Center finding not accurate due to silk screen

[dzid26]

I wanted this to work, because for my footprint anchors are defined at pin1. Unfortunately, it seems GetBoundingBox takes the silk screen into account. https://github.com/Bouni/kicad-jlcpcb-tools/blob/eca019d8366539c363e5b429c2e8e5bf4560052a/fabrication.py#L118

As a result for a footprint like this with dot on silk:

the calculated center is too low.

[dzid26]

For Kicad 7.99, this seems to work for some reason without even selecting copper layers:

footprint.GetLayerBoundingBox(footprint.GetLayerSet()).GetCenter()

Alternatively combining boundboxes of each pad works with Kicad 7:

                pads: list[pcbnew.PAD] = footprint.Pads()
                bbox : pcbnew.BOX2I = pads[0].GetBoundingBox()
                for pad in pads:
                    bbox.Merge(pad.GetBoundingBox())
                return bbox.GetCenter()

[Bouni]

@dzid26 are you submitting a PR for this?

Is your approach with combining the bounding boxes of all pads working for V7 and V7.99?

[dzid26]

I can submit the PR.

Bounding box logic will work with 7.0.

Should the same logic be applied to SMD components though? https://github.com/Bouni/kicad-jlcpcb-tools/blob/eca019d8366539c363e5b429c2e8e5bf4560052a/fabrication.py#L116 I tested it on my old board with SMD footprints as well and it works.

1. On one hand, I can imagine people having footprints with SMD property set and the anchor at pin 1 (like mine), so they would benefit from the bounding box calculation.
2. On the other hand, moving anchor relative to footprints can be used to offset component placement in relation to the pads. With the bounding box logic, this would not be possible. However, this would become a moot point if we had a translation correction similar to rotations. It doesn't matter to me, because my crappy footprints (imported from Altium) have this property unspecified, so the new logic will apply regardless.

[dzid26]

In the PR, I prioritized point 1. (I removed if get_smd(footprint)) so that if people have an anchor not in the center, the plugin will help them. Point 2. I assume that eventually will be solved with translations - moving anchor on the footprint is a big pain anyway in kicad.