QMdiSubWindow not accepting drops - qt

Question

I have this small QT program:
from PyQt4 import QtGui
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.backends.backend_qt4agg import NavigationToolbar2QT as NavigationToolbar
from matplotlib.figure import Figure
import sys
class QtZListView(QtGui.QListView):
def __init__(self, *args, **kwargs):
QtGui.QListView.__init__(self, *args, **kwargs)
self.model = QtGui.QStringListModel(['a','b','c'])
self.setEditTriggers(QtGui.QAbstractItemView.NoEditTriggers)
self.setModel(self.model)
self.setSelectionMode(QtGui.QAbstractItemView.ExtendedSelection)
self.setDragEnabled(True)
def setStringList(self, *args, **kwargs):
return self.model.setStringList(*args, **kwargs)
class mplsubwindow(QtGui.QMdiSubWindow):
def __init__(self, *args, **kwargs):
QtGui.QMdiSubWindow.__init__(self, *args, **kwargs)
self.setWindowTitle("testing")
self.setAcceptDrops(True)
fig = Figure(figsize=(5, 4), dpi=100,
facecolor = self.palette().color(QtGui.QPalette.Background).name()
)
p = FigureCanvas(fig)
self.axes = fig.add_subplot(111)
self.axes.hold(False)
FigureCanvas.setSizePolicy(
self,
QtGui.QSizePolicy.Expanding,
QtGui.QSizePolicy.Expanding
)
FigureCanvas.updateGeometry(self)
fig.tight_layout()
toolbar = NavigationToolbar(p, self)
self.layout().addWidget(toolbar)
self.layout().addWidget(p)
self.resize(400,400)
self.show()
def dragEnterEvent(self, event):
print('entering')
super(mplsubwindow, self).dragEnterEvent(event)
def dragMoveEvent(self, event):
print('drag moving')
super(mplsubwindow, self).dragMoveEvent(event)
def dropEvent(self, event):
print('dropped')
super(mplsubwindow, self).dropEvent(event)
class ExampleApp(QtGui.QMainWindow):
def __init__(self):
super(self.__class__, self).__init__()
mainwid = QtGui.QWidget()
layout = QtGui.QGridLayout()
mainwid.setLayout(layout)
self.mdiarea = QtGui.QMdiArea()
self.setCentralWidget(mainwid)
layout.addWidget(self.mdiarea)
sub = mplsubwindow(self.mdiarea)
fig = Figure()
p = FigureCanvas(fig)
sub.layout().addWidget(p)
sub.show()
layout.addWidget(QtZListView())
def main():
app = QtGui.QApplication(sys.argv)
form = ExampleApp()
form.show()
app.exec_()
if __name__ == '__main__':
main()
I want to be able to drag one or more items from the list in the bottom into the matplotlib canvas. For some reason only the enter-event is invoked...the remaining drag/drop events seems to be ignored...and furthermore it seems like the QMdiSubWindow does not accept drops even though i set setAcceptDrops(True).
What am I missing here?

Answer 1

You need to accept the event in the dragEnterEvent method or else move and drop events are ignored.
def dragEnterEvent(self, event):
print('entering')
event.accept()
super(mplsubwindow, self).dragEnterEvent(event)
Note that I really want to emphasise you should be adding the widget via QMdiSubWindow.setWidget(). Any of the other methods (like using QMdiSubWindow.layout() or QMdiSubWindow.setCentralWidget()) are not fully supported by MDI windows and will likely lead to other issues down the road. If you feel that setWidget() is not doing what you want, ask a new question detailing the issue so that it can be resolved while still using setWidget().