def paintEvent(self, event):
        painter = QPainter(self)
        painter.setRenderHint(QPainter.Antialiasing)
        # 背景白色
        painter.fillRect(event.rect(), QBrush(Qt.white))
        # 绘制边缘虚线框
        painter.setPen(Qt.DashLine)
        painter.setBrush(Qt.NoBrush)
        painter.drawRect(self.rect())
        # 随机画条线
        for _ in range(3):
            painter.setPen(QPen(QTCOLORLIST[qrand() % 5], 1, Qt.SolidLine))
            painter.setBrush(Qt.NoBrush)
            painter.drawLine(QPoint(0, qrand() % self.height()),
                             QPoint(self.width(), qrand() % self.height()))
            painter.drawLine(QPoint(qrand() % self.width(), 0),
                             QPoint(qrand() % self.width(), self.height()))
        # 绘制噪点
        painter.setPen(Qt.DotLine)
        painter.setBrush(Qt.NoBrush)
        for _ in range(self.width()):  # 绘制噪点
            painter.drawPoint(QPointF(qrand() % self.width(), qrand() % self.height()))
        # super(WidgetCode, self).paintEvent(event)  # 绘制文字
        # 绘制跳动文字
        metrics = QFontMetrics(self.font())
        x = (self.width() - metrics.width(self.text())) / 2
        y = (self.height() + metrics.ascent() - metrics.descent()) / 2
        for i, ch in enumerate(self.text()):
            index = (self.step + i) % 16
            painter.setPen(TCOLORLIST[qrand() % 6])
            painter.drawText(x, y - ((SINETABLE[index] * metrics.height()) / 400), ch)
            x += metrics.width(ch) 

def __init__(self, model_item: Participant, parent=None):
        super().__init__(parent)

        self.model_item = model_item

        self.text = QGraphicsTextItem(self)

        self.line = QGraphicsLineItem(self)
        self.line.setPen(QPen(Qt.darkGray, 1, Qt.DashLine, Qt.RoundCap, Qt.RoundJoin))

        self.refresh() 

def refresh(self):
        self.text.setPlainText("?" if not self.model_item else self.model_item.shortname)
        if hasattr(self.model_item, "simulate") and self.model_item.simulate:
            font = QFont()
            font.setBold(True)
            self.text.setFont(font)
            self.text.setDefaultTextColor(Qt.darkGreen)
            self.line.setPen(QPen(Qt.darkGreen, 2, Qt.SolidLine, Qt.RoundCap, Qt.RoundJoin))
        else:
            self.text.setFont(QFont())
            self.text.setDefaultTextColor(settings.LINECOLOR)
            self.line.setPen(QPen(Qt.darkGray, 1, Qt.DashLine, Qt.RoundCap, Qt.RoundJoin)) 

def add_grid(self):
        """Add axis and ticks to figure.

        Notes
        -----
        I know that visvis and pyqtgraphs can do this in much simpler way, but
        those packages create too large a padding around the figure and this is
        pretty fast.

        """
        value = self.config.value

        # X-AXIS
        # x-bottom
        self.scene.addLine(value['x_min'], value['y_min'],
                           value['x_min'], value['y_max'],
                           QPen(QColor(LINE_COLOR), LINE_WIDTH))
        # at y = 0, dashed
        self.scene.addLine(value['x_min'], 0,
                           value['x_max'], 0,
                           QPen(QColor(LINE_COLOR), LINE_WIDTH, Qt.DashLine))
        # ticks on y-axis
        y_high = int(floor(value['y_max']))
        y_low = int(ceil(value['y_min']))
        x_length = (value['x_max'] - value['x_min']) / value['x_tick']
        for y in range(y_low, y_high):
            self.scene.addLine(value['x_min'], y,
                               value['x_min'] + x_length, y,
                               QPen(QColor(LINE_COLOR), LINE_WIDTH))
        # Y-AXIS
        # left axis
        self.scene.addLine(value['x_min'], value['y_min'],
                           value['x_max'], value['y_min'],
                           QPen(QColor(LINE_COLOR), LINE_WIDTH))
        # larger ticks on x-axis every 10 Hz
        x_high = int(floor(value['x_max']))
        x_low = int(ceil(value['x_min']))
        y_length = (value['y_max'] - value['y_min']) / value['y_tick']
        for x in range(x_low, x_high, 10):
            self.scene.addLine(x, value['y_min'],
                               x, value['y_min'] + y_length,
                               QPen(QColor(LINE_COLOR), LINE_WIDTH))
        # smaller ticks on x-axis every 10 Hz
        y_length = (value['y_max'] - value['y_min']) / value['y_tick'] / 2
        for x in range(x_low, x_high, 5):
            self.scene.addLine(x, value['y_min'],
                               x, value['y_min'] + y_length,
                               QPen(QColor(LINE_COLOR), LINE_WIDTH))