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();
}

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);
}
...

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();
}
...


hope it works.

[emilio]

Hello cooper,


ui->viewer it's a QGraphicsview widget, thanks anyway.

[cooper]

does it work after you add:


ui->viewer->show();

[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();
}

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

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();
}

[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