c++ - Qt Signals and Slots - nothing happens -
i'm trying connect qml signal c++ slot unsuccessfully.
i had on several other examples think didn't got how root object of qml document...
my problem is, seems signal sent qml file, not received in cpp file. there no errors when execute code.
//counter.h #ifndef counter_h #define counter_h #include <qobject> class counter : public qobject { q_object private: int counter; public: explicit counter(qobject *parent = 0); signals: void counterhaschanged(int); public slots: void click(); }; #endif // counter_h //counter.cpp #include "counter.h" #include <qdebug> counter::counter(qobject *parent) : qobject(parent) { this->counter = 0; qdebug() << "class counter created"; } void counter::click() { this->counter++; qdebug() << "clickregistered() - emit counterhaschanged()"; emit counterhaschanged(counter); } //main.cpp #include <qtgui/qguiapplication> #include "qtquick2applicationviewer.h" #include "counter.h" #include <qobject> #include <qtquick> #include <qdebug> #include <qquickitem> #include <qqmlcontext> #include <qtcore> int main(int argc, char *argv[]) { qguiapplication app(argc, argv); qtquick2applicationviewer viewer; viewer.setmainqmlfile(qstringliteral("qml/statestest2/main.qml")); viewer.showexpanded(); qquickview view; view.setsource(qurl::fromlocalfile("qml/statestest2/main.qml")); qobject *item = view.rootobject(); counter counter; qobject::connect(item, signal(click()), &counter, slot(click())); return app.exec(); } //main.qml import qtquick 2.0 rectangle { id: root width: 360 height: 360 signal click text { text: qstr("hello world") anchors.centerin: parent } mousearea { anchors.fill: parent onclicked: { root.click console.log("click() qml") } } text { text: "clicks: " x: 30 y: 250 } text { id: counter text: "0" x: 75 y: 250 } } i know there tons of topics this.. reason, no other solution worked me.. maybe should change ide :d
i suggest add counter context property.. requires following changes.
//counter.h #ifndef counter_h #define counter_h #include <qobject> class counter : public qobject { q_object private: int counter; public: explicit counter(qobject *parent = 0); signals: void counterhaschanged(int value); public slots: void click(); }; #endif // counter_h the counter.cpp file
//counter.cpp #include "counter.h" #include <qdebug> counter::counter(qobject *parent) : qobject(parent) { this->counter = 0; qdebug() << "class counter created"; } void counter::click() { this->counter++; qdebug() << "clickregistered() - emit counterhaschanged()"; emit counterhaschanged(counter); } the main.cpp file
//main.cpp #include <qtgui/qguiapplication> #include "qtquick2applicationviewer.h" #include "counter.h" #include <qobject> #include <qtquick> #include <qdebug> #include <qquickitem> #include <qqmlcontext> #include <qtcore> int main(int argc, char *argv[]) { qguiapplication app(argc, argv); counter counter; qtquick2applicationviewer viewer; viewer.rootcontext()->setcontextproperty("counterobj",&counter); viewer.setmainqmlfile(qstringliteral("qml/so_qmlcppcommunication/main.qml")); viewer.showexpanded(); return app.exec(); } and in qml file, can access slot of counter object referring counterobj.
//main.qml import qtquick 2.0 rectangle { id: root width: 360 height: 360 signal click text { text: qstr("hello world") anchors.centerin: parent } mousearea { anchors.fill: parent onclicked: { counterobj.click() console.log("click() qml") } } text { text: "clicks: " x: 30 y: 250 } text { id: counter text: "0" x: 75 y: 250 } connections { id:cppconnection target:counterobj ignoreunknownsignals : true oncounterhaschanged:{ //to access signal parameter,please name parameter. console.debug("counter value changed") counter.text = value } } }
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