[cairo] How to texturing a self-defined pattern(or image) along line and fill a polygon?

[Lawrence D'Oliveiro]

On Sat, 5 Dec 2015 08:56:53 +1300, I wrote:

> You could flatten the path to a sequence of straight lines. Then do
> your own patterning along each of those straight lines.

Like this
<http://default-cube.deviantart.com/art/Pattern-Dash-576369003>, source
code here
<https://github.com/ldo/qahirah_examples/blob/master/pattern_dash>.