我有两个列表小部件，基本上是项目选择器。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。这里只有一个问题。我需要在选择更改或单击某个项目时执行该过程，但我不希望该事件发生两次，这是我遇到的问题
有点难以描述，但请看下面的代码。
场景1：两个列表仅连接＆＃34; itemSelectionChanged＆＃34; 点击＆＃34;奶酪＆＃34; 点击＆＃34;否＆＃34; 现在两者都被选中，当你交替点击它们时没有任何事情发生，因为没有选择正在改变，但是当我从不同的列表中选择一个项目时，我需要调用something_happened方法。
场景2：两个列表仅连接＆＃34;点击＆＃34; 点击后会发生一些事情，但当我点击并拖动以更改选择时，不会触发任何事件，因为＆＃34;点击＆＃34;没有发生，并且itemSelectionChanged没有连接到任何东西。当选择以这种方式改变时，我需要调用something_happened方法。
场景3：两个列表都连接＆＃34; itemSelectionChanged＆＃34;还有＆＃34;点击＆＃34; 单击并拖动以更改选择会使某些事情发生（很好），但是当我执行单个＆＃34;单击＆＃34;在一个新项目上，两个信号都被发送，我想要发生的事件发生两次（坏）。
鉴于上述情况，我希望同时实现以下所有目标：
以下是示例代码：
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_()
答案 0 :(得分：3)
在这个例子中，我是QListWidget的子类。这没有必要，但我认为如果您在窗口小部件本身中封装选择更改的决定，它将使代码更清晰。我制作了两种类型的小部件，每种小部件都有自己的行为，以决定选择是否改变。你可以使用mousePress / mouseRelease / selectionChanged组合，希望这段代码能为你提供所需的工具。 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：我意识到我从未说过“当我点击已经选中的项目（发出项目点击信号）时处理一个事件”。 我将其视为单项单击，但也可以针对相同的多项目点击进行解决（使用mouseReleaseEvent，并比较旧的新列表）。 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，以及它是否是同一个项目。
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()