Update to 4.4.2 - Now I Have A Transparent Dialog

[mclark]

You cannot block the event loop with a busy loop (in fact, in the minimal test case you don't run an event loop at all). The application has no chance to deliver paint events, thus nothing gets painted.

In that case this example should perform the same using both versions of Qt, no?

[jpn]

In that case this example should perform the same using both versions of Qt, no?

Perhaps 4.3.4 creates the native window handle upon show(), whereas 4.4.0 probably doesn't do it at that point yet. It doesn't mean that the minimal test app works with either version. You MUST let the application process its events in order to make the dialog responsive.

for ( int i = 0; i < 0x7FFFFFFF; i++ ) // Simulate some work...
    app.processEvents();

for ( int i = 0; i < 0x7FFFFFFF; i++ ) // Simulate some work...
    app.processEvents();

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[mclark]

You MUST let the application process its events in order to make the dialog responsive.

Ahhhh.... Now I see what you mean about the minimal test app.

So, what would you recommend for a solution for the real app?

I have a QDialog which needs to make a library call that may take 3-7 seconds (on average) to complete. I want to display something to let a user know that processing is happing (the app is NOT hung). I was using the GenericWaitDlg class described above.

[jpn]

So, what would you recommend for a solution for the real app?

I have a QDialog which needs to make a library call that may take 3-7 seconds (on average) to complete. I want to display something to let a user know that processing is happing (the app is NOT hung). I was using the GenericWaitDlg class described above.

What kind of library call is that? Unless there is a way to split the task into smaller chunks, I'm afraid you have to process it in a worker thread and deliver results to the main GUI thread for example by using queued signals.

[mclark]

What kind of library call is that?

The call is to a library I have no control over (not a Qt call). I was hoping there might be a solution other than using a worker thread.

Does this sound reasonable:

1. create my GenericWaitDlg
2. create a worker thread
3. connect a slot (closeGenericWaitDlg()) to the finished() signal of the thread
4. in the run() method of the thread, make my library call
5. when the library call is finished the thread should shutdown
6. in the closeGenericWaitDlg() method call dlg.done(0) to close the wait dialog

[jpn]

Yes, sounds reasonable. Just remember not to touch GUI in the worker thread.

[mclark]

Thanks for your help, jpn. It is much appreciated!