Review Request 128858: [frameworks] Hide cursor when tablet pen leaves proximity of the screen

[Oliver Sander]

> On Oct. 4, 2016, 9:21 p.m., Albert Astals Cid wrote:
> > ui/presentationwidget.cpp, line 544
> > <https://git.reviewboard.kde.org/r/128858/diff/3/?file=481683#file481683line544>
> >
> >     You should return true for the events you actually handle i guess

Not sure, but so far I have read the documentation differently.  On http://doc.qt.io/qt-5/qobject.html#eventFilter it says:

"In your reimplementation of this function, if you want to filter the event out, i.e. stop it being handled further, return true; otherwise return false."

I want to do something when the event happens, but I don't want to filter it out.  Others may still be allowed to act on the event after me.  Therefore I always return false.

Does that make sense?


- Oliver


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On Oct. 4, 2016, 8:13 p.m., Oliver Sander wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/128858/
> -----------------------------------------------------------
> 
> (Updated Oct. 4, 2016, 8:13 p.m.)
> 
> 
> Review request for Okular.
> 
> 
> Repository: okular
> 
> 
> Description
> -------
> 
> I am trying to fix the following papercut:  I regularly write on pdf files in presentation mode, using the pen that comes with my Lenovo ThinkPad Yoga.  When I approach the screen with the pen, the cursor appears, and it follows the pen tip during writing.  When I lift off the pen, the cursor stays on, and auto-hides only a few seconds later (because of Okular::Settings::EnumSlidesCursor::HiddenDelay).  As a consequence, the cursor frequently hides the last bits of what I have just written.  This is a nuisance, because I do this in front of an audience, and a lot of it is math (where every detail matters).
> 
> Ideally, the cursor would auto-hide when I lift the pen off the screen.  Luckily, Qt has an event for this: QEvent::TabletLeaveProximity.  Unluckily, the documentation says (http://doc.qt.io/qt-5/qtabletevent.html):
> 
> "TabletEnterProximity and TabletLeaveProximity events [...] are only sent to QApplication"
> 
> Therefore, this patch introduces a new class TabletApplication, which inherits from QApplication, and is used in main.cpp instead of QApplication.  The proximity events are really caught, and each time a short note is printed on the console.
> 
> Unfortunately, at this point I am stuck and need some help.  Apparently, I cannot control the cursor from a QApplication.  How do I get the information that a TabletProximity has been caught to the presentation widget? Maybe the answer is trivial, but I have very little Qt programming experience.  Thanks for your help!
> 
> 
> Diffs
> -----
> 
>   ui/presentationwidget.h 69574d2 
>   ui/presentationwidget.cpp c16d616 
> 
> Diff: https://git.reviewboard.kde.org/r/128858/diff/
> 
> 
> Testing
> -------
> 
> 
> Thanks,
> 
> Oliver Sander
> 
>

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