Error with pen_width

Hello Tiago,

It looks like the commit "e3c57b270640f9948d7fda7459376eb40d600719" has introduced a bug in the cairo_draw that I have fixed on my machine but I would like to create a merge request for the same. In short the following code throws the error:

import graph_tool.all as gt
g =['karate']
gt.graph_draw(g, vertex_pen_width=5, vertex_color = 'k', output='test.png')

The error is:

Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/graph_tool/draw/", line 1145, in graph_draw
x, y, w, h = fit_view
TypeError: cannot unpack non-iterable bool object

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "", line 4, in <module>
gt.graph_draw(g, vertex_pen_width=1, output='test.png')
File "/usr/lib/python3/dist-packages/graph_tool/draw/", line 1153, in graph_draw
x, y, zoom = fit_to_view_ink(g, pos, output_size, vprops,
File "/usr/lib/python3/dist-packages/graph_tool/draw/", line 1345, in fit_to_view_ink
eprops = dict(eprops, pen_width=min_lw(eprops.get("pen_width")))
File "/usr/lib/python3/dist-packages/graph_tool/draw/", line 1342, in min_lw
lw = max(lw, 0.1)
TypeError: '>' not supported between instances of 'float' and 'NoneType'

I tracked the error and it looks to me that in the function ``min_lw`` which itself is inside ``fit_to_view_ink``, if user passes ``pen_width`` only for edges or only for vertices, the other becomes ``None`` and should be handled properly. I could fix this by adding an extra ``if`` condition as follows:

# work around cairo bug with small line widths

def min_lw(lw):

if isinstance(lw, PropertyMap):

lw = lw.copy()

x = lw.fa

x[x < 0.05] = 0.1

lw.fa = x

if lw == None:
lw = 0.1
lw = max(lw, 0.1)

return lw

I would like to push this change upstream, but you seem to have denied my access request so I can't create a merge request. If you think this is fine, could you make the change? In general, how do I fix bugs if/when I find them if access on git.skewed is not available?

Thanks and regards,
Snehal Shekatkar

attachment.html (7.41 KB)