Python：如何使用 PyQt 跟踪从一个 QListWidget 拖放到另一个 QListWidget 的列表项

Question

有两个启用拖放功能的 ListWidgets（示例取自上一篇文章）。 当放置事件发生时，droppedOnA(arg) 和 droppedOnA(arg) 方法被调用。从对话框窗口的“外部”（例如从文件浏览器）拖放到列表小部件上效果很好。但是从一个 listWidget 拖放到另一个 listWidget 不会。因为没有办法跟踪丢弃了哪些项目，因为 droppedOnA(arg) 和 droppedOnA(arg) 方法没有接收任何参数（当从对话框窗口的“外部”拖动丢弃的项目时会发生这种情况。在我开始使用之前解决它的混乱方法我想确保没有其他方法可以做到这一点。有吗？

from PyQt4 import QtGui, QtCore
import sys, os

class MyClassItem(QtGui.QListWidgetItem):
    def __init__(self, parent=None):
        super(QtGui.QListWidgetItem, self).__init__(parent)       


class ThumbListWidget(QtGui.QListWidget):
    def __init__(self, type, parent=None):
        super(ThumbListWidget, self).__init__(parent)
        self.setIconSize(QtCore.QSize(124, 124))
        self.setDragDropMode(QtGui.QAbstractItemView.DragDrop)
        self.setSelectionMode(QtGui.QAbstractItemView.ExtendedSelection)
        self.setAcceptDrops(True)

    def dragEnterEvent(self, event):
        if event.mimeData().hasUrls():
            event.accept()
        else:
            super(ThumbListWidget, self).dragEnterEvent(event)

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

    def dropEvent(self, event):
        if event.mimeData().hasUrls():
            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.MoveAction)
            super(ThumbListWidget, self).dropEvent(event)
            self.emit(QtCore.SIGNAL("dropped"))


class Dialog_01(QtGui.QMainWindow):
    def __init__(self):
        super(QtGui.QMainWindow,self).__init__()
        self.listItems={}

        myQWidget = QtGui.QWidget()
        myBoxLayout = QtGui.QVBoxLayout()
        myQWidget.setLayout(myBoxLayout)
        self.setCentralWidget(myQWidget)

        self.listWidgetA = ThumbListWidget(self)
        self.listWidgetB = ThumbListWidget(self)

        for i in range(3):
            listItemAInstance=MyClassItem()
            name='A'+'%04d'%i
            listItemAInstance.setText(name)
            listItemAInstance.setBackgroundColor(QtCore.Qt.darkGray)   
            if i%2: listItemAInstance.setBackgroundColor(QtCore.Qt.gray)

            icon=self.getIcon(name)
            listItemAInstance.setIcon( icon ) 

            self.listWidgetA.addItem(listItemAInstance) 

            listItemBInstance=MyClassItem()
            name='B'+'%04d'%i
            listItemBInstance.setText(name)
            icon=self.getIcon(name)
            listItemBInstance.setIcon( icon )

            if i%2: listItemBInstance.setBackgroundColor(QtCore.Qt.lightGray)
            self.listWidgetB.addItem(listItemBInstance) 

        myBoxLayout.addWidget(self.listWidgetA)      

        myBoxLayout.addWidget(self.listWidgetB)   
        self.connect(self.listWidgetA, QtCore.SIGNAL("dropped"), self.droppedOnA)
        self.connect(self.listWidgetB, QtCore.SIGNAL("dropped"), self.droppedOnB)

        Button_01 = QtGui.QPushButton("Print Dropped Items")
        Button_01.clicked.connect(self.printWhatItemsWereDropped)
        myBoxLayout.addWidget(Button_01)


    def printWhatItemsWereDropped(self):
        print "List of items dropped: "


    def getThumbPath(self, name):
        thumb_dirpath=os.path.expanduser("~")+'/thumbs/' +name+'/'+name+'.jpg'
        return thumb_dirpath

    def getIcon(self, name):
        thumbpath=self.getThumbPath(name)

        if not thumbpath: return
        color='black'
        if os.path.exists( os.path.dirname( thumbpath ) ) == False: os.makedirs( os.path.dirname( thumbpath ) )

        img = QtGui.QImage(64, 64, QtGui.QImage.Format_RGB32)
        img.fill(QtGui.QColor(96,96,96))     

        painter = QtGui.QPainter(img)
        font = painter.font()
        font.setBold(True)
        font.setPointSize(48)

        filename, fileExtension = os.path.splitext( os.path.basename( thumbpath ) )  

        text=filename.upper()
        font.setPointSize(18)        

        painter.setPen(QtGui.QColor(color))
        painter.setFont(font)
        painter.drawText(img.rect(), QtCore.Qt.AlignCenter, text)
        painter.end()
        img.save(thumbpath, 'JPG')

        icon = QtGui.QIcon( thumbpath )
        pixmap = icon.pixmap(64, 64)
        icon = QtGui.QIcon(pixmap)
        return icon


    def droppedOnA(self, arg=None):
        print '\n\t droppedOnA', arg

    def droppedOnB(self, arg=None):
        print '\n\t droppedOnB', arg


if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    dialog_1 = Dialog_01()
    dialog_1.show()
    dialog_1.resize(720,480)
    sys.exit(app.exec_())

Answer 1

我已经在comment to a previous answer 中建议了如何执行此操作。但无论如何，这是一个稍微粗略的实现，它应该打印一个源列表小部件名称的列表，然后是删除的索引。

class ThumbListWidget(QtGui.QListWidget):
    _drag_info = []

    def __init__(self, type, name, parent=None):
        super(ThumbListWidget, self).__init__(parent)
        self.setObjectName(name)
        ...

    def startDrag(self, actions):
        self._drag_info[:] = [str(self.objectName())]
        for item in self.selectedItems():
            self._drag_info.append(self.row(item))
        super(ThumbListWidget, self).startDrag(actions)

    def dropEvent(self, event):
        if event.mimeData().hasUrls():
            ...
        elif self._drag_info:
            event.setDropAction(QtCore.Qt.MoveAction)
            super(ThumbListWidget, self).dropEvent(event)
            self.emit(QtCore.SIGNAL("dropped"), list(self._drag_info))

    ...

    self.listWidgetA = ThumbListWidget(self, 'A')
    self.listWidgetB = ThumbListWidget(self, 'B')