[cairo] Obtaining two parallel paths from a single curve

[archee@126]

Yes, it does work for a simple road. But what if you want to draw two 
directions of a road? In that case, each direction is actually an independent 
road but with the same shape.

----- Original Message ----- 
From: "John Ellson" <ellson at research.att.com>
To: "archee at 126" <archee at 126.com>
Cc: <cairo at cairographics.org>
Sent: Tuesday, July 29, 2008 9:10 PM
Subject: Re: [cairo] Obtaining two parallel paths from a single curve


> archee at 126 wrote:
>> Hi,
>>
>> How to obtain two parallel paths from a single curve?
>> Say, these two parallel paths are N pixels away from each other.
>>
>> Thanks!
> Perhaps a dumb idea, with all these math wiz's around describing
> envelopes of circles....,
> but couldn't you just draw a wide line in the color of your parallel
> lines, then draw another
> slightly narrower wide line with the same coordinates in the color for
> the road, leaving just parallel borders?
> 
> John
>