I got stuck with GUI update. I have 2 classes : ControlWidget in main thread and CameraController in the separate thread.
Qt Code: 
  1. int main(int argc, char **argv)
  2. {
  3.     QApplication app(argc, argv);
  4.     CameraController *cameraController = new CameraController;;
  5.     ControlWidget *main_window = new ControlWidget;
  6.     Thread getImageThread; 
  7.     cameraController->moveToThread(&getImageThread);
  8.     getImageThread.start();
  9.     QTimer get_images_timer;
  10.     QObject::connect(&get_images_timer, SIGNAL(timeout()), cameraController, SLOT(onTimerOut()), Qt::QueuedConnection);
  11.     QObject::connect(cameraController, SIGNAL(sendLabel(QImage)), main_window, SLOT(getImage(QImage)), Qt::QueuedConnection);
  12.     QObject::connect(&get_images_timer, SIGNAL(timeout()), main_window, SLOT(update()), Qt::QueuedConnection);
  13.     get_images_timer.start(2000);
  14.     app.exec();
  15.     return 0;
  16. }
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so every 2 seconds i want to get images from camera thread and send them to main thread (that actionally happens, so I have QImage at the main_window object). Then I want to put this QImage to the cam1 and cam2 QLabels. And here I am stuck:

First: when I use setPixmap() method the QLabel.width() and QLabel.height() are different then image.width() and image.height() or pixmap.width() and pixmap.height().

Second: I can not visualize the QLabel. If I do this->ImageLayout->addWidget(cam1) nothing really happens. this->update doesn't help either.

Shall I have an extra worker for GUI Update?

What am I doing wrong?

Source code for more information :

CameraController.h


Qt Code: 
  1. class CameraController : public QObject
  2. {
  3. 	Q_OBJECT 
  4.  
  5. private: 
  6. 	CoreApi::InstanceHandle g_hApi;
  7. 	CoreApi::DeviceCollectionHandle hDeviceCollection;
  8. 	CoreApi::DeviceHandle hDevice;
  9. 	CoreApi::CameraPortHandle first_cam;
  10. 	Common::FrameHandle frame;
  11.  
  12. 	QPixmap pixmap;
  13. 	QImage image;
  14.  
  15. public: 
  16. 	CameraController();
  17. 	~CameraController();
  18. 	QLabel outLabel;
  19.  
  20. public slots:
  21. 	void onTimerOut();
  22.  
  23. signals:
  24. 	QImage sendLabel(QImage image);
  25. };
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CameraController.cpp
Qt Code: 
  1. CameraController::CameraController()
  2. {
  3. 	try
  4. 	{
  5. 		this->g_hApi = CoreApi::Instance::initialize();
  6. 		this->hDeviceCollection = this->g_hApi->deviceCollection();
  7. 		this->hDevice = hDeviceCollection->device(0);
  8. 		this->first_cam = hDevice->cameraPort(0);
  9. 		first_cam->autoConfigure();
  10. 		first_cam->liveStart();
  11. 	}
  12. 	catch (GeneralException& e)
  13. 	{
  14. 	std::cout << e.what() << std::endl;
  15. 	}
  16. }
  17.  
  18. CameraController::~CameraController()
  19. {
  20. }
  21.  
  22. void CameraController::onTimerOut()
  23. {
  24. 	if (this->first_cam->liveFrameReady())
  25. 	{
  26. 		this->frame = first_cam->liveFrame();
  27. 		this->image =  QImage((uchar*)this->frame->buffer()->data(), this->frame->dataType()->width(), this->frame->dataType()->height(), QImage::Format::Format_RGB888);
  28. 		this->image = this->image.scaled(QSize(this->image.width()/10, this->image.height()/10));
  29. 		std::cout << "width = "<<this->image.width() << "height = " << this->image.height() << std::endl;
  30. 		emit sendLabel(this->image.copy());
  31. 	}
  32. }
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ControlWidget.h

Qt Code: 
  1. class ControlWidget :public QDialog
  2. {
  3. 	Q_OBJECT
  4. private:
  5. 	QGLCanvas *osCanvas;
  6. 	QGridLayout *mainLayout;
  7. 	QGridLayout *buttonLayout;
  8.  
  9. 	QVBoxLayout *settingsLayout;
  10. 	QHBoxLayout *controlLayout;
  11. 	QListWidget *cameraListWidget, *devicesListWidget;
  12. 	QLabel *cameraListLabel, *devicesListLabel, *cameraSettingsLabel, *fpsLabel, *shutterLabel;
  13. 	QHBoxLayout *fpsLayout, *shutterLayout;
  14. 	QLineEdit *fpsEdit, *shutterEdit;
  15. 	QPushButton *saveButton, *saveSettingButton, *applySettingsButton, *chooseFolderButton;
  16. 	QTimer* m_timer;
  17. public:
  18. 	ControlWidget(QWidget *parent = 0);
  19. 	~ControlWidget();
  20. 	QVBoxLayout *imageLayout = new QVBoxLayout;
  21. 	QLabel *cam1 = new QLabel;
  22. 	QLabel *cam2 = new QLabel;
  23. 	QImage *camera_1, *camera_2;
  24. 	void createWidgets();
  25. public slots:
  26. 	void getImage(QImage new_frame);
  27. 	void displayImages();
  28. signals: 
  29. 	void images_loaded();
  30. private slots:
  31. 	void onTimeout()
  32. 	{
  33. 		qDebug() << "Worker::onTimeout get called from controlWidget timer and  ?: " << QThread::currentThreadId();
  34. 	};
  35. };
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ControlWidget.cpp

Qt Code: 
  1. ControlWidget::ControlWidget(QWidget *parent)
  2. {
  3. 	//this->createWidgets();
  4. 	this->m_timer = new QTimer;
  5. 	connect(this->m_timer, SIGNAL(timeout()),this, SLOT(update()));
  6. 	m_timer->start(1000);
  7. }
  8.  
  9. ControlWidget::~ControlWidget()
  10. {
  11. 	delete this->mainLayout;
  12. }
  13.  
  14. void ControlWidget::createWidgets() 
  15. {
  16. 	this->imageLayout->addWidget(cam1);
  17. 	this->imageLayout->addWidget(cam2);
  18. 	this->setLayout(this->imageLayout);
  19. 	this->show();
  20. }
  21.  
  22. void ControlWidget::displayImages()
  23. {
  24. 	QLabel tmp_label ;
  25.  
  26. 	std::cout << "********************************************************************************" << std::endl;
  27. 	std::cout <<"  camera height  = " <<this->camera_1->height() << "   camera width = " << this->camera_1->width() << std::endl;
  28. 	std::cout << "********************************************************************************" << std::endl;
  29. 	QPixmap tmp_pixmap = QPixmap::fromImage(this->camera_1->copy());
  30. 	std::cout << "PIXMAP WIDTH = " << tmp_pixmap.width() << "Pixmap Height = " << tmp_pixmap.height() <<std::endl;
  31. 	tmp_label.setGeometry(200, 200, tmp_pixmap.width(), tmp_pixmap.height());
  32. 	std::cout << "LABELWIDTH = " << tmp_label.width() << "LabelHeight =  " << tmp_label.height() << std::endl; 
  33. 	tmp_label.show();
  34. 	this->cam1 = &tmp_label;
  35. 	this->cam2 = &tmp_label;
  36. 	std::cout << "CAM1 Width = " <<this->cam1->width() << std::endl;
  37. 	this->createWidgets();
  38. }
  39. void ControlWidget::getImage(QImage img)
  40. {
  41. 	std::cout << "********************************************************************************" << std::endl;
  42. 	std::cout << "  img height  = " << img.height() << "   img width = " << img.width() << std::endl;
  43. 	std::cout << "********************************************************************************" << std::endl;
  44. 	this->camera_1 = &QImage(img);
  45. 	this->camera_2 = &QImage(img);
  46. 	this->displayImages();
  47. }
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