Thank you Mathias, Very helpful as usual.
If I wanted to convey a bit more information between SurfaceFlinger and the client, would it be best to convey it via the control block or add it to the Parcel? Fred. On 1/22/09, Mathias Agopian <pixelflin...@google.com> wrote: > > Hi, > > On Tue, Jan 20, 2009 at 3:37 AM, F H <expelia...@googlemail.com> wrote: >> Hi Mathias, >> >> Android typically creates two buffers per surface. Presumably this is so >> that one of them can be locked by an application for rendering while the >> other (complete buffer) is available to SurfaceFlinger for compositing? > > correct. > >> What kinds of surfaces would have only one associated buffer? > > Surfaces with content that never changes? :-) > But why do you ask? SurfaceFlinger never allocate a surface with only 1 > buffer. > > >> Surface Buffer access is guarded by calls to Lock/Unlock(andPost) - there >> is >> another fcunction - nextBuffer which looks like it always returns data >> pertinent to the front buffer without effecting a lock. > > nextBuffer() was an experiment which was never cleaned-up. Don't use > it (I mean it). nextBuffer will most likely disapear in cupcake. > >> Are all accesses to buffers gated through either lockSurface (& >> corresponding unlock..) > > correct. > >> or nextBuffer? When is nextBuffer used as opposed to >> the lockSurface? (Seems like a misleading name). > > see above. > >> Does the information ultimately get conveyed to a GGLSurface object before >> any Android rendering is done? > > I need to double-check on that. I think this might still be the case. > >> I also noticed a limit on the number of Layers a client can have >> (NUM_LAYERS_MAX), which is set to 31. Does this pose a problem for >> applications that for example use lots of UI type widgets? > > No. A "layer" correspond to a "window" in the UI (like a status-bar, a > dialog, or the main window). > >> Also I guess 31 >> is used as a number just so that the control block stays smaller than 4k? > > Yes. It also simplifies a few things to keep track of surfaces (the > implementation uses an uint32 as a bit set). > > > Mathias > > >> >> Thanks, >> Fred. >> >> >> > >> > > > > --~--~---------~--~----~------------~-------~--~----~ unsubscribe: android-porting+unsubscr...@googlegroups.com website: http://groups.google.com/group/android-porting -~----------~----~----~----~------~----~------~--~---
