A camera problem.

jenya7

@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...

I see. I'll try to understand what causes the crash.

JonB

@jenya7 said in A camera problem.:

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

QCameraViewfinder is a QWidget, so don't know what this means. In your case you may need to give it a parent or add it somewhere. I have suggested code you might try before turning to your own code....

jenya7

@JonB said in A camera problem.:

@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
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....

bool supported = m_camera->isCaptureModeSupported(QCamera::CaptureStillImage);

Yes. It's supported.
I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.
Is it normal?

jsulm

@jenya7 said in A camera problem.:

I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.

Where do you see it and where do you create camera object? Can you please post relevant code?

JonB

@jenya7
OK, but why not try the example from the docs, in a standalone test program? Not going to say it again.....

jenya7

@JonB said in A camera problem.:

@jenya7
OK, but why not try the example from the docs, in a standalone test program? Not going to say it again.....

It runs on Windows machine. Have to arrange some camera....

JonB

@jenya7
What runs on Windows machine? It's just sample code, does it not run on whatever platform you are on? You may know better than I, I'll keep quiet now.

jenya7

@jsulm said in A camera problem.:

@jenya7 said in A camera problem.:

I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.

Where do you see it and where do you create camera object? Can you please post relevant code?

I put a break point in the MainWindow constructor and Camera constructor and see which hits the first.
This way it works without errors

QCameraViewfinder *v_finder;

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

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

void Camera::setCamera(const QCameraInfo &cameraInfo)
{
       //........................

     m_camera->setViewfinder(v_finder);

      //............................
}

Is it OK?

JonB

@jenya7 said in A camera problem.:

I put a break point in the MainWindow constructor and Camera constructor and see which hits the first.

And what was the result?!

I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.

At the time your Camera::setCamera() is called, has v_finder = new QCameraViewfinder(this); been executed yet? If not then v_finder in m_camera->setViewfinder(v_finder) will be nullptr....

jenya7

@JonB said in A camera problem.:

@jenya7 said in A camera problem.:

I put a break point in the MainWindow constructor and Camera constructor and see which hits the first.

And what was the result?!

I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.

At the time your Camera::setCamera() is called, has v_finder = new QCameraViewfinder(this); been executed yet? If not then v_finder in m_camera->setViewfinder(v_finder) will be nullptr....

m_camera->setViewfinder(v_finder) is executed first

JonB

@jenya7
Then obviously it is not the right place to put m_camera->setViewfinder(v_finder);.... You cannot execute that line until both m_camera & v_finder have been initialized, so move it somewhere suitable.

jenya7

@JonB said in A camera problem.:

@jenya7
Then obviously it is not the right place to put m_camera->setViewfinder(v_finder);.... You cannot execute that line until both m_camera & v_finder have been initialized, so move it somewhere suitable.

I'll try

mchinand

It seems your code is largely based on the Camera Example; is that correct? Does that example work for you unmodified?

jenya7

@mchinand said in A camera problem.:

It seems your code is largely based on the Camera Example; is that correct? Does that example work for you unmodified?

It's a widget based example. I removed all widget related stuff cause I don't have all these controls for camera operating in my app. I control the camera with commands I type in a terminal.

jsulm

@jenya7 Come on, the question is whether this example works with your camera or not! Can't you simply try that?

jenya7

@jsulm said in A camera problem.:

@jenya7 Come on, the question is whether this example works with your camera or not! Can't you simply try that?

I'll try tomorrow. I have to get a camera.

well...in the original example I press on Capture Photo and it stays inactive forever.

jenya7

How can I pass a default camera instance to use it later?
In camera.h

class Camera : public QMainWindow
{
    Q_OBJECT

    public:
    Camera();
    void Camera::setCamera(const QCameraInfo &cameraInfo);

    const QCameraInfo* default_camera;   
}

in camera.cpp in a constructor

if (cameraInfo == QCameraInfo::defaultCamera())
{
       default_camera = new QCameraInfo(cameraInfo );
        videoDeviceAction->setChecked(true);
}

in main.cpp

g_camera.SetCamera(g_camera.default_camera );

I get
error: reference to type 'const QCameraInfo' could not bind to an lvalue of type 'const QCameraInfo *'

J.Hilk

@jenya7 said in A camera problem.:

I'll try tomorrow. I have to get a camera.

wait!

how do you expect the state to change to a ready for capture == true, when you have no camera connected that could be used ?

jenya7

@J-Hilk said in A camera problem.:

@jenya7 said in A camera problem.:

I'll try tomorrow. I have to get a camera.

wait!

how do you expect the state to change to a ready for capture == true, when you have no camera connected that could be used ?

It's connected. The constructor detects it - "dev/video0".

I just wonted to try the original example on Windows. my app is running on Linux.

jenya7

@JonB said in A camera problem.:

@jenya7
Then obviously it is not the right place to put m_camera->setViewfinder(v_finder);.... You cannot execute that line until both m_camera & v_finder have been initialized, so move it somewhere suitable.

I resolved the issue. Now I get

Ready for capture: true

But on takeImage

QWidget::paintEngine: Should no longer be called
CameraBin warning: "Resource busy or not available."