Virtual Printer Driver – Embedded fonts issues

At the moment, there are two problems with embedded fonts:

Subsetting problem:

Most fonts are too large if they were to be entirely embedded in an output PDF file. The so-called subsetting technique allows one to make files much smaller. By subsetting, only required characters are embedded (only several glyphs instead of the full set of glyphs). Since this process is not standardized, there could be unexpected problems. For example, the POST table (that links each glyph ID to a unicode value for further creation of PDF) could be empty.

Delta font problem:

– There are three types of embedded fonts in EMF files:

– Engine font – is a normal TrueType font that could be packed via dttf table. There are no problems with such fonts.

– Subset font – is a subfont of TrueType. This font could be also packed via dttf table and there are no problems with such fonts as well.

Delta font – this is a part of a TrueType subfont. Such a font contains a set of glyphs and this font has no name. Although Microsoft writes in its documentation that this font must be combined with a subset font used previously, it doesn’t explain how to find this subset font. The solution we found at the moment requires too much RAM.

We are aware of these problems and are going to solve them, but we are not sure how long it will take us.

Please feel free to write comments.

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