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

From: Liu Jin (cpp_at_[hidden])
Date: 2005-10-05 11:50:49

>>>>> "Joel" == Joel de Guzman <joel_at_[hidden]> writes:
    > Why not ;-) ? Replace "screen" with "paper" and you'll want to
    > have accurate 1:1 layouts. This is the very essence of device
    > independence. If, say, I want to print a PCB (printed circuit
    > board) on a 300DPI laser printer, I'd want absolute accuracy,
    > otherwise, my components will not fit the holes. Device
    > independence means that both "screen" and "paper" should behave
    > identically. If I want 10cm on paper how can I create such a
    > thing in an abstracted relative coordinate system?

But you aren't going to draw a PCB on screen with boost.GUI widgets.
Neither is it very likely that someone needs to print a copy of some
on-screen dialog, in WYSIWYG manner.

So yes, the underlying (vector) graphic library should handle a whole
collection of units and transformations. But widgets and the layout
engine generally don't care about units. In the rare cases that they
do, (e.g. you want a ruler widget exactly 10cm long) you can always
use the graphic library to transform among units.

Regards,
Jin