At the end it turned out that it was easier than I thought:
intentScan.putExtra("ASSUME_GS1", true);
The hints can be set with extras.
I just had to figure it out, because I couldn't find it anywhere how to do that.
I downloaded the code of the Barcode Scanner and did a little debugging.
But now I can use the original app and get the barcode via Intent. :-)
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…