Launch a second view on a pushed button

Lucian

Hey guys,

I am new with Qt and i have a problem.
I try to make a nice interface and my interface has tow view. First one is launch from main. First view has a button that launch a process (QProces) and after the process is finished it start the second view.
Now i wold like when the process launch also start a new view with a progress bar.

Right now i don't really want the process bar to reflect the real time that takes the process the finish. I just want to be able to start them at once.

In main i have something like this :

    QQuickView firstview;
    view.setSource(QUrl("qrc:/firstView.qml"));
    view.setResizeMode(QQuickView::SizeRootObjectToView);
    firstview.show();

My QML for progress bar looks like this:

import QtQuick 2.3
import QtQuick.Controls 1.4
Item{
    ProgressBar {
        id: pb1
        minimumValue: 0
        maximumValue: 100
        value: 0
    }

    // Timer to show off the progress bar
    Timer {
        id: simpletimer
        interval: 100
        repeat: true
        running: true
        onTriggered: pb1.value < pb1.maximumValue ? pb1.value += 1.0 : pb1.value = pb1.minimumValue
    }
}

If i replace in main firstview.qml with loding.qml it works.
But if i add them in the method that handle the pushed button it popup an empty window.
My button handle looks like this:

void Test::Butt() {
    this->proc->start("some_executabele", QIODevice::ReadWrite);
    this->proc->waitForFinished(-1);
}

If i modify the function like this

    view->setSource(QUrl("qrc:/loading.qml"));
    view->setResizeMode(QQuickView::SizeRootObjectToView);
    view->show();
    this->proc->start("some_executabele", QIODevice::ReadWrite);
    this->proc->waitForFinished(-1);

The output is something like this:
alt text
While if i run the some code from main:

    QQuickView view;
    view.setSource(QUrl("qrc:/test.qml"));
    view.setResizeMode(QQuickView::SizeRootObjectToView);
    view.show();

The output looks like this:
alt text

Can somebody give me a clue, why doesn't load ok the qml file when is call from button handler? :D
Thx :)

Lucian

Please...any idea are welcome. :(

mrjj

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

this->proc->start("some_executabele", QIODevice::ReadWrite);
this->proc->waitForFinished(-1);

If you remove this from void Test::Butt()
does it work then ?

Lucian

Hey @mrjj ,
I have also try this but doesn't work eider. :(

mrjj

@Lucian

ok can u try

QQuickView * view = new QQuickView(this)
view->setSource(QUrl("qrc:/test.qml"));
view->setResizeMode(QQuickView::SizeRootObjectToView);
view->show();

(it leaks but , just for test)

Lucian

No @mrjj
Still have the same problem. I can't solve this thing. (

mrjj

@Lucian
Ok then its not a variable running out of scope.

And you have tested that
Test::Butt()
is called?

Also try
QQuickView * view = new QQuickView;
instead of
QQuickView * view = new QQuickView()

Not sure if u want the view to be inside something or in a window.
IF you dont give a Qwidget a parent it will become a window.
Else its inserted into parent.

Also the code

  QQuickView view;
    view.setSource(QUrl("qrc:/test.qml"));
    view.setResizeMode(QQuickView::SizeRootObjectToView);
    view.show();

Can work from main but if u do the same in a function, you have this problem that
as soon as functions ends, it will delete view
so right after view.show(); is called it will be deleted. ( so might not show at all)
That is why i showed
QQuickView * view = new QQuickView(this)
That wont run out of scope.

Lucian

I have try everything, it doesn't work. Every time creates a new window but is empty.
I don't understand why doesn't work..
If i remove

this->proc->start("some_executabele", QIODevice::ReadWrite);
this->proc->waitForFinished(-1);

Works ok...
My function in pushed button now looks like this:

    QQuickView* view
    view = new QQuickView();
    view->setSource(QUrl("qrc:/loading.qml"));
    view->setResizeMode(QQuickView::SizeRootObjectToView);
    view->show();
    this->proc->start("some_executabele", QIODevice::ReadWrite);
    this->proc->waitForFinished(-1);

Thank you for your help @mrjj

mrjj

@Lucian
Hi
It looks ok.
( Note, u create a new QQuickView each time. So its a leak but that u can fix later )

I would look at what
http://doc.qt.io/qt-5/qquickview.html#errors
returns.

To see if it has some issue running/loading.

Update:
Just to be sure. We are debugging the QQuickView and setSource
and nothing related to waitForFinished ?

Or are you saying that it works until you use QProcess then windows is empty?

Lucian

Yes,,works until i use QProcess.
If i let the button handle without QProcess it works.
It is possible so lunch a QQuickView in a new QProcess? Maybe current process is the reason why doesn't work .

mrjj

@Lucian

Then i think is what happens.
The setSource starts to load. its still loading when functions returns.

then waitForFinished blocks the event loop
so there is no time to draw when the QML is ready.

so I would try to use the
http://doc.qt.io/qt-5/qquickview.html#statusChanged

and if status is ready, then there in that slot i would run the QProcess.

In that way you first block the event loop when the
QML is 100% finished loading and that should work better.

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.