无法使用svglib将svg转换为png

Question

当我将svg转换为png时，出现了不完整的png文件和错误。请有人帮忙。

from reportlab.graphics import renderPM
from svglib.svglib import svg2rlg

svg_file = 'svgfile.svg'

drawing = svg2rlg(svg_file)
renderPM.drawToFile(drawing, "new_file.png", fmt="PNG")

Can't handle color: url(#a)
Can't handle color: url(#b)
Can't handle color: url(#c)