Move QGraphicsScene? - c++

Question

How is it possible to move a QGraphicsscene inside a View?
I have a Scene filling the entire View. The Scene is containing one (will be more later) Item (QImage for now), which is updated every few seconds.
My goal is to move the content of the item with mouseMoveEvent. While the item is beeing updated (lasts a few seconds) i want to move the whole Scene and reset the movement after the item is fully updated.
For now I tried overriding the mouseMoveEvent of QGraphicsScene and emit a signal to PPI-Class containintg the QGraphicsScene Objet. The onMouseMoveEvent-slot then tries to set the sceneRect. But this does not work, I get a StackOverflow-Exception.
How can i get this to work? Thank you!
main.cpp
#include "ppi.h"
#include <QtGui/QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
PPI w;
w.show();
return a.exec();
}
ppi.ui (just added a graphicsview with size of 1024x1024 and name gVPPI to the mainwindow)
<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>PPIClass</class>
<widget class="QMainWindow" name="PPIClass">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>1079</width>
<height>1113</height>
</rect>
</property>
<property name="windowTitle">
<string>PPI</string>
</property>
<widget class="QWidget" name="centralWidget">
<widget class="QGraphicsView" name="gVPPI">
<property name="geometry">
<rect>
<x>10</x>
<y>10</y>
<width>1024</width>
<height>1024</height>
</rect>
</property>
</widget>
</widget>
<widget class="QMenuBar" name="menuBar">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>1079</width>
<height>21</height>
</rect>
</property>
</widget>
<widget class="QToolBar" name="mainToolBar">
<attribute name="toolBarArea">
<enum>TopToolBarArea</enum>
</attribute>
<attribute name="toolBarBreak">
<bool>false</bool>
</attribute>
</widget>
<widget class="QStatusBar" name="statusBar"/>
</widget>
<layoutdefault spacing="6" margin="11"/>
<resources>
<include location="ppi.qrc"/>
</resources>
<connections/>
</ui>
ppi.h
#ifndef PPI_H
#define PPI_H
#include <QtGui/QMainWindow>
#include "ui_ppi.h"
#include "ppiscene.h"
#include <QGraphicsView>
#include <QGraphicsPixmapItem>
#include <QDebug>
class PPI : public QMainWindow
{
Q_OBJECT
public:
PPI(QWidget *parent = 0, Qt::WFlags flags = 0);
~PPI();
private:
Ui::PPIClass ui;
PPIScene* ppiScene;
QGraphicsPixmapItem *videoPixmap;
QImage newImage();
bool moveReset;
QPointF moveCoordinates;
QPointF startMoveCoordinates;
protected slots:
void onMouseMoved(QPointF coordinates, QGraphicsSceneMouseEvent *event);
};
#endif // PPI_H
ppi.cpp
#include "ppi.h"
PPI::PPI(QWidget *parent, Qt::WFlags flags)
: QMainWindow(parent, flags)
{
ui.setupUi(this);
ppiScene = new PPIScene(this);
ppiScene->setSceneRect(0,0,1024,1024);
ui.gVPPI->setScene(ppiScene);
ui.gVPPI->setMouseTracking(true);
videoPixmap = ppiScene->addPixmap(QPixmap::fromImage(newImage()));
startMoveCoordinates = QPointF(0,0);
connect(ppiScene, SIGNAL(mouseMoved(QPointF, QGraphicsSceneMouseEvent*)), this, SLOT(onMouseMoved(QPointF, QGraphicsSceneMouseEvent*)));
}
PPI::~PPI()
{
}
void PPI::onMouseMoved(QPointF coordinates, QGraphicsSceneMouseEvent *event)
{
//move view
if(event->modifiers() & Qt::ControlModifier)
{
moveCoordinates = coordinates;
//ui.gVPPI->translate(moveCoordinates.x() - startMoveCoordinates.x(), moveCoordinates.y() - startMoveCoordinates.y());
ppiScene->setSceneRect(moveCoordinates.x() - startMoveCoordinates.x(), moveCoordinates.y() - startMoveCoordinates.y(), 1024, 1024);
qDebug() << coordinates;
qDebug() << "dx" << moveCoordinates.x() - startMoveCoordinates.x();
qDebug() << "dy" << moveCoordinates.y() - startMoveCoordinates.y();
qDebug() << "";
}
}
QImage PPI::newImage() {
QImage image = QImage(1024, 1024, QImage::Format_Indexed8);
image.setColorCount(256);
for (int i = 0; i < 256; ++i)
image.setColor(i, qRgb(i, 0, 0));
image.fill(200);
return image;
}
ppiscene.h
#ifndef PPISCENE_H
#define PPISCENE_H
#include <QGraphicsScene>
#include <QGraphicsSceneMouseEvent>
class PPIScene : public QGraphicsScene
{
Q_OBJECT
public:
PPIScene(QObject *parent);
~PPIScene();
QPointF mouseCoordinates;
private:
protected:
void mouseMoveEvent(QGraphicsSceneMouseEvent *event);
signals:
void mouseMoved(QPointF coordinates, QGraphicsSceneMouseEvent *event);
};
#endif // PPISCENE_H
ppiscene.cpp
#include "ppiscene.h"
PPIScene::PPIScene(QObject *parent)
: QGraphicsScene(parent)
{
}
PPIScene::~PPIScene()
{
}
void PPIScene::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
mouseCoordinates = event->scenePos();
emit mouseMoved(mouseCoordinates, event);
QGraphicsScene::mouseMoveEvent(event);
}