OpenType font kerning with itext

Question

I am using itext and ColdFusion (java) to write text strings to a PDF document. I have both trueType and openType fonts that I need to use. Truetype fonts seem to be working correctly, but the kerning is not being used for any font file ending in .otf. The code below writes "Line 1 of Text" in Airstream (OpenType) but the kerning between "T" and "e" is missing. When the same font is used in other programs, it has kerning. I downloaded a newer version of itext also, but the kerning still did not work. Does anyone know how to get kerning to work with otf fonts in itext?

<cfscript>
pdfContentByte = createObject("java","com.lowagie.text.pdf.PdfContentByte");
BaseFont= createObject("java","com.lowagie.text.pdf.BaseFont");
bf = BaseFont.createFont("c:\windows\fonts\AirstreamITCStd.otf", "" , BaseFont.EMBEDDED);
document = createobject("java","com.lowagie.text.Document").init();
fileOutput = createObject("java","java.io.FileOutputStream").init("c:\inetpub\test.pdf");
writer = createobject("java","com.lowagie.text.pdf.PdfWriter").getInstance(document,fileOutput);
document.open();    
cb = writer.getDirectContent(); 
cb.beginText();
cb.setFontAndSize(bf, 72);
cb.showTextAlignedKerned(PdfContentByte.ALIGN_LEFT,"Line 1 of Text",0,72,0);
cb.endText();
document.close();

bf.hasKernPairs(); //returns NO
bf.getClass().getName(); //returns "com.lowagie.text.pdf.TrueTypeFont"
</cfscript>

qinxian qinxian · Accepted Answer · 2012-05-16T21:49:02

according the socalled spec: http://www.microsoft.com/typography/otspec/kern.htm OpenType™ fonts containing CFF outlines are not supported by the 'kern' table and must use the 'GPOS' OpenType Layout table.

I checked out the source, IText implementation only check the kern for truetype font, not read GPOS table at all, so the internal kernings must be empty, and the hasKernPairs must return false.

So, there have 2 way to solove:

get rid of the otf you used:)
patch the truetypefont by reading the GPosition table
wait for me, I'm processing the cff content, but PDF is optional of ever of my:) but not exclude the possibility:)

OpenType font kerning with itext

2 Answers