Re: Dots vs. dashes

On Jan 28, 2008, at 1:12 AM, David Woolley wrote:

> Brad Kemper wrote:
>> The border-style definition [1] gives only the most cursory  
>> definition of dotted and dashed border-styles, as being a series  
>> of dots or dashes. It doesn't say anything about the shape of the  
>> dot, but shows an illustration of the dot being round. It seems  
>> reasonable that dots should be round and that dashes rectangular,  
>> as the illustration shows.
>
> To a large extent, typography is about an idealized imitation of  
> hand produced material.  A hand produced dotted line is unlikely to  
> be composed of very small, closed, circular movements of the pen,  
> as used to create neat full stops.  That's even more true of the  
> dots in an alternating dot-dash line.  I'd suggest that, where one  
> gets round dots and square dashes, it an imitation the limitations  
> of using a typewriter.

The history of the modern convention is less important in this case  
than modern expectations of what is meant by "dashed" or "dotted" in  
line styles (expectations that are mirrored by the illustration of  
dotted and dashed lines in the spec).

> PostScript (second edition) does not use different pens for dots  
> and dashes in lines, and the example shows square edges, although I  
> think that is subject to other parameters.

PostScript has the concept of strokes and fills. The strokes can be  
specified with a high level of designer control, including length of  
dashes and gaps, whether each stroke segment (including dashes)  
should have end-caps,  and wether those end-caps should be square or  
round. To get a traditionally round dot in PostScript, you can  
specify the line to have zero length segments with round end-caps,  
and gaps between dots that are at least as long as the line is thick  
(twice the width works pretty well).