Trying to use QMap to access dynamically added QGraphicObjects

frnklu20

Hi,

I'm adapting the DiagramScene qt example to use pixmap instead of polygons and now i'm trying to use QMap to add an access data of the qgraphic objects that i place on the screen.

The idea is:
Besides creating the graphic object and place it on the screen, create another object(a non-graphic one) and use QMap to link this 2 objects

addItem(item);
item->setPos(mouseEvent->scenePos()); //creating the graphical object
Barramento *barramento=new Barramento(this);
//creating the non-graphical object
BarramentoMap["barramento"+QString::number(i)]=barramento;
item->setProperty("datakey","barramento"+QString::number(i));
//creating a link between  this 2 objects

But i'm having a problem

barramento.h

class Barramento
{

public:
    explicit Barramento(QWidget* parent =0 );
    Barramento();
    QString nome="padrão";
    int num;
    float tensao;
    float ang;


    void setnome(QString &);
    void setnum(int &);
    void settensao(float &);
    void setang(float &);

};

barramento.cpp

Barramento::Barramento(QWidget *parent)
{
}

void Barramento::setnome(QString & new_nome)
{
    nome=new_nome;
}

void Barramento::setnum(int & new_num)
{
    num=new_num;
}

void Barramento::settensao(float &new_tensao)
{
    tensao=new_tensao;
}

void Barramento::setang(float &new_ang)
{
    ang=new_ang;
}

DiagramScene is the widget responsible to add graphical itens

diagramscene.cpp

.... 
void DiagramScene::mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent)
{
    if (mouseEvent->button() != Qt::LeftButton)
        return;

    DiagramItem *item;
    switch (myMode) {
        case InsertItem:
            
            item = new DiagramItem(myItemType, myItemMenu);

            addItem(item);
            item->setPos(mouseEvent->scenePos());
            emit itemInserted(item);
            if(myItemType==0)
            {
                Barramento barramento=new Barramento(this);
                 //error here
                BarramentoMap["barramento"+QString::number(i)]=barramento;
                item->setProperty("datakey","barramento"+QString::number(i));
            }

            break;
....

the error is "no matching constructor fot initialization of 'Barramento'"
, how can I fix it?is my logic correct?

SGaist

Hi,

Why are you passing that "parent" parameter to your Barramento class constructor ? You're not making any use of it neither in your constructor nor the rest of your class.

frnklu20

ok, i removed the parent parameter

but now it gives me another error:
"no member named 'setProperty' in 'DiagramItem'" that is the class of the item

so i cant use QMap with QGraphicsPixmapItem?

SGaist

From your code you are not using a QMap<Barramento, QGraphicsPixmapItem *> map but a QMap<QString, Barramento> which is not the same. And the setProperty call is unrelated to your QMap use.

From the looks of it, you are trying to use DiagramItem as if it is a QObject based class, which is not. Not all classes of Qt inherits QObject.

frnklu20

I didn't know that, thanks

but now how am i going to link these to objects?
i thought something like this:

 case InsertItem:
            
            item = new DiagramItem(myItemType, myItemMenu);

            addItem(item);
            item->setPos(mouseEvent->scenePos());
            emit itemInserted(item);
            if(myItemType==0)
            {
                int i=0;
                i+=1;
                        
                Barramento *barramento=new Barramento();
                BarramentoMap[barramento]=item;
}

but it gives the no viable overload operator [] error

SGaist

How did you declare your map ?

frnklu20

in the first time i defined as
QMap<QString, Barramento>

but after you answered me defined this way:

QMap<Barramento, QGraphicsPixmapItem *> how can i do it?

SGaist

Then why are you trying to store a pointer to a Barramento object ?

frnklu20

I'm trying to link the graphical object to the non-graphic object, and the baramento class represents the data of that specific graphical object on the screen.

In the older version of my program i represented the image on the screen in a label, and to make this link that i want to do now i did:

 Barramento barramento=new Barramento(this);
 BarramentoMap["barramento"+QString::number(i)]=barramento;
 item->setProperty("datakey","barramento"+QString::number(i));

i defined my Qmap as:

QMap<QString, Barramento>

that's why i want your help, because that doesn't work anymore with QGraphicsPixmapItem as it did with QLabel
So how can i make it work?

after you answered me i define my QMap as:

QMap<Barramento, QGraphicsPixmapItem >

it is not a pointer, i'm sorry.
I really need your help, thanks for the attention!

SGaist

Barramento barramento=new Barramento(this);

This is wrong and can compile. You either want Barramento barramento(this); or Barramento *barramentoPtr = new Barramento(this);

To use QMap<QString, Barramento>, you need the first option, for the second you need to declare QMap<QString, Barramento *>.