我尝试将matplotlib.lines.Line2D子类化，创建宽度和虚线间距与绘制数据坐标相同的线，我对this answer进行了扩展，尝试支持虚线（虚线间距也是数据单位），目前代码如下：

import matplotlib.pyplot as plt
from matplotlib.lines import Line2D

class LineDataUnits(Line2D):
    """
    A Line2D object, but with the linewidth and dash properties defined in data coordinates.
    """
    def __init__(self, *args, **kwargs):
        _lw_data = kwargs.pop("linewidth", 1)
        _dashes_data = kwargs.pop("dashes", (1,))
        super().__init__(*args, **kwargs)
        self._lw_data = _lw_data
        self._dashes_data = _dashes_data
        self._dashOffset = 0

    def _get_lw(self):
        if self.axes is not None:
            ppd = 72./self.axes.figure.dpi
            trans = self.axes.transData.transform
            return ((trans((1, self._lw_data))-trans((0, 0)))*ppd)[1]
        else:
            return 1

    def _set_lw(self, lw):
        self._lw_data = lw

    def _get_dashes(self):
        if self.axes is not None:
            ppd = 72./self.axes.figure.dpi
            trans = self.axes.transData.transform
            return tuple([((trans((1, dash_data))-trans((0, 0)))*ppd)[1] for dash_data in self._dashes_data])
        else:
            return tuple((1, 0))

    def _set_dashes(self, dashes):
        self._dashes_data = dashes

    _linewidth = property(_get_lw, _set_lw)
    _dashSeq = property(_get_dashes, _set_dashes)

if __name__ == "__main__":
    fig, ax = plt.subplots()
    line1 = Line2D([0, 10], [3, 3], linewidth=10, color="blue", dashes=(3, 3), dash_capstyle="round")
    line2 = LineDataUnits([0, 10], [6, 6], linewidth=0.5, color="red", dashes=(1, 1), dash_capstyle="round")
    print("dash_capstyle:", line2.get_dash_capstyle())
    ax.add_line(line1)
    ax.add_line(line2)
    ax.set_xticks(range(10))
    ax.grid()
    ax.set_xlim(0, 10)
    ax.set_ylim(0, 10)
    plt.show()

生成以下图形：

当我放大和缩小时，虚线间距在数据单元中似乎保持不变，但是如图所示，它们的值计算不正确。此外，在该类中设置dash_capstyle参数似乎没有效果。
任何帮助都将不胜感激。