QGraphicsView Drag&Drop issue

Question

I have issue with PyQt4 GraphicsView. I want to use drag&drop from listview into a graphics scene/view and place item exactly at the position of mouse cursor.

from PyQt4 import QtCore, QtGui
import sys

class GraphicsScene(QtGui.QGraphicsScene):

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

    def dragEnterEvent(self, event):
        event.accept()

    def dragMoveEvent(self, event):
        event.accept()

    def dragLeaveEvent(self, event):
        event.accept()

    def dropEvent(self, event):
        text = QtGui.QGraphicsTextItem(event.mimeData().text())
        text.setPos(event.scenePos())
        self.addItem(text)
        event.accept()

class ListView(QtGui.QListView):

    def __init__(self, parent = None):
        super(ListView, self).__init__(parent)
        self.setDragEnabled(True)

    def dragEnterEvent(self, event):
        event.setDropAction(QtCore.Qt.MoveAction)
        event.accept()

    def startDrag(self, event):
        index = self.indexAt(event.pos())
        if not index.isValid():
            return

        selected = self.model().data(index, QtCore.Qt.DisplayRole)

        mimeData = QtCore.QMimeData()
        mimeData.setText(selected.toString())

        drag = QtGui.QDrag(self)
        drag.setMimeData(mimeData)

        result = drag.start(QtCore.Qt.MoveAction)
        if result: # == QtCore.Qt.MoveAction:
            pass

    def mouseMoveEvent(self, event):
        self.startDrag(event)

class MainWindow(QtGui.QMainWindow):

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

        self.setGeometry(100, 100, 400, 400)

        self.widget = QtGui.QWidget()
        self.setCentralWidget(self.widget)
        layout = QtGui.QGridLayout(self.widget)

        self.ListView = ListView()

        data = QtCore.QStringList()
        data << "one" << "two" << "three"
        self.model = QtGui.QStringListModel(data)

        self.ListView.setModel(self.model)

        self.GraphicsView = QtGui.QGraphicsView()
        self.scene = GraphicsScene()
        self.GraphicsView.setScene(self.scene)

        layout.addWidget(self.ListView, 0, 0, 5, 5)
        layout.addWidget(self.GraphicsView, 0, 1, 5, 5)

        self.show()

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    window = MainWindow()
    sys.exit(app.exec_())

Problem appears while dropping first item. It goes straight into center of view, but I want it to stay at cursor position. Any ideas?

Green Cell Green Cell · Accepted Answer · 2015-08-29T01:40:55

Looks like you need to set the QGraphicsView's rect first to initialize it properly. Then the first item added will work as expected.

self.GraphicsView.setSceneRect(0, 0, self.GraphicsView.width(), self.GraphicsView.height())

This needs to be added after the show event though, as calling the QGraphicsView's width and height will throw out wrong values beforehand.

QGraphicsView Drag&Drop issue

1 Answers