Picture is used in addressee.cpp or vcardtools, so if you import vcard it will use Picture too so I don't see how you want to avoid QtGui linking.

You can't avoid the linkage of QtGui inside KContacts, that is correct and I don't have plans to change this. The usage of QImage is only internaly in the library. The only external usage is KContacts::Picture::data/ KContacts::Picture::setData. Okay we have to move Qt:Gui to PRIVATE library.

The point I'm talking about is about using KContacts in external applications (f.ex. R9:f198198b9b08b331873185f66cd370e63ee46564 for Sink)

I'm doing only things that do not using picture at all:

Sink::ApplicationDomain::Contact contact;
KContacts::VCardConverter converter;
const auto addressee = converter.parseVCard(contact.getVcard());
contact.setUid(addressee.uid());
contact.setFn(addressee.formattedName());

until I don't really use addresse.picture.data() or addresse.picture.setData() - I don't need a full class defintion of QImage and the forward declaration of QImage is enough for the compiler/linker. I could also create and modify Picture objects without linking QtGui into Sink:

KContacts::Picture picture;
picture.setData("IMAGEBYTESTRING", "png");
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