Drill file coordinates are inaccurate

[Stephen Ecob]

When exporting "Gerbers" the drill files round drill coordinates to the nearest whole mil-inch. For example a via located
at X=514.6 mil-inch on the PCB results in a drill file entry that looks like this:

X0005150Y0027370

The file format used appears to have enough digits to support an accuracy of 0.1 mil-inch but all coordinates are rounded to the nearest whole mil-inch

Drilling holes with errors of up to 0.5 mil-inch generally won't matter, but PCB internally supports accuracy down to 1nm and the drill file format appears to support down to 0.1 mil-inch so we can do better.

The problem mainly affects me when I'm visually checking my Gerbers with Gerbv in high quality mode - the rounding is actually visible and distracting in the worst cases. See the attached image for an example - the drill holes *should* be centered on the pads but obviously aren't.

It is probably the case that the problem is exacerbated by scaling and pixel snapping within Gerbv+Cairo, but the source of the problem is the mismatch between the accuracies of the Gerber files and drill files exported by PCB.

I'm working with PCB head as at 2011-Dec-28 on Linux and Gerbv 2.6.0 on Cairo 1.11.5 (Beta release)

[Traumflug (mah-jump-ing)]

Since the last release the option for metric Gerbers was added, which rewrote much of the coordinate formatting:

http://git.geda-project.org/pcb/commit/?id=e4f7e6158881f59033fd3b20a149677c9bc7ef96

Is this bug still happening? In case you don't feel like compiling pcb from Git yourself, please add a layout demonstrating the issue. Thanks.