Difftool for schematic and pcb

[Thomas Pointhuber]

To proper handle multi-user editing of schematics/pcb's/symbols/footprints it is important to have the possibility to review the changes.

One easy but still powerful approach to show geometric changes is the addition of a graphical diff. The most basic implementation would simply render layer-per-layer and checks for changed pixels. A more advanced approach would do a per-net diff I think, which would allow us to visualize for example tracks overlaying previous tracks way better.

Existing 3rd-party programs:

* https://github.com/Gasman2014/KiCad-Diff
* https://neo900.org/git/eeshow
* https://github.com/madworm/KiCad-Stuff/tree/master/scripts/visual-diffs_on_gerber-files
* https://jnavila.github.io/plotkicadsch

[Jeff Young (jeyjey)]

Big feature, but it would be really cool.

[Jeff Young (jeyjey)]

From Leandro Heck (in the duplicate):

I found some tools, like:
https://github.com/jnavila/plotkicadsch
https://github.com/Gasman2014/KiCad-Diff
https://github.com/UltimateHackingKeyboard/electronics/issues/24

And also, there is also an old discussion on Kicad Forum about that
https://forum.kicad.info/t/creating-a-diff-tool-for-kicad-pcb/1872

[Thomas Pointhuber (pointhi)]

My diff tool implementation:

https://github.com/pointhi/kicad-python/blob/master/examples/pcbnew_diff/pcbnew_diff.py

in contrast to other difftools this is 100% KiCad based (no external dependencies for polygon operations) which makes it suitable as reference-implementation of an upstream diff-tool.

[Leandro Heck (leoheck)]

For schematics, I tested the https://github.com/jnavila/plotkicadsch
It works.

Thomas, that is cool. I want to give a try on yours too.

Also, I want to test something for the layout but I didn't have time yet.

[Thomas Pointhuber (pointhi)]

Some examples of commercial EDA diff-tools:

* https://www.orcad.com/resources/library/orcad-172-2016-capture-design-difference-viewer
* https://www.altium.com/documentation/18.1/display/ADES/WorkspaceManager_Pnl-Differences((Differences))_AD
* http://wiki.altium.com/pages/viewpage.action?pageId=20120536
* https://community.cadence.com/cadence_blogs_8/b/pkg/posts/see-the-differences-between-your-designs-visually-with-the-layer-compare-toolset-in-16-6-apd-and-sip-layout
* http://documentation.solidworkspcb.com/display/SWPCB/WorkspaceManager_Pnl-Differences((Differences))_PW
* https://www.ptc.com/en/cad-software-blog/comparing-drawings-models-and-pcbs-with-ptc-creo-view

[Thomas Pointhuber (pointhi)]

And some blog post related to EDA diffs:

* https://www.evilmadscientist.com/2011/improving-open-source-hardware-visual-diffs/

I really like the way the pcb-diff looks in this post: https://www.flickr.com/photos/oskay/6193638191/in/photostream/

[KiCad Janitor (kicad-janitor)]

KiCad bug tracker has moved to Gitlab. This report is now available here: https://gitlab.com/kicad/code/kicad/-/issues/2151