Re: Motivation for having a 'text color' that is invisible

[christian ridderstrom gmail com]

On Fri, 26 Oct 2007, Jens Getreu wrote:

> > > Well, if text could be made invisible, then why not other things?  It 
> > > could make sense to have an "invisible" color -- any renderer can 
> > > handle that simply be not rendering the thing in question.  That way 
> > > we provide much more than by having an extra option to turn any text 
> > > field on/off.
>
> > This is a case of the classic arguments about content v/s style. To 
> > make a perfect analogy, if appearance defined the role of an element, 
> > HTML wouldn't need the H1 tag. An invisible object is not the same as 
> > an undisplayed object. It is still around, and participates in other 
> > interactions. For example, an invisible object near the border could 
> > result in a strange blank area on the periphery if you export a bit 
> > map. Demanding that every renderer handles this correctly can get 
> > tricky. If you group an invisible object with other objects, the border 
> > of the group would include a similar strange blank area.

> In TeX this effect is widely used as "struts" and quite convenient. 
> Sometimes you want a group of objects or a page to take more space than 
> the visible parts of it.

I've used "invisible" objects now and then to make objects take up more 
space, it's extremely useful at times. With "invisible", I mean that I 
manually set their colour to that of the background.

I do agree that 'undisplayed' and 'invisible/hidden' is not the same. In 
the original case I mentioned, I should have used 'undisplayed' as my 
intention at that time was not to make the object larger.

So perhaps I should propose a general colour (apperance attribute) called 
'undisplayed', and a separate one called 'invisible'.  Then again, maybe 
the latter should be generalized to 'level of transparancy'.

/Christian

--
Christian Ridderström, +46-8-768 39 44               http://www.md.kth.se/~chr