It is required to resolve the actual TTF file on the current system, because TTF files cannot be embedded into the QR Invoice Native Library due to license restrictions.

font_manager is responsible for doing so. Currently it looks for specific files name in the current directory.

Font Family File name regular File name bold

Helvetica

Helvetica.ttf

HelveticaBd.ttf

Instead of looking for the font files in the current directory a different font path can be set by means of environment variables.

QR_INVOICE_FONT_PATH=c:/path/to/a/fontdirectory
There may be improvements in this field (greater flexibility or the like). If you struggle with current possibilities, please contact us.