Drag and drop with Qt and PySide

I have always been using (well at least the past 7 years) QT for creating interfaces for my PySide/PyQt applications. Lately I've decided to dive a bit deeper to create and experiment with more complex behaviours. 

Starting with a convenient behaviour : Drag and Drop.

In the example I am sharing here I re-implemented the drag and drop related methods of a QLabel and a QWidget so we are able to drag the label into the widget. What actually happens is that when we drop the label on  the widget we create another Label with the same information,  it is a Copying action.

TODO: In the upcoming weeks we will add the functionality of re-arranging the labels in the Drop widget and also from one Drop widget to another.

import sys
from PySide import QtCore, QtGui

class InitialCard(QtGui.QLabel):
    def __init__(self, text, parent):
        super(InitialCard, self).__init__(text, parent)
        self.setAutoFillBackground(True)
        self.setFrameStyle(QtGui.QFrame.WinPanel|QtGui.QFrame.Sunken)
        newFont = QtGui.QFont("MsReferenceSansSerif", 10)
        newFont.setBold(False)
        self.setFont(newFont)
        self.setMinimumSize(90, 25)
        self.setMaximumHeight(30)
        self.setAlignment(QtCore.Qt.AlignCenter)
        self.mimeText=self.text()

    def mouseMoveEvent(self, event):
        if not self.text():
            return
        mimeData = QtCore.QMimeData()
        mimeData.setText(self.mimeText)
        drag = QtGui.QDrag(self)
        drag.setMimeData(mimeData)
        drag.exec_(QtCore.Qt.CopyAction | QtCore.Qt.MoveAction, QtCore.Qt.CopyAction)

class CardsDropWidget(QtGui.QWidget):

    def __init__(self, parent):
        super(CardsDropWidget, self).__init__(parent)
        self.setAcceptDrops(True)
        self.contentsVLO = QtGui.QVBoxLayout()
        self.contentsVLO.setAlignment(QtCore.Qt.AlignTop)
        self.setLayout(self.contentsVLO)
    
    def dragEnterEvent(self, event):
        if event.mimeData().hasText():
            event.setDropAction(QtCore.Qt.CopyAction)
            event.accept()
        else:
            event.ignore()

    def dropEvent(self, event):
        if event.mimeData().hasText():
            cardSource=event.source()
            cardText=cardSource.text()
            if not cardSource in self.children():
                newCard = InitialCard(cardText, self)
                self.contentsVLO.addWidget(newCard)
                cardSource.clear()
            else:
                event.ignore()
        else:
            event.ignore()

class MainDialogue(QtGui.QDialog):
    def __init__(self, parent=None):
        super(MainDialogue, self).__init__(parent)
        self.label=InitialCard("initial", self)
        self.lineEdit=QtGui.QLineEdit("Create a Card Here!!")
        self.lineEdit.selectAll()
        self.scrollArea = QtGui.QScrollArea()
        self.scrollArea.setWidgetResizable(True)
        self.scrollContent = CardsDropWidget(self.scrollArea)
        self.scrollArea.setMinimumWidth(150)
        self.scrollArea.setWidget(self.scrollContent)
        self.dialogueLayout=QtGui.QHBoxLayout()
        self.labelLayout=QtGui.QVBoxLayout()
        self.labelLayout.addWidget(self.label)
        self.labelLayout.addWidget(self.lineEdit)
        self.labelLayout.addStretch()
        self.dialogueLayout.addWidget(self.scrollArea)
        self.dialogueLayout.addLayout(self.labelLayout)
        self.setLayout(self.dialogueLayout)
        self.setWindowTitle("Drag and Drop")
        self.setMinimumSize(300, 150)
        self.lineEdit.returnPressed.connect(self.createCardTxt_fn)
        
    def createCardTxt_fn(self):
        cardTxt=unicode(self.lineEdit.text())
        self.label.setText(cardTxt)

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    window = MainDialogue()
    window.show()
    sys.exit(app.exec_())