Add support for Fuji's CropMode tag (0.27->master)

[FreddieWitherden]

This small PR adds support for a missing tag in the Fuji Makernotes that I've discovered I need for my lens correction work. Details for the tag were taken from https://exiftool.org/TagNames/FujiFilm.html

[kmilos]

Translated values are incomplete?

[FreddieWitherden]

Translated values are incomplete?

Good spot. I have fixed the issue when the tag value is one.

As an aside, when this tag is 2 or 4 the image has an additional 1.25 crop factor attached to it. However, this does not appear to be reflected in the Exif.Photo.FocalLengthIn35mmFilm tag written out by the camera (it assumes the crop is 1.5 rather than 1.5*1.25). I am unsure how we want to handle this.

[kmilos]

this does not appear to be reflected in the Exif.Photo.FocalLengthIn35mmFilm tag written out by the camera

It's not a job for Exiv2 to "fix" (hide) this IMHO.

[clanmills]

Let's try to minimise "interpreting" the metadata. It's like the lens recognition which should never have been in Exiv2. It has created end-less work. So, let's do as little as possible.

If you have to do this "when there is an R in the month, multiply by 1.25, you'll have to do it in code by supplying a specialised PrintFct. When we print the value (not the interpreted value), we print the value in the metadata.

[clanmills]

There is a PrintFnc already defined: print0xa405. We shouldn't touch this.

862 rmills@rmillsmbp:~/gnu/github/exiv2/0.27-maintenance/build $ exiv2 -pt -g 35  ~/Downloads/sample1.raf 
Exif.Photo.FocalLengthIn35mmFilm             Short       1  83.0 mm
863 rmills@rmillsmbp:~/gnu/github/exiv2/0.27-maintenance/build $ 

The tag is written by the manufacturer in Exif.Photo.FocalLengthIn35mmFilm. All the PrintFct does is to decorate the output:

    std::ostream& print0xa405(std::ostream& os, const Value& value, const ExifData*)
    {
        long length = value.toLong();
        if (length == 0) {
            os << _("Unknown");
        }
        else {
            os << length << ".0 mm";
        }
        return os;
    }

[clanmills]

Thanks you, Gentlemen for working on this.