[interfacekit] Re: a "dirty" thing...

On Wed, 16 Apr 2003, Adi Oanca wrote:

> Guys I want you to answer to the following question with as much of detail
> as you can. This involves: concept, principles, BeOS specific, -->code
> implementation <-- all you can, BUT, don't go over the hill.
>
> What means, a "dirty" view ?

Here's my little knowledge:
Assuming a view to be a visualization of data, it can be considered dirty,
if it doesn't reflect the current state of the data -- because the data
have changed or the view was obscured by other components on screen and
has now become visible, and thus needs to be redrawn. Shortly, a view is
dirty, if it (or parts of it) needs to be redrawn.

In GUI systems views or parts of it are usually marked dirty by the GUI
manager (app server in our case) -- e.g. when obscured parts have become
visible -- or explicitly by the application -- when the data model has
changed. About the app server internals I don't know much, but on the
application side BView::Invalidate() can be used.

I suspect most of the work -- management of dirty regions and such -- is
done in the app server, while the API side classes do little more than
forwarding the update requests issued by the app server, eventually
resulting in BView::Draw() invocations.

CU, Ingo

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