Drawing rectangles in QT

[wayfaerer]

Then you should reimplement some protected functions in your QGraphicsItems, particularly mousePressEvent, mouseMoveEvent, and mouseReleaseEvent. mousePressEvent would notify the item to draw a line (probably another QGraphicsItem), from the initial click location to mouseMoveEvent's current location. mouseReleaseEvent could call scene().itemAt() to determine which node is at the mouse release location. Something like that.

[ChrisW67]

The Diagram Scene Example would be a good starting place

[andreahmed]

How to draw circles around triangles? and those circles can be connected to other circles ?!