Clients reading their surface position on screen

[Daniel van Vugt]

I think it's mathematically pedantic to say the function does not exist. 
Acknowledging that such a function would theoretically return a set; 
one, multiple or none coordinates (offscreen or occluded), we can dumb 
it down to the simple case that's important -- give one or zero results:

// Returns one screen location where the specified surface coordinate
// is visible. Returns false if the coordinate is not visible on
// screen at all.

MirBool mir_surface_coord_to_screen(MirSurface* surf,
                                     int localx, int localy,
                                     int* screenx, int* screeny);

Admittedly that only works for your own surfaces created in your own 
process.


On 12/08/14 10:56, Christopher James Halse Rogers wrote:
> On Tue, Aug 12, 2014 at 12:33 PM, Daniel van Vugt
> <daniel.van.vugt at canonical.com> wrote:
>> There is a 5th option which would satisfy more (not all) of the people
>> mentioned:
>>
>> 5. Shell mediates if a client has permission to ask for surface
>> coordinates. The API is restricted by default. The API _does_not_
>> return the top-left corner of the surface. Instead it maps a local
>> surface coordinate (x,y) to screen coordinates (x',y'). This way we
>> can still map correct coordinates for arbitrary 3D transformations (if
>> we want to, but don't need to initially).
>
> Again, this assumes that there exists a function whose domain is surface
> coordinates and range is screen coordinates. This function does not
> necessarily exist.
>
> There *is* a unique mapping from screen coordinates to {surfaces} × (ℚ ×
> ℚ), but (a) I don't think that's what AP is after - although it could
> implement it - and (b) it would require us to make all surfaces visible
> in some way to all clients.
>
>