Can't emit signal in android.

bmeric

I have this signal in my project;

void sendImage(cv::Mat &imgMat, QImage &imgQImage);

Project compiles on both Mingw and Visual Studio but when i try to build for Android, i get "error: no matching function for call to imageReader::sendImage(cv::Mat&, QImage)" error.

I tested my pro file on different project, try clean/run qmake/clean/rebuild, remove cv::Mat from signal but nothing worked.

What can be the problem?

Edit;

#ifndef READERMANAGERQMLINTERFACE_H
#define READERMANAGERQMLINTERFACE_H

#include <QObject>
#include <QDebug>

#include "readermanager.h"
class ReaderManagerQMLInterface : public QObject
{
    Q_OBJECT
public:
    explicit ReaderManagerQMLInterface(QObject *parent = 0);
    ~ReaderManagerQMLInterface();

    readerManager rManager;
  
private:

signals:
    void reqIm();

public slots:
    void sendImage(QImage &imgQImage); //cv::mat removed
};

#endif // READERMANAGERQMLINTERFACE_H

imageReader;

#ifndef IMAGEREADER_H
#define IMAGEREADER_H

#include <QObject>
#include <QImage>
#include <QDebug>
#include <QThread>
#include <QDir>
#include <QFile>

#include <opencv/cv.h>
class imageReader : public QObject
    {
        Q_OBJECT
    public:
        explicit imageReader(QObject *parent = 0);
        ~imageReader();
        imgHelpers imHelpers;

    signals:
        void sendImage(QImage &imgQImage);//cv::mat removed
    public slots:
        void requestImage();
        void setFrame(int frameID);
        void loadImage(QString fileName);
    }

SGaist

Hi and welcome to devnet,

Do you get any warning related to that function when building for Windows ?

bmeric

@SGaist said:

Hi and welcome to devnet,

Do you get any warning related to that function when building for Windows ?

Hi, thanks :)

No, i get no warning with -Wall.

SGaist

I meant on stdout when running your application. Which connection syntax are you using ?

bmeric

Nope, i get nothing on stdout.

I connect signal/slot like this;

QObject::connect(this->rManager.imreader, SIGNAL(sendImage(QImage&)), this, SLOT(sendImage(QImage&)) );

I also tried new syntax but nothing changed :/

connect(this->rManager.imreader, &imageReader::sendImage, this, &MainWindow::sendImage );

bmeric

Hi,

I opened an issue in bugreports.qt.io, you can find details in there.

SGaist

To sum up what happened is that you were trying to send a reference to a temporary object thus it failed

bmeric

@SGaist

Yes, basically; "emit signal( Object() );" works with Visual C++(and iirc Intel) but not with GCC.

And for the Mingw; it was my mistake :)(sorry about that), when i tested my codebase with it, i didn't use "signal( Object() )" but didn't realize i didn't tested with final codebase(sometimes Qt Creator does not build with final changes-especially with qml- unless clean/rebuild)