python-3.x - 在 PyQt5 中，如何使用拖放正确移动 QTableView 中的行

Question

我(只是)希望能够使用 QTableView ■ 拖放机制以移动现有行。我找到了很多来源(例如 here 、 here 或 here )，它们描述了拖放、插入等的某些方面，但我仍在努力使其适用于我的情况。

这是我正在寻找的解决方案应该具备的能力:

处理“Qt-free”数据结构，例如元组列表。

对数据结构进行操作。即当项目的顺序得到
在 View 中修改它应该在数据结构中修改

标准拖放启用列表的外观和感觉:

选择/移动整行

显示整条线的下降指示器

必须仍然可以进行进一步的操作，例如删除/编辑单元格
即不受拖放方法的影响

This tutorial显示了一个非常接近我需要的解决方案，但它使用了 QStandardItemModel而不是 QAbstractTableModel这对我来说看起来是半最佳的，因为我必须在基于 QStandardItem 的“镜像”数据结构上进行操作这是QStandardItemModel 所需要的(我对吗？)

下面附上了代表我当前进度的代码。

目前我看到两种可能的方法:

方法一 :针对QAbstractTableModel实现并实现所有需要的事件/插槽来修改底层数据结构:
* pro:最通用的方法
* pro:无冗余数据
* con:我不知道如何获知已完成的拖放
操作以及什么索引被移动到哪里

在我附加的代码中，我跟踪我知道的所有相关方法并打印出所有参数。这是我将第 2 行拖到第 3 行时得到的结果

dropMimeData(data: ['application/x-qabstractitemmodeldatalist'], action: 2, row: -1, col: -1, parent: '(row: 2, column: 0, valid: True)')
insertRows(row=-1, count=1, parent=(row: 2, column: 0, valid: True))
setData(index=(row: 0, column: 0, valid: True), value='^line1', role=0)
setData(index=(row: 0, column: 1, valid: True), value=1, role=0)
removeRows(row=1, count=1, parent=(row: -1, column: -1, valid: False))

此输出为我提出了以下问题:

为什么要moveRow/moveRows不被叫？他们什么时候会被召唤？

为什么是 insertRow/removeRow不叫，只叫 insertRows/removeRows ?

-1 的行索引是什么？意思？

我可以用 dropMimeData 中提供的 MIME 数据做什么?我以后应该用它来复制数据吗？

方法二 : 使用 QStandardItemModel并与 QStandardItemModel 管理的数据并行修改您的数据.
* 专业人士:有一个 working example
* 反对:您管理一个必须一致的冗余数据结构
与另一个内部管理的数据结构。
* 反对:也没有确切地知道如何做到这一点

Here is my current approach using QAbstractTableModel:

from PyQt5 import QtWidgets, QtCore, QtGui

class MyModel(QtCore.QAbstractTableModel):
    def __init__(self, data, parent=None, *args):
        super().__init__(parent, *args)
        self._data = data

    def columnCount(self, parent):
        return 2

    def rowCount(self, parent):
        return len(self._data)

    def headerData(self, column: int, orientation, role: QtCore.Qt.ItemDataRole):
        return (('Regex', 'Category')[column] 
                if role == QtCore.Qt.DisplayRole and orientation == QtCore.Qt.Horizontal
                else None)

    def data(self, index, role: QtCore.Qt.ItemDataRole):
        if role not in {QtCore.Qt.DisplayRole, QtCore.Qt.EditRole}:
            return None

        print("data(index=%s, role=%r)" % (self._index2str(index), self._role2str(role)))
        return (self._data[index.row()][index.column()] 
               if index.isValid()
               and role in {QtCore.Qt.DisplayRole, QtCore.Qt.EditRole} 
               and index.row() < len(self._data)
               else None)

    def setData(self, index: QtCore.QModelIndex, value, role: QtCore.Qt.ItemDataRole):

        print("setData(index=%s, value=%r, role=%r)" % (self._index2str(index), value, role))
        return super().setData(index, value, role)

    def flags(self, index):
        return (
           super().flags(index) 
            | QtCore.Qt.ItemIsDropEnabled
            | (QtCore.Qt.ItemIsEditable | QtCore.Qt.ItemIsDragEnabled)
              if index.isValid() else QtCore.Qt.NoItemFlags)

    def dropMimeData(self, data, action, row, col, parent: QtCore.QModelIndex):
        """Always move the entire row, and don't allow column 'shifting'"""
        print("dropMimeData(data: %r, action: %r, row: %r, col: %r, parent: %r)" % (
            data.formats(), action, row, col, self._index2str(parent)))
        assert action == QtCore.Qt.MoveAction
        return super().dropMimeData(data, action, row, 0, parent)

    def supportedDragActions(self):
        return QtCore.Qt.MoveAction

    def supportedDropActions(self):
        return QtCore.Qt.MoveAction | QtCore.Qt.CopyAction

    def removeRow(self, row: int, parent=None):
        print("removeRow(row=%r):" % (row))
        return super().removeRow(row, parent)

    def removeRows(self, row: int, count: int, parent=None):
        print("removeRows(row=%r, count=%r, parent=%s)" % (row, count, self._index2str(parent)))
        return super().removeRows(row, count, parent)

    def insertRow(self, index, parent=None):
        print("insertRow(row=%r, count=%r):" % (row, count))
        return super().insertRow(row, count, parent)

    def insertRows(self, row: int, count: int, parent: QtCore.QModelIndex = None):
        print("insertRows(row=%r, count=%r, parent=%s)" % (row, count, self._index2str(parent)))
        return super().insertRows(row, count, parent)

    @staticmethod
    def _index2str(index):
        return "(row: %d, column: %d, valid: %r)" % (index.row(), index.column(), index.isValid())

    @staticmethod
    def _role2str(role: QtCore.Qt.ItemDataRole) -> str:
        return "%s (%d)" % ({
            QtCore.Qt.DisplayRole: "DisplayRole",
            QtCore.Qt.DecorationRole: "DecorationRole",
            QtCore.Qt.EditRole: "EditRole",
            QtCore.Qt.ToolTipRole: "ToolTipRole",
            QtCore.Qt.StatusTipRole: "StatusTipRole",
            QtCore.Qt.WhatsThisRole: "WhatsThisRole",
            QtCore.Qt.SizeHintRole: "SizeHintRole",

            QtCore.Qt.FontRole: "FontRole",
            QtCore.Qt.TextAlignmentRole: "TextAlignmentRole",
            QtCore.Qt.BackgroundRole: "BackgroundRole",
            #QtCore.Qt.BackgroundColorRole:
            QtCore.Qt.ForegroundRole: "ForegroundRole",
            #QtCore.Qt.TextColorRole
            QtCore.Qt.CheckStateRole: "CheckStateRole",
            QtCore.Qt.InitialSortOrderRole: "InitialSortOrderRole",
        }[role], role)


class MyTableView(QtWidgets.QTableView):
    class DropmarkerStyle(QtWidgets.QProxyStyle):
        def drawPrimitive(self, element, option, painter, widget=None):
            """Draw a line across the entire row rather than just the column we're hovering over.
            This may not always work depending on global style - for instance I think it won't
            work on OSX."""
            if element == self.PE_IndicatorItemViewItemDrop and not option.rect.isNull():
                option_new = QtWidgets.QStyleOption(option)
                option_new.rect.setLeft(0)
                if widget:
                    option_new.rect.setRight(widget.width())
                option = option_new
            super().drawPrimitive(element, option, painter, widget)

    def __init__(self):
        super().__init__()
        self.setStyle(self.DropmarkerStyle())
        # only allow rows to be selected
        self.setSelectionBehavior(QtWidgets.QAbstractItemView.SelectRows)
        # disallow multiple rows to be selected
        self.setSelectionMode(QtWidgets.QAbstractItemView.SingleSelection)
        self.setDragEnabled(True)

        self.setDragDropMode(QtWidgets.QAbstractItemView.InternalMove)
        self.setDropIndicatorShown(True) # default
        self.setAcceptDrops(False)           # ?
        self.viewport().setAcceptDrops(True) # ?
        self.setDragDropOverwriteMode(False)


class HelloWindow(QtWidgets.QMainWindow):
    def __init__(self) -> None:
        super().__init__()

        model = MyModel([("^line0", 0),
                         ("^line1", 1),
                         ("^line2", 2),
                         ("^line3", 3)])

        table_view = MyTableView()
        table_view.setModel(model)
        table_view.verticalHeader().hide()
        table_view.setShowGrid(False)

        self.setCentralWidget(table_view)


def main():
    app = QtWidgets.QApplication([])
    window = HelloWindow()
    window.show()
    app.exec_()

if __name__ == "__main__":
    main()

Answer 1

MyData 类应该从 QStandardItemModel 继承
修改您的代码以解决拖放和扩展类函数调用问题。

from PyQt5 import (QtWidgets, QtCore)
from PyQt5.QtWidgets import (QApplication, QTableView)
from PyQt5.QtGui import (QStandardItem, QStandardItemModel)


class MyModel(QStandardItemModel):
    def __init__(self, data, parent=None, *args):
        super().__init__(parent, *args)
        self._data = data

        for (index, data) in enumerate(data):
            first = QStandardItem('Item {}'.format(index))
            first.setDropEnabled(False)
            first.setEditable(False)
            second = QStandardItem(data[0])
            second.setDropEnabled(False)
            second.setEditable(False)
            self.appendRow([first, second])

    def columnCount(self, parent):
        return 2

    def rowCount(self, parent):
        return len(self._data)

    def headerData(self, column: int, orientation, role: QtCore.Qt.ItemDataRole):
        return (('Regex', 'Category')[column]
                if role == QtCore.Qt.DisplayRole and orientation == QtCore.Qt.Horizontal
                else None)

    def data(self, index, role: QtCore.Qt.ItemDataRole):
        if role not in {QtCore.Qt.DisplayRole, QtCore.Qt.EditRole}:
            return None

        print("data(index=%s, role=%r)" % (self._index2str(index), self._role2str(role)))
        return (self._data[index.row()][index.column()]
                if index.isValid() and role in {QtCore.Qt.DisplayRole, QtCore.Qt.EditRole} and index.row() < len(
            self._data)
                else None)

    def setData(self, index: QtCore.QModelIndex, value, role: QtCore.Qt.ItemDataRole):
        print("setData(index=%s, value=%r, role=%r)" % (self._index2str(index), value, role))
        return super().setData(index, value, role)

    def flags(self, index):
        return (
            super().flags(index)
            | QtCore.Qt.ItemIsDropEnabled
            | (QtCore.Qt.ItemIsEditable | QtCore.Qt.ItemIsDragEnabled)
            if index.isValid() else QtCore.Qt.NoItemFlags)

    def dropMimeData(self, data, action, row, col, parent: QtCore.QModelIndex):
        """Always move the entire row, and don't allow column 'shifting'"""
        print("dropMimeData(data: %r, action: %r, row: %r, col: %r, parent: %r)" % (
            data.formats(), action, row, col, self._index2str(parent)))
        assert action == QtCore.Qt.MoveAction
        return super().dropMimeData(data, action, row, 0, parent)

    def supportedDragActions(self):
        return QtCore.Qt.MoveAction

    def supportedDropActions(self):
        return QtCore.Qt.MoveAction | QtCore.Qt.CopyAction

    def removeRow(self, row: int, parent=None):
        print("removeRow(row=%r):" % (row))
        return super().removeRow(row, parent)

    def removeRows(self, row: int, count: int, parent=None):
        print("removeRows(row=%r, count=%r, parent=%s)" % (row, count, self._index2str(parent)))
        return super().removeRows(row, count, parent)

    def insertRow(self, index, parent=None):
        print("insertRow(row=%r, count=%r):" % (row, count))
        return super().insertRow(row, count, parent)

    def insertRows(self, row: int, count: int, parent: QtCore.QModelIndex = None):
        print("insertRows(row=%r, count=%r, parent=%s)" % (row, count, self._index2str(parent)))
        return super().insertRows(row, count, parent)

    @staticmethod
    def _index2str(index):
        return "(row: %d, column: %d, valid: %r)" % (index.row(), index.column(), index.isValid())

    @staticmethod
    def _role2str(role: QtCore.Qt.ItemDataRole) -> str:
        return "%s (%d)" % ({
                                QtCore.Qt.DisplayRole: "DisplayRole",
                                QtCore.Qt.DecorationRole: "DecorationRole",
                                QtCore.Qt.EditRole: "EditRole",
                                QtCore.Qt.ToolTipRole: "ToolTipRole",
                                QtCore.Qt.StatusTipRole: "StatusTipRole",
                                QtCore.Qt.WhatsThisRole: "WhatsThisRole",
                                QtCore.Qt.SizeHintRole: "SizeHintRole",

                                QtCore.Qt.FontRole: "FontRole",
                                QtCore.Qt.TextAlignmentRole: "TextAlignmentRole",
                                QtCore.Qt.BackgroundRole: "BackgroundRole",
                                # QtCore.Qt.BackgroundColorRole:
                                QtCore.Qt.ForegroundRole: "ForegroundRole",
                                # QtCore.Qt.TextColorRole
                                QtCore.Qt.CheckStateRole: "CheckStateRole",
                                QtCore.Qt.InitialSortOrderRole: "InitialSortOrderRole",
                            }[role], role)


class MyTableView(QTableView):
    class DropMarkerStyle(QtWidgets.QProxyStyle):
        def drawPrimitive(self, element, option, painter, widget=None):
            """Draw a line across the entire row rather than just the column we're hovering over.
            This may not always work depending on global style - for instance I think it won't
            work on OSX."""
            if element == self.PE_IndicatorItemViewItemDrop and not option.rect.isNull():
                option_new = QtWidgets.QStyleOption(option)
                option_new.rect.setLeft(0)
                if widget:
                    option_new.rect.setRight(widget.width())
                option = option_new
            super().drawPrimitive(element, option, painter, widget)

    def __init__(self):
        super().__init__()
        self.setStyle(self.DropMarkerStyle())
        self.verticalHeader().hide()
        self.setShowGrid(False)
        # only allow rows to be selected
        self.setSelectionBehavior(self.SelectRows)
        # disallow multiple rows to be selected
        self.setSelectionMode(self.SingleSelection)
        self.setDragDropMode(self.InternalMove)
        self.setDragDropOverwriteMode(False)


class HelloWindow(QtWidgets.QMainWindow):
    def __init__(self) -> None:
        super().__init__()
        model = MyModel([("^line0", 0),
                         ("^line1", 1),
                         ("^line2", 2),
                         ("^line3", 3)])
        table_view = MyTableView()
        table_view.setModel(model)
        self.setCentralWidget(table_view)


def main():
    app = QApplication([])
    window = HelloWindow()
    window.show()
    app.exec_()


if __name__ == "__main__":
    main()