Barcodes are detected by catching keypresses. When a keypress is not
part of a barcode, it is 'released' by forging a keypress event.
For security reasons, a non-native keypress doesn't trigger the native
input mechanism. So in order to make both barcode-scanning and manual
keypresses work in a field, it is necessary to have a handler listen
to the 'false' keypresses and simulate the native input behaviour.
For a model to use it, it must :
- Inherit barcodes.barcode_events_mixin and override on_barcode_scanned(self, barcode)
- Add <field name=barcode_scanned widget=barcode_handler/> to each form view that
should listen to barcode events and trigger on_barcode_scanned.
The method on_barcode_scanned works just like an onchange.
If the module barcodes is installed, a BarcodeEvents singleton is
automatically instanciated. It listens to keypresses and, when a
sequence of keys represents a barcode, it broadcasts a 'barcode_scanned'
event on core.bus containing the barcode string.
Ranjit Pillai