So you’ve written a cool new layout modification utility in python. It sure would be nice to see the results on the screen. This is an issue I faced with my placement replicator script. It does what I want except that the user has to click the refresh button to see the results.Now there’s a way to trigger zoom, pan, and refresh from python. As of this writing (March 20, 2017), you need to use one of the nightlies or build yourself. To refresh the screen:

pcbnew.Refresh()

To pan and zoom, you need to supply x,y, width, height:

x = pcbnew.FromMM(10)
y = pcbnew.FromMM(10)
width  = pcbnew.FromMM(20)
height = pcbnew.FromMM(20)
pcbnew.WindowZoom(x, y, width, height)

Contributing to Kicad is painless

I initially searched and searched in pcbnew’s C code for python APIs like these. Eventually, I came to realize that they didn’t exist yet in pcbnew. So finally, I have my very first code contribution to an open source project. I’ve been paid to write software for many years but it’s all been in-house stuff. My professional environment was pretty loosey-goosey, with very few formal constraints. 1 Over the years, I’ve read lots of stories about how open source projects can be a pain to deal with. Lots of coding standards, lots of requirements,… lots of hoops to jump through.2 This was not my experience with proposing these code changes to Kicad. I read the developer wiki, and attempted with follow the directions. I mailed the patch file to the developer email list, along with an introduction of who I am and what I’m trying to accomplish. It was committed the same day. Wayne, the kicad project lead, was very welcoming and encouraging. Although there were a couple things I missed, he went ahead and did the tweaks and pushed the change. Next time, I’ll know. Most important to me, I’m excited to do more.