A camera problem.

[J.Hilk]

@jenya7
maybe its a typical object lifetime problem.

where does your Camera instance exist/live ?

[JonB]

@jenya7
Just to make sure, what happens in your code after you call your takeImage()? Do you allow the main event loop to run, or do you have other code which does not?

[jenya7]

@J-Hilk said in A camera problem.:

@jenya7
maybe its a typical object lifetime problem.

where does your Camera instance exist/live ?

It's a global object. I call it's methods from a command line parser object.

[J.Hilk]

@jenya7 soooo, inside main() ?

[jenya7]

@JonB said in A camera problem.:

@jenya7
Just to make sure, what happens in your code after you call your takeImage()? Do you allow the main event loop to run, or do you have other code which does not?

well..I guess it's running, cause my command lines parser reacts and process my commands.

[jenya7]

@J-Hilk said in A camera problem.:

@jenya7 soooo, inside main() ?

actually for debug purposes I instantiated it in other module - command line parser, but it's static and never goes out of scope.

[J.Hilk]

@jenya7

static

thats actually forbidden, no QObject based object must be created before the QCoreApplication instance. Static objects will be created before the QCoreApplication instance.

[jenya7]

@J-Hilk said in A camera problem.:

@jenya7

static

thats actually forbidden, no QObject based object must be created before the QCoreApplication instance. Static objects will be created before the QCoreApplication instance.

I mean it it's created without static attribute, but i's not locally allocated.

[jenya7]

If I only could drill down to the cause of
"Image Capture Error: Camera not ready"
What makes it not ready for m_imageCapture...

[JonB]

@jenya7
I know nothing about cameras and captures, so no idea about causes. I will say your definition of void Camera::ReadyForCaptureChanged(bool ready) is wrong, since it does not examine the ready parameter value. But if you say it's never hit that is moot.

[jenya7]

@JonB said in A camera problem.:

@jenya7
I know nothing about cameras and captures, so no idea about causes. I will say your definition of void Camera::ReadyForCaptureChanged(bool ready) is wrong, since it does not examine the ready parameter value. But if you say it's never hit that is moot.

Yes. But it never hits if (ready) line.

void Camera::ReadyForCaptureChanged(bool ready)
{
    if (ready)
    {
        m_isCapturingImage = true;
        m_imageCapture->capture();

        m_camera->unlock();
    }
}

[J.Hilk]

@jenya7
do you call show() on your viewfinder instance ? It will probably never change its state, if the viewfinder is not "visible"

[JonB]

@jenya7
Yes, at least the code is right, but won't help if that never gets hit.
Bearing in mind I know nothing about cameras, why did you comment out the m_camera->isCaptureModeSupported(...) lines, what do these actually return? If they return false presumably that would explain why you never get QCameraImageCapture::readyForCaptureChanged ?

Oh I see @J-Hilk has chimed in with some knowledge of this camera stuff....

[jenya7]

@J-Hilk said in A camera problem.:

@jenya7
do you call show() on your viewfinder instance ? It will probably never change its state, if the viewfinder is not "visible"

It can be an issue.
Although I create an object in mainwindow.cpp

QCameraViewfinder *v_finder;

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    v_finder= new QCameraViewfinder(this);

    ui->setupUi(this);
    ui->textEditTerminalTx->installEventFilter(this);
}

It's not physically allocated. The app wasn't suppose to have such widget.
So on v_finder->show() I get an exception.
Is it possible to emulate the viewfinder ?

[jenya7]

This post is deleted!

[jsulm]

@jenya7 said in A camera problem.:

It's not physically allocated

It is, see the first line in the constructor

[JonB]

@jenya7
What is "not physically allocated", and why do you get an exception on what?

There is a basic example at https://doc.qt.io/qt-5/qcameraviewfinder.html

camera = new QCamera;

viewfinder = new QCameraViewfinder();
viewfinder->show();

camera->setViewfinder(viewfinder);

imageCapture = new QCameraImageCapture(camera);

camera->setCaptureMode(QCamera::CaptureStillImage);
camera->start();

Did you test whether just this code might work for you?

You also ought check those m_camera->isCaptureModeSupported(...) I mentioned, else you are whistling in the wind....

[jenya7]

@JonB
viewfinder = new QCameraViewfinder(); is an empty object, not tied to any widget. in the original example viewfinder is tied to a StackedWidget panel.

[jenya7]

@jsulm said in A camera problem.:

@jenya7 said in A camera problem.:

It's not physically allocated

It is, see the first line in the constructor

It doesn't work

[jsulm]

@jenya7 said in A camera problem.:

viewfinder = new QCameraViewfinder(); is an empty object, not tied to any widget.

It's not "empty". And a widget does not have to be "tied" to another widget. If it is not and you call show() on it it will be shown in its own window, but it should not crash...