We accidentally removed the code updating the data index in 8a189a6,
resulting in the decoder newer consuming any data. So the data would
be parsed as the next rect, causing weird errors.
This change adds support for the VMware Mouse Position
pseudo-encoding[1], which is used to notify VNC clients when X11 clients
call `XWarpPointer()`[2]. This function is called by SDL (and other
similar libraries) when they detect that the server does not support
native relative motion, like some RFB clients.
With this, RFB clients can choose to adjust the local cursor position
under certain circumstances to match what the server has set. For
instance, if pointer lock has been enabled on the client's machine and
the cursor is not being drawn locally, the local position of the cursor
is irrelevant, so the RFB client can use what the server sends as the
canonical absolute position of the cursor. This ultimately enables the
possibility of games (especially FPS games) to behave how users expect
(if the clients implement the corresponding change).
Part of: #619
1: https://github.com/rfbproto/rfbproto/blob/master/rfbproto.rst#vmware-cursor-position-pseudo-encoding
2: https://tronche.com/gui/x/xlib/input/XWarpPointer.html
3: https://hg.libsdl.org/SDL/file/28e3b60e2131/src/events/SDL_mouse.c#l804
We computed a safe area if a client gave us a bogus one, but we didn't
actually use it. Fix this properly and make sure we don't pass on bad
coordinates further.
Now measures over an entire update, which should hopefully give us more
stable values. They are still small values for fast networks though so
increase precision in the values we keep.
We can't safely use the normal timers in base classes as we cannot
guarantee that subclasses will call the base class' handleTimeout()
properly if the subclass overrides it.
