[Interest] [QtGui] Clip cursor position

[Jan Dasselaar]

Hello Konstantin,

I figured it would be possible to add an event filter to the overlay 
window to:
a. restrict the mouse to the desired area
b. dispatch other mouse event to widgets below.

Won't be easy, but it seems not impossible.

Regards,
Jan

On 22-12-2015 12:22, Nye wrote:
> Hello Jan,
> Thanks for the suggestion, but I'm not really convinced that this'd 
> help, since installing an event filter on the application object is 
> effectively doing the same thing as grabbing the mouse (at least while 
> the mouse is over an application window). Additionally the "grabMouse" 
> runs into the trouble that I'd have to manually dispatch the messages 
> to their corresponding widgets and it doesn't really prevent the mouse 
> from leaving an area (or widget/window), it just ensures that the 
> particular widget will get all mouse events (whether or not they occur 
> in its client area). In windows the API seems to allow the behavior 
> I'm after 
> (https://msdn.microsoft.com/en-us/library/windows/desktop/ms648383(v=vs.85).aspx 
> <https://msdn.microsoft.com/en-us/library/windows/desktop/ms648383%28v=vs.85%29.aspx>) 
> but I'm not sure if this is even possible for X11.
>
> Kind regards,
> Konstantin.
>
> On Tue, Dec 22, 2015 at 12:52 PM, Jan Dasselaar <jan at altus-escon.com 
> <mailto:jan at altus-escon.com>> wrote:
>
>     Hello Nye,
>
>     Maybe you can use the QWidget::grabMouse() function for that.
>     This in combination with an overlay widget (visible but fully
>     transparent) over your application.
>
>     Regards,
>     Jan
>
>
>     On 22-12-2015 10:44, Nye wrote:
>>     Hello,
>>     Is it possible to clip the mouse cursor to a specific area of the
>>     screen? I've tried to limit the cursor movement by installing an
>>     event filter on the application object and moving it back when
>>     its position got outside of my target rectangle, but the results
>>     proved to be unsatisfactory, as there is considerable "flicker".
>>     I then dig deeper and tried installing a window system event
>>     handler on QWindowSystemInterfacePrivate by subclassing the
>>     QWindowSystemEventHandler class available, reimplementing the
>>     sendEvent() function, and plugging that in the appropriate place,
>>     but (as expected) the behavior was only marginally better. I'm
>>     considering changing the QPlatformWindow and trying to do it
>>     directly from there (actually from QXcbWindow) but decided to ask
>>     first if there is actually a better way. Any input is highly
>>     appreciated.
>>
>>     Kind regards.
>>
>>
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