Circular board outlines are not supported

[follower]

I initially tested gerber2png.py with a PCB that had a circular edge cuts like this one:

• https://github.com/follower/led-spinner-toy/tree/master/pcb

The result was two 78 x 78 pixel images, one filled with black, the other filled with white.

It wasn't immediately obvious that the issue was due to the circular board outline as the second board I tested with also had a circular outline. (What can I say, I like circles... :D )

Underlying issue

I eventually tracked the apparent underlying cause down to how the circular board outline is handled by draw_arc(). (I'm not 100% sure why draw_arc() is used rather than Circle etc but I didn't investigate further to understand it better. )

My understanding is that when the arc is a complete circle, the start_angle & end_angle variables both end up having the value 0.0 so the drawing of the outline is skipped entirely!

Potential solutions

I originally used this patch (but I've just realized there's a simpler option earlier in the method):

--- a/gerber2png.py
+++ b/gerber2png.py
@@ -339,6 +339,8 @@ class GerberData:
                # Where r is the radius, cx,cy the origin, and a the angle from 0..2PI radians or 0..360 degrees.
                if line.endswith("D01*"): # move with shutter OPEN
                        # make a path from lastPoint to x,y
+                       if (start_angle == end_angle == 0):
+                               end_angle = DOUBLE_PI
                        angle = start_angle
                        while angle < end_angle:
                                xx = int( round(centerx + radius * math.cos(-angle)))

The simpler patch is to handle the issue where there's a similar check/adjustment already:

diff --git a/gerber2png.py b/gerber2png.py
index e743fd7..435c61e 100755
--- a/gerber2png.py
+++ b/gerber2png.py
@@ -326,7 +326,7 @@ class GerberData:
                arc_resolution = 0.00175
 
 #              if not clockwise:
-               if start_angle > end_angle:
+               if start_angle >= end_angle:
                        end_angle += DOUBLE_PI

led_spinner-Edge.Cuts.gbr.txt

I'll pop in a PR in with this change.