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

[Oliver Sander]

> On Oct. 2, 2016, 12:33 p.m., Martin Tobias Holmedahl Sandsmark wrote:
> > maybe try with installEventFilter(qApp) in the presentation widget, override eventFilter() and check for the tablet events in PresentationWidget and call setCursor(Qt::BlankCursor) and unsetCursor().
> > 
> > you could also call setOverrideCursor() and unsetOverrideCursor() in your custom QApplication, but then it's tricky to track when the presentation widget is used and I'd prefer not having a new application class just for this.
> 
> Albert Astals Cid wrote:
>     What sandsmark says try installing an event filter, the syntax of what he suggested is wrong, what you want is not installEventFilter(qApp) but qApp->installEventFilter(this), with this being the presentationwidget.
> 
> Oliver Sander wrote:
>     Thanks guys.  I rewrote the patch, and it now uses eventFilter.  That's indeed much nicer!
>     
>     In principle, the new patch does what it is supposed to do.  However, two problems remain:
>     
>     a) I had to add code to the mouseMoveEvent class, to make the arrow cursor appear when the mouse is moved.
>        Otherwise, after a TabletLeaveProximity event causes the cursor to disappear, moving the mouse will
>        not make it reappear.  I don't think my solution is very elegant.  Do you guys know a better way?
>        
>     b) When in drawing mode, upon removing the stylus from the screen, the cursor will briefly switch to an
>        arrow cursor before disappearing.  That is because mouseReleaseEvent calls routeMouseDrawingEvent
>        which calls slotChangeDrawingToolEngine which sets the arrow cursor.  Any ideas how to avoid this?
>        
>     Thanks again for your help!

I fixed b) by manually inlining the calls to slotChangeDrawingToolEngine, without the calls to setCursor.  I do not think that setCursor is actually needed here, and inlining replaced two lines of by only three new ones.


- 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/
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> 
> (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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