[vbox-dev] mouse integration concept level overview?
michael.thayer at oracle.com
Fri Sep 2 13:47:16 PDT 2011
On Thu, 2011-09-01 at 20:56 -0700, Huihong Luo wrote:
> I need to know a bit more about the mouse integration. Can someone explain in big picture on what happened when a mouse pointer is moving from host to the guest? once the mouse inside the guest window, host informs the guest about the mouse positions? etc.
> I need to get some ideas on this in order to implement the drag-and-drop feature for vbox. Right now, it's stuck when the mouse is dragged from host to vm, how the guest side knows about that. I need to press a key for now to tell the guest side, so the dnd isn't smooth yet. A good understanding on mouse integration would be very helpful.
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I'm afraid that this will be a quick-ish explanation for now. When
absolute pointer reporting is enabled (see the VMMDevReq_GetMouseStatus
VMM device request) the current pointer position can be requested with
the VMMDevReqMousePointer request. This is reported as a percentage of
the width and height (respectively) of the guest screen - expressed as a
value from 0 to 0xFFFF - or of the virtual desktop for multi-monitor
guests. The host works out what percentage values correspond to the
position of the host pointer relative to the host window the machine is
running in, and the Additions report the position back to the guest in a
way that the guest OS can convert to the correct pixel offset. The host
sends a VMM device event (basically an interrupt and a data word) when
absolute reporting is enabled or disabled and when new position data is
Hope that helps a bit.
ORACLE Deutschland B.V. & Co. KG Michael Thayer
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