refactor(font): rewrite mapping.pl in Python
#3715
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The old version was a big list of commands to `mftrace` in a single target. Now the code uses a pattern to create the different files in a more idiomatic way. It is not necessary to explicitly state the encoding for some files. The `mftrace` script can always find the correct encoding automatically.
This list isn't necessary because we generate a bunch of fonts in the docker container, and copy everything over. This list is implicitly defined by the output of `.ff` scripts.
Rewriting `makeFF` in Python improves the code in several ways: - Increases maintainability as Python code is more readable than dense Perl code using mostly string substitutions (sometimes with regular expressions) to write scripts, and rewrite other files. - Pair kerning is a feature that requires us to read the `.tfm` files that contain those metric tables. The current codebase contains a `.tfm` parser written in Python, not in Perl. This commit makes it possible to use that to build pair kerning tables in the FontForge scripts. This new code also splits the mapping between the old TeX font codepoints and the modern Unicode scalar values into a separate module that can in the future be reused for metrics generation. This decreases code duplication, and makes changes more robust. It's also easier to write sanity checks in the new mappings to catch easy-to-miss mistakes like codepoints being mapped twice.
Python's module resolution rules requires us to have a slightly different directory structure in order to properly share the mapping code in a separate file.
This rewrite is almost trivial, as we can reuse the mapping from the font generation code. Because this deduplicates code, there is no need to keep the mappings in sync. The only real rewrite is the inversion of the mapping from the original Perl code, the rest of the code was a duplication of the mapping. This commit also contains the newly generated `fontMetricsData.js`. The changes in this file correspond to adding all of the metrics of two fonts (`Caligraphic-Bold` and `Fraktur-Bold`), and a few touch-ups for several glyphs: - In `Main-Italic` we add metrics for two glyphs: - 305 / 0x131: dotless i - 567 / 0x237: dotless j - The rest of the additions are in `Typewriter-Regular`: - 168 / 0xA8: diereses - 710 / 0x2C6: circumflex - 729 / 0x2D9: dot above (but the glyph is a line below?) - 732 / 0x2DC: small tilde - 733 / 0x2DD: double acute accent 729 and 733 are a little weird as the Unicode descriptions do not match their glyphs. - Three glyphs are removed from `Typewriter-Regular`: (770, 771, 776) / (0x302, 0x303, 0x308). These are not present in the generated font files, so it's save to remove them. - Only 126: 0x7E in `Typewriter-Regular` has changed metrics, its height and depth change.
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Assumes #3714 gets merged, and likewise this PR is ready for merging.
This rewrite is almost trivial, as we can reuse the mapping from the font generation code. Because this deduplicates code, there is no need to keep the mappings in sync. The only real rewrite is the inversion of the mapping from the original Perl code, the rest of the old Perl code was a duplication of the mapping.
This commit also contains the newly generated
fontMetricsData.js. The changes in this file correspond to adding all of the metrics of two fonts (Caligraphic-BoldandFraktur-Bold), and a few touch-ups for several glyphs:In
Main-Italicwe add metrics for two glyphs:The rest of the additions are in
Typewriter-Regular:729 and 733 are a little weird as the Unicode descriptions do not match their glyphs.
Three glyphs are removed from
Typewriter-Regular: (770, 771, 776) / (0x302, 0x303, 0x308). These are not present in the generated font files, so it's save to remove them.Only 126: 0x7E in
Typewriter-Regularhas changed metrics, its height and depth change.Disregarding the added metrics in the generated file, merging this chain of PR's removes a net of 1K LOC.
Closes #3702.