My assumption is that your app is opening an existing web admin interface via the InAppBrowser.
However, I am not entirely sure if you would like your remote web page to have a button that opens the QR/barcode scanner on the device in the app, is this correct? If this is the case I am afraid that this cannot be achieved and you will need to add the logic in the mobile app, for example, you may point the user to open a menu in the app an access the scanner.
The reason for this limitation is that the web browser is isolated from the app and cannot influence its behavior (as far as I am aware). Unfortunately, there is no meaningful way for the in app browser and the app to communicate (for example you can examine this issue
in the Cordova framework).
One idea which you may try with the existing options which may also come in handy in some case is to:
- execute a script with the plugin methods and its API
(for example, executeScript
- pass data from between pages or something similar to the approach shown in this blog post
Make note for any possible security implications as with any browser requests or redirects, the same security problems as with other browsers apply to the InAppBrowser, especially if you need to make some modifications to the current web pages.
I also advocate that you use a more straightforward approach by using a dedicated menu in the mobile app because of the following.
If your app is going to be submitted to the Apple App Store it may not be approved if it only opens a web page inside an app. Apple require that applications give a different look and feel by accessing native device capabilities and options available on mobile devices. You can examine on this matter the following list of common rejections
(see Web clippings, content aggregators, or a collections of links) or the official guidelines.
I hope this answers your question.