[ft] Using FreeType for matching font metrics

[Martin Kotulla (SoftMaker)]

List,

I am looking at the following problem and hope that FreeType allows me 
to implement a solution:

Office documents are created by our customers on Windows using fonts 
that are available there. These document shall then be rendered by our 
software on other platforms (such as Linux). When the original font is 
missing, we currently use a replacement font that is available on the 
destination platform.

The replacement font has different metrics, so line breaks and sometimes 
even page breaks will vary (the Office files contain no linebreak 
information; a paragraph is just a stream of characters). This is 
something we wish to avoid. Breaks should be the same as on the PC the 
documents have been created on.

My idea is to create a Multiple Master font with a "width" axis and 
provide this as a replacement font. Our software would then use FreeType 
to create a font instance from the Multiple Master font where each glyph 
is individually scaled so that it mimics the width of the same character 
in the original font.

As far as I can see, the FreeType API provides functions for creating 
instances from Multiple Master fonts, but the same design vector is 
applied to all characters.

Is it possible to apply individual design scalings to individual glyphs?

Note that this is not the same as just scaling glyphs. Such scaling 
leads to unpleasant looks because the ratio of vertical and horizontal 
stem widths is not preserved.

Any hints or ideas appreciated.

Martin Kotulla