Accessing the functions of custom QWidget class using Signals and Slots - c++

Question

I have a MediaView class which inherits QWidget and has GUI components. And i have another class MediaController which handles the changes made on the GUI components.
I need:
to enable buttons when i receive the signal finishedLoadingFile()
So here is a sample how my class looks:
MediaView.cpp
MediaView::MediaView(QWidget* parent) : QWidget(parent)
{
m_controller = new MediaController(this);
m_btnPlay = new QPushButton(m_mediaButtons);
m_btnPlay->setIcon(QIcon(":/images/play.png"));
m_btnPlay->setIconSize(QSize(32, 32));
m_btnPlay->move(100, 10);
m_btnPlay->resize(39, 38);
m_btnPlay->setToolTip("Play");
m_btnPause = new QPushButton(m_mediaButtons);
m_btnPause->setIcon(QIcon(":/images/pause.png"));
m_btnPause->setIconSize(QSize(32, 32));
m_btnPause->move(150, 10);
m_btnPause->resize(39, 38);
m_btnPause->setToolTip("Pause");
m_btnPlay->setEnabled(false);
m_btnPause->setEnabled(false);
connect(m_btnOpen, SIGNAL(clicked(bool)), m_controller, SLOT(loadFile()));
connect(m_btnPlay,SIGNAL(clicked(bool)),m_controller,SLOT(buttonPlayClicked()));
connect(m_btnPause,SIGNAL(clicked(bool)),m_controller,SLOT(buttonPauseClicked()));
}
void MediaView::enableButtons()
{
m_btnPlay->setEnabled(true);
m_btnPause->setEnabled(true);
}
MediaController.cpp
MediaController::MediaController(QWidget* parent) : QWidget(parent)
{
MediaView* view = new MediaView(this); //loop here
connect(this, SIGNAL(loadingFileFinished(), view, SLOT(enableButtons()));
}
void MediaController::loadFile()
{
m_filePath = "";
m_filePath = QFileDialog::getOpenFileName(this, "Choose a .txt file with paths to gtt streams", QString(),
QString("text file(*.txt)"));
if (m_filePath.isEmpty())
{
return;
}
m_file = "";
m_file.append(m_filePath.toLocal8Bit().constData());
emit finishedLoadingFile();
}
Issue:
I wish to call the enableButtons() in the MediaView class. But when i instantiate the MediaView class inside MediaController, app crashes because they keep calling each others constructors in a loop. Reason being, they both communicate using signals and slots so i need to instantiate objects of their respective classes.
Alternatives:
I would like to know whether if it is possible to access the widgets from MediaController class so that i can use them there itself?
If not, a better way to communicate between view and controller?

Answer 1

Each MediaView creates a MediaController, and each MediaController creates another MediaView, that generates the infinite loop, the appropriate thing is to create a MediaController in MediaView and make the connections:
MediaView::MediaView(QWidget* parent) : QWidget(parent)
{
m_controller = new MediaController(this);
connect(m_controller, &MediaController::loadingFileFinished, this, &MediaView::enableButtons);
[...]
}
it is not necessary to create a new MediaView within MediaController.
If you want to access MediaView from MediaController you can do it through parent since MediaView is the parent of MediaController:
MediaController.h
MediaView *view;
MediaController.cpp
MediaController::MediaController(QWidget* parent) : QWidget(parent)
{
view = qobject_cast<QMediaView *>(parent);
//or
// connect(this, &MediaController::loadingFileFinished, view, &MediaView::enableButtons);
}