将 QGraphicsLineItem 添加到 pyqt / pyqtgraph 中的场景/视图

Question

我正在尝试为 pyqtgraph 中的图形制作自定义边框。我这样做是通过向场景/图形视图（pyqtgraph 中的 ViewBox）添加 QGraphicsLineItem 来实现的，但是这两种方法都有问题。将 QGraphicsLineItem 添加到场景中给了我想要得到的东西（上轴和右轴周围的边框），但它不会缩放：

upperplot = graphics_layout_widget.addPlot(0, 0, 1, 1)
self.curve_upper = upperplot.plot(np.linspace(0,0,8192),
                                  np.linspace(0,0,8192), # loaded_file.data.vm_array[0]
                                  pen=plotpen)

tl = upperplot.getViewBox().boundingRect().topLeft()
tr = upperplot.getViewBox().boundingRect().topRight()

topline = QtGui.QGraphicsLineItem(tl.x(), tl.y(), tr.x(), tr.y())
topline.setParentItem(upperplot.getViewBox())
topline.setPen(pg.mkPen(color=(211, 211, 211), width=10))

upperplot.getViewBox().scene().addItem(topline)

我看到 GraphicsView 处理所有调整大小，并尝试将项目直接添加到 GraphicView：

upperplot.getViewBox().addItem(topline)

除了线现在以 Y = 0 为中心，而不是左上角。有趣的是，X 轴还可以。

我觉得这是一个简单的解决方案，但无法为我的一生找到答案 - 我不确定将场景映射到视图或视图框中的场景对齐是否存在问题，但我没有成功玩弄任何一个。任何帮助将不胜感激。

最小的可重现示例：

from PyQt5 import QtWidgets, QtGui
import pyqtgraph as pg
import numpy as np

class UiMainWindow(QtWidgets.QMainWindow):
    def __init__(self):
        super(UiMainWindow, self).__init__()

        # set mainwindow + widgets
        self.mainwidget = QtWidgets.QWidget(self)
        self.mainwidget_gridlayout = QtWidgets.QGridLayout(self.mainwidget)
        self.setCentralWidget(QtGui.QWidget(self))
        self.centralWidget().setLayout(self.mainwidget_gridlayout)

        self.graphics_layout_widget = pg.GraphicsLayoutWidget()  # contains a graphicsview
        self.graphics_layout_widget.setBackground('w')
        pg.setConfigOption('foreground', 'k')
        self.mainwidget_gridlayout.addWidget(self.graphics_layout_widget)

        # make plot
        plotpen = pg.mkPen(color='k', width=1)
        self.upperplot = self.graphics_layout_widget.addPlot(0, 0, 1, 1)
        self.curve_upper = self.upperplot.plot(np.linspace(0, 100, 8192),
                                               np.linspace(0, 0, 8192),
                                               pen=plotpen)

        # draw top border line
        QtWidgets.QApplication.processEvents()      # I could not get the boundingRect of the ViewBox without drawing first
        tl = self.upperplot.getViewBox().boundingRect().topLeft()
        tr = self.upperplot.getViewBox().boundingRect().topRight()
        br = self.upperplot.getViewBox().boundingRect().bottomRight()

        topline = QtGui.QGraphicsLineItem(tl.x(), tl.y(), tr.x(), tr.y())
        topline.setParentItem(self.upperplot.getViewBox())
        topline.setPen(pg.mkPen(color=(211, 211, 211), width=10))

        rightline = QtGui.QGraphicsLineItem(tr.x(), tr.y(), br.x(), br.y())
        rightline.setParentItem(self.upperplot.getViewBox())
        rightline.setPen(pg.mkPen(color=(211, 211, 211), width=10))

        self.upperplot.getViewBox().addItem(topline)  # correct scaling, but Y axis is centered as zero
        self.upperplot.getViewBox().addItem(rightline)

        # vs
#        self.upperplot.getViewBox().scene().addItem(topline)  # correct position, but cannot scale
#        self.upperplot.getViewBox().scene().addItem(rightline)


if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    mw = UiMainWindow()
    mw.show()
    sys.exit(app.exec_())

更新边框：

self.upperplot.getViewBox().setBorder(color=(211, 211, 211), width=10)

给出：

而不是：

Answer 1

一种可能的解决方案是通过自定义绘制来实现自定义 ViewBox：

class CustomViewBox(pg.ViewBox):
    def paint(self, p, opt, widget):
        super().paint(p, opt, widget)
        r = QtCore.QRectF(self.boundingRect())
        p.save()
        tl = r.topLeft()
        tr = r.topRight()
        br = r.bottomRight()
        pen = pg.mkPen(color=(211, 211, 211), width=10)
        p.setPen(pen)
        p.drawLine(tl, tr)
        p.drawLine(tr, br)
        p.restore()

self.upperplot = self.graphics_layout_widget.addPlot(
    0, 0, 1, 1, viewBox=CustomViewBox()
)