If I use a circle to make a top silkscreen figure for an LED, put it on the “Top Placement” layer, and DO NOT select “Area: _ Filled”, I get a filled circle when exporting to Gerber. Other data: the circle’s line width is 0.4mm and the circle diameter 5.2mm. Several Gerber viewers were used to check this.
The expected behavior is to output a donut with an unfilled hole unless I select filled. Without this functionality, I cannot create a conventional LED silkscreen image on the board.
I am on MacOS Catalina 10.15.7 and LibrePCB 0.1.5.
I cannot reproduce this, actually I already ordered PCBs with such circles and it was correct. But I noticed that some Gerber viewer do not render such circles correctly. I recommend to check the Gerber files either at the Reference Gerber Viewer and/or at aisler.net.
If the problem still exists, could you provide some more details (e.g. screenshot of the footprint, and the generated gerber files)?
Did you try both forms of export - Protel and default? I had a vendor say they could not read the default (I think this was their mistake, however) and I switched to Protel. That said, I looked at the default Gerber data and it had a D03 flash at with a donut style aperture. I have not looked again at the Protel version. Oh, by the way, I was using a few online Gerber viewers of vendors to see the error of filled-in LED silkscreens. At that time I was probably using Protel output. I will revert to Protel and check again. I have not changed my LED silkscreen layers since then, so if the problem is gone we have a very weird error.
Thank you, thank you for looking into this.
Dave
The content of the Gerber files is always the same, no matter if you choose Protel or default This feature only changes the naming of the files and whether drill files are merged or not. Unfortunately some PCB manufacturers are incredibly stupid and therefore not able to read Gerber files if they are not named the same way as Protel does
OK. So if I see the problem again, my plan is to text view the gerber file and check its aperture for an OD and ID as well as a D03 flash. If those things are correct is it safe to assume the viewers are incorrect?
I don’t know what you mean with OD and ID - this is how a circle looks in Gerber:
Anyway, yes it should be easy to manually check the Gerber file. And I’m pretty sure the Gerber data is correct, but the PCB manufacturers preview are wrong I really recommend to use the two viewers I mentioned above since they seem to be very reliable.
However, I don’t know if your PCB will be manufactured correctly even if the preview is wrong. I think the software they use for manufacturing is much better than the one they use for the preview, so the chance is high to get correct PCBs. If you want to be sure, I recommend to order at Aisler since they guarantee that the final PCBs will look the same as the preview.
This feature only changes the naming of the files and whether drill files are merged or not. Unfortunately some PCB manufacturers are incredibly stupid and therefore not able to read Gerber files if they are not named the same way as Protel does 
I really recommend to use the two viewers I mentioned above since they seem to be very reliable.