How to iterate through GraphicsScene items using items()

[MercyYuen]

I would like my QGraphicsScene to go through the GraphicItems that are on the screen, check some of the properties and then change the GraphicItems' color accordingly.

In my QGraphicsScene class I have this code fragment. I expect it to only go through the foreach loop ONCE because there is only one item on the screen right now. But instead, it tries to go through twice. This is a problem because I get a segmentation fault when it tries to go through the loop the second time.

Ideas??

foreach(QGraphicsItem *item, items())
{
            DiagramItem *zone = qgraphicsitem_cast<DiagramItem *>(item);
            myPenColor = zone->zoneColor;
            zone->setPen(myPenColor);
}

foreach(QGraphicsItem *item, items())
{
            DiagramItem *zone = qgraphicsitem_cast<DiagramItem *>(item);
            myPenColor = zone->zoneColor;
            zone->setPen(myPenColor);
}

To copy to clipboard, switch view to plain text mode 

Here is my complete class for context:

#include <QtGui>
#include <sstream>
#include <QGraphicsItem>
 
#include "scribblearea.h"
#include "diagramitem.h"
 
QVector <QPoint> polygonPoints(4);
QPolygon polygon(4);
 
 
QPolygon ScribbleArea::getPoly()
{
    return polygon;
}
 
//! [0]
ScribbleArea::ScribbleArea(QWidget *parent)
    : QGraphicsScene(parent)
{
    //setAttribute(Qt::WA_StaticContents);
    modified = false;
    scribbling = false;
    myPenWidth = 1;
    myPenColor = Qt::blue;
    newZone = false;
    polyIndex = 0;
    zoneCount = 0;
 
 
    QPixmap pix;
    if (!pix.load( ":/images/iterislogo.jpg" ))
    {
        qWarning("Failed to load iterislogo.png");
    }
    else
    {
        QGraphicsPixmapItem *item = this->addPixmap(pix);
            item->setPos(0,500);
    }
}
//! [0]
 
//! [1]
bool ScribbleArea::openImage(const QString &fileName)
//! [1] //! [2]
{
 
    return true;
}
//! [2]
 
//! [3]
bool ScribbleArea::saveImage(const QString &fileName, const char *fileFormat)
//! [3] //! [4]
{
 
    return false;
}
//! [4]
 
//! [5]
void ScribbleArea::setPenColor(const QColor &newColor)
//! [5] //! [6]
{
    myPenColor = newColor;
}
//! [6]
 
//! [7]
void ScribbleArea::setPenWidth(int newWidth)
//! [7] //! [8]
{
    myPenWidth = newWidth;
}
//! [8]
 
void ScribbleArea::timesUp()
{
 
    //DiagramItem *zone = qgraphicsitem_cast<DiagramItem *>(all);
 
    for (int i = 0; i < zoneCount; i++)
    {
        foreach(QGraphicsItem *item, items())
        {
            DiagramItem *zone = qgraphicsitem_cast<DiagramItem *>(item);
            myPenColor = zone->zoneColor;
            zone->setPen(myPenColor);
        }
    }
 
 
 
}
 
void ScribbleArea::activateImage()
//! [9] //! [10]
{
    foreach (QGraphicsItem *item, selectedItems()) {
        DiagramItem *zone = qgraphicsitem_cast<DiagramItem *>(item);
        myPenColor= Qt::red;
        zone->setPen(myPenColor);
 
        zone->toggleState();
 
       }
}
 
void ScribbleArea::deactivateImage()
//! [9] //! [10]
{
    foreach (QGraphicsItem *item, selectedItems()) {
        DiagramItem *zone = qgraphicsitem_cast<DiagramItem *>(item);
        myPenColor = Qt::blue;
        zone->setPen(myPenColor);
 
        zone->toggleState();
 
       }
}
 
//! [9]
void ScribbleArea::clearImage()
//! [9] //! [10]
{
    foreach (QGraphicsItem *item, selectedItems()) {
        delete item;
        zoneCount--;
       }
}
//! [10]
void ScribbleArea::drawZone()
{
    newZone = true;
}
 
//! [11]
void ScribbleArea::mousePressEvent(QGraphicsSceneMouseEvent *event)
//! [11] //! [12]
{
    if (event->button() == Qt::LeftButton) {
        lastPoint = event->scenePos();
        scribbling = true;
 
        if( newZone )       // If drawing a new zone
        {
            polygon.setPoint(polyIndex++, event->scenePos().x(), event->scenePos().y());
 
            if( polyIndex > 3)
            {
                newZone = false;
 
 
                DiagramItem *item;
 
                item = new DiagramItem(this);
                item->setPen(myPenColor);
                addItem(item);
 
                QPointF details = event->scenePos();    // debug purposes only
 
                polyIndex = 0;
                zoneCount++;
            }
        }
    }
        QGraphicsScene::mousePressEvent(event);
}
 
void ScribbleArea::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
 
    QGraphicsScene::mouseMoveEvent(event);
}
 
 
//! [14]
 
//! [15]
 
//! [18]
 
//! [19]
void ScribbleArea::resizeImage(QImage *image, const QSize &newSize)
//! [19] //! [20]
{
    if (image->size() == newSize)
        return;
 
    QImage newImage(newSize, QImage::Format_RGB32);
    newImage.fill(qRgb(255, 255, 255));
    QPainter painter(&newImage);
    painter.drawImage(QPoint(0, 0), *image);
    *image = newImage;
}
//! [20]
 
 
//! [22]

#include <QtGui>
#include <sstream>
#include <QGraphicsItem>

#include "scribblearea.h"
#include "diagramitem.h"

QVector <QPoint> polygonPoints(4);
QPolygon polygon(4);


QPolygon ScribbleArea::getPoly()
{
    return polygon;
}

//! [0]
ScribbleArea::ScribbleArea(QWidget *parent)
    : QGraphicsScene(parent)
{
    //setAttribute(Qt::WA_StaticContents);
    modified = false;
    scribbling = false;
    myPenWidth = 1;
    myPenColor = Qt::blue;
    newZone = false;
    polyIndex = 0;
    zoneCount = 0;


    QPixmap pix;
    if (!pix.load( ":/images/iterislogo.jpg" ))
    {
        qWarning("Failed to load iterislogo.png");
    }
    else
    {
        QGraphicsPixmapItem *item = this->addPixmap(pix);
            item->setPos(0,500);
    }
}
//! [0]

//! [1]
bool ScribbleArea::openImage(const QString &fileName)
//! [1] //! [2]
{

    return true;
}
//! [2]

//! [3]
bool ScribbleArea::saveImage(const QString &fileName, const char *fileFormat)
//! [3] //! [4]
{

    return false;
}
//! [4]

//! [5]
void ScribbleArea::setPenColor(const QColor &newColor)
//! [5] //! [6]
{
    myPenColor = newColor;
}
//! [6]

//! [7]
void ScribbleArea::setPenWidth(int newWidth)
//! [7] //! [8]
{
    myPenWidth = newWidth;
}
//! [8]

void ScribbleArea::timesUp()
{

    //DiagramItem *zone = qgraphicsitem_cast<DiagramItem *>(all);

    for (int i = 0; i < zoneCount; i++)
    {
        foreach(QGraphicsItem *item, items())
        {
            DiagramItem *zone = qgraphicsitem_cast<DiagramItem *>(item);
            myPenColor = zone->zoneColor;
            zone->setPen(myPenColor);
        }
    }



}

void ScribbleArea::activateImage()
//! [9] //! [10]
{
    foreach (QGraphicsItem *item, selectedItems()) {
        DiagramItem *zone = qgraphicsitem_cast<DiagramItem *>(item);
        myPenColor= Qt::red;
        zone->setPen(myPenColor);

        zone->toggleState();

       }
}

void ScribbleArea::deactivateImage()
//! [9] //! [10]
{
    foreach (QGraphicsItem *item, selectedItems()) {
        DiagramItem *zone = qgraphicsitem_cast<DiagramItem *>(item);
        myPenColor = Qt::blue;
        zone->setPen(myPenColor);

        zone->toggleState();

       }
}

//! [9]
void ScribbleArea::clearImage()
//! [9] //! [10]
{
    foreach (QGraphicsItem *item, selectedItems()) {
        delete item;
        zoneCount--;
       }
}
//! [10]
void ScribbleArea::drawZone()
{
    newZone = true;
}

//! [11]
void ScribbleArea::mousePressEvent(QGraphicsSceneMouseEvent *event)
//! [11] //! [12]
{
    if (event->button() == Qt::LeftButton) {
        lastPoint = event->scenePos();
        scribbling = true;

        if( newZone )       // If drawing a new zone
        {
            polygon.setPoint(polyIndex++, event->scenePos().x(), event->scenePos().y());

            if( polyIndex > 3)
            {
                newZone = false;


                DiagramItem *item;

                item = new DiagramItem(this);
                item->setPen(myPenColor);
                addItem(item);

                QPointF details = event->scenePos();    // debug purposes only

                polyIndex = 0;
                zoneCount++;
            }
        }
    }
        QGraphicsScene::mousePressEvent(event);
}

void ScribbleArea::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{

    QGraphicsScene::mouseMoveEvent(event);
}


//! [14]

//! [15]

//! [18]

//! [19]
void ScribbleArea::resizeImage(QImage *image, const QSize &newSize)
//! [19] //! [20]
{
    if (image->size() == newSize)
        return;

    QImage newImage(newSize, QImage::Format_RGB32);
    newImage.fill(qRgb(255, 255, 255));
    QPainter painter(&newImage);
    painter.drawImage(QPoint(0, 0), *image);
    *image = newImage;
}
//! [20]


//! [22]

To copy to clipboard, switch view to plain text mode