Re: [boost] GUI library - another one

From: Arvid Norberg (c99ang_at_[hidden])
Date: 2004-03-04 06:15:05

Me and Daniel Walling have been toying some with a gui library approach
where the user would build the gui trees using a DSEL. Something like
this:

void clicked_ok(button::clicked_event e)
{ /* .. */ }

void clicked_cancel(button::clicked_event e)
{ /* .. */ }

int main()
{
     window w("my gui");

     gadget my_gui =
         + vgroup()
             + "Buttons below me!"
             + hgroup()
                 + button("OK") [ button::clicked = &clicked_ok ]
                 + space()
                 + button("Cancel") [ button::clicked = &clicked_cancel ]
             - hgroup()
                 + button("Maybe") [ button::clicked = &clicked_maybe ]
                 + space()
                 + button("Foobar") [ button::clicked = &clicked_foobar ]
         ;

     w.set_gadget(my_gui);
     w.show();

     /* ... */
}

which would produce a gui like this:

     +---------------------------+
     |     Buttons below me!     |
     |                           |
     | +----------+ +----------+ |
     | |    OK    | |  Cancel  | |
     | +----------+ +----------+ |
     | +----------+ +----------+ |
     | |   Maybe  | |  Foobar  | |
     | +----------+ +----------+ |
     +---------------------------+

of course the functions would be boost::function and possible to
boost::bind to member functions. The expressions within the
[]-operators should of course be a list where it's possible to
assign callbacks for more than one event.

One important requirement I see with a gui lib is to be able to
easily create dynamic guis. Where sub-trees can be exchanged, removed
or added on the fly.

-- 
Arvid Norberg
David Turner wrote:
> Hello
> 
> It seems that the idea of adding a medium-complexity GUI library to boost
> is popular, but that there are widely varying opinions on how it should be
> done.
> 
> I've written a first draft of a library that fulfils most of my
> expectations.  It's available at http://www.turn.co.za/david/gui.  It
> supports two platforms (Win32 and GTK2), and four user interface elements
> or widgets (window, label, button, text-entry).  The design is such that
> it is extremely easy to support new platforms or widgets.
> 
> These are my expectations of how a good C++ GUI library should behave:
> 
> 1.  It should be a consistent yet thin wrapper around the platform's
> native functionality.
> 2.  It should degrade gracefully in the absence of certain features on the
> platform.
> 3.  It should be extensible through the factory pattern.
> 4.  It should couple loosely with user code - this means no inheriting
> from an abstract Window class.
> 5.  It should do what the user (programmer) expects, whenever possible
> (i.e. no leaky metaphors).
> 6.  Widgets that contain things should behave like containers, whenever
> this is practical.
> 7.  It should not use device-specific units like pixels, wherever this is
> practical.
> 
> and finally
> 
> 8.  It should be extremely easy to use.
> 
> The library at the link above fulfils most of these requirements.  But
> it's not perfect.  There are some interesting design choices.
> 
> In many respects the most difficult design work is still to be done (list
> boxes, menus, drawing areas).  However, the code that exists has the great
> advantage of working.
> 
> I'd like to know what the boost community thinks before proceeding.
> 
> Regards
> David Turner
>