Add support for TrueType format 12 cmaps (issue 14881)

[Snuffleupagus]

This is, as far as I can tell, the first case we've seen of a format 12 cmap.
Please see https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6cmap.html

[Snuffleupagus]

/botio test

[pdfjsbot]

From: Bot.io (Linux m4)

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Received

Command cmd_test from @Snuffleupagus received. Current queue size: 0

Live output at: http://54.241.84.105:8877/1c5dfd3a61d10d9/output.txt

[pdfjsbot]

From: Bot.io (Windows)

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Received

Command cmd_test from @Snuffleupagus received. Current queue size: 0

Live output at: http://54.193.163.58:8877/e2c6d4c4ba1e278/output.txt

[pdfjsbot]

From: Bot.io (Linux m4)

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Failed

Full output at http://54.241.84.105:8877/1c5dfd3a61d10d9/output.txt

Total script time: 26.14 mins

• Font tests: Passed
• Unit tests: Passed
• Integration Tests: Passed
• Regression tests: FAILED

  different ref/snapshot: 8

Image differences available at: http://54.241.84.105:8877/1c5dfd3a61d10d9/reftest-analyzer.html#web=eq.log

[pdfjsbot]

From: Bot.io (Windows)

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Failed

Full output at http://54.193.163.58:8877/e2c6d4c4ba1e278/output.txt

Total script time: 31.15 mins

• Font tests: Passed
• Unit tests: Passed
• Integration Tests: FAILED
• Regression tests: Passed

[timvandermeij]

/botio-linux preview

[pdfjsbot]

From: Bot.io (Linux m4)

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Received

Command cmd_preview from @timvandermeij received. Current queue size: 0

Live output at: http://54.241.84.105:8877/6784e6ab3f85701/output.txt

[pdfjsbot]

From: Bot.io (Linux m4)

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Success

Full output at http://54.241.84.105:8877/6784e6ab3f85701/output.txt

Total script time: 2.67 mins

Published

• Viewer: http://54.241.84.105:8877/6784e6ab3f85701/web/viewer.html
• Viewer (legacy): http://54.241.84.105:8877/6784e6ab3f85701/legacy/web/viewer.html

[timvandermeij]

Thank you for implementing this!

/botio makeref

[pdfjsbot]

From: Bot.io (Linux m4)

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Received

Command cmd_makeref from @timvandermeij received. Current queue size: 0

Live output at: http://54.241.84.105:8877/b91499d816fb2cf/output.txt

[pdfjsbot]

From: Bot.io (Windows)

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Received

Command cmd_makeref from @timvandermeij received. Current queue size: 1

Live output at: http://54.193.163.58:8877/697a5a7af381a44/output.txt

[pdfjsbot]

From: Bot.io (Linux m4)

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Success

Full output at http://54.241.84.105:8877/b91499d816fb2cf/output.txt

Total script time: 23.30 mins

• Lint: Passed
• Make references: Passed
• Check references: Passed

[pdfjsbot]

From: Bot.io (Windows)

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Success

Full output at http://54.193.163.58:8877/697a5a7af381a44/output.txt

Total script time: 24.73 mins

• Lint: Passed
• Make references: Passed
• Check references: Passed

[Snuffleupagus]

@timvandermeij Thanks a lot for reviewing/merging my patches!

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A possible follow-up here could be to add support for format 13 cmaps as well, since according to the specification those are nothing more than a special-case of format 12; see https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6cmap.html

Based on the specification text it seems to me that format 13 might be quite rare, and I'd not be able to supply a test-case, but do you think that it'd make sense to add support for those cmaps as well to prevent a possible future bug report?

[timvandermeij]

Given the "[...] used internally by Apple for its last resort font and by Unicode's last resort font. It would, in general, not be appropriate for any font other than a last resort font" part of the specification, I don't really think we'll see it in practice. Moreover, I think it's good to only implement this if we actually have a file that uses it, otherwise it will be hard to verify the correctness of the implementation and we won't have a regression test. For now I'd say we don't implement this until we actually find/make a file with format 13 cmaps.