On Wed, 25 Sep 2013 20:37:42 +0200 Johan Engelen <jbc.engelen@...2592...> wrote:
I guess we agree overall. (your inline replies during my argument of why something is not a good idea make it very hard to see where you are disagreeing / adding something new that was not written later on!)
I don't think we disagree. I just wanted to show that what I was proposing could address all the concerns that you mentioned, and to suggest that since "DPI" is not necessarily relevant in the context of vector graphics, a more general unit ratio setting would be a better option.
One big issue is what to do with the "px" unit description in Inkscape's UI. It means "pixel" for most people I think. My question is, if it is OK to have the "px" unit in Inkscape's UI mean something different than the "px" (=user unit) in SVG.
It seems that this is really the only viable option. But to clarify that there is a distinction, for people familiar with the unfortunately-named SVG "px", perhaps it would be better to use the term "pixel" or "pxl" in the Inkscape UI.
If no, then I believe we should remove "px" from Inkscape's UI. Given that some people do want to use pixel units (e.g. our icons file), I don't know how much trouble that removal will cause to people. So I'd like to keep the "px" unit description, and have it mean pixel with an explicitly defined DPI (if undefined, use 90dpi as old Inkscape did).
For "explicitly defined DPI", I suggest the use of my "display scale factor" preference setting. (Improved version attached here, detailed explanation in another message.)
Sidenote: most Inkscape document do not have proper units defined. So almost all the "mm" stuff currently is ill-defined. We need some kind of fallback that works with older documents too, where 90userunits = 1 inch (if I'm not mistaken).
If it is possible to autodetect "older documents" when opened, then the drawing:export unit ratio on my proposed preference setting could be initialized to [90 pixels : 1 inches], or any other appropriate value.
If the user doesn't like that default setting, then they can just change it to something else; if they don't even notice it, everything works as it did before.
-- Ian Bruce
