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Re: Re: Metric and English grids sizes.
jean-pierre charras - INPG <jean-pierre.charras@...>
Mon, 12 Oct 2009 12:47:06 +0200
Thunderbird 126.96.36.199 (Windows/20090812)
Dick Hollenbeck a écrit :
> --- In kicad-devel@ yahoogroups. com
<mailto:kicad-devel%40yahoogroups.com>, Dick Hollenbeck <dick@...> wrote:
>> Then we need something more stable. I'd switch over to a 0 based index
>> into the list of grid sizes, but maybe treat user size as special,
>> assigning it -1, just so it does not get moved in the future if more
>> sizes are added.
> What about the 'obvious' solution, i.e. just saving the grid size in
decimils like all the other things in pcbnew?
> Something like:
> GridSize 1000 1000
> for a 100mil grid...
> A lookup on the dozen or so predefined values is not so heavy (and
anyway is only done on load)
This is obvious, and quite agreeable. I'd like to have a grid offset in
there too. See next posting.
Unfortunately, grid size cannot be handled in decimils.
In pcbnew grid is handled as double.
This is because for many grids values in mm, using a value rounded in
decimils creates a cummulative error that can be important
(some mm for a 300 mm board)
So grid sizes must be given
- always in inches or decimils but using a floating point value, for non
integer values as needed for metric grids
- or as an integer in decimils or um units and give the used unit (um ou
decimil) as parameter
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