如何通过从一个列表中拖放进行复制，但使用移动进行内部拖放

Question

我需要能够将项目从一个 listWidget 复制到另一个。这很容易做到，但我似乎无法找到一种方法来根据被拖动的项目是否起源于它被拖放到的列表中来区分拖放操作，而不必用我的几乎所有拖放功能覆盖自己的。当我将一个项目从一个列表拖到另一个列表时，我想复制它，但是当我在同一个列表中拖动该项目时，我想移动它。

我一直在研究设置 mimetypes，但后来我不得不编写自己的 mouseMoveEvent 作为一种方法，或许可以判断拖动的项目来自何处，但到目前为止，尝试这样做会破坏一切。不覆盖 mouseMoveEvent 就不能为项目设置 MIME 类型吗？

由于我拖动的项目是自定义的，因此当它被移动或复制到第二个列表时，我必须编写自己的定义来重建它。使用默认的拖动功能，这一切都适用于内部移动。但到目前为止，我还无法弄清楚当拖动是内部移动时如何使用默认的拖放功能，然后当拖放来自不同的列表时切换到我的自定义功能来复制项目。

import sys
from PyQt4 import QtGui , QtCore


def main():

    app = QtGui.QApplication(sys.argv)

    w = QtGui.QWidget()
    w.resize(250, 150)
    w.move(300, 300)
    w.setWindowTitle('Simple')
    layout=QtGui.QHBoxLayout(w)
    dragList=DragDropListWidget()
    layout.addWidget(dragList)
    dragList.setDragDropMode(QtGui.QAbstractItemView.InternalMove)
    dragList.name='dragList'
    dragList.populate(['one','two','three'])
    dragList2=DragDropListWidget()
    dragList2.setDragDropMode(QtGui.QAbstractItemView.DragDrop)
    dragList2.name='dragList'


    layout.addWidget(dragList2)
    w.show()

    sys.exit(app.exec_())

class scriptsWidget(QtGui.QWidget):


    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self)

        self.name=''

        self.widget_QHBoxLayout = QtGui.QHBoxLayout(self)
        self.widget_QHBoxLayout.setSpacing(0)
        self.widget_QHBoxLayout.setContentsMargins(0, 0, 0, 0)

        self.name_QLabel = QtGui.QLabel(self)
        self.widget_QHBoxLayout.addWidget(self.name_QLabel)

        self.user_QLabel = QtGui.QLabel(self)
        self.widget_QHBoxLayout.addWidget(self.user_QLabel)

        self.widget_QHBoxLayout.setSpacing(0)
        self.widget_QHBoxLayout.setContentsMargins(0, 0, 0, 0)



    def setName(self,name):
        self.name_QLabel.setText(name)
        self.name=name

    def setUser(self,user):
        self.user_QLabel.setText(user)

class customQListWidgetItem(QtGui.QListWidgetItem):


    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self)
        self.name=''

    def setName(self,name):
        self.name=name   




class DragDropListWidget(QtGui.QListWidget):
    _drag_info = []
    def __init__(self, parent = None):

        super(DragDropListWidget, self).__init__(parent)


        self.name=''


    def dragMoveEvent(self, event):
        if event.mimeData().hasUrls():
            event.setDropAction(QtCore.Qt.CopyAction)
            event.accept()

        else:
            super(DragDropListWidget, self).dragMoveEvent(event)


    def dropEvent(self, event):
        if event.mimeData().hasText():
            event.setDropAction(QtCore.Qt.CopyAction)
            event.accept()
            links = []
            for url in event.mimeData().urls():
                links.append(str(url.toLocalFile()))
            self.emit(QtCore.SIGNAL("dropped"), links)

        else:
            event.setDropAction(QtCore.Qt.CopyAction)
            items = []
            for index in xrange(self.count()):
                items.append(self.item(index))

            super(DragDropListWidget, self).dropEvent(event)

            for index in xrange(self.count()):
                if self.item(index) not in items:
                    self.populateDrop(self.item(index), index, [self.item(index).data(QtCore.Qt.UserRole).toPyObject()])

    def populateDrop(self,item,row,items=[]):
        for i in items:
            widget = scriptsWidget()
            widget.setName(i)
            widget.setUser('x')
            self.takeItem(row)
            item = customQListWidgetItem()
            item.setName(i)
            item.setWhatsThis(i)
            data = (i)
            item.setData(QtCore.Qt.UserRole, data)
            self.insertItem (row, item)
            self.setItemWidget(item,widget)



    def populate(self,items=[]):
        self.clear()
        for i in items:
            print(i)
            widget = scriptsWidget()
            widget.setName(i)
            widget.setUser('x')
            item = customQListWidgetItem()
            item.setName(i)
            data = (i)
            item.setData(QtCore.Qt.UserRole, data)
            self.addItem(item)
            self.setItemWidget(item,widget)



if __name__ == '__main__':
    main()

Answer 1

嗯，这就是我想出的。我在单击项目时设置了一个 class 数据变量，这样我就可以在项目被删除时知道它来自哪里。我尝试在 DragDropListWidget 中使用 class 变量，但出于某种原因，它只会存储当前列表的本地名称……很奇怪。全局变量也有效但不可取。

import sys
from PyQt4 import QtGui , QtCore

def main():

    app = QtGui.QApplication(sys.argv)

    w = QtGui.QWidget()
    w.resize(250, 150)
    w.move(300, 300)
    w.setWindowTitle('Simple')
    layout=QtGui.QHBoxLayout(w)
    dragList=DragDropListWidget()
    layout.addWidget(dragList)
    d=data()
    dragList.setDragDropMode(QtGui.QAbstractItemView.InternalMove)
    dragList.name='dragList'
    dragList.populate(['one','two','three'])
    dragList.data=d
    dragList2=DragDropListWidget()
    dragList2.setDragDropMode(QtGui.QAbstractItemView.DragDrop)
    dragList2.name='dragList2'
    dragList2.external='dragList2'
    dragList2.data=d


    layout.addWidget(dragList2)
    w.show()

    sys.exit(app.exec_())

class data(object):
    def __init__(self, parent=None):
        self.origin='new'




class scriptsWidget(QtGui.QWidget):


    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self)

        self.name=''

        self.widget_QHBoxLayout = QtGui.QHBoxLayout(self)
        self.widget_QHBoxLayout.setSpacing(0)
        self.widget_QHBoxLayout.setContentsMargins(0, 0, 0, 0)

        self.name_QLabel = QtGui.QLabel(self)
        self.widget_QHBoxLayout.addWidget(self.name_QLabel)

        self.user_QLabel = QtGui.QLabel(self)
        self.widget_QHBoxLayout.addWidget(self.user_QLabel)

        self.widget_QHBoxLayout.setSpacing(0)
        self.widget_QHBoxLayout.setContentsMargins(0, 0, 0, 0)



    def setName(self,name):
        self.name_QLabel.setText(name)
        self.name=name

    def setUser(self,user):
        self.user_QLabel.setText(user)

class customQListWidgetItem(QtGui.QListWidgetItem):


    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self)
        self.name=''
        self.list=''

    def setName(self,name):
        self.name=name   




class DragDropListWidget(QtGui.QListWidget):

    def __init__(self, parent = None):

        super(DragDropListWidget, self).__init__(parent)
        self._dropping = False
        self.itemPressed.connect(self.clicked)

        self.data=''

        self.name=''
        self.external=''
        self.internal=False

    def clicked(self):
        global origin 
        self.data.origin=self.name


    def dragMoveEvent(self, event):

        if event.mimeData().hasUrls():
            event.setDropAction(QtCore.Qt.CopyAction)
            event.accept()

        else:

            super(DragDropListWidget, self).dragMoveEvent(event)


    def dropEvent(self, event):

        if event.mimeData().hasText():
            event.setDropAction(QtCore.Qt.CopyAction)
            event.accept()
            links = []
            for url in event.mimeData().urls():
                links.append(str(url.toLocalFile()))
            self.emit(QtCore.SIGNAL("dropped"), links)

        else:
            if self.external is self.name and self.data.origin is not self.name:
                print('external')
                event.setDropAction(QtCore.Qt.CopyAction)
                items = []
                for index in xrange(self.count()):
                    items.append(self.item(index))
                print items

                super(DragDropListWidget, self).dropEvent(event)

                for index in xrange(self.count()):
                    if self.item(index) not in items:
                        print(index)
                        self.populateDrop(self.item(index), index, [self.item(index).data(QtCore.Qt.UserRole).toPyObject()])

            else:
                print('internal')
                event.setDropAction(QtCore.Qt.MoveAction)

                super(DragDropListWidget, self).dropEvent(event)

        self.data.origin = None       

    def populateDrop(self,item,row,items=[]):
        for i in items:
            widget = scriptsWidget()
            widget.setName(i)
            widget.setUser('x')
            self.takeItem(row)
            item = customQListWidgetItem()
            item.setName(i)
            item.setWhatsThis(i)
            item.list=self.name
            data = (i)
            item.setData(QtCore.Qt.UserRole, data)
            self.insertItem (row, item)
            self.setItemWidget(item,widget)



    def populate(self,items=[]):
        self.clear()
        for i in items:
            print(i)
            widget = scriptsWidget()
            widget.setName(i)
            widget.setUser('x')

            item = customQListWidgetItem()
            item.setName(i)
            item.list=self.name
            data = (i)
            item.setData(QtCore.Qt.UserRole, data)
            self.addItem(item)
            self.setItemWidget(item,widget)



if __name__ == '__main__':
    main()

Answer 2

辨别拖动是来自此小部件还是来自其他小部件很简单 - 只需在任何 drag/drop 事件中使用事件源即可。例如：

void MyWidget::dragMoveEvent(QDragMoveEvent *event) 
{
    if (event->source() != this) {
        // the drag comes from another widget
    }
}

如何通过从一个列表中拖放进行复制，但使用移动进行内部拖放

How can copy with drag and drop from one list but use move for internal drag and drop

python

drag-and-drop

pyqt

qlistwidget

qlistwidgetitem