menu on right click on canvas

[quickNitin]

greetings,
i want to have a contect menu over canvas and its items. This items wil contain the operation i want to perform over it.
I have gone throught doc there is contextMenuEvent() for qwidget but nothing such for QCanvas. How i can code such functionality.

quickNitin

[jpn]

Like I just said in the overlapping canvases (http://www.qtcentre.org/forum/f-newbie-4/t-overlapping-canvases-3928.html) thread,

Well, Q3Canvas isn't a widget and can't be displayed on its own. You're displaying the canvas in a Q3CanvasView, right? Q3CanvasView is a widget and can be moved, resized, etc. like any other widget.
The same applies in this. You are supposed to handle the context menu event for Q3CanvasView, not the Q3Canvas.

[quickNitin]

i tried and menu did worked.
I need some advice on how to proceed further.
As we discussed in thread http://www.qtcentre.org/forum/f-newbie-4/t-overlapping-canvases-3928.html
, i have a large canvas , over this i have many canvs elements and some other smallcanvas. Now i want this context menu to be specific to element on which it is clicked.I mean i have diffrent function corresponding to diffrent element. These operation includes , changing elements shape and displayig information(selective) about that element.

if i do this, this is generating a general context menu, orignating same at each place irrespective of click where it happenend or i can get position from QContextMenuEvent class.


...
abc=new QAction(tr("hello"),this);
connect(abc,SIGNAL(triggered()),this,SLOT(ABC()));
...
void ABC()
{
QMessageBox::information(this,tr("Hello"),tr("Sample Context Menu Acion"));

}
...
void contextMenuEvent(QContextMenuEvent *event)
{
QMenu mn(this);
mn.addAction(abc);
mn.exec(event->globalPos());

}




same here


void contentsMousePressEvent( QMouseEvent *e )
{
Q3CanvasItemList il = canvas()->collisions( e->pos() );
if(e->button()==Qt::LeftButton)
{
for( Q3CanvasItemList::Iterator it=il.begin(); it!=il.end(); ++it ) {
if( (*it)->rtti() != Q3CanvasText::RTTI )
{
dragging = (*it);

xoffset = (int)(e->x() - dragging->x());
yoffset = (int)(e->y() - dragging->y());

return;
}
}
}
else if(e->button()==Qt::RightButton)
{
for( Q3CanvasItemList::Iterator it=il.begin(); it!=il.end(); ++it ) {
if( (*it)->rtti() != Q3CanvasText::RTTI )
{
if( (*it)->rtti() == Q3CanvasRectangle::RTTI)
{
QMessageBox::information(this,tr("Hello"),tr("Sample Context Menu Acion on rectangle"));
//can generate a specific menu here but how will pass this canvas element to that action for operations over that
}
}
}
}
}


i know on which element i clicked but how i can pass this information( on which object on canvas or window i clicked ) to actions on context menu. Why i need context menu is since i have 5-6 oprns. User will select between them.

all advices are welcome in this regard as i am getting very raw ideas(working on such task for first time).

[jpn]

Maybe you could just simply store the item as a member variable? Or use QAction::setData() for storing a pointer to the item. It's totally up to you how do you want to implement it. It might also depend on which slots and where do the actions trigger..

[quickNitin]

i am getting some feel of it.
Ihave declared a member variable Q3canvasitem class pointer.in contentsMousePressEvents() i am checking rtti() of canvas item( obatained through collision) .There i am storing corresponding item in member pointer and generating menu there only.
With other development i will keep updating.