Need to help to select the QGraphicsPixmapItem when click on it.

Himanshu Rohilla

Hello everyone,

I want to draw image on QGraphicsView. For this, I created a sub class of QGraphicsPixmapItem. When i click on QGraphicsView, it shows a QFileDialog to select image from the system and displaying successfully on view.
Now, I want to select this image when i click on this. For this, I write the code but it does not work. The following is the my code.

@/* This is my HEADER File which is subclass of QGraphicsPixmapItem */

#include <QGraphicsPixmapItem>
#include <QDebug>

class WhiteBoardItems : public QGraphicsPixmapItem
{
public:
WhiteBoardItems(QWidget *parent = 0);

virtual ~WhiteBoardItems();

virtual void mousePressEvent(QGraphicsSceneMouseEvent *event);
virtual void mouseMoveEvent(QGraphicsSceneMouseEvent *event);
virtual void mouseReleaseEvent(QGraphicsSceneMouseEvent *event);

};
@

This is Header File of subclass of QGraphicsView.

@#include "WhiteBoardItems.h"

class WhiteBoardItems;

class WhiteBoardView : public QGraphicsView
{
Q_OBJECT

public:
WhiteBoardView(QWidget* pParent = 0);
virtual ~WhiteBoardView();

protected:

void mousePressEvent(QMouseEvent *event);
void mouseMoveEvent(QMouseEvent *event);
void mouseReleaseEvent(QMouseEvent *event);

private:

void AddImgToview(QString fileName);

bool vbMousePressed, vbImageSelected;

QString vstrImgFileName;

WhiteBoardItems* mImageItem;

};@

@/* This is CPP File of the subclass */

#include "WhiteBoardItems.h"

WhiteBoardItems::WhiteBoardItems(QWidget *parent) :
QGraphicsPixmapItem()
{

}

WhiteBoardItems::~WhiteBoardItems()
{

}

void WhiteBoardItems::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
qDebug() << "Mouse is clicked in QGraphicsItem";

}

void WhiteBoardItems::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{

}

void WhiteBoardItems::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
{

}
@

This is CPP File of subclass of QGraphicsView .

@void WhiteBoardView::mousePressEvent (QMouseEvent *event)
{
if(event->button() == Qt::LeftButton)
{
vbMousePressed = true;

    if(vbImageSelected)
    {
        previousPt = event->pos();
    }
}

}

void WhiteBoardView::mouseReleaseEvent (QMouseEvent event)
{
if(vbImageSelected)
{
vstrImgFileName = QFileDialog::getOpenFileName(this,"OPEN FILE", QDir::currentPath(),tr("Image Files (.png *.jpg *.bmp *.jpeg *.gif)"));

        if (QImage(vstrImgFileName).isNull() && !vstrImgFileName.isEmpty())
        {
               QMessageBox::information(this,"White Board","There is some problem with image file. This file can't be loaded.");

               return;
        }

        AddImgToview(vstrImgFileName);

    }
    
    vbMousePressed = false;

}

void WhiteBoardView::AddImgToview(QString fileName)
{
mImageItem = new WhiteBoardItems();

mImageItem = (WhiteBoardItems*)(this->scene()->addPixmap(QPixmap(fileName)));
mImageItem->setFlag(QGraphicsItem::ItemIsMovable);
mImageItem->setFlag(QGraphicsItem::ItemIsSelectable);

mImageItem->setX(previousPt.x());
mImageItem->setY(previousPt.y());

mImageItem->setScale(0.5);

}@

Himanshu Rohilla

Thanks in advance ...... :)

raven-worx

it should be enough to call this on your QGraphicsPixmapItem:
@item->setFlag(QGraphicsItem::ItemIsSelectable);@

Himanshu Rohilla

But, I also want to draw rectangle around the image when i click on or select it ...

Himanshu Rohilla

I am attaching the URL of images of my desire result.

The following link is just my normal image on view.

http://www.image-upload.net/di/28SA/33.png

The following link will show my desirable result.

http://www.image-upload.net/di/QQVM/44.png

raven-worx

then also implement the paint method:
@
void MyGraphicsPixmapItem::paint(QPainter painter, const QStyleOptionGraphicsItem option, QWidget *widget)
{
Q_UNUSED(widget);

painter->setRenderHint(QPainter::SmoothPixmapTransform, (d->transformationMode == Qt::SmoothTransformation));

painter->drawPixmap(this->offset(), this->pixmap());

if (option->state & QStyle::State_Selected)
{
    //draw your selection frame
}

}
@

But since it seems that you also want interaction with the graphicsitem it would be better to introduce a subclassed QGraphicsItemGroup and do your painting and interaction there. Because you would also have to update the bounding rect of the pixmap item once it is selected, etc. ...

Himanshu Rohilla

Ok....

Can i do same task for QGraphicsPathItem or whatever i draw on View using this method ?

raven-worx

as long as you stay generic to QGraphicsItem ... why not.

Himanshu Rohilla

paint method is not calling ..... :(

Himanshu Rohilla

sry.... i forgot to addItem in the scene. :P

Himanshu Rohilla

But when i click on or select the image, it does not show its Selected State(i.e. QStyle::State_Selected) .