Add Bluetooth support for Brother label printers (QL series)

[thvranken]

Currently, the app supports the use of Brother label printers (QL series), connected via LAN/WLAN or USB. The Brother QL-820NWB and QL-1100NWB, however, also support printing via Bluetooth, the use of which for these printers is not yet supported by the pretixPRINT Android app.

Adding Bluetooth support for these printers to the pretixPRINT app would be interesting to us for the following reasons:

• The Brother QL-820NWB can optionally be equipped with a battery pack, providing large flexibility for where it can be used. It can thus be used in a very mobile way, as no power socket is required.
• Printing via Bluetooth does not require the presence of and access to a WIFI network (as connecting via WLAN does). This is thus very convenient when organising events at a location which you do not own yourself, but for instance rent for an evening. No network configuration is thus necessary. The mobile phone running the pretixSCAN app can connect to WIFI (if present) or 3G/4G/5G, while for printing, only a one-off Bluetooth pairing with the printer is necessary.
• These Brother label printers, offer the DK-11234 60mm x 86mm name badge media format, which would be very interesting to use as badges in combination with pretix.

[raphaelm]

Yes, that absolutely makes sense.

We will currently probably not invest time here, though, since we don't have one of these printers at hand for testing and we don't have a big priority on Brother printers business-wise.

So this will probably (a) require someone to send a contribution or (b) require someone to pay us for doing it.

[thvranken]

I have implemented this using the Brother Print SDK for Android. I have submitted a pull request (#43).

[raphaelm]

I'm pretty sure we decided deliberately against the brother sdk back when we introduced brother support (and I don't think we want two brother implementations) but I don't remember why, maybe @robbi5 does