带有复选框的 QFileSystemModel

Question

所以，我有这个简单的 PyQt5 代码，它本质上是一个文件浏览器。我需要能够选择任意文件或文件组（目录和所有子文件）。我想：

1. 在每个项目旁边添加一个复选框
2. 如果一个项目被选中/取消选中并且有子项目，子项目的状态应该设置为项目的状态。所以如果你检查一个目录，它下面的所有东西也应该被检查。
3. 当项目检查状态直接或间接更改时，我需要使用项目的完整路径（相对于根路径）调用回调。

我实际上是在构建一个要处理的选定文件列表。

import sys
from PyQt5.QtWidgets import QApplication, QFileSystemModel, QTreeView, QWidget, QVBoxLayout
from PyQt5.QtGui import QIcon

class App(QWidget):

    def __init__(self):
        super().__init__()
        self.title = 'PyQt5 file system view - pythonspot.com'
        self.left = 10
        self.top = 10
        self.width = 640
        self.height = 480
        self.initUI()
    
    def initUI(self):
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)
        
        self.model = QFileSystemModel()
        self.model.setRootPath('')
        self.tree = QTreeView()
        self.tree.setModel(self.model)
        
        self.tree.setAnimated(False)
        self.tree.setIndentation(20)
        self.tree.setSortingEnabled(True)
        
        self.tree.setWindowTitle("Dir View")
        self.tree.resize(640, 480)
        
        windowLayout = QVBoxLayout()
        windowLayout.addWidget(self.tree)
        self.setLayout(windowLayout)
        
        self.show()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = App()
    sys.exit(app.exec_())

Answer 1

在明确请求之前，QFileSystemModel 不会加载目录的内容（在树视图的情况下，它只会在目录第一次展开时发生）。

这需要仔细验证和递归设置每个路径的检查状态，不仅是在添加（或重命名/删除）新文件或目录时，而且在实际加载目录内容时。

为了正确实现这一点，检查状态也应该使用文件路径来存储，因为当目录的内容发生变化时，一些索引可能会失效。

下面的实现应该照顾上面写的所有内容，并且仅在项目状态被主动更改时发出信号并且父状态发生更改，但不是已检查目录的子项。
虽然这个选择可能看起来部分不连贯，但这是一个性能要求，因为您无法获得每个子目录的单独信号（您也可能想要）：如果您检查顶级目录，您可能会收到数千条不需要的通知；另一方面，如果父目录状态已更改，则无论何时所有项目都变为选中或未选中，接收通知可能很重要。

from PyQt5 import QtCore, QtWidgets

class CheckableFileSystemModel(QtWidgets.QFileSystemModel):
    checkStateChanged = QtCore.pyqtSignal(str, bool)
    def __init__(self):
        super().__init__()
        self.checkStates = {}
        self.rowsInserted.connect(self.checkAdded)
        self.rowsRemoved.connect(self.checkParent)
        self.rowsAboutToBeRemoved.connect(self.checkRemoved)

    def checkState(self, index):
        return self.checkStates.get(self.filePath(index), QtCore.Qt.Unchecked)

    def setCheckState(self, index, state, emitStateChange=True):
        path = self.filePath(index)
        if self.checkStates.get(path) == state:
            return
        self.checkStates[path] = state
        if emitStateChange:
            self.checkStateChanged.emit(path, bool(state))

    def checkAdded(self, parent, first, last):
        # if a file/directory is added, ensure it follows the parent state as long
        # as the parent is already tracked; note that this happens also when 
        # expanding a directory that has not been previously loaded
        if not parent.isValid():
            return
        if self.filePath(parent) in self.checkStates:
            state = self.checkState(parent)
            for row in range(first, last + 1):
                index = self.index(row, 0, parent)
                path = self.filePath(index)
                if path not in self.checkStates:
                    self.checkStates[path] = state
        self.checkParent(parent)

    def checkRemoved(self, parent, first, last):
        # remove items from the internal dictionary when a file is deleted; 
        # note that this *has* to happen *before* the model actually updates, 
        # that's the reason this function is connected to rowsAboutToBeRemoved
        for row in range(first, last + 1):
            path = self.filePath(self.index(row, 0, parent))
            if path in self.checkStates:
                self.checkStates.pop(path)

    def checkParent(self, parent):
        # verify the state of the parent according to the children states
        if not parent.isValid():
            return
        childStates = [self.checkState(self.index(r, 0, parent)) for r in range(self.rowCount(parent))]
        newState = QtCore.Qt.Checked if all(childStates) else QtCore.Qt.Unchecked
        oldState = self.checkState(parent)
        if newState != oldState:
            self.setCheckState(parent, newState)
            self.dataChanged.emit(parent, parent)
        self.checkParent(parent.parent())

    def flags(self, index):
        return super().flags(index) | QtCore.Qt.ItemIsUserCheckable

    def data(self, index, role=QtCore.Qt.DisplayRole):
        if role == QtCore.Qt.CheckStateRole and index.column() == 0:
            return self.checkState(index)
        return super().data(index, role)

    def setData(self, index, value, role, checkParent=True, emitStateChange=True):
        if role == QtCore.Qt.CheckStateRole and index.column() == 0:
            self.setCheckState(index, value, emitStateChange)
            for row in range(self.rowCount(index)):
                # set the data for the children, but do not emit the state change, 
                # and don't check the parent state (to avoid recursion)
                self.setData(index.child(row, 0), value, QtCore.Qt.CheckStateRole, 
                    checkParent=False, emitStateChange=False)
            self.dataChanged.emit(index, index)
            if checkParent:
                self.checkParent(index.parent())
            return True

        return super().setData(index, value, role)


class Test(QtWidgets.QWidget):
    def __init__(self):
        super().__init__()
        layout = QtWidgets.QVBoxLayout(self)

        self.tree = QtWidgets.QTreeView()
        layout.addWidget(self.tree, stretch=2)

        model = CheckableFileSystemModel()
        model.setRootPath('')
        self.tree.setModel(model)
        self.tree.setSortingEnabled(True)
        self.tree.header().setSectionResizeMode(QtWidgets.QHeaderView.Stretch)

        self.logger = QtWidgets.QPlainTextEdit()
        layout.addWidget(self.logger, stretch=1)
        self.logger.setReadOnly(True)

        model.checkStateChanged.connect(self.updateLog)
        self.resize(640, 480)
        QtCore.QTimer.singleShot(0, lambda: self.tree.expand(model.index(0, 0)))

    def updateLog(self, path, checked):
        if checked:
            text = 'Path "{}" has been checked'
        else:
            text = 'Path "{}" has been unchecked'
        self.logger.appendPlainText(text.format(path))
        self.logger.verticalScrollBar().setValue(
            self.logger.verticalScrollBar().maximum())


if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    test = Test()
    test.show()
    sys.exit(app.exec_())