QCameraImageCapture is saving image only on program exit

[carobnodrvo]

Recently I've been testing my Qt 5.5 C++ (Win7) program on one older laptop and found a weird bug, namely I'm displaying camera image and on some action (when letter P is pressed on keyboard) save that image in Pictures folder. Everything works fine (on P click image is saved) until I start new thread (for doing some background process). After the new thread is started, on "take a picture" event nothing happens (image is not visible in Pictures folder; onImageError[/ is not called) and after I close the application all images that are being captured are saved.

I'm not sure if I made myself clear so here is one more time steps I perform:
Open app -> take a photo -> photo is saved -> start new thread -> take couple of pictures (they are not saved) -> close app -> app closed (ALL pictures are saved)

The important part I have to mention is that all object I use (QCamera, QCameraImageCapture and thread that I start) are pointers.
And I am not 100% sure that starting this thread cause the issue but every time I start the thread, images are not saved.

Here are source that I am using:

Capturing camera image:

void MyClass::onCameraSeleced(QCameraInfo camera_info) {
	camera_ = new QCamera(camera_info);
pture(camera_);
	camera_image_capture_->setCaptureDestination(QCameraImageCapture::CaptureToFile);
 
	camera_image_capture_ = new QCameraImageCa
	// connect to capture signals
	connect(camera_image_capture_, SIGNAL(imageCaptured(int, const QImage&)), 
		this, SLOT(onImageCaptured(int, const QImage&)));
	connect(camera_image_capture_, SIGNAL(imageSaved(int, const QString&)), 
		this, SLOT(onImageSaved(int, const QString&)));
	connect(camera_image_capture_, SIGNAL(error(int,QCameraImageCapture::Error,QString)), this,
            SLOT(onImageError(int,QCameraImageCapture::Error,QString)));
 
	camera_->setCaptureMode(QCamera::CaptureStillImage);
	camera_->setViewfinder(ui->cameraWidget);
	camera_->start();
}
 
void MyClass::takeScreenShot(){
	camera_->searchAndLock();
 
	camera_image_capture_->capture(name);
 
	camera_->unlock();
}
 
MyClass::~MyClass()
{	
	if(camera_ != NULL)
  {
  	camera_->unload();
  	delete camera_;
  }
}

void MyClass::onCameraSeleced(QCameraInfo camera_info) {
	camera_ = new QCamera(camera_info);
pture(camera_);
	camera_image_capture_->setCaptureDestination(QCameraImageCapture::CaptureToFile);

	camera_image_capture_ = new QCameraImageCa
	// connect to capture signals
	connect(camera_image_capture_, SIGNAL(imageCaptured(int, const QImage&)), 
		this, SLOT(onImageCaptured(int, const QImage&)));
	connect(camera_image_capture_, SIGNAL(imageSaved(int, const QString&)), 
		this, SLOT(onImageSaved(int, const QString&)));
	connect(camera_image_capture_, SIGNAL(error(int,QCameraImageCapture::Error,QString)), this,
            SLOT(onImageError(int,QCameraImageCapture::Error,QString)));

	camera_->setCaptureMode(QCamera::CaptureStillImage);
	camera_->setViewfinder(ui->cameraWidget);
	camera_->start();
}

void MyClass::takeScreenShot(){
	camera_->searchAndLock();

	camera_image_capture_->capture(name);

	camera_->unlock();
}

MyClass::~MyClass()
{	
	if(camera_ != NULL)
  {
  	camera_->unload();
  	delete camera_;
  }
}

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Starting new thread that cause this issue:

my_thread_ = new MyThread();
 
QThreadPool::globalInstance()->start(my_thread_);

my_thread_ = new MyThread();

QThreadPool::globalInstance()->start(my_thread_);

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MyThread:

void MyThread::run()
{
  while(run_)
  {
    .
    .
    .
    QThread::msleep(static_speed_yaw_data_->getTimeInterval());
  }
}

void MyThread::run()
{
  while(run_)
  {
    .
    .
    .
    QThread::msleep(static_speed_yaw_data_->getTimeInterval());
  }
}

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[Lesiok]

Method MyThread::run() is blocking thread event loop. Use standard QThread::run() and create a method fired by QTimer with static_speed_yaw_data_->getTimeInterval() period.

[carobnodrvo]

Method MyThread::run() is blocking thread event loop. Use standard QThread::run() and create a method fired by QTimer with static_speed_yaw_data_->getTimeInterval() period.

Thread which captures image is different from MyThread. Do I still need to do stuff you mentioned above? (it's not really clear to me why is image not captured and why should it be with our response)

[anda_skoa]

You probably shouldn't call "MyThread" like that since it is obviously a QRunnable and not a QThread.

Or maybe better make it an actual thread, the while loop suggests that you want to control it, not hand over to some thread pool.

Cheers,
_

[carobnodrvo]

You were right!

I have no idea how that part slipped me.

After changing QRunnable to QThread everything worked (tested it today).

Thanks!