- Indexed engine operator list (would be better as second set of calls)
 > Arguments can be passed using custom attributes
- GL-centric operations (would be better with read_buffer/write_buffer calls)
- No status returned from operations most
- Input data format specifcation
 > Engine operator list specifies it, but in an abstract way (which would require quite smart code to determine)
 > Doable though, but having a RO property on the engine that notes if it uses a standard pixel format would be nice


Engine inspection API:
> Readonly? Property for number of operations
 - Readonly because modifcation of the count is not possible
 - Attributes can be read, so that's your config mechanisim
> udi_gfx_engine_getop_req(udi_gfx_state_cb_t *cb);
> udi_gfx_engine_getop_ack(udi_gfx_state_cb_t *cb, udi_ubit8_t operation, udi_ubit32_t arg1, udi_ubit32_t arg2, udi_ubit32_t arg3);


Buffer manipulation API:

  struct {
      udi_cb_t	gcb;
      udi_index_t buffer_idx;
      udi_ubit32_t offset;
      udi_buffer_t *data;
  } udi_gfx_buffer_cb_t;

> udi_gfx_buffer_write_req(udi_gfx_buffer_cb_t *cb);
> udi_gfx_buffer_write_ack(udi_gfx_buffer_cb_t *cb, udi_status_t status);
> (OPTIONAL) udi_gfx_buffer_read_req(udi_gfx_buffer_cb_t *cb);