[vbox-dev] IFramebuffer changes from 4.x to 5.0

Vitali Pelenjow Vitali.Pelenjow at oracle.com
Tue Jan 5 09:22:30 UTC 2016

Hi Rudolfs,

if you are launching the machine inside you own process, then use 
notifyUpdate. You are right that in this case you get the pointer to the 
framebuffer bitmap using the IDisplaySourceBitmap interface.

You should call IDisplaySourceBitmap::queryBitmapInfo from notifyChange 
handler (see implementations in src\VBox\Frontends). The returned bitmap 
info is valid until the next notifyChange call.

notifyUpdateImage is used to get bitmap updates in a different process.


Rūdolfs Bundulis wrote:
> Hi,
> I am porting my custom frontend to VirtualBox 5.0 and had a couple of 
> questions about how IFramebuffer works now. I see that all the stuff 
> regarding VRAM and implementing it inside the framebuffer is gone, 
> which I was told would happen. What confuses me is usage of 
> notifyUpdate vs notifyUpdateImage. I am launching the machine inside 
> my own process - so then which is the most efficient way to receive 
> notifications about updates? Which one is more efficient? As I 
> understand if I use notifyUpdate (and do not retur the UpdateImage 
> capability) I must get the pointer to the bitmap and all the data from 
> the IDisplaySourceBitmap interface? Is that thread safe? Can I read 
> the pixels without any explicit locking? And what about changes to the 
> pixel format - they are no longer part of the notifications. Does that 
> mean I need to call IDisplaySourceBitmap::queryBitmapInfo() each time 
> i receive a notifyUpdate call?
> Best Regards,
> Rudolfs Bundulis
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