Ca fait plaisir d'avoir des méssages comme le tiens, tu n'es pas modérateur pour rien je pense !! Et ça donne envie de s'abonner ^^...

Tous mes objets graphiques dessinés dérivent de cette classe :

class ObjectUI(QtGui.QWidget):
    """ Graphical Objects wich are displayed on the screen (virtual object) """
    def __init__(self, _QSSize, _QPPosition, parent=None):
        super (ObjectUI, self).__init__ (parent)
        self.QPPosition = _QPPosition
        self.QSSize = _QSSize
        
        # Properties of the font
        newFont = self.font()
        newFont.setPixelSize(12)
        self.setFont(newFont)
        self.setFixedSize(self.getSize())     
        fontMetrics = QtGui.QFontMetrics(newFont)
        
        self.QPaint = QtGui.QPainter()
      
#=================================
# Public accessors
#=================================
    def setPosition(self,P):
        """ set the position of the action object block """
        self.QPPosition = P
    
    def getPosition(self):
        """ return the position of the action object block """
        return self.QPPosition   

    def setSize(self,_QSSize):
        """ set the size of the current object user interface """
        self.QSSize = _QSSize
    
    def getSize(self):
        """ return the size of the current object user interface """
        return self.QSSize
    
    def getPainter(self):
        """ return the qpainter """
        return(self.QPaint)
    
#=================================
# Manage the mouse
#=================================
    def mousePressEvent(self, event): 
        """ action performed when the mouse is clicked """
        raise NotImplementedError("Method mousePressEvent not defined in class " + self.__class__.__name__)   

    def mouseMoveEvent(self, event): 
        """ action performed when the mouse is moved """
        raise NotImplementedError("Method mouseMoveEvent not defined in class " + self.__class__.__name__)   
    
    def mouseReleaseEvent(self, event): 
        """ action performed when the mouse is released """
        raise NotImplementedError("Method mouseReleaseEvent not defined in class " + self.__class__.__name__)   

Et voici le code d'un widget graphique qui dessine un carré:

#==================================
# Import modules
#==================================
from PyQt4 import QtGui, QtCore
from ObjectUI import ObjectUI
#==================================
# Constructor
#==================================
class PlaceObjectUI(ObjectUI, QtGui.QLabel):
    colorFix = QtCore.Qt.darkGray
    colorMoving = QtCore.Qt.gray
    colorFill = QtCore.Qt.gray
    """ Graphical Objects of places (represent variables """
    def __init__(self, _QPPosition, parent=None):
        ObjectUI.__init__(self, QtCore.QSize(10, 10), _QPPosition, parent)
        # Attributes
        self.m_place = 0
        self.m_ascendant = 0
        self.m_ascPosition = 0
        self.m_descendants = []
        
        # Color of the picture drawn
        self.color = self.colorFix
               
        # get the painter
        self.painter = self.getPainter()
        
        # Draw the shape
        self.setupShape()

        
#=================================
# Public painting
#=================================         
    def paintEvent(self, event):
        # Go to the position where to draw the object
        self.move(self.getPosition().x(), self.getPosition().y())
        
        self.painter = QtGui.QPainter()
        self.painter.begin(self)
        #painter.setRenderHint(QtGui.QPainter.Antialiasing)
        self.painter.fillRect(event.rect(), QtGui.QBrush(self.colorFix))
        self.drawShape(self.painter)
        self.painter.end()

    def drawShape(self, painter):
        self.painter.fillPath(self.shape, QtGui.QBrush(self.colorFix))

    def setupShape(self):
        QPpath = QtGui.QPainterPath()
        QPpath.setFillRule(QtCore.Qt.OddEvenFill)
        
        QPpath.addRect(0, 0, self.getSize().width(), self.getSize().height())    
        self.shape = QPpath
        
#=================================
# Public accessors
#=================================  
    def setPlace(self, _place):
        self.m_place = _place
    
    def getPlace(self):
        return self.m_place
    
    def setAscendant(self, _asc):
        self.m_ascendant = _asc
        
    def addDescendant(self, _desc):
        self.m_descendants.append(_desc)
    
    def getAscendant(self):
        return self.m_ascendant

#=================================
# Public functions
#=================================  
    def getNbDescendants(self):
        return len(self.m_descendants)
    
    def getDescendant(self, _position):
        return self.m_descendants[_position]
    
    def removeAscendant(self):
        self.m_ascendant = 0

#=================================
# Manage the mouse
#=================================
    def mouseMoveEvent(self, event):
        """ Redraw the current block when the mouse is being moved """
        # shape of the cursor
        self.setCursor(QtCore.Qt.SizeAllCursor)
        # Catch the position of the mouse
        position = event.pos()
        # newPosition is the new position of the QLabel
        newPosition = QtCore.QPointF(self.getPosition().x()+position.x(),self.getPosition().y()+position.y())
        # Move to the current position of the mouse
        self.move(newPosition.x(),newPosition.y())
        # update the position of the QLabel
        self.QPPosition = newPosition
        self.color = self.colorMoving
        self.update()
        
    def mousePressEvent(self, event):
        return 
    
    def mouseReleaseEvent(self, event):
        # shape of the cursor
        self.setCursor(QtCore.Qt.SizeAllCursor)
        self.color = self.colorFix
        self.update()