QWidget::update() qeustion

[tanki95]

Yes.

Actually many dialogs are updated by threads.

Is there any thing to consider to update GUI for the multiple threads?

Thanks.

[wysota]

You can't access GUI objects (dialogs included) from within worker threads.

[tanki95]

I cannot understand I can't access GUIs in worker thread.

CUIGOCIImgStatus is a class which inherits QWidget. It also includes <ui_gociimgstatus.h> generated by qmake.

I updates by using a thread which check status of other system.
If status is changed,
I set values in member variables in CUIGOCIImgStatus to update , then I call updates().
Then paintEvent() is called.
CUIGOCIImgStatus objects is a global variable to share.
It is created by main thread but is updated by only one other threads.

Usually, this works well.

but 1 out of 10, segment fault happens.

anything wrong??

[wysota]

I cannot understand I can't access GUIs in worker thread.

Well... you just can't.

I updates by using a thread which check status of other system.
If status is changed,
I set values in member variables in CUIGOCIImgStatus to update , then I call updates().

Sorry, that's forbidden.

Usually, this works well.

Yes... usually That's the key word here.

[tanki95]

Ok... I think I understand what you meant.

You mean I should call 'update()' in the main GUI thread?

But how do I call update() in the main GUI thread if the content of the GUI is changed from the other thread?

If I use timer thread by using QTimer, it is also forbidden. right?

Do you have any suggestion for the current my situation??

Thank you very much for your reply.

[wysota]

You mean I should call 'update()' in the main GUI thread?

Yes, that too.

But how do I call update() in the main GUI thread if the content of the GUI is changed from the other thread?

Use signals and slots or custom events.

If I use timer thread by using QTimer, it is also forbidden. right?

I'm not sure I understand what you mean. You can use timers in other threads.