"Joel" == Joel de Guzman <joel@boost-consulting.com> 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