Documentation?

[Peter Harris]

Michel Dänzer wrote:
> On Wed, 2009-04-08 at 10:30 -0400, Patrick O'Donnell wrote:
>>> From: Michel =?ISO-8859-1?Q?D=E4nzer?= <michel at daenzer.net>
>>> Date: Wed, 08 Apr 2009 15:58:18 +0200
>>>
>>> On Wed, 2009-04-08 at 09:55 -0400, Patrick O'Donnell wrote:
>>>>> From: Michel =?ISO-8859-1?Q?D=E4nzer?= <michel at daenzer.net>
>>>>> Date: Wed, 08 Apr 2009 15:29:28 +0200
>>>>>
>>>>> On Wed, 2009-04-08 at 09:14 -0400, Patrick O'Donnell wrote:
>>>>>> Unfortunately, that's not going to be available for all the platforms
>>>>>> we must support.
>>>>> Why not?
>>>> Ummmm...  Because the servers on those platforms do not offer it?
>>> What are 'those platforms'? Which X.org servers offer neither the
>>> Composite extension nor backing store?
>> The world is not all X.org.  Not all the X servers on Windows that we
>> have to deal with offer the Composite extension (or backing store --
>> sigh).
> 
> Ah, I thought this was about X.org changes making things worse for you.
> Guess I lost track. :}

It is. New X.org servers dropped SaveUnders. Many other X servers
(including X.org builds from a couple of years ago) don't have the
purported replacement. Now he has to support both. Needing to support
both is worse than having to support only one.

Honestly, SaveUnders and BackingStore were always just hints, so relying
on them has always been broken. But that doesn't make his life any
easier just now, so I can understand his frustration.

As a constructive suggestion: For expensive drawing, you can draw to a
pixmap and just copy from that pixmap to the window every time you get
an Expose event. This should require relatively small changes to your
code, and will work on all servers. The main downside is the lack of
visible user-feedback while drawing, so you may want to implement a
swirly or a progress bar or something so your users don't think the app
has hung.

Peter Harris
-- 
               Open Text Connectivity Solutions Group
Peter Harris                    http://www.opentext.com/connectivity
Research and Development        Phone: +1 905 762 6001
pharris at opentext.com            Toll Free: 1 877 359 4866