Get a direct pointer to the internal pixel data, if available.
This will return null
unless Efl.Gfx.Buffer.buffer_managed_set was used to pass in an external data pointer.
Overridden from Efl.Gfx.Buffer.buffer_managed_get.
buffer_managed_get @pure_virtual { params { @in plane: int @optional; } return: Eina.Slice; }
Eina_Slice efl_gfx_buffer_managed_get(Eo *obj, int plane);