Re: [boost] GUI coordinate units (Was: GUI foundations)

From: Dave Harris (brangdon_at_[hidden])
Date: 2005-10-04 14:48:21

In-Reply-To: <4342AC3C.1060100_at_[hidden]>
seefeld_at_[hidden] (Stefan Seefeld) wrote (abridged):
> Exactly. To be clear: moving from a 15" to a 17" monitor would, in my
> ideal world, have *no* impact on the physical size of the displayed
> graphics, but rather, would add ~ 1.4" in both dimensions to the useful
> screen area. How many pixels your display has then only affects the 
> quality of the rendering, exactly as what you were looking for.

Isn't that quite hard?

Specifically, it sounds rather like the problem of drawing text nicely at 
various resolutions. Consider TrueType, or Type 1 Postscript fonts. The 
basic character shape is defined by vectors, by Bezier curves. To render 
it prettily, so that, for example, all the vertical strokes on an 'm' are 
the same thickness regardless of how the letter falls onto the pixel grid, 
you need to add what Adobe call hints and Microsoft call grid-fitting.

Are you intending this system to be usable only on high-res desktop 
machines? Or are you including hand-held devices, phones and wotnot, that 
have relatively slow CPUs and where 640x320 is ambitiously high 
resolution?

There is some discussion about TrueType grid-fitting about half-way down 
this page: 
  http://www.microsoft.com/typography/otspec/TTCH01.htm

> Of course, this requires a completely vector-graphics-based GUI, which
> is still the exception.

Maybe there's a reason for that. I'm not saying don't do it, but I'd 
recommend doing some experiments that prove it's actually possible before 
investing too much.

-- Dave Harris, Nottingham, UK.