In Qt tell the main class that an item was clicked

Question

Situation:

I have a Dialog class in QT on which I draw a raster of squares. The squares are implemented in the MySquare class (MySquare: QGraphicsItem).

Inside the MySquare there are a number of functions (mysquare.h protected: )

    void mousePressEvent(QGraphicsSceneMouseEvent *event);
    void mouseReleaseEvent(QGraphicsSceneMouseEvent *event);
    void keyPressEvent(QKeyEvent *event);
    void mouseMoveEvent(QGraphicsSceneMouseEvent *event);

When I click on a square it gives me the relative coordinates of the square using the following function.

void MySquare::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
    update();
    QGraphicsItem::mousePressEvent(event);
    qDebug() << "mouse Pressed";
    qDebug() << "coordinates:";
    qDebug() << "X:"<< x/w << " Y:" << y/h ;
}

enter image description here

Where x and y are the x and y position in the raster and w and h stand for width and height

However my question is how can I let my Dialog class know what square was clicked on?

score 1 · Accepted Answer · answered Jan 05 '13 at 12:25

You can communicate between MySquare and and your Dialog by means of the signal/slot mechanism of Qt. When a square gets clicked, it emits a signal, and the Dialog has a slot that is connected to that signal.

To identify which square sent the signal, there are several possibilities:

The coordinates of the square are passed along in the signal
The this pointer of the MySquare that emits the signal is passed along
In the slot, you can use the sender function to determine who emitted the signal.

In Qt tell the main class that an item was clicked

1 Answers1