Question

OS::win_xp_sp3

Qt::4.6

Is it possible to use QMouseEvent inside QRect?
I have parent widget and inside is some QLabel with text “status unchanged”.

Also , inside parent widget is MyRect which is derived from QRect.

Now I want to MouseEvent act only inside this MyRect. For example , if I act on MyRect , text in parent widget need to be changed.

For example:

class MyRect : public QRect  {
      public:
      MyRect(int x, int y, int w, int h, ParentWidget* parent)
            : QRect(x,y,w,h) 
            {
               itsParent = parent;
            }
      ~MyRect() {}

      protected:
      void mouseMoveEvent(QMouseEvent* event)  

      private:
      ParentWidget* itsParent

  };  

void MyRect::mouseMoveEvent(QMouseEvent* event)
{
    if(event->buttons() == Qt::LeftButton)
    {
        itsparent->label->setText("status changed");
    }

}

nothing happens

question:: is it possible to use QMouseEvent like this (only on QRect)?

Answer 1

A QRect is neither a QObject nor a QWidget, so it doesn’t receive events.
It’s just four numbers describing a rectangle (and it doesn’t make sense to derive from it).
You can check if a point is the given rect in the mouse event handler of your widget. Like:

void MyLabel::mouseMoveEvent( QMouseEvent* e ) {
    if ( !rect.contains( e->pos() ) )
        return;
    //... handle mouse move
}

An alternative to subclassing is using an event filter.