Python QListWidget处理来自单击和itemSelectionChanged的多个信号

我有两个基本上是项目选择器的列表小部件。当我在任一列表中选择一个项目时，我需要它来触发一个方法。这里只讨论一个程序。我需要在选择更改或单击某个项目时执行该过程，但我不希望这种情况发生两次，这是我遇到的问题

这有点难以描述，但请看下面的代码

场景1：两个列表仅连接“itemSelectionChanged” 点击“奶酪” 单击“否” 现在这两个都被选中了，当您交替单击它们时，不会发生任何事情，因为没有选择发生更改，但是当我从不同的列表中选择一个项目时，我需要调用某个方法

场景2：两个列表仅连接“已单击” 单击某个对象时会发生，但当我单击并拖动以更改选择时，不会触发任何事件，因为“单击”不会发生，并且itemSelectionChanged不会连接到任何对象。当选择也以这种方式更改时，我需要调用something_ocated方法

场景3：两个列表都连接“itemSelectionChanged”和“clicked” 单击并拖动以更改选择会使某些事情发生（好），但当我对一个新项目进行一次“单击”时，两个信号都会发送，并且我想要发生的事件会发生两次（坏）

鉴于上述情况，我希望同时实现以下所有目标：

• 单击新项目时，仅处理一个事件（同时发出itemSelectionChanged和itemClicked，导致两个事件）
• 当我单击一个已选择的项目（发出itemClicked信号）时，处理一个事件
• 通过单击并拖动更改选择时处理一个事件（会发出itemSelectionChagned信号）

下面是示例代码：

from PyQt4 import QtGui
QtWidgets = QtGui
# from PyQt5 import QtWidgets
import sys
import time


def something_happened():
    print(time.time())

app = QtWidgets.QApplication(sys.argv)

widget = QtWidgets.QWidget(None)
vlay = QtWidgets.QVBoxLayout(widget)

list_widget1 = QtWidgets.QListWidget(None)
list_widget1.setSelectionMode(QtWidgets.QAbstractItemView.ExtendedSelection)
list_widget1.addItems(("Cheese", "Whiz", "tastes", "great"))
list_widget1.itemSelectionChanged.connect(something_happened)
list_widget1.clicked.connect(something_happened)

list_widget2 = QtWidgets.QListWidget(None)
list_widget2.setSelectionMode(QtWidgets.QAbstractItemView.ExtendedSelection)
list_widget2.addItems(("No", "it", "tastes", "bad"))
list_widget2.itemSelectionChanged.connect(something_happened)
# list_widget2.clicked.connect(something_happened)

vlay.addWidget(list_widget1)
vlay.addWidget(list_widget2)

widget.show()

app.exec_()

---

在本例中，我将对QListWidget进行子类化。这是没有必要的，但我认为如果您将选择更改的决定封装在小部件本身中，那么代码会更干净。我制作了两种类型的小部件，每个小部件都有自己的行为来决定选择是否改变。您可以使用mousePress/mouseRelease/selectionChanged组合，希望这段代码能为您提供所需的工具。 运行此程序，并注意两个小部件之间的差异

class SomeFrame(object):
    """A container to place all the widgets, and control
       present the output from the selections.
    """
    def __init__(self):
        self.frame = QtWidgets.QFrame()

        # Creating content
        list_widget1 = MyQListWidgetA()
        list_widget1.setSelectionMode(QtWidgets.QAbstractItemView.ExtendedSelection)
        list_widget1.addItems(("Cheese", "Whiz", "tastes", "great"))

        list_widget2 = MyQListWidgetB()
        list_widget2.setSelectionMode(QtWidgets.QAbstractItemView.ExtendedSelection)
        list_widget2.addItems(("No", "it", "tastes", "bad"))

        # Creating Layout
        layout = QtWidgets.QHBoxLayout()
        layout.addWidget(list_widget1)
        layout.addWidget(list_widget2)

        self.frame.setLayout(layout)

        # Connections
        from functools import partial
        list_widget1.selection_changed.connect(partial(self.selectionChangedCB, 'list_1'))
        list_widget2.selection_changed.connect(partial(self.selectionChangedCB, 'list_2'))

        self.frame.show()

    def selectionChangedCB(self, list_name, selected_items):
        print(list_name + ' changed: ' + str(selected_items))


from PyQt5 import QtWidgets, QtCore
class MyQListWidgetA(QtWidgets.QListWidget):
    """This widget emits selection_changed whenever its
       itemSelectionChanged signal is emitted, AND there
       was an actual change in the selected items.
    """
    selection_changed = QtCore.pyqtSignal(object)

    def __init__(self):
        QtWidgets.QListWidget.__init__(self)

        self.selected_items = set()

        self.itemSelectionChanged.connect(self.something_happened)

    def something_happened(self):
        # Create a set of the newly selected items, so we can compare
        # to the old selected items set
        newly_selected_items = set([item.text() for item in self.selectedItems()])
        if newly_selected_items != self.selected_items:
            # Only emit selection_changed signal if a change was detected.
            self.selected_items = newly_selected_items
            self.selection_changed.emit(self.selected_items)


class MyQListWidgetB(QtWidgets.QListWidget):
    """This widget emits selection_changed whenever it is pressed
       (mimic "clicked" signal) and again when the user is done
       selecting the items (mouse release) IFF the selection
       has changed.
    """
    selection_changed = QtCore.pyqtSignal(object)

    def __init__(self):
        QtWidgets.QListWidget.__init__(self)

        self.selected_items = set()

    def something_happened(self, initial_click=False):
        # Create a set of the newly selected items, so we can
        # compare to the old selected items set
        newly_selected_items = set([item.text() for item in self.selectedItems()])
        if newly_selected_items != self.selected_items:
            # Only emit selection_changed signal if a change was detected
            self.selected_items = newly_selected_items
            self.selection_changed.emit(self.selected_items)

    def mousePressEvent(self, event):
        QtWidgets.QListWidget.mousePressEvent(self, event)
        self.something_happened()

    def mouseReleaseEvent(self, event):
        QtWidgets.QListWidget.mouseReleaseEvent(self, event)
        self.something_happened()


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)         
    theFrame = SomeFrame()
    sys.exit(app.exec_())

编辑：我意识到我从来没有考虑过“当我点击一个已经选择的项目时处理一个事件（它发出itemClicked信号）”。 我将其视为相同的单个项目单击，但也可以解决相同的多个项目单击（使用mouseReleaseEvent，并比较新旧列表）。 只需添加MyQListWidgetC，并将其连接到两个信号。B和C之间的主要区别在于，在mousePressEvent中，我们检查是否按下了单个项目，以及它是否是相同的项目

class MyQListWidgetC(QtWidgets.QListWidget):
    """This widget emits selection_changed whenever it is pressed
       (mimic "clicked" signal) and again when the user is done
       selecting the items (mouse release) IFF the selection
       has changed. If a single item was clicked, AND it is the
       same item, the widget will emit same_item_clicked, which
       the owner can listen to and decide what to do.
    """
    selection_changed = QtCore.pyqtSignal(object)
    same_item_clicked = QtCore.pyqtSignal(object)

    def __init__(self):
        QtWidgets.QListWidget.__init__(self)

        self.selected_items = set()

    def something_happened(self, initial_click=False):
        # Create a set of the newly selected items, so we can
        # compare to the old selected items set
        newly_selected_items = set([item.text() for item in self.selectedItems()])
        if newly_selected_items != self.selected_items:
            # Only emit selection_changed signal if a change was detected
            self.selected_items = newly_selected_items
            self.selection_changed.emit(self.selected_items)

    def mousePressEvent(self, event):
        QtWidgets.QListWidget.mousePressEvent(self, event)
        newly_selected_items = set([item.text() for item in self.selectedItems()])
        if len(newly_selected_items) == 1 and newly_selected_items == self.selected_items:
            self.same_item_clicked.emit(self.selected_items)
        else:
            self.something_happened()

    def mouseReleaseEvent(self, event):
        QtWidgets.QListWidget.mouseReleaseEvent(self, event)
        self.something_happened()

---

令人惊叹的。非常感谢。我喜欢你是怎么想出来的，这样物体就能跟踪自己了。我想我必须将列表中的所有信号通过一个外部对象进行路由，但这要好得多。谢谢