__init__.py 文件源码

def add_crosshair(plot, render_measurements, color=Qt.gray):
    pen = mkPen(color=QColor(color), width=1)
    vline = InfiniteLine(angle=90, movable=False, pen=pen)
    hline = InfiniteLine(angle=0, movable=False, pen=pen)

    plot.addItem(vline, ignoreBounds=True)
    plot.addItem(hline, ignoreBounds=True)

    current_coordinates = None
    reference_coordinates = None

    def do_render():
        render_measurements(current_coordinates, reference_coordinates)

    def update(pos):
        nonlocal current_coordinates
        if plot.sceneBoundingRect().contains(pos):
            mouse_point = plot.getViewBox().mapSceneToView(pos)
            current_coordinates = mouse_point.x(), mouse_point.y()
            vline.setPos(mouse_point.x())
            hline.setPos(mouse_point.y())
            do_render()

    def set_reference(ev):
        nonlocal reference_coordinates
        if ev.button() == Qt.LeftButton and current_coordinates is not None:
            reference_coordinates = current_coordinates
            do_render()

    plot.scene().sigMouseMoved.connect(update)
    plot.scene().sigMouseClicked.connect(set_reference)