为什么 QTableWidgetItem 不不断更新它的颜色？

Question

我的程序中有一个 QTableWidget。我希望它的行和列根据表格小部件中的时间条目来改变颜色。当我第一次添加时间时，它与当前系统时间进行比较，颜色变化确实生效，但随着时间的推移，它并没有跟上，颜色保持不变。我希望它不断更新表格项目的颜色。我无法包含所有代码，因为它太长了，但我已经包含了相关部分。

#Operations_Tree is the QTABLEWIDGET
def Scheduler_Loop(self):
    Timer = QtCore.QTimer(self)
    Timer.start(1000)
    Timer.timeout.connect(self.test)

def test(self):

    time = QtCore.QTime.currentTime()
    current_time_text = time.toString('hh:mm:ss')
    for row in range(0,self.Operations_Tree.rowCount()):
        time = self.Operations_Tree.item(row,1)
        time_text = time.text()
        #print(time_text)
        if time_text >= current_time_text :
            for column in range(0,6):
                #print("TEST")
                try:
                    table_widget_item = self.Operations_Tree.item(row, column)
                    table_widget_item.setForeground(QtGui.QColor(0,0,255)) #BLue
                    table_widget_item.setBackground(QtGui.QColor(238,233,233)) #
                    table_widget_item.viewport.update()
                except AttributeError:
                    pass
        else:
            for column in range(0,6):
                #print("TEST")
                try:
                    table_widget_item = self.Operations_Tree.item(row, column)
                    #table_widget_item.setForeground(QtGui.QColor(0,255,0)) #
                    table_widget_item.setBackground(QtGui.QColor(238,233,233)) #
                    table_widget_item.viewport.update()
                except AttributeError:
                    pass
    self.Operations_Tree.update()  

这是我的程序的快照：

Answer 1

对我来说，主要问题是你在比较字符串而不是时间，同样在 Qt 中也没有必要使用 try-except 因为很多时候它们会隐藏错误并浪费不必要的资源，最好验证一下。

PyQt5：

from PyQt5 import QtCore, QtGui, QtWidgets


class Widget(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Widget, self).__init__(parent)
        self.lcd_number = QtWidgets.QLCDNumber()
        self.lcd_number.setFrameShape(QtWidgets.QFrame.NoFrame)
        self.lcd_number.setFixedHeight(100)
        self.lcd_number.setDigitCount(8)
        self.Operations_Tree = QtWidgets.QTableWidget()
        self.Operations_Tree.setColumnCount(6)
        labels = ["On AIR", "TIME", "ITEM", "DURATION", "B.ITEM", "B.I.DURATION"]
        self.Operations_Tree.setHorizontalHeaderLabels(labels)

        lay = QtWidgets.QVBoxLayout(self)
        lay.addWidget(self.lcd_number)
        lay.addWidget(self.Operations_Tree)

        for i, t in enumerate(("10:10:10", "12:12:12")):
            self.Operations_Tree.insertRow(self.Operations_Tree.rowCount())
            it = QtWidgets.QTableWidgetItem(t)
            self.Operations_Tree.setItem(i, 1, it)

        self.resize(640, 480)
        self.Scheduler_Loop()

    def Scheduler_Loop(self):
        Timer = QtCore.QTimer(self)
        Timer.timeout.connect(self.test)
        Timer.start(1000)
        self.test()

    @QtCore.pyqtSlot()
    def test(self):
        time = QtCore.QTime.currentTime()
        self.lcd_number.display(time.toString())
        for row in range(self.Operations_Tree.rowCount()):
            it = self.Operations_Tree.item(row, 1)
            r_time = QtCore.QTime.fromString(it.text(), "h:mm:ss")
            flag = r_time >= time
            f_color = QtGui.QColor(0, 0, 255) if flag else QtGui.QColor(0, 255, 0)
            b_color = QtGui.QColor(238, 233, 233) if flag else QtGui.QColor(238,233,233)
            for column in range(0, 6):
                it = self.Operations_Tree.item(row, column)
                if it is None:
                    it = QtWidgets.QTableWidgetItem()
                    self.Operations_Tree.setItem(row, column, it)
                it.setForeground(f_color)
                it.setBackground(b_color)

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

PyQt4：

from PyQt4 import QtCore, QtGui


class Widget(QtGui.QWidget):
    def __init__(self, parent=None):
        super(Widget, self).__init__(parent)
        self.lcd_number = QtGui.QLCDNumber()
        self.lcd_number.setFrameShape(QtGui.QFrame.NoFrame)
        self.lcd_number.setFixedHeight(100)
        self.lcd_number.setDigitCount(8)
        self.Operations_Tree = QtGui.QTableWidget()
        self.Operations_Tree.setColumnCount(6)
        labels = ["On AIR", "TIME", "ITEM", "DURATION", "B.ITEM", "B.I.DURATION"]
        self.Operations_Tree.setHorizontalHeaderLabels(labels)

        lay = QtGui.QVBoxLayout(self)
        lay.addWidget(self.lcd_number)
        lay.addWidget(self.Operations_Tree)

        for i, t in enumerate(("10:10:10", "12:12:12")):
            self.Operations_Tree.insertRow(self.Operations_Tree.rowCount())
            it = QtGui.QTableWidgetItem(t)
            self.Operations_Tree.setItem(i, 1, it)

        self.resize(640, 480)
        self.Scheduler_Loop()

    def Scheduler_Loop(self):
        Timer = QtCore.QTimer(self)
        Timer.timeout.connect(self.test)
        Timer.start(1000)
        self.test()

    @QtCore.pyqtSlot()
    def test(self):
        time = QtCore.QTime.currentTime()
        self.lcd_number.display(time.toString())
        for row in range(self.Operations_Tree.rowCount()):
            it = self.Operations_Tree.item(row, 1)
            r_time = QtCore.QTime.fromString(it.text(), "h:mm:ss")
            flag = r_time >= time
            f_color = QtGui.QColor(0, 0, 255) if flag else QtGui.QColor(0, 255, 0)
            b_color = QtGui.QColor(238, 233, 233) if flag else QtGui.QColor(238,233,233)
            for column in range(0, 6):
                it = self.Operations_Tree.item(row, column)
                if it is None:
                    it = QtGui.QTableWidgetItem()
                    self.Operations_Tree.setItem(row, column, it)
                it.setForeground(f_color)
                it.setBackground(b_color)

if __name__ == '__main__':
    import sys
    app = QtGui.QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())