> > I'm somewhat curious on your implementation ;-) How will you solve this? > > Are you using some kind of background process or thread to update > > peridodically the status? What is the callback, or the corresponding > > sane_ function, that a frontend can use? > > As mentioned in the last button thread (from January or so), I use > normal options. Proposed capabilities have been SANE_CAP_SOFT_DETECT | > SANE_CAP_HARD_SELECT (| SANE_CAP_ADVANCED). But I think > SANE_CAP_HARD_SELECT is missleading: > > "The option value can be set by user-intervention (e.g., by flipping a > switch). The user-interface should prompt the user to execute the > appropriate action to set such an option. This capability is mutually > exclusive with SANE_CAP_SOFT_SELECT (either one of them can be set, > but not both simultaneously)." > > The user should not be able to toggle the option in the interface ...
do any other backends currently use hard_select? if not, perhaps that description should be updated slightly? > > So currently I use "SANE_CAP_SOFT_DETECT (|SANE_CAP_ADVANCED)". > > Since there is yet no way to mark it as "auto-pull" / "auto-refresh" > or whatever I must rely, on the tiny example "buttond" program to > reload options with the name "button" periodically. So I have no > thread or singalling in the backend. i dont understand. is there a separate program that runs, and talks to the backend, and just polls the status of the buttons every few seconds? does this program close the scanner and execv() over to a front end when that happens? > > And as work around for my "when to flush the state to false" for the > buttons I only re-fetch them from the scanner if sane_control_option > is called for the first button available. > that is the easiest, i guess. > Of course the interface details can be easily changed - and I'm open > for suggestions or interfaace additions to mark to-be-polled options. > i think we need a polling capability, though that would mean changes to front-ends.... allan > Sincerely yours, > René Rebe > - ROCK Linux stable release maintainer > > -- > René Rebe - Europe/Germany/Berlin > r...@rocklinux.org r...@rocklinux-consulting.de > http://www.rocklinux.org http://www.rocklinux-consulting.de > > > -- > sane-devel mailing list: sane-devel@lists.alioth.debian.org > http://lists.alioth.debian.org/mailman/listinfo/sane-devel > Unsubscribe: Send mail with subject "unsubscribe your_password" > to sane-devel-requ...@lists.alioth.debian.org > -- "so don't tell us it can't be done, putting down what you don't know. money isn't our god, integrity will free our souls" - Max Cavalera
