javapdfboxfont-embedding

PdfBox embed fonts into existing document

I have a pdf file which shows font properties in Okular (or whatever PDF viewer) like that:

Name: Helvetica 
Type: Type1
File: /usr/share/fonts/truetype/liberation2/LiberationSans-regular.ttf
Embedded: No

I want to embed Helvetica with PDFBox 2xx without modifying file content (text) itself so it would always available with a file. Is it possible at all? I tried something like:

PDDocument document = PDDocument.load(myFile);

InputStream stream = new FileInputStream(new File("/home/user/fonts_temp/Helvetica.ttf"));
PDFont fontToEmbed = PDType0Font.load(document, stream, true);              
PDResources resources = document.getPage(pageNumber).getResources();
resources.add(fontToEmbed);
//or use the font from pdfbox:
resources.add(PDType1Font.HELVETICA);

document.save(somewhere);
document.close();

I also tried to call

COSName fontCosName = resources.add(PDType1Font.HELVETICA);
resources.put(fontCosName, font);

What am I doing wrong?

Edit:

@TilmanHausherr thank you for the clue! But I'm still missing something. Currently my code looks like:

PDFont helvetica = PDType0Font.load(document, new FileInputStream(new File("/path/Helvetica.ttf")), false);
...
PDResources resources = page.getResources();
for (COSName fontCosName : resources.getFontNames()){
    if(resources.getFont(fontCosName).getName().equals("Helvetica")) {
        resources.put(fontCosName, helvetica);
    }
}

End result shows Helvetica CID TrueType Fully Embedded But the font is not displayed in PDF file at all now. I mean those places where the font is used are literally empty, blank page... Still something is not there. Font itself was downloaded from here

Solution

    You'd need to know the name that is currently used in the resources, so check these with resources.getFontNames()

    2. To replace a standard 14 font, use this font object:

    PDTrueTypeFont.load(document, file, oldFont.getEncoding() /* or WinAnsiEncoding.INSTANCE which is usually right */ );

    this ensures that the same encoding is used as the standard 14 font. (It's different for the Zapf Dingbats and the Symbol font)