Hey guys! I'm sorry! I was not following the topic!
In the repository has a capx example. Basically I have created a C2 plugin that calls the cordova-gizwits-scan-qrcode code.
To get it working you have to:
1. Add the cordova-gizwits-scan-qrcode plugin to your config.xml. I made a copy of the original repository in github.com/rafaelfl/cordova-gizwits-scan-qrcode.
<plugin name="https://github.com/rafaelfl/cordova-gizwits-scan-qrcode.git" spec="https://github.com/rafaelfl/cordova-gizwits-scan-qrcode.git"/>
Another way to do this is cordova plugin add https://github.com/rafaelfl/cordova-gizwits-scan-qrcode.git .
2. Create a folder named simpleqrscanner in your "Construct 2\exporters\html5\plugins" and copy the content of the src folder to it.
3. Restart C2. In your C2 project, using the double-click, include the plugin simpleqrscanner into your project.
4. Follow the sample file: create the action Decode QR Code and handle the conditions QR Code has been decoded, QR Code was cancelled and Error decoding the QR Code.
That's all folks! I didn't tried to use it in C3 (I don't know how plugins are managed in it), but when I have some time I will read about it.
Regards!
Rafael.