gEDA-dev: Checking for mm vs. mil display modes in PCB

[Michael Stovenour]

Is there a better way than this to check for mm vs. mil modes?  I'm working on a quick patch to allow decrementing the grid all the way down to 1 (effectively off).  I have it working, see the bottom code, except that, when the grid bottoms out at 1; the funky check for mm vs. mil modes prevents mm mode from incrementing up from 1.
 
ORIGINAL:  src/action.c
...
        case F_Grid:
          if (!r)
            {
              if ((value == (int) value && PCB->Grid == (int) PCB->Grid)
                  || (value != (int) value && PCB->Grid != (int) PCB->Grid))
                SetGrid (value + PCB->Grid, False);
              else
                Message (_
                         ("Don't combine metric/English grids like that!\n"));
            }

 
This code mostly works.  It fixes a nasty "feature" that I found by mistake where I set the grid to 1 with :SetValue(Grid,1) (effectively off) so that I could make some measurements.  I then I incremented the grid +5 mil with <key>G.  The status window indicated 5.0 mil snap, but the coordinate window indicated that the mouse was moving 5.01 mm.  If I can just solve the "how to tell I'm in mm display mode" problem this is a good fix.  BTW, this patch works at least as well as the original code since it only requires the user to explicitly pick a grid size from the menu or set it with SetValue.  At least it doesn't allow the grid increment to a slightly wrong grid spacing.  Any it only misbehaves this way for mm;  mil works great.
 
 
NEW:  src/action.c
...
        case F_Grid:
          if (!r)
            {
              if ((value == (int) value && PCB->Grid == (int) PCB->Grid)
                  || (value != (int) value && PCB->Grid != (int) PCB->Grid))
                {
                  //On the way down short against the minimum PCB drawing unit
                  if ((value + PCB->Grid) < 1)
                    SetGrid (1, False);
                  else if (PCB->Grid == 1)
                    SetGrid ( value, False);
                  else
                    SetGrid (value + PCB->Grid, False);
                }
              else
                Message (_
                         ("Don't combine metric/English grids like that!\n"));
            }
          else
            SetGrid (value, False);
          break;