How to show a Dialog from loop - wait - return to caller

[ademmler]

Hi there,

I have a question regarding loops and Events.
I loop through a list of colors. If a color is missing I show a search dialog.
When another color is selected the user fires a signal by pressing a button.
After this he closes the dialog ... the loop should proceed from here - but it simply stops.

thx in advance

for (unsigned int i = 0; i < IP.inkList.size(); i++) {

if(IP.inkList.name == "") {
               ColorList *mColorList = new ColorList("color", this);                
               connect(mColorList, &ColorList::signalSetColor, this, &MyApp::slotSetColor);
               mColorList->setModal(true);
               mColorList->show();

               //Stop loop until dialog is closed
               QEventLoop loop;
               connect(mColorList, SIGNAL(destroyed()), & loop, SLOT(quit()));
               loop.exec();

//How do I write the connect with new syntax - I tried this but it did not work:
//connect(mColorList, &mColorList::destroyed, this, &loop::quit);               
}

... go ahead and do more
}

[mpergand]

@ademmler said in How to show a Dialog from loop - wait - return to caller:

mColorList->show();

Why not call exec() instead ?

[ademmler]

@mpergand

I tried and it did not worked also.

[mpergand]

@ademmler
Show your code.

[ademmler]

@mpergand

my mistake - I have overseen and had

loop.exec(); instead of mColorList->exec();

Hence you are right and provided the correct answer. Thank you!

[Pl45m4]

@ademmler said in How to show a Dialog from loop - wait - return to caller:

//How do I write the connect with new syntax - I tried this but it did not work:
//connect(mColorList, &mColorList::destroyed, this, &loop::quit);

connect(mColorList, &ColorList::destroyed, this, &QEventLoop::quit);

[ademmler]

@Pl45m4 said in How to show a Dialog from loop - wait - return to caller:

onnect(mColorList, &ColorList::destroyed, this, &QEventLoop::quit);

thx for your suggestion. If I use this I get this error:

*/Users/ademmler/GitSpace/spectraproof3/spectraproof.cpp:1865: error: no matching member function for call to 'connect'
spectraproof.cpp:1865:17: error: no matching member function for call to 'connect'
connect(mColorList, &ColorList::destroyed, this, &QEventLoop::quit);

/Users/ademmler/Qt/5.15.13/clang_64/lib/QtCore.framework/Headers/qobject.h:242:43: note: candidate function [with Func1 = void (QObject::*)(QObject ), Func2 = void (QEventLoop::)()] not viable: no known conversion from MyApp ' to 'const typename QtPrivate::FunctionPointer<void (QEventLoop::)()>::Object *' (aka 'const QEventLoop *') for 3rd argument
static inline QMetaObject::Connection connect(const typename QtPrivate::FunctionPointer<Func1>::Object sender, Func1 signal,

If I do this

connect(mColorList, &ColorList::destroyed, &loop, &QEventLoop::quit);

the app compiles, stops but does not run again after the window have closed. When I close the main window in the background, than the application finishes this task in the "background" ... kind of wired behavoir I think.

[JonB]

@ademmler
We could spend time discussing/diagnosing this (hint: closing dialog does not generate destroyed signal, so QEventLoop::quit() is not called and loop continues to run). But it's pointless since what you want is mColorList->exec() anyway, no QEventLoop, no connect()s.

[ademmler]

@JonB You are right - I use mColorList->exec() now!

But I took the chance, which @Pl45m4PI gave me,
to check the syntax of the connect statement also.