On Tue, 27 Jan 2004, Christopher Marshall wrote: > > > > not so simple as that. for machines with adf, you will usually have a > > couple other sensors like paper thickness, input or output hopper > > empty/full, cover open, lamp warm, etc. if the scanner sends all those as > > a bitmask in one packet, then the user doing a button-press might show up > > as a dozen different codes, based on those other flags. your 'generic' > > button monitor would have to know a whole lot more about each individual > > model than you would want (esp when things like which usb endpoint to use > > and bulk v/s interrupt are taken into account) > > > > all-in-all this sort of thing (reading the raw output from the scanner) > > belongs in the backend, with suitable abstraction that a frontend could > > use. finding that abstraction is more problematic... > > > > allan > > > > How about adding a front-end switch that instead of requesting a scan, > requests the backend to sit > and listen for button events and write them out to stdout? The format of the > message written > could vary by backend. > > For example, the command > > scanimage -d plustek:libusb:001:004 -report-button > > would wait for the next button press. Pressing a button would cause the > command to exit and write > a text description of the button pressed to stdout. > > This would allow the user to write bash scripts to respond to the button > presses. This style of > interaction is close to how xmessage works when invoked with -print. > > button=$(scanimage -d plustek:libusb:001:004 -report-buttons) > if [ "$button" == "copy" ] ; then > # scan and print > scanimage -d plustek:libusb:001:004 > image.pnm > pnmtops iamge.pnm > image.ps > lpr print.ps > elif ... > else > echo "unrecognized button" > exit 1 > fi > > This scheme might not solve all problems but it would be a big step up from > no support at all.
you could have a flag to a front-end that told it to load the backend, but instead of scan, constantly check the option descriptor for a button's status. the front-end could print this, or even take a series of command line switches that tell it what to do in case of a particular event. but in all cases, this front-end would have to disconnect from the scanner, so that the second front-end could load the backend and connect. but, it would have to still run, so that it could re-connect and continue monitoring. unless, you wanted to re-start it from your script. but you definately dont want backends printing. allan > > Chris Marshall > > > > __________________________________ > Do you Yahoo!? > Yahoo! SiteBuilder - Free web site building tool. Try it! > http://webhosting.yahoo.com/ps/sb/ > > -- "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
