/EDIT: solved, see my comment in the 1st answer!/
I am currently building an application which only has a tray icon displayed, so it doesn't have any windows.
Well, in the tray icon I've included a QAction so as to close the application. The thing is, that I get seg fault when I call exit(0); from that function. This is some example code:
//I have a reason for setting it to be a QTimer, please don't even comment on this
class Boot_Timer : public QTimer {
Q_OBJECT
public:
explicit Boot_Timer(QObject *parent = 0) : QTimer(parent) {
}
public Q_SLOTS:
void set_up_command_line_tray(){
//Setting up the tray Icon.
QSystemTrayIcon *trayIcon_cmd = new QSystemTrayIcon(this);
trayIcon_cmd->setIcon(QIcon(":/icons/Pictures/myapp.png"));
trayIcon_cmd->setToolTip("My tray tooltipp");
QMenu *changer_menu = new QMenu;
QAction *Quit_action = new QAction(tr("&Quit"), this);
Quit_action->setIconVisibleInMenu(true);;
connect(Quit_action, SIGNAL(triggered()), this, SLOT(close_application()));
changer_menu->addAction(Quit_action);
trayIcon_cmd->setContextMenu(changer_menu);
trayIcon_cmd->show();
}
void close_application(){
//HERE I GET SEG FAULT
exit(0);
}
};
Boot_Timer boottimer;
#include "main.moc"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
//making some checks (code omitted)
...
boottimer.set_up_command_line_tray()
return app.exec();
}
So, the tray icon is shown normally and perfectly, but when I choose to Quit the application using the menu I've added to the tray icon, I get a seg fault. I guess that I cannot quit the application using exit(int state) outside main() function and its functions that don't have a parent...
What is the correct way to quit my application, then?
Thanks in advance for any answers!
Try to call
qApp->quit(0);
instead of
exit(0);
Remember to #include <QApplication>.
Thanks, that didn't solve it. For some reason, the thing that solved it was to do the following: QSystemTrayIcon *trayIcon_cmd = new QSystemTrayIcon(0); instead of QSystemTrayIcon *trayIcon_cmd = new QSystemTrayIcon(this)
Related
My application is designed in that way that different plugins can set the central widget of the main windows to show the desired content.
This works so far.
But if I set a QQuickView-WindowContainer as central widget, the app does not quit when I close the main window.
If I set a "normal" widget like QPushButton as central widget the appliation quits just fine. Why is that?
This is the code of a minimal example which shows this behaviour (MainWindow is a class created from the QtCreator wizard):
class AppCore : public QObject
{
Q_OBJECT
public:
explicit AppCore(QObject *parent = 0);
signals:
public slots:
void showMainWindow();
private:
MainWindow *m_mainWindow;
};
AppCore::AppCore(QObject *parent) :
QObject(parent)
{
}
void AppCore::showMainWindow()
{
QQuickView *view;
QWidget *container;
view = new QQuickView();
container = QWidget::createWindowContainer(view);
view->setSource(QUrl("qrc:/main.qml"));
m_mainWindow = new MainWindow();
//m_mainWindow->setCentralWidget(new QPushButton("Button"));
m_mainWindow->setCentralWidget(container);
m_mainWindow->show();
}
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
AppCore appCore;
appCore.showMainWindow();;
return a.exec();
}
This looks like a bug. I see a dead lock in debugger: v8::internal::RuntimeProfiler::WaitForSomeIsolateToEnterJS and QQmlDataLoader::shutdownThread wait for each other. I can't find a good workaround for this issue.
I found a dirty hack that solved the issue. If container is deleted a bit earlier, all works ok:
void MainWindow::closeEvent(QCloseEvent *e) {
QMainWindow::closeEvent(e);
if (e->isAccepted() && centralWidget()) {
delete centralWidget();
}
}
You probably should send a bug report. Note that m_mainWindow is not needed to reproduce the issue. Using container->show(); gives the same result.
This was my original question:
I just want to take a screenshot (using the Print key) of my fullscreen QtQuick 2 application. But all I get is a black or sometimes white screenshot. When the application is not started in fullscreen it works.
SOLUTION
I thought I post a really nice solution here,
even though it does not solve the original problem of taking the screenshot with an external tool.
Starting with the suggestion from the accepted answer I did the following:
First I added a signal to my QML main class (in main.qml)
signal takeScreenShot()
This signal is emmited by pressing a certain button.
Then I wrote a C++ / QT class autside the QML code to handle this signal:
class QMLSupplement : public QObject
{
Q_OBJECT
public:
QQuickView* view;
public:
QMLSupplement(QObject* parent = 0);
public slots:
void takeScreenShot();
};
The reference to QQuickView is used to take the screenshot.
void QMLSupplement::takeScreenShot()
{
QString file;
file = QDateTime::currentDateTime().toString("yyyy-MM-dd_hhmmss");
file += ".png";
qDebug() << "taking screenshot, saving here:" << file;
view->grabWindow().save(file);
}
Finally I connect the signal and the slot in main.cpp:
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
QQuickView view;
view.setSource(QUrl::fromLocalFile("./qml/main.qml"));
view.setResizeMode(QQuickView::SizeRootObjectToView);
QObject* rootObject = (QObject*) view.rootObject();
QMLSupplement supplement;
supplement.view = &view;
QObject::connect(rootObject, SIGNAL(takeScreenShot()),
&supplement, SLOT(takeScreenShot()));
view.show();
// view.showFullScreen();
return app.exec();
}
That's a limitation of the platform where you're running. If you care about this working, you need to implement the functionality yourself. Qt provides you with enough to get the contents of the Qt Quick 2 window and post it to the clipboard as an image.
In your print key handler, if you detect that the window is full-screen, you need to pass the QQuickWindow instance to a helper function:
void grabAndCopy(QQuickWindow * window) {
QApplication::clipboard()->setImage(window->grabWindow());
}
...
if (window->windowState() == Qt::WindowFullScreen) grabAndCopy(window);
I am trying to open a new dialog Window from a existing dialog on a a button click event,but I am not able to do this as i opened the dialog window from MainWindow.
I am trying with:
Dialog1 *New = new Dialog1();
New->show();
Is there a different way of opening dialog window form existing dialog Window???
There must be some other problem, because your code looks good to me. Here's how I'd do it:
#include <QtGui>
class Dialog : public QDialog
{
public:
Dialog()
{
QDialog *subDialog = new QDialog;
subDialog->setWindowTitle("Sub Dialog");
QPushButton *button = new QPushButton("Push to open new dialog", this);
connect(button, SIGNAL(clicked()), subDialog, SLOT(show()));
}
};
class MainWindow : public QMainWindow
{
public:
MainWindow()
{
Dialog *dialog = new Dialog;
dialog->setWindowTitle("Dialog");
dialog->show();
}
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.setWindowTitle("Main Window");
w.show();
return a.exec();
}
By the way, note how I've connected QPushButton's "clicked" signal to QDialog's "show" slot. Very handy.
I am new to QT and I did have a similar problem. In my case, I was calling the new dialog from a function from the main dialog. I was using dlg->show which does not wait until the result of the new dialog. Hence the program still running. I change dlg->show for dlg->exec and the dialog works now. In your code, the dialog seems to be a local variable, perhaps you have the same problem. Other option could be to use a static pointer instead.
Dialog1 *newDlg = new Dialog1();
this->hide();
int result = newDlg->exec();
this->show();
delete newDlg;
in mainwindow.h file you should declare a pointer to your new dialog
and include the new dialog.h like
#include <myNewDialog.h>
private:
Ui::MainWindow *ui;
MyNewDialog *objMyNewDialog;
and after that you can call your dialog to be shown up in mainwindow.cpp
like
void MainWindow::on_btnClose_clicked()
{
objMyNewDialog= new MyNewDialog(this);
objMyNewDialog->show();
}
I'm just starting out with Qt on a Mac and working through:
http://doc.qt.nokia.com/4.7/gettingstartedqt.html
When I run the second example which has the following code:
#include <QtGui>
int main(int argv, char **args)
{
QApplication app(argv, args);
QTextEdit textEdit;
QPushButton quitButton("Quit");
QObject::connect(&quitButton, SIGNAL(clicked()), qApp, SLOT(quit()));
QVBoxLayout layout;
layout.addWidget(&textEdit);
layout.addWidget(&quitButton);
QWidget window;
window.setLayout(&layout);
window.show();
return app.exec();
}
The application starts up fine and works fine. The only issue occurs when I click the "Quit" button. When I do that the crash reporter is invoked and osx says the app quit unexpectedly.
Anything obvious I'm doing wrong?
Thanks
The problem is the order of the delete if you declare variables on the stack. The best it to give your object parents so that they can destroy the children.
int main(int argc, char **argv)
{
QApplication app(argc, argv);
QWidget window;
// If window get's destroyed, it will destroy it's children...
QTextEdit textEdit(&window);
QPushButton quitButton("Quit",&window);
QObject::connect(&quitButton, SIGNAL(clicked()), qApp, SLOT(quit()));
QVBoxLayout layout;
layout.addWidget(&textEdit);
layout.addWidget(&quitButton);
window.setLayout(&layout);
window.show();
return app.exec();
}
PS: Did you actually try a debugger to see where it crashes? It will give you an idea ;) My suggestion is to take a working Qt example and play with it.
PS2: The order I created the widgets also prevents the crash...
Try:
QTextEdit * textEdit = new QTextEdit;
QPushButton * quitButton = new QPushButton("Quit");
I'm adding a bunch of QActions to my main window's menus. These actions can also be triggered by the keyboard, and I want the shortcut to be visible in the menu, as usual, e.g.
-----------------
|Copy Ctrl+C|
-----------------
I can do this using QAction.setShortcut(). However, I don't want these QActions to be triggered by the shortcuts; I'm handling all keyboard input separately elsewhere.
Is this possible? Can I disable the shortcut in the QAction but still have the shortcut text (in this example Ctrl + C) in my menus?
EDIT: The way I ended up doing it is connecting to the menu's aboutToShow() and aboutToHide() events, and enabling/disabling the shortcuts so they are only active when the menu is shown. But I'd appreciate a cleaner solution...
You could inherit from QAction and override QAction::event(QEvent*):
class TriggerlessShortcutAction : public QAction
{
public:
...ctors...
protected:
virtual bool event(QEvent* e)
{
if (e->type() == QEvent::Shortcut)
return true;
else
return QAction::event(e);
}
};
This will cause any events of type QEvent::Shortcut sent to your actions to not trigger the 'triggered()' signals.
action.setText("Copy\tCtrl+C");
This will look like an action with a shortcut, but the shortcut is not actually installed.
Here is a full example:
#include <QtGui>
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
QMainWindow win;
QMenu *menu = win.menuBar()->addMenu("Test");
// This action will show Ctrl+T but will not trigger when Ctrl+T is typed.
QAction *testAction = new QAction("Test\tCtrl+T", &win);
app.connect(testAction, SIGNAL(triggered(bool)), SLOT(quit()));
menu->addAction(testAction);
// This action will show Ctrl+K and will trigger when Ctrl+K is typed.
QAction *quitAction = new QAction("Quit", &win);
quitAction->setShortcut(Qt::ControlModifier + Qt::Key_K);
app.connect(quitAction, SIGNAL(triggered(bool)), SLOT(quit()));
menu->addAction(quitAction);
win.show();
return app.exec();
}