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Signal Slot connection from different classes

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  • A Offline
    A Offline
    aamer4yu
    wrote on last edited by
    #7

    Just use
    class Class_B : public QThread

    QThread is already inherited from QObject.
    Does it work ?

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    0
    • R Offline
      R Offline
      rokemoon
      wrote on last edited by
      #8

      QThread inherits from QObject, so class Class_B : public QThread -,public QObject-

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      0
      • H Offline
        H Offline
        huckfinn
        wrote on last edited by
        #9

        Ok, removed.

        @
        const Class_B * pCB = ref2ClassB.GetInstance();
        /// error C2594: 'argument' : ambiguous conversions from 'const Class_B *' to 'const QObject *'
        connect( pCB, SIGNAL(trigger_Do_Some(int, int)), this, SLOT( slot_Do_Some(int, int)) );
        /// error C2664: 'bool QObject::connect(const QObject *,const char *,const QObject *,const char *,Qt::ConnectionType)' : cannot convert parameter 1 from 'Class_B' to 'const QObject *'
        1> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
        connect( ref2ClassB, SIGNAL(trigger_Do_Some(int, int)), this, SLOT( slot_Do_Some(int, int)) );
        @

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        0
        • R Offline
          R Offline
          rokemoon
          wrote on last edited by
          #10

          [quote]
          All classes that contain signals or slots must mention Q_OBJECT at the top of their declaration. They must also derive (directly or indirectly) from QObject.
          [/quote] from "here":http://doc.qt.nokia.com/4.7/signalsandslots.html

          const Class_B * pCB = ref2ClassB.GetInstance();
          // here the Class_B must inherit from QOBject
          connect( pCB, SIGNAL(trigger_Do_Some(int, int)), this, SLOT( slot_Do_Some(int, int)) );

          // here you need the pointer
          connect( &ref2ClassB, SIGNAL(trigger_Do_Some(int, int)), this, SLOT( slot_Do_Some(int, int)) );

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          0
          • H Offline
            H Offline
            huckfinn
            wrote on last edited by
            #11

            [quote author="rokemoon" date="1313050079"]
            // here you need the pointer
            connect( &ref2ClassB, SIGNAL(trigger_Do_Some(int, int)), this, SLOT( slot_Do_Some(int, int)) );
            [/quote]

            This way I get an error C2594: 'argument' : ambiguous conversions from 'Class_B *' to 'const QObject *'

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            0
            • R Offline
              R Offline
              rokemoon
              wrote on last edited by
              #12

              Class_B must inherite QObject (directly or indirectly), can you give us latest code of your Class_B?

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              0
              • H Offline
                H Offline
                huckfinn
                wrote on last edited by
                #13

                Latest Class_B:
                @
                #include <QtCore/QThread>

                template class SWITCHEXPORT QMap< int, QString >;

                class Class_A;
                class QModelIndex;

                class SWITCHEXPORT Class_B : public QThread {
                Q_OBJECT

                public:
                /// @brief Constructor
                Class_B( void );

                void aMethod();

                signal:
                void trigger_Do_Some(int, int);

                private:
                QMap< int, QString > categoryNameByID;
                }
                @

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                • R Offline
                  R Offline
                  rokemoon
                  wrote on last edited by
                  #14

                  Can you tell us why you use QThread? Can you try inherite from QObject and tell us about result?

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                  0
                  • H Offline
                    H Offline
                    huckfinn
                    wrote on last edited by
                    #15

                    There is a @QThread::start();@ in the source .cpp .

                    So when I inherit from both @clas.s Class_B : public QThread, public QObject@ and I am able to compile it.

                    But now I have linking errors:
                    @
                    3>Linking...
                    3> Creating library C:\MyProject\Debug\MyProject.lib and object C:\MyProject\Debug\MyProject.exp
                    3>Class_B.obj : error LNK2001: unresolved external symbol "public: static struct QMetaObject const Class_B::staticMetaObject" (?staticMetaObject@Class_B@@2UQMetaObject@@B)
                    3>Class_A.obj : error LNK2001: unresolved external symbol "public: static struct QMetaObject const Class_B::staticMetaObject" (?staticMetaObject@Class_B@@2UQMetaObject@@B)
                    3>Class_3.obj : error LNK2001: unresolved external symbol "public: static struct QMetaObject const Class_B::staticMetaObject" (?staticMetaObject@Class_B@@2UQMetaObject@@B)
                    3>Class_B.obj : error LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __thiscall Class_B::metaObject(void)const " (?metaObject@Class_B@@UBEPBUQMetaObject@@XZ)
                    3>Class_B.obj : error LNK2001: unresolved external symbol "public: virtual void * __thiscall Class_B::qt_metacast(char const *)" (?qt_metacast@Class_B@@UAEPAXPBD@Z)
                    3>Class_B.obj : error LNK2001: unresolved external symbol "public: virtual int __thiscall Class_B::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@Class_B@@UAEHW4Call@QMetaObject@@HPAPAX@Z)
                    3>Class_B.obj : error LNK2019: unresolved external symbol "protected: void __thiscall Class_B::trigger_Do_Some(long,long)" (?trigger_Do_Some@Class_B@@IAEXJJ@Z) referenced in function "public: virtual void __thiscall Class_B::HandleMessage(void * const)" (?HandleMessage@Class_B@@UAEXQAX@Z)
                    3>C:\MyProject\Debug\MyProject.dll : fatal error LNK1120: 5 unresolved externals
                    @

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                    • M Offline
                      M Offline
                      mrtc3
                      wrote on last edited by
                      #16

                      When you have added Q_OBJECT to Class_B.h recently, then assure yourself that moc_ClassB.cxx has been generated as well.
                      If that is the case, this moc-file should be listed in the .pro or .vcpro file as Source
                      e.g.:
                      @
                      <Files>
                      <Filter Name="Source Files">
                      <File RelativePath="C:\path\moc_Class_B.cxx">
                      </File>
                      <!-- ....etc...-->
                      @

                      There are 10 types. Those who understand binary and those who don't .)

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                      0
                      • H Offline
                        H Offline
                        huckfinn
                        wrote on last edited by
                        #17

                        I added these tags to the vcpro file, now I can compile and run my application.

                        However, now I have a
                        @
                        warning C4584: 'Class_B' : base-class 'QObject' is already a base-class of 'OtherClass'
                        @

                        I dont like warnings :(

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                        • L Offline
                          L Offline
                          loladiro
                          wrote on last edited by
                          #18

                          Multiple inheritance is NOT supported for QObject based classes. Can you change your code?

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                          • R Offline
                            R Offline
                            Ramin7000
                            wrote on last edited by
                            #19

                            main.cpp :
                            @
                            #include <QtGui>
                            #include <converter.h>

                            int main(int argc,char *argv[])
                            {
                            QApplication app(argc,argv);

                            QGraphicsScene scene(0,0,500,300);
                            QGraphicsView view(&scene);
                            
                            QLabel *l = new QLabel();
                            QSlider *s = new QSlider();
                            
                            l->setText("Move the slider handle");
                            s->setOrientation(Qt::Horizontal);
                            
                            l->setGeometry(100,100,150,50);
                            s->setGeometry(100,200,150,50);
                            
                            Converter *ms = new Converter(s,l);
                            
                            
                            scene.addWidget(l);
                            scene.addWidget(s);
                            
                            view.show();
                            return app.exec&#40;&#41;;
                            

                            }@

                            converter.cpp :
                            @
                            #include "converter.h"

                            Converter::Converter(QSlider *s, QLabel *l)
                            {
                            connect(s,SIGNAL(valueChanged(int)),this,SLOT(Changer(int)));
                            connect(this,SIGNAL(Changer(QString)),l,SLOT(setText(QString)));
                            }

                            void Converter::Changer(int x)
                            {
                            Changer(QString::number(x));
                            }
                            @

                            converter.h :
                            @
                            #ifndef CONVERTER_H
                            #define CONVERTER_H

                            #include <QtGui>

                            class Converter : public QObject
                            {
                            Q_OBJECT

                            public:
                            Converter(QSlider*,QLabel*);

                            protected slots:
                            void Changer(int);

                            signals:
                            void Changer(QString);

                            };

                            #endif // CONVERTER_H
                            @

                            [Edit: Please use @ tags around code. I have added them here. -- mlong]

                            Ramin Lohrasbi

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                            0
                            • V Offline
                              V Offline
                              vittalonline
                              wrote on last edited by
                              #20

                              Use Q_PROPERTY for passing arguments in Class-B

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                              0

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