Launch a second view on a pushed button

[Lucian]

Ok, i will try to find an example and i will post if i solve this.

[Lucian]

Hey @mrjj

Can you give me one last hand of help ?:D
Look what i have done

class Process : public QObject
{
    Q_OBJECT
private:
    QProcess* proc = new QProcess(this);
    QQuickView* view = new QQuickView();

public slots:
    void startProcess();
};

In process.cpp

void Process::startProcess()
{
    this->proc->start("C:\\Windows\\System32\\calc.exe", QIODevice::ReadWrite);
    this->proc->waitForFinished(-1);
}

void Process::run() {
    view->setSource(QUrl("qrc:/loading.qml"));
    view->setResizeMode(QQuickView::SizeRootObjectToView);
    view->show();

    QObject::connect(view,SIGNAL(view::statusChanged),this, SLOT(Process::startProcess()));
}

Now the qml is show correct but doesn't start the calc.exe after the qml is load.
Is corect how i use QObject::connect?

[mrjj]

@Lucian said in Launch a second view on a pushed button:

Hi
Good work
There is a slight adjustment

QObject::connect(view,SIGNAL(view::statusChanged),this, SLOT(Process::startProcess()));

should be

QObject::connect(view,SIGNAL(statusChanged() ),this, SLOT(startProcess() ) );
( no class:: in front when using the old syntax)

And i would love if you did

qDebug() << "status sig:" << QObject::connect(view,SIGNAL(statusChanged() ),this, SLOT(startProcess() ) );

so you can check it says TRUE;

Also
void Process::startProcess() {
qDebug() << "startProcess called";
...

So we know it connects works and the startProcess is called.

[Lucian]

Something is wrong.
It say : "status sig: false"
So the signal is not generated.

Also say:
QObject::connect: No such signal QQuickView::statusChanged()

[mrjj]

@Lucian
ahh sorry.
Didnt check the docs. ( shame on me)

its just missing the parameter.

void QQuickView::statusChanged(QQuickView::Status status)

so its
QObject::connect(view,SIGNAL(statusChanged(QQuickView::Status) ),this, SLOT(startProcess(QQuickView::Status) ) );

NOte. only Type is added. NOT the paramtername

and u need/could to change slot too

void Process::startProcess( QQuickView::Status thesatus) {
so here u can actually see if its ready etc.

but u dont need to use the status :)

[jsulm]

@Lucian
Please check documentation: http://doc.qt.io/qt-5/qquickview.html#statusChanged
The signal has a parameter, so it should be:

qDebug() << "status sig:" << QObject::connect(view,SIGNAL(statusChanged(QQuickView::Status) ),this, SLOT(startProcess() ) );

[Lucian]

Thanks @mrjj , @jsulm
Now it's better.
"status sig: true"

But the startProcess() still isn't call yet.
The message from slot is not printed and the calc.exe doesn't show up, but at lest the status from QQuickView is changed.

[jsulm]

@Lucian Try to connect first:

void Process::run() {
    QObject::connect(view,SIGNAL(view::statusChanged),this, SLOT(Process::startProcess()));
    view->setSource(QUrl("qrc:/loading.qml"));
    view->setResizeMode(QQuickView::SizeRootObjectToView);
    view->show();
}

[Lucian]

Yes @jsulm .
It work but this doesn't solve my problem.
I try to connect status change with startProcess because the progress bar (loading.qml) was block by waitForFinish(-1).
Now is happening the same.
The signal and the slot are called in the right order but also loading.qml doesn't popup until i close the calc.exe.

[jsulm]

@Lucian Why do you wait for the process to finish?

this->proc->waitForFinished(-1);

Are you aware that this call blocks the event loop (so your app is blocked)?

[Lucian]

Yes @jsulm .
I need to do that because the process what will be launch will create a txt file. This file will be use farder so i need to be sore the process has finished his job and has created the txt.

[jsulm]

@Lucian No need to wait for this! Just connect to http://doc.qt.io/qt-5/qprocess.html#finished signal - when it is called the process has finished...
Qt is an asynchronous framework - you should adapt to asynchronous programming.

[Lucian]

But how will wait my application to create the txt file ? Because after the process is finished i want to read from that .txt file created by him and if i read before creation the application will fail.
So i need to connect the finish signal from QProcess with a slot that make the read from .txt file? :D

[jsulm]

@Lucian Yes, you simply connect a slot to that signal and do what you want with that file in this slot.

[Lucian]

I have made some changes and now look like this:

void Process::startProcess()
{
    qDebug() << "startProcess called";
    this->proc->start("C:\\Windows\\System32\\calc.exe", QIODevice::ReadWrite);
    qDebug() << "connect status :" << QObject::connect(proc,SIGNAL(QProcess::finished()),this, SLOT(addData()));
}

And the slot:

void Process::addData()
{
    qDebug() << "addData call:";
    SomeClasss c;    
    c.read();
}

The problem is again with type of the signal:
*QObject::connect: No such signal QProcess::QProcess::finished()

From documentation (Qt doc) doesn't seems to be something wrong.

[Lucian]

I have solved the problem like this:

    qDebug() << "connect status :" << QObject::connect(proc,SIGNAL(finished(int, QProcess::ExitStatus)),this, SLOT(addData()));

I will mark this as Solved.
Thank you for your help @jsulm , @mrjj .