Unable to open file with qt app on mac - c++

Question

I am trying to associate custom files with an osx app. I have a plist that associates files with the app, but double clicking a file opens the app with no data inside.
Calling
someapp.app/Contents/MacOs/someapp somefile.abc
from the terminal opens the file correctly inside the app.
MyApp::MyApp(int& argc, char**argv): QApplication(argc, argv)
{
...
m_MainWindow = new MainWindows();
m_MainWindow->show();
if(argc > 1 && argv[1])
m_MainWindow->openFile(QString(argv[1]);
else
m_MainWindow->showStartupDialog(); // to create a new document
}
Searching around I found that I should somehow implement QFileOpenEvent... how ?
This example looks good... but I don't understand how to combine the constructor and the event...
How do I make this work ?
(OS X 10.6-10.9, app created using Qt 4.8)

Answer 1

The following is the adapted code, that will respond to the OpenFileEvent either on start or during the normal functioning - and also allow opening o file from command line or creating a new file
MyApp::MyApp(int& argc, char**argv): QApplication(argc, argv)
{
...
m_MainWindow = new MainWindows();
m_MainWindow->show();
if(argc > 1 && argv[1])
m_MainWindow->openFile(QString(argv[1]);
else if (m_macFileOpenOnStart != "")
m_MainWindow->openFile(m_macFileOpenOnStart); // open file on start if it exists
else
m_MainWindow->showStartupDialog(); // to create a new document
}
// responds to FileOpenEvent specific for mac
bool MyApp::event(QEvent *event)
{
switch(event->type())
{
case QEvent::FileOpen:
{
QFileOpenEvent * fileOpenEvent = static_cast<QFileOpenEvent *>(event);
if(fileOpenEvent)
{
m_macFileOpenOnStart = fileOpenEvent->file();
if(!m_macFileOpenOnStart.isEmpty())
{
if (m_MainWindow)
{
m_MainWindow->openFile(m_macFileOpenOnStart); // open file in existing window
}
return true;
}
}
}
default:
return QApplication::event(event);
}
return QApplication::event(event);
}

Answer 2

i'm using a QApplication derived class that emits a signal when file is ready:
#ifndef OPENWITHAPPLICATION_H
#define OPENWITHAPPLICATION_H
#include <QApplication>
#include <QFileOpenEvent>
#include <QMessageBox>
class OpenWithApplication : public QApplication
{
Q_OBJECT
public:
QString fileName;
OpenWithApplication(int &argc, char **argv)
: QApplication(argc, argv)
{
}
signals:
void fileReady(QString fn);
protected:
bool event(QEvent *event)
{
if (event->type() == QEvent::FileOpen) {
QFileOpenEvent *openEvent = static_cast<QFileOpenEvent *>(event);
fileName = openEvent->file();
emit fileReady(fileName); // the file is ready
}
return QApplication::event(event);
}
};
#endif // OPENWITHAPPLICATION_H
main.cpp connects created OpenWindowApplication with the MainWindow object so once the file is ready, the signal is emitted and received by it for processing
#include "mainwindow.h"
#include <openwithapplication.h>
int main(int argc, char *argv[])
{
OpenWithApplication a(argc, argv);
MainWindow w;
w.connectOpenWithApp(&a);
w.show();
return a.exec();
}
and MainWindow connects fileReady signal with a lambda func that opens the file and updates widget
void MainWindow::connectOpenWithApp(OpenWithApplication*app) {
connect(app, &OpenWithApplication::fileReady, [this](QString fileName){
bw->open(fileName);
bw->update();
});
}
here's the result: