x11 limit mouse movements - qt

Question

I try to lock mouse cursor movements to the left half of the screen. I have following screen setup:
On the left side is a Qt window of size 1120x1080, on the right side a GL window of size 800x1080.
I use Openbox window manager under Ubuntu 12.10. The window layout stays fixed.
I need to restrict mouse movement to the Qt window.

Answer 1

To get the mouse to stay in the window, enable mouse movement with:
setMouseTracking(true);
and override void QWidget::mouseMovement( QMouseEvent * event )
void TheWindow::mouseMoveEvent ( QMouseEvent * event )
{
// get window size without frame
QRect s = geometry();
// get current cursor position
int x = event->globalX();
int y = event->globalY();
bool reset = false;
// Check cursor position relative to window
if (event->x() < 0)
{
x -= event->x();
reset = true;
}
else if (event->x() >= s.width())
{
x += s.width() - event->x() - 1;
reset = true;
}
if (event->y() < 0)
{
y -= event->y();
reset = true;
}
else if (event->y() >= s.height())
{
y += s.height() - event->y() - 1;
reset = true;
}
// if reset needed move cursor
if (reset) QCursor::setPos(x,y);
}

Answer 2

this involving QGraphicsItem::itemChange(). If you have an item which you want to restrict to a certain area then reimplement itemChange() for that item and monitor QGraphicsItem::ItemPositionHasChanged changes to see whether the items wants to be placed outside your area of interest and prevent that by returning a position from inside that area. for example:
QVariant QGraphicsItem::itemChange(GraphicsItemChange change, const QVariant &value)
{
switch (change) {
case ItemPositionHasChanged:
if(x() < -200 || y() < -200 || x() > 200 || y() > 200)
setPos(0, 0);
graph->itemMoved();
break;
default:
break;
};
return QGraphicsItem::itemChange(change, value);
}