[PySide] QGraphicsView and QGraphicsScene

[Lucas Tanure]

Hi,

I'm trying to develop an Drag And Drop with QGraphicsView and
QGraphicsScene. An image comes from another widget and I drop at the scene.
When I add this item I set (at dropEvent)

item.setFlags(QtGui.QGraphicsItem.ItemIsSelectable |
QtGui.QGraphicsItem.ItemIsMovable)
self.addItem(block)

Well, this works, and I can move this item on the scene. But I have two
problems. First is that the first item always goes to position (0,0), but
the second one I can add at any position. Just the first that anywhere I
drop goes to (0,0).
This is because I don't set the size of the scene, and the first one  grows
the scene, so for the second works. But here comes my second problem, if I
set some size to this scene I lose the auto scrollbar from the view
(QGraphicsView).
So If drop somewhere on the scene near of the edge or out of the view, I
can't go to this position , because there isn't scrollbars. But I can drop
at anywhere, and the item stays there.

Please Help.

*CODE*

*Main Controll*
self.scene = dragGraphicsScene()
self.ui.blocksGraphicsView.setScene(self.scene)



class dragGraphicsScene(QtGui.QGraphicsScene):

    def __init__(self, parent=None):
        super(dragGraphicsScene,self).__init__(parent)


    def dragEnterEvent(self, event):
        if event.mimeData().hasFormat('image/x-block'):
            event.accept()
        else:
            event.ignore()

    def dragMoveEvent(self, event):
        if event.mimeData().hasFormat('image/x-block'):
            #event.setDropAction(QtCore.Qt.MoveAction)
            event.accept()
        else:
            event.ignore()

    def dropEvent(self, event):
        if event.mimeData().hasFormat('image/x-block'):
            itemData = event.mimeData().data('image/x-block')
            dataStream = QtCore.QDataStream(itemData,
QtCore.QIODevice.ReadOnly)

            pixmap = QtGui.QPixmap()
            offset = QtCore.QPoint()
            dataStream >> pixmap >> offset

            block = QtGui.QGraphicsPixmapItem(pixmap)

            block.setPos(event.scenePos()-offset)
            block.setFlags(QtGui.QGraphicsItem.ItemIsSelectable |
QtGui.QGraphicsItem.ItemIsMovable)
            self.addItem(block)

            if event.source() == self:
                event.setDropAction(QtCore.Qt.MoveAction)
                event.accept()
            else:
                event.acceptProposedAction()
        else:
            event.ignore()



*Widget where the drag starts:*

class dragWidget(QtGui.QWidget):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)
        self.setAcceptDrops(True)

    def dragEnterEvent(self, event):
        if event.mimeData().hasFormat('image/x-block'):
            event.accept()
        else:
            event.ignore()

    def mousePressEvent(self, event):
        child = self.childAt(event.pos())

        pixmap = QtGui.QPixmap(child.pixmap())

        itemData = QtCore.QByteArray()
        dataStream = QtCore.QDataStream(itemData,
QtCore.QIODevice.WriteOnly)
        dataStream << pixmap << QtCore.QPoint(event.pos() - child.pos())


        mimeData = QtCore.QMimeData()
        mimeData.setData("image/x-block", itemData)
        #mimeData.setImageData(pixmap)

        drag = QtGui.QDrag(self)
        drag.setMimeData(mimeData)
        drag.setPixmap(pixmap)
        drag.setHotSpot(event.pos() - child.pos())

        #use exec_ instead of start.
        drag.exec_(QtCore.Qt.CopyAction | QtCore.Qt.MoveAction)




Lucas A. Tanure Alves
Skype : lucas.tanure
+55 (19) 88176559
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