Re: [boost] GUI Windowing Framework in C++

From: John Torjo (john.lists_at_[hidden])
Date: 2004-09-24 04:13:22

Reece Dunn wrote:

> A windowing framework should abstract the windowing facilities of a 
> particular platform. Here are my list of requirements for this type of 
> framework:
> 
> [1] Support constructor-based window creation, e.g.:
> 
>    frame.add( new gui::button( "Boost!" ));

did you mean frame->add(..)?

I really think that every window object should have - behind the scenes 
- a shared pointer.
One reason for this is:

// I assume you want another pointer to the window,
// not another on-the-screen window.
frame a = b;

> 
> The justification for this is that I find using an OnCreate + Create 
> style for creating windows (MFC and WTL) or similar is too complex: the 

indeed so ;)

> There has been discussions in earlier threads (Java style GUI in C++) 
> about using boost::signal as an event handler. I have two questions 
> regarding this:
> (1) if I have n message types, do I need n boost::signal objects? If so, 
> this would increase the size of each component. Also, what if you want a 
> "handle all events" handler.
> (2) if generic events are defined in an 'event' object, and a handler 
> function has the form:
> 
>    event_handled_type eventfn( const event & e );
> 
> what if you want to support:
> 
>    event_handled_type pressed( const mouse_event & me );
>    event_handled_type key_down( const key_event & ke );

In my view, I assume this is possible.
All you need is a constructor for mouse_event that takes an event param.
Something like:

mouse_event::mouse_event(const event & e) {
   // interpret the event as a mouse event
}

Same goes for key_event. In fact, Dec 04 issue of CUJ should be dealing 
with this issue ;)

Best,
John

-- 
John Torjo
-- john_at_[hidden]
Contributing editor, C/C++ Users Journal
-- "Win32 GUI Generics" -- generics & GUI do mix, after all
-- http://www.torjo.com/win32gui/
-- v1.4 - save_dlg - true binding of your data to UI controls!
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