I don't know how the iPhone apps like this work, but the Barcode Scanner for Android doesn't take a picture. You just hover your camera over the barcode and it

I don't know how the iPhone apps like this work, but the Barcode Scanner for Android doesn't take a picture. You just hover your camera over the barcode and it figures it out from the preview. I suppose it's technically taking a picture, but you could argue that you're not pressing the camera button, so you're not really taking a picture.