Thanks Dianne,

I'm trying to figure out the best way of creating a Surface that can be
displayed on an alternative display.  I know that Android doesn't support
multiple displays.  Our version of SurfaceFlinger does though,  so I was
hoping to talk to it using a low-level interface in order to obtain a
Surface on the alternative display. The Surface in question being one that
is suitable for using in a media player for example.

The WM doesn't manage multiple displays and from what I can tell, unless you
have low-level access you can't tell SF to create a Surface on a different
display.

Do you have any thoughts on the best way of implementing such a feature
without contaminating any of Android's API's.



On Mon, Mar 16, 2009 at 4:51 PM, Dianne Hackborn <[email protected]>wrote:

> On Mon, Mar 16, 2009 at 8:28 AM, F H <[email protected]> wrote:
>
>> Is it intended that low level access to Surface Flinger is granted only to
>> components that a part of the system and not to applications developed using
>> the SDK and signed using an arbitrary certificate?
>
>
> Yes.
>
>
>> Is it the intention that an Android platform be signed with a certificate
>> unique to an android provider,
>
>
> Yes.
>
>
>> who if they wished could enable applications to be signed by the same
>> certificate.
>
>
> No, this would allow you to write third party applications that are either
> significant security vulnerabilities and/or break across platform releases.
> The platform certificate is intended to be exclusive to the device
> manufacturer, and something they keep private.
>
>
>> When an android system is built - where is the certificate that is used
>> for signing the system and does it need to be generated in a particular way
>> (e.g. does it need to be generated by some signing authority).
>
>
> No it can be generated the normal way you general one for an SDK developer.
>
> The development certs are here:
>
>
> http://android.git.kernel.org/?p=platform/build.git;a=tree;f=target/product/security;h=be33ff699f23419ffd2067daf5489f785551df70;hb=HEAD
>
> I don't know off-hand how you sign with your "real" certs; but a basic rule
> is that these are not checked in to any source repository but done as a
> separate step as part of making a final release image, and only accessible
> to a few select people.
>
>
>> Presumably applications that connect up to surface flinger are routed
>> through something that has the requisite permission. (Or is it that apps in
>> general do not use low-level access?).
>
>
> Applications do not get to use surface flinger.  The window manager uses
> surface flinger, and provides the higher-level access that can be kept
> stable across releases.
>
> --
> Dianne Hackborn
> Android framework engineer
> [email protected]
>
> Note: please don't send private questions to me, as I don't have time to
> provide private support.  All such questions should be posted on public
> forums, where I and others can see and answer them.
>
>
> >
>

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