Why are only some glyphs implemented as composites? What is the criterium for determining if the glyph should be/remain composite?
I understand leaving the accented letters in Calibri as composites, but why are /questiondown and /exclamdown in Calibri composites, if colon, semicolon, ellipsis, quotes or any of the braces, brackets, parentheses, are not? All of the listed are identical with their rotated versions etc., there were no tweaks applied to them that would justify copying instead of referencing. It seems like the designer:
a) copied the glyphs expecting some tweaks might be needed, but then decided they looked fine and didn't bother to replace them with references, or
b) copied any glyphs that he thought were essential for the English language, and referenced all the glyphs they could that were only needed in some minor useless languages, like Spanish.
Point counts in the glyphs of Calibri that could be utilized as base glyphs for references but were not:
comma/quoteright/quoteleft 23, quotedblright/quotedblleft 46 (wow, the number of chromosomes in human genome:)
Point counts in base glyphs that were used as base for composites:
One could wonder if the cost (in file size) of referencing a glyph is between the cost of a 27-node path and a 34-node one.
Some other fonts implement inverted Spanish punctuation as copies, and composites are only used for accents, though.
And one final question, does implementing a glyph as composite have any side effects? Is that why it is avoided for basic glyphs (legacy / backward compatibility issues?)
I edited the title to match more closely what I meant, the original title was: "Why are composite glyphs used sparingly?"