[sane-devel] option size = 0 allowed ?

Michael Herder crapsite@gmx.net
Wed, 18 Dec 2002 19:50:39 +0100

Oliver Rauch, Mittwoch, 18. Dezember 2002 16:46:
> On Wednesday 18 December 2002 11:55, Henning Meier-Geinitz wrote:
> Please can you point me to the paragraph where you think it is
> mentioned that it is not allowed to change constraints and option sizes?

2 problems:
- The frontend is allowed to ignore the info parameter in sane_control_option 
completely (i.e. it can be set to 0). If you allow this, you can't change 
e.g. the option size (only possible, if you *force* the frontend to reload 
the options)
- Nothing in the standard states, that an option descriptor can only be 
changed by the backend after a call to sane_control_option. If you allow 
changes to the option size, a frontend would have to requery the option 
descriptors *every time* before it can safely set an option.