如何在 QtChart 中更改 QPieSlice 的标签大小答案

【问题标题】：How to change Label size of QPieSlice in QtChart如何在 QtChart 中更改 QPieSlice 的标签大小
【发布时间】：2021-07-25 01:01:53
【问题描述】：

我尝试使用 slice.setLabelFont(font) 但它不起作用，我在下面附上了我的代码

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, *args, **kwargs):
        super(MainWindow, self).__init__(*args, **kwargs)

        #Load the UI Page
        THIS_FOLDER = os.path.dirname(os.path.abspath(__file__))
        my_file = os.path.join(THIS_FOLDER, 'main.ui')
        uic.loadUi(my_file, self)

        # changing the background color to cyan
        self.setStyleSheet("background-color: #363636;")
  
        # set the title
        self.setWindowTitle("Screen Time")

        # self.graphWidget = pg.PlotWidget()
        # self.setCentralWidget(self.graphWidget)

        font=QtGui.QFont()
        font.setPixelSize(20)
        font.setPointSize(20)
        

        series = QtChart.QPieSeries()
        series.setHoleSize(0.5)
        series.append("Example1 40%",40.0)
        
      
        slice = QtChart.QPieSlice()

        slice.setLabelFont(font)

        slice = series.append("Example1 30%",30.0)
        slice.setLabelVisible()
        
        series.append("Example1 30%",30.0)

        chart = QtChart.QChart()
        
        chart.addSeries(series)
        chart.setTitleFont(font)
        chart.setTitle('usage time')
        
        chart.setAnimationOptions(QtChart.QChart.SeriesAnimations)
        chart.setTheme(QtChart.QChart.ChartThemeDark)
        #chart.animation

        chart.setBackgroundBrush(QtGui.QBrush(QtGui.QColor("transparent")))
        chart.legend().setVisible(True)
        chartview = QtChart.QChartView(chart)
        chartview.setRenderHint(QtGui.QPainter.Antialiasing)

        self.chart_container.setStyleSheet("background-color: #363636;")

        self.chart_container.setContentsMargins(0, 0, 0, 0)
        lay = QtWidgets.QHBoxLayout(self.chart_container)
        lay.setContentsMargins(0, 0, 0, 0)
        lay.addWidget(chartview)

【问题讨论】：

标签： python python-3.x pyqt pyqt5 pyqtchart

【解决方案1】：

有两个问题。首先，您在从未添加到 QPieSeries 的 QPieSlice 上调用 setLabelFont。

slice = QtChart.QPieSlice() # this is never added to the series
slice.setLabelFont(font)

slice = series.append("Example1 30%",30.0) # creates and returns a new pie slice
slice.setLabelVisible()

其次，将图表主题设置为QChart.ChartThemeDark会将字体改回默认值，因此必须在QPieSlice标签字体之前设置。正如docs中提到的：

更改主题将覆盖之前应用于该系列的所有自定义设置。

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, *args, **kwargs):
        super(MainWindow, self).__init__(*args, **kwargs)

        #Load the UI Page
        THIS_FOLDER = os.path.dirname(os.path.abspath(__file__))
        my_file = os.path.join(THIS_FOLDER, 'main.ui')
        uic.loadUi(my_file, self)
        self.setStyleSheet("background-color: #363636;")
        self.setWindowTitle("Screen Time")

        chart = QtChart.QChart()
        chart.setTheme(QtChart.QChart.ChartThemeDark)

        font=QtGui.QFont()
        font.setPixelSize(20)
        font.setPointSize(20)
        
        series = QtChart.QPieSeries()
        series.setHoleSize(0.5)
        series.append("Example1 40%",40.0)
        
        slice = series.append("Example1 30%",30.0)
        slice.setLabelVisible()
        slice.setLabelFont(font)
        
        series.append("Example1 30%",30.0)
        chart.addSeries(series)
        
        chart.setTitleFont(font)
        chart.setTitle('usage time')
        chart.setAnimationOptions(QtChart.QChart.SeriesAnimations)
        chart.setBackgroundBrush(QtGui.QBrush(QtGui.QColor("transparent")))
        chart.legend().setVisible(True)
        chartview = QtChart.QChartView(chart)
        chartview.setRenderHint(QtGui.QPainter.Antialiasing)

        self.chart_container.setStyleSheet("background-color: #363636;")

        self.chart_container.setContentsMargins(0, 0, 0, 0)
        lay = QtWidgets.QHBoxLayout(self.chart_container)
        lay.setContentsMargins(0, 0, 0, 0)
        lay.addWidget(chartview)

【讨论】：