[maemo-developers] Strange problem with Maemo5ShowProgressIndicator

[From: Robin Burchell]

On Tue, Jun 8, 2010 at 1:35 PM, Daniil Ivanov <daniil.ivanov at gmail.com> wrote:
> Hi Robin!
>
>   The question was how to make indicator to appear, not how to avoid
> blocking of UI
>   during long synchronous operation. Sleeping was used just as
> simulation of long blocking
>   operation.

Yes, I know what the question was. And my point is that really, if you
are performing blocking operations in the UI thread, you're probably
doing it wrong - and this is one of the symptoms you'll get as a
result. Others can include but are not limited to nothing responding
at all to presses, visual updates performing slowly (or not at all)
for e.g. progress bars..

It's possible to work around it, but that's compounding more wrong on
top of it. Users don't normally tend to like unresponsive UIs, long
operations that they can't cancel, etc.

In short, I'm pointing out that there is probably a better way to
solve this: by using an asynchronous operation, and cancelling the
progress indicator when the callback returns, or performing the slow
operation on a thread, and letting the GUI thread do what the GUI
thread does best: update the GUI.

An example of the former (asynchronous operation) can be seen at
http://gitorious.org/~w00t/qfacebookconnect/facebrick/blobs/master/src/newsfeedpostview_addcomment.cpp
- I'm also happy to explain this (both the concept and the example
code) in more detail to anyone who wants on IRC or mail.

Robin Burchell
mob: +447702671419
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