Re: [boost] GUI foundations

From: Stefan Seefeld (seefeld_at_[hidden])
Date: 2005-10-04 07:58:50

John Torjo wrote:
>>>I might go further  and add units (maybe defaulting to pixels)
>>>
>>>typedef gui::rect<px,int> rect 1;
>>>typedef gui::rect<pc,double> rect 2;
>>>typedef gui:rect<mm,int> rect 3;
>>
>>
>>That looks great :)!
>>
> 
> 
> I disagree. I think you should stick to only one type (probably float 
> for now, and eventually allow overriding it -- but, use this 
> consistently throughout the app).
> 
> Just think of the many places you'll need to deal with geometry 
> (rectangle/point/size), and converting from one type of unit (px to cm, 
> cm to in, etc) to another.

I agree. In particular, I'd strongly suggest to draw a clear distinction between
physical dimension and resolution. Most current GUIs did get that wrong, I believe
in that they conditioned us all to think of size when talking about number of pixels.

The consequence is similar to the Y2K bug: applications won't easily adapt to
displays with different resolutions (well, may be within a narrow range), and
so a lot of efford is needed on a high (application) level to compensate for that
lack of abstraction.

Let's hope that in the not-so-distant future 'pixel' will be an artefact of
graphic / video card drivers and not be exposed to an API at all.

Regards,
                Stefan