qt - In QGraphicsScene how to catch a particular item

Question

I have so many things in my QGraphicsScene. The situation is I am creating a chessboard, and is using Graphics scene. So the QGraphicsScene is having so many QGraphicsPixmapItems. Now In this how can I get the King.

Update: In this QGraphicsScene, I am adding QGraphicsPixmapItems which are nothing but coins(board,king,queen,soldiers,etc). Now if I want to move a particular coin say King, then How can I get it. There are some methods like using iterators. But is there any way to find a particular QGraphicsPixmapItem by it's name.

Answer 1

When you say you need to get the King, how do you make the difference in your program between the white King and the black one ?

If you need to get a Pawn, how do you know which one ? Anyone ? The first one you can find in your items ?

I haven't thought a lot about it, but maybe what you can do is using a QMap. The key would be a enumeration of the different pieces and the value would be a pointer to the relevant QGraphicsItem. Something like this :

enum Piece_e {
    KING,
    QUEEN,
    ROOK1,
    ROOK2,
    ...
    PAWN1,
    PAWN2,
    ...
};

QMap<Piece_e, QGraphicsPixmapItem*> WhitePiecesItems;
QMap<Piece_e, QGraphicsPixmapItem*> BlackPiecesItems;

When you are creating your scene and instanciating your pieces, you'll fill the map :

...
WhitePiecesItem[KING] = new QGraphicsPixmapItem(QPixmap("whiteking_pic"));
WhitePiecesItem[PAWN1] = new QGraphicsPixmapItem(QPixmap("whitepawn_pic"));
...

BlackPiecesItem[QUEEN] = new QGraphicsPixmapItem(QPixmap("whitequeen_pic"));
BlackPiecesItem[PAWN1] = new QGraphicsPixmapItem(QPixmap("whitepawn_pic"));
...

When you need to find the object corresponding to the white king, you could do something like this :

QGraphicsPixmapItem* pItem = WhitePiecesItem[KING];