[boost] Re: boost Windowing Toolkit

From: Dave Abrahams (abrahams_at_[hidden])
Date: 1999-12-12 20:30:31

>>How much wrapping is required for a standard component like a
>>scrollbar? Probably enough to do the following:
>>
>>1. place it as a leaf in some user-defined window hierarchy
>>2. get it to collaborate in a coherent way with other (user-
>>    written) GUI components.
>>
>>#2 includes many aspects, like size and placement constraints and
>>positioning feedback.
>
> Number 2 is just events right? The scrollbar is being
> scrolled and a function gets called repeatedly to tell
> you this. A button is clicked and a user-defined function
> gets fired to let you handle it... I say *just* events
> but of course it's a big issue. You mention something
> about event queuing in your original post. Is that
> something workable for what we're talking about here or
> is it something completely different?

Well, I see "Events" as meaning input from the OS and user which is
dispatched in a particular manner possibly determined by the structure of
the window hierarchy. Things like mouse clicks, key presses, and screen
update requests. "Event queueing" has to do with taking input from arbitrary
(and extensible) sources and allowing the application GUI, which should
usually be single-threaded, to deal with these inputs in time/priority
order.

I have a different idea about how arbitrary objects in an application
framework should be made to collaborate. Maybe it's really all the same, but
I see it differently. Collaboration should usually rely on a
broadcaster/receiver paradigm (using RTTI to identify appropriate receivers
of particular messages).

-Dave