RE: Better with units

["Young, Robert" <Robert Young dsto defence gov au>]

Lars Clausen wrote:
>
> On Tue, 28 Aug 2001, Robert Young wrote:
> 
> > Dolores Alia de Saravia wrote:
> > 
> >>  Dia deals with three different  length magnitudes: 
> >> ---  one for paper, or printed diagram;  unit: cm
> >> ---  one for canvas, or working diagram; unit without a 
> name, it could
> >> be "virtual cm", or simply  "canvas_unit".  
> >> ---  one for the window trough which we see part of the 
> canvas; unit: 
> >> pixel.
> >> 
> >>  I  beleive it would be better (less confusing) to make 
> the user aware
> >> of the units.
> > 
> > I agree with making the user aware of the units (it would 
> mean that dia
> > could be used for rudimentary CAD!).
> > 
> > I think, however, that it would be useful to be able to set 
> the default
> > units in the Preferences dialog (ft, cm, mm, m, pt, inch, 
> nmi, lyr etc)
> > and then all the dialogs display values in terms of this e.g. line
> > thickness, grid spacing. Lars originally suggested 
> something like this
> > (Re: StdProp overhaul, take 2 on 14/8/01). The only pixel 
> unit would be
> > the new window width and height (though I have other ideas 
> about this -
> > new window defaults to A4 with 10% 'bleed' area with all of this
> > selectable).
> > 
> > The "virtual cm", or simply  "canvas_unit" concerns me 
> because it is not
> > obvious to a user what it is. Even the word pixels may 
> confuse the user.
> 
> Unless we make the window dimensions match the screen 
> dimensions (currently
> "100% zoom" does not mean that one cm in the diagram shows up 
> as one cm on
> the screen.  In fact, with the 'Fit to' page setup, we would 
> need to zoom
> in and out all the time.), the user should be able to specify 
> the window
> dimensions.

Yes. I see the problem here - probably two separate issues:
1. Initial window size, specified in pixels.
2. Initial extents, e.g. 2x2 A4 + 10% bleed or user definable (allow dia to
decide when to increase this number of pages?) Why? Because I am currently
frustrated by the diagram always being exactly the diagram extents. Maybe I
should fix this...

In my mind both should be definable in the Properties dialog.

I'm not certain that 1cm on screen = 1cm in diagram is that much of a
problem - it depends on display device (e.g 17" monitor, 12" LCD display
both using 800x600 have completely different dimensions for a pixel). The
only importance is 1cm in diagram must be 1cm on page when printed
scale=100% in postscript. What do other users think?? 

> > To ease the implementation, the dia_unit_spinner could be used (see
> > app/diaunitspinner.[ch]). Currently (AFAIK) the only place 
> it is used is
> > the paper size dialog - try typing 2ft for the page width 
> and it cleverly
> > converts it to cm! - cool, James)
> 
> Letting the input boxes convert from various units is cool, 
> but we need to
> let the unit converted _to_ be changed.

Agreed. Let the user select a default unit (I quite like drawing in units of
light years :-)

>  We'd also need to add a number of
> frequently used unit designations, like "ft" and "feet".

Agreed. It's good that US inches are the same as real proper English inches
(unlike gallons and other interesting units).

> Also, the font
> size input boxes should probably use a separate unit -- many 
> people like to
> have 'points' for font units.

Agreed. Select a default unit for fonts and a default unit for everything
else.

The extension of this concept can be seen in a publishing prorgam Ovation
Pro (http://www.davidpilling.co.uk) which allows a user to enter maths (e.g.
10pt+10%) into a field and it will calculate what the user wanted. I think
this is a version 5.0 milestone though :-)

Just my thoughts...
Rob.