[SOLVED] Bring to front window application managed with QProcess

[Bonride]

Hello, I'm developing a Qt desktop app. This app executes another external app (assistant) managed with QProcess. But when I push the button that shows the assistant, that window does not appear in front of the mainwindow.
I've tryed with:

• In mainwindow.h:

@public slots:
void on_actionAssistant_triggered();

private:
QProcess assistantProcess;@

• In mainwindow.cpp:

@void MainWindow::on_actionAssistant_triggered()

{
if(!assistantProcess.isOpen())
{
const QStringList args = getAssistantProcessArguments();

    assistantProcess.start(QLatin1String("assistant"), args);

    if (!assistantProcess.waitForStarted())
    {
        return;
    }
}

QByteArray byteArray;
byteArray.append("show contents;");
assistantProcess.write(byteArray);
...@

But it does not work. Any suggestion?
Thanks in advance.

[vittalonline]

Hi Bonride

use this flag in mainwindow
setWindowFlags(windowFlags()|Qt::WindowStaysOnBottomHint);

or

setWindowFlags(windowFlags()|Qt::WindowStaysOnTopHint);
in external app

[MuldeR]

I don't think he want's the new process' window to permanently stay or on top, nor his "main" process' window to permanently stay on bottom.

--

I'd rather do:
@unsigned long childPID= assistantProcess.pid()->dwProcessId;
EnumWindows(focusChildProcWindow, reinterpret_cast<LPARAM>(&childPID));@

Using a callback function like this:
@static BOOL CALLBACK focusChildProcWindow(HWND hwnd, LPARAM lParam)
{
DWORD processId = reinterpret_cast<WORD>(lParam);
DWORD windowProcessId = NULL;
GetWindowThreadProcessId(hwnd, &windowProcessId);
if(windowProcessId == processId)
{
SwitchToThisWindow(hwnd, TRUE);
SetForegroundWindow(hwnd);
return FALSE;
}

return TRUE;
}@

This will enumerate all windows and bring the desired window (the window belonging to your child process) to the front.

[Bonride]

Thank you both for answering, I really needed is what has answered MuldeR, but I get an error. Do not quite understand the code so i do not understand the error. I put the error text below (the first two are warning):

In function 'BOOL focusChildProcWindow(HWND, LPARAM)':
warning: converting to non-pointer type 'DWORD {aka long unsigned int}' from NULL [-Wconversion-null]

At global scope:
warning: 'BOOL focusChildProcWindow(HWND, LPARAM)' defined but not used [-Wunused-function]

In function ZN10MainWindow34on_actionNeuralAssistant_triggeredEv':* error: undefined reference to MainWindow::focusChildProcWindow(HWND__, long)@8'
ld returned 1 exit status

This is what I've done:

In mainwindow.h:
@static BOOL CALLBACK focusChildProcWindow(HWND hwnd, LPARAM lParam);@

In mainwindow.cpp:
@static BOOL CALLBACK focusChildProcWindow(HWND hwnd, LPARAM lParam)
{
DWORD processId = reinterpret_cast<WORD>(lParam);
DWORD windowProcessId = NULL;
GetWindowThreadProcessId(hwnd, &windowProcessId);
if(windowProcessId == processId)
{
SwitchToThisWindow(hwnd, TRUE);
SetForegroundWindow(hwnd);
return FALSE;
}

return TRUE;
}

void MainWindow::on_actionNeuralAssistant_triggered()
{
unsigned long childPID= assistantProcess.pid()->dwProcessId;

EnumWindows(focusChildProcWindow, reinterpret_cast<LPARAM>(&childPID));

...
}@

Regards

[MuldeR]

1. Remove function declaration of focusChildProcWindow() from your .h file. You only need that function in the same .cpp file where the function is defined, so no need to add a forward declaration to the "public" header file.

2. You can ignore the type-cast warning for now ;)

3. Not quite sure about the linker error, but probably will go away when you fix the first issue.

[Bonride]

It works!
Thank you very much MuldeR.