[Interest] mouse events: how to handle left and right button pressed?

[Philipp Menke]

why dont you use:

if (event->buttons() == (Qt::LeftButton | Qt::RightButton) )
{
     std::cerr << "both" << std::endl;
}
  else if ( event->buttons() == Qt::LeftButton)
{
     std::cerr << "left" << std::endl;
}
else if ( event->buttons() == Qt::RightButton)
{
     std::cerr << "right" << std::endl;
}
else
{
     std::cerr << "other" << std::endl;
}

I know some people who think switch is ugly or unsafe because you might 
forget a break, they use this style every time...



Philipp

Am 04.03.2012 16:59, schrieb Rui Maciel:
> I'm trying to handle mouse events which include the case where multiple
> mouse buttons are pressed. The reference page on QMouseButton[1] states
> that "[t]he button state is a combination of Qt::LeftButton
> <http://doc.qt.nokia.com/4.7/qt.html#MouseButton-enum>, Qt::RightButton
> <http://doc.qt.nokia.com/4.7/qt.html#MouseButton-enum>, Qt::MidButton
> <http://doc.qt.nokia.com/4.7/qt.html#MouseButton-enum>  using the OR
> operator." From this, it would be expected that an event where multiple
> buttons were pressed would be handled in a way similar to the following
> code:
>
>
> <code>
> switch(event->buttons() )
> {
> case Qt::LeftButton:
> std::cerr<<  "left"<<  std::endl;
> break;
>
> case Qt::RightButton:
> std::cerr<<  "right"<<  std::endl;
> break;
>
> case (Qt::LeftButton | Qt::RightButton):
> std::cerr<<  "both"<<  std::endl;
> break;
>
> default:
> std::cerr<<  "other"<<  std::endl;
> break;
> }
> </code>
>
> Yet, when I try to compile this code, the following error message is
> displayed:
>
> <message>
> InputState.c++:22:41: error: temporary of non-literal type
> ‘QFlags<Qt::MouseButton>’ in a constant expression
> </message>
>
>
> Does anyone know if it's possible to handle mouse events with multiple
> buttons pressed through a switch() statement? If it isn't possible then
> what alternatives are available?
>
>
> Thanks in advance,
> Rui Maciel
>
> [1] http://doc.qt.nokia.com/4.7/qmouseevent.html#buttons
> _______________________________________________
> Interest mailing list
> Interest at qt-project.org
> http://lists.qt-project.org/mailman/listinfo/interest