如何以编程方式退出QListWidget中的拖放操作?
问题描述:
我正在使用一个简单显示对象列表的QListWidget。我允许用户通过内部拖放来重新排序这些项目。一切正常,但我现在需要在用户尝试删除(重新排序)时添加检查,如果检查失败,请以编程方式重新建立原始订单。这是我得到的:如何以编程方式退出QListWidget中的拖放操作?
class SequenceControl(QListWidget):
def __init__(self, parent = None):
super(SequenceControl, self).__init__(parent)
self.initialIndex = 0
self.selectedObject = None
self.setAcceptDrops(True)
self.setDragEnabled(True)
self.setDragDropMode(QAbstractItemView.InternalMove)
def dragEnterEvent(self, event):
super(SequenceControl, self).dragEnterEvent(event)
self.selectedObject = self.currentItem()
self.initialIndex = self.currentRow()
def dropEvent(self, event):
super(SequenceControl, self).dropEvent(event)
# Some logic here (not shown) to see if the drop is not
# allowed. Assume it isn't:
warningDialog = MyWarningDialog(self.parent)
ProceedAnyway = warningDialog.exec_()
if ProceedAnyway:
# Do stuff...
else:
# Here's the problem. I need to place the item being dropped
# back in its initial pre-drag/drop location. The following
# naïve attempt doesn't work:
self.insertItem(self.initialIndex, self.selectedObject)
以上绝对是错误的(我相信),因为它可能会重复项目。但除此之外,问题在于它似乎没有效果。我认为放弃事件重写我在重新排序方面的任何事情。但这只是一个理论。有谁知道正确的方法来做到这一点?
答
要恢复更改,我们必须首先删除目标项目,为此我们使用takeItem()
,除了删除它将返回项目,然后在insertItem()
函数的帮助下将其插入源位置。
class SequenceControl(QListWidget):
def __init__(self, parent=None):
super(SequenceControl, self).__init__(parent)
self.fromPos = None
self.setAcceptDrops(True)
self.setDragEnabled(True)
self.setDragDropMode(QAbstractItemView.InternalMove)
def dragEnterEvent(self, event):
super(SequenceControl, self).dragEnterEvent(event)
self.fromPos = self.currentRow()
def dropEvent(self, event):
super(SequenceControl, self).dropEvent(event)
reply = QMessageBox.question(None, "Revert to Drag and Drop",
"Do you want to keep the change?",
QMessageBox.Yes | QMessageBox.No)
if reply == QMessageBox.Yes:
print("Do stuff...")
else:
currentItem = self.takeItem(self.currentRow())
self.insertItem(self.fromPos, currentItem)