Edward: "Is the “[=]()” a place holder?"
He's using C++11 lambdas. There are a couple of good explanations here: https://stackoverflow.com/questions/7627098/what-is-a-lambda-expression-in-c11 --- Andy Maloney // https://asmaloney.com twitter ~ @asmaloney <https://twitter.com/asmaloney> On Mon, Feb 1, 2016 at 12:12 PM, Edward Sutton <edward.sut...@subsite.com> wrote: > Hi Prashanth, > > I do not understand how the connect syntax example or how the signal > *filteredEvent* is raised? > > Could you please elaborate on implementation of the connect? > > On Feb 1, 2016, at 10:28 AM, Prashanth Udupa <prashanth.ud...@gmail.com> > wrote: > > Create a Event2Signal class as follows. > > #include <QMap> > #include <QList> > #include <QEvent> > #include <QObject> > > class Event2Signal : public QObject > { > Q_OBJECT > > public: > Event2Signal(QObject *parent=0) : QObject(parent) { } > ~Event2Signal() { } > > void filterEvent(QObject *o, QEvent::Type type) { > if(!o) return; > if( m_objectEventsMap.contains(o) ) { > QList<QEvent::Type> &events = m_objectEventsMap[o]; > if(events.contains(type)) > return; > events.append(type); > } else { > m_objectEventsMap[o].append(type); > o->installEventFilter(this); > } > } > > signals: > void filteredEvent(QObject *o, QEvent *e, bool *filtered); > > protected: > bool eventFilter(QObject *obj, QEvent *e) { > bool filtered = false; > emit filteredEvent(obj, e, &filtered); > return filtered; > } > > private: > QMap<QObject *, QList<QEvent::Type> > m_objectEventsMap; > }; > > Now, lets say you want to take some action when user mouse-presses on a > lineEdit. You can do this > > Event2Signal *e2s = new Event2Signal(lineEdit); > e2s->filterEvent(lineEdit, QEvent::MouseButtonPress); > connect(e2s, &Event2Signal::filteredEvent, [=]() { > // Activate your form and do other things here.. > }); > > > I do not understand how the connect syntax example or how the signal > *filteredEvent* is raised? > > Is the “[=]()” a place holder? > > If I had: > > FormInputData::FormInputData(QWidget *parent) : > > QDialog(parent) > > ,ui(new Ui::FormSoftwareUpdateCheck) > > { > > ui->setupUi(this); > > > // What does the connect code look like ? > connect(e2s, &Event2Signal::filteredEvent, > this, SLOT(mouseButtonPressHandler))); > } > > > void FormInputData::mouseButtonPressHandler() > { > // Show custom calculator entry form > } > > Thanks, > > -Ed > > > > You can reuse this method for handling other kinds of events in > signal-slot style. > > Hope this helps. > > / Prashanth > > On Mon, 1 Feb 2016 at 21:41 Edward Sutton <edward.sut...@subsite.com> > wrote: > >> I want to display a form with a numeric touch key pad plus a decimal >> point when user clicks on a QLIneEdit field. >> >> I did not see any signal such as editingStarted. >> >> What are approaches to implementing a custom data entry? >> >> I am targeting Android and iOS with a QWidget app. >> >> -Ed >> > >> > This email and any files transmitted with it from The Charles Machine > Works, Inc. are confidential and intended solely for the use of the > individual or entity to which they are addressed. If you have received this > email in error please notify the sender. Our company accepts no liability > for the contents of this email, or for the consequences of any actions > taken on the basis of the information provided, unless that information is > subsequently confirmed in writing. Please note that any views or opinions > presented in this email are solely those of the author and do not > necessarily represent those of the company. Finally, the recipient should > check this email and any attachments for the presence of viruses. The > company accepts no liability for any damage caused by any virus transmitted > by this email. > > _______________________________________________ > Interest mailing list > Interest@qt-project.org > http://lists.qt-project.org/mailman/listinfo/interest > >
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