Setting focus to a running QProcess

[vezprog]

So I am having trouble figuring out a way to bring an application to the forefront for a QProcess. My application is a System Dock that allows users to drag executables from their local PC, and add it to the dock. When adding to the dock, it creates a button with the object name as the directory location of the application added.

The thread is created in the Widget window like so:
@
/*
// app button clicked (slot)
*/
void Widget::appButtonClicked()
{
// get sender of the signal
QToolButton *button = qobject_cast<QToolButton *>(sender());

// format the exe location
QString temp = button->objectName();
temp = temp.replace("/", "\\\\");
temp = "\"" + temp + "\"";

// start the new process
newProcess = new Process();
newProcess->exeLocation = temp;
newProcess->start();

}
@

On the button push, I run a QProcess in a thread so that I don't freeze the GUI and allows other processes to be opened as well:
@
#include "process.h"

/*
// cc
*/
Process::Process(QObject *parent) :
QThread(parent)
{
exeLocation = "";
}

/*
// class execution loop
*/
void Process::run()
{
// start the proccess
QProcess process;
process.start(exeLocation);
process.waitForFinished(-1);
}
@

What I also am going to do is append the thread to a QList<QThread *> on creation so that I know which process's are active at all times.

But, I am looking to change the code for button press signal to check if the application has already been opened. As in, I only want one instance of the application running at a time. If it is already running, then I want bring that process to focus / bring the screen to the front.

Is there any that there is a way to do this in Qt, or is this going to be platform specific? I am currently developing on Windows 7.

[mlong]

Bringing the process to the front will be a system-specific thing, I believe.

Also, there's no need to run your QProcesses in separate threads. You can use "QProcess:startDetached()":/doc/qt-4.8/qprocess.html#startDetached to run the process without blocking, and you can connect to the QProcess's "finished()":/doc/qt-4.8/qprocess.html#finished signal to catch when the process ends.

[vezprog]

Ah, very nice. Thanks! I have just read this snipet actually that I am going to try to do using the process id:
http://www.qtcentre.org/threads/42554-QProcess-and-focus-problem

So I will save my QProcess to a list when created, then to bring it to focus ill have to search the list on click and compare the process id's, then bring it to focus.

I think it may work :)

[aabc]

Gread idea

[vezprog]

Actually, for some reason, the finished signal is not working with the startDetached() call after I create it on the heap...very odd.

@
/*
// app button clicked (slot)
*/
void Widget::appButtonClicked()
{
// get sender of the signal
QToolButton *button = qobject_cast<QToolButton *>(sender());

// format the exe location
QString temp = button->objectName();
temp = temp.replace("/", "\\\\");
temp = "\"" + temp + "\"";

QProcess *exeprocess = new QProcess(this);
connect(exeprocess, SIGNAL(finished(int)), this, SLOT(processFinished(int)));
exeprocess->setObjectName(button->objectName());
exeprocess->startDetached(temp);

// append the process to the list
processList.append(exeprocess);

}

/*
// process finished
*/
void Widget::processFinished(int state)
{
// get sender of the signal
QProcess *exitprocess = qobject_cast<QProcess *>(sender());

// loop through the list and match the process id
for (i=0;i<processList.size();i++){
    if (processList[i]->pid() == exitprocess->pid()){
        // delete the icon
        delete (processList.takeAt(i));
        return;
    }
}

}
@

[aabc]

That is odd...

[vezprog]

Found this on another thread:

QProcess::startDetached() [doc.qt.nokia.com] are static methods and therefore never send signals.

[vezprog]

So I have somewhat figured it out...and I am kind of stuck but I think I know why. Here's what I did.

@
/*
// app button clicked (slot)
*/
void Widget::appButtonClicked()
{
// get sender of the signal
QToolButton *button = qobject_cast<QToolButton *>(sender());

for (i=0;i<processList.size();i++){
    // check if the process is already open
    QStringList objectNameSplit;
    objectNameSplit = QString(processList[i]->objectName()).split("*");
    if (objectNameSplit.size() > 1){
        if (objectNameSplit[0] == button->objectName()){
            Q_PID pidQt = (Q_PID)QString(objectNameSplit[1]).toInt();
            EnumWindows(EnumWindowsProc, (LPARAM)pidQt);  // get the window handles
            return;
        }
    }
}

// format the exe location
QString temp = button->objectName();
temp = temp.replace("/", "\\\\");
temp = "\"" + temp + "\"";

QString tempWd;
QStringList tempArgs;
qint64 tempPid;

// start the process
QProcess *exeprocess = new QProcess();
exeprocess->startDetached(temp, tempArgs, tempWd, &tempPid);

// set the object name for future reference
QString objectName = button->objectName() + "*" + QVariant(tempPid).toString();
exeprocess->setObjectName(objectName);

// append the process to the list
processList.append(exeprocess);

}
@

When I started the process, I got the process ID. Next if the application is already open, I used the windows API EnumWindows which loops through each window until call false within the callback functions.

Here is the standard windows api call back function:
@
/*
// window enumeration callback (GLOBAL FUNCTION NOT IN CLASS)
*/
BOOL CALLBACK EnumWindowsProc(HWND hWnd, LPARAM lParam)
{
// get the window process ID
DWORD searchedProcessId = (DWORD)lParam;
DWORD windowProcessId = 0;
GetWindowThreadProcessId(hWnd,&windowProcessId);

// check the process id match
if (windowProcessId == searchedProcessId){
    ShowWindow(hWnd, SW_SHOW);
    return FALSE;
}
return TRUE;  //continue enumeration

}
@

where I pass in the process ID...If it matches, then I return false and stop the enumeration loop. Unfortunately the ShowWindow function fails to bring the window to the foreground...

Question, when QProcess starts, does it handle a point to the parent process? or the child process created by the QProcess? Because I might be trying to bring the dock app to the foreground instead of the opened exectuable.