= 1); //<--- Fails because m_dwRef is 3
#endif
m_pModuleState = NULL;
}
I built the (native C++) application with VC9.
When I compile the application with VC6, it behaves nicely.
What could be the reason for this?
That looks like a reference count. Could this "target" be referenced by something else, something that's not releasing it?
You can trace the Addref and Release calls defining _ATL_DEBUG_INTERFACES
from http://msdn.microsoft.com/en-us/library/sycfy8ec(VS.80).aspx
_ATL_DEBUG_INTERFACES
Define this macro before including any ATL header files to trace all AddRef and Release calls on your components' interfaces to the output window.
Using _ATL_DEBUG_INTERFACES did not yield any additional output...
I defined it on the first line of stdafx.h, directly after #pragma once so I guess this is early enough.
Maybe the reason is how I am using the ActiveX control:
I'm not calling AddRef() or Release() by myself.
The MapObjects Installer comes with sample code with lots of wrapper classes which must have been generated by VC6 or something earlier.
I tried to generate wrapper classes myself with VC9 but there occured errors which I wasn't able to fix.
I use the control by letting one of my windows have a member of type CMap1 (derived from CWnd), which is one of those generated wrapper classes. In CMyWnd::OnCreate() I also call CMap1::Create() and that's it, I'm finished: I can add a layer and the control displays a world map.
I have pretty much no idea what the reference-count stuff is about as I have not added or released any references. At least not knowingly...
The control is pretty old: The .OCX file has the year 2000 in its version information.
It's also not officially supported anymore but I don't have any substitue.
The following solved it for me:
In the window that contains the control, add an OnDestroy() handler:
void CMyWnd::OnDestroy()
{
// Apparently we have to disconnect the (ActiveX) Map control manually
// with this undocumented method.
COleControlSite* pSite = GetOleControlSite(MY_DIALOG_CONTROL_ID);
if(NULL != pSite)
{
pSite->ExternalDisconnect();
}
CWnd::OnDestroy();
}