Display an image in a QGraphicsview

[emilio]

Hello,

I'm developing an application that displays a default image in a QGraphicsiew (named viewer) when it's executed and displays other image when a button it's clicked but my code doesn't work:

main.cpp

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    catiz w;    
    w.showFullScreen();
 
    return a.exec();
}

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    catiz w;    
    w.showFullScreen();

    return a.exec();
}

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catiz.cpp

...
catiz::catiz(QWidget *parent) : QWidget(parent),ui(new Ui::catiz)
{
    ui->setupUi(this);
 
    QGraphicsScene scene;
    QPixmap pixmap(":/init.jpg");
    scene.addPixmap(pixmap);
    ui->viewer->setScene(&scene);
}
...

...
catiz::catiz(QWidget *parent) : QWidget(parent),ui(new Ui::catiz)
{
    ui->setupUi(this);

    QGraphicsScene scene;
    QPixmap pixmap(":/init.jpg");
    scene.addPixmap(pixmap);
    ui->viewer->setScene(&scene);
}
...

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What could be wrong? I'm using QtCreator.

Best regards.

[cooper]

Hi emilio,

try to use a graphic view widget on your frame. and add the following code in your app:

...
catiz::catiz(QWidget *parent) : QWidget(parent),ui(new Ui::catiz)
{
    ui->setupUi(this);
 
    QGraphicsScene scene;
    QPixmap pixmap(":/init.jpg");
    scene.addPixmap(pixmap);
    //ui->viewer->setScene(&scene);
 
    // add here
    ui->graphicsView->setScene(scene);
    ui->graphicsView->show();
}
...

...
catiz::catiz(QWidget *parent) : QWidget(parent),ui(new Ui::catiz)
{
    ui->setupUi(this);

    QGraphicsScene scene;
    QPixmap pixmap(":/init.jpg");
    scene.addPixmap(pixmap);
    //ui->viewer->setScene(&scene);

    // add here
    ui->graphicsView->setScene(scene);
    ui->graphicsView->show();
}
...

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hope it works.

[emilio]

Hello cooper,

ui->viewer

ui->viewer

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it's a QGraphicsview widget, thanks anyway.

[cooper]

does it work after you add:

ui->viewer->show();

ui->viewer->show();

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[emilio]

I tried but it still doesn't work.

[sibercekirge]

Hello, I am new to Qt an C++. I had the same problem. After looking for the forum I managed to display an image on an graphicsView which is on QWidget user form
I created a new project with QtGui App. put a push button and a graphicsView widget. when I push the button. it creates a scene object, a pixmap and attach it to the viewer
Below is the code

#include <QtGui>
#include "resimoku.h"
#include "ui_resimoku.h"
 
ResimOku::ResimOku(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::ResimOku)
{
    ui->setupUi(this);
 
}
 
ResimOku::~ResimOku()
{
    delete ui;
}
 
void ResimOku::on_pushButton_clicked()
{
    QGraphicsScene *scene =  new QGraphicsScene;
    QPixmap pixmap("C:/resim.jpg");
    scene->addPixmap(pixmap);
    ui->view->setScene(scene);
    ui->view->show();
}

#include <QtGui>
#include "resimoku.h"
#include "ui_resimoku.h"

ResimOku::ResimOku(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::ResimOku)
{
    ui->setupUi(this);

}

ResimOku::~ResimOku()
{
    delete ui;
}

void ResimOku::on_pushButton_clicked()
{
    QGraphicsScene *scene =  new QGraphicsScene;
    QPixmap pixmap("C:/resim.jpg");
    scene->addPixmap(pixmap);
    ui->view->setScene(scene);
    ui->view->show();
}

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The decleration of the scene object is solved the problem I think. It is a matter of C++ knowledge which i have a little.
Thanks for forum users.

[jano_alex_es]

Try to create the QGraphicsScene dinamically... because static variables are deleted when you are out of the scope. If it's dinamic going out of the scope only deletes the pointer.

[sibercekirge]

I made a change to scene object decleration in order to use it out of pushbuttons scope. I declare it as a private member of ResimOku object. create it in ResimOku decleration and use it in pushbutton events. With this the scope of scene object is ResimOku object scope.
Header file

#ifndef RESIMOKU_H
#define RESIMOKU_H
#include <QtGui>
#include <QMainWindow>
 
namespace Ui {
    class ResimOku;
}
 
class ResimOku : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit ResimOku(QWidget *parent = 0);
 
    ~ResimOku();
 
private:
    Ui::ResimOku *ui;
    QGraphicsScene *scene;
private slots:
    void on_pushButton_2_clicked();
    void on_pushButton_clicked();
};
 
#endif // RESIMOKU_H

#ifndef RESIMOKU_H
#define RESIMOKU_H
#include <QtGui>
#include <QMainWindow>

namespace Ui {
    class ResimOku;
}

class ResimOku : public QMainWindow
{
    Q_OBJECT

public:
    explicit ResimOku(QWidget *parent = 0);

    ~ResimOku();

private:
    Ui::ResimOku *ui;
    QGraphicsScene *scene;
private slots:
    void on_pushButton_2_clicked();
    void on_pushButton_clicked();
};

#endif // RESIMOKU_H

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CPP FILE

#include "resimoku.h"
#include "ui_resimoku.h"
 
 
ResimOku::ResimOku(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::ResimOku)
{
    ui->setupUi(this);
    scene = new QGraphicsScene;
}
 
ResimOku::~ResimOku()
{
    delete ui;
}
 
void ResimOku::on_pushButton_clicked()
{
    QPixmap pixmap("C:/resim.jpg");
    scene->addPixmap(pixmap);
    ui->view->setScene(scene);
    ui->view->show();
}
 
void ResimOku::on_pushButton_2_clicked()
{
    QPixmap pixmap("C:/resim2.jpg");
    scene->addPixmap(pixmap);
    ui->view->setScene(scene);
    ui->view->show();
}

#include "resimoku.h"
#include "ui_resimoku.h"


ResimOku::ResimOku(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::ResimOku)
{
    ui->setupUi(this);
    scene = new QGraphicsScene;
}

ResimOku::~ResimOku()
{
    delete ui;
}

void ResimOku::on_pushButton_clicked()
{
    QPixmap pixmap("C:/resim.jpg");
    scene->addPixmap(pixmap);
    ui->view->setScene(scene);
    ui->view->show();
}

void ResimOku::on_pushButton_2_clicked()
{
    QPixmap pixmap("C:/resim2.jpg");
    scene->addPixmap(pixmap);
    ui->view->setScene(scene);
    ui->view->show();
}

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[Harry443]

Hello QtCentre......

How can we display the image on GraphicsView in widget.ui using the above code through pushbutton signals???
I had used QWidget and unable to succeed in doing so.
plzz help me in achieving the same