ENH: Font: Initialise a Font from an embedded font file#3704
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PJBrs wants to merge 6 commits intopy-pdf:mainfrom
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ENH: Font: Initialise a Font from an embedded font file#3704PJBrs wants to merge 6 commits intopy-pdf:mainfrom
PJBrs wants to merge 6 commits intopy-pdf:mainfrom
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This patch adds a character_map when initialising from an embedded font. This patch uses getGlyphOrder when trying to create a character_map from an embedded font file. getGlyphOrder is sure to include all glyphs in a font, not just the ones that are mapped by a unicode code point. For now, this does not make a lot of difference, but in the future it might make it easier to collect all widths in the font.
This patch more comprehensivel tries to detect font flags. Furthermore, it adds some checks to deal with missing tables in truetype fonts. It is a bit of a question what to do when the cmap itself is missing. In this version, we just continue, but perhaps we should raise a warning or even an error, because, in practice, it would mean that the font that results isn't usable.
This patch adds a test and a file with some sample font resources that all have specific font flags and/ or specific missing tables, to test all the if conditions in _font.py. The font resources were added using pypdf itself, and lifted from pdf files used as part of the current test suite.
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #3704 +/- ##
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+ Coverage 97.43% 97.45% +0.02%
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Files 55 55
Lines 10016 10117 +101
Branches 1841 1855 +14
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+ Hits 9759 9860 +101
Misses 149 149
Partials 108 108 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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This PR adds the capability to initialise a Font instance from an embedded font file. It adds fonttools as an optional dependency to parse the font file.
I tested this to see if the resulting Font instances can be used for text extraction, and it mostly can, barring a couple of exceptions. Then again, this ultimately isn't intended for text extraction but for creating new appearance streams.
I also added a fontsampler file that I created using pypdf and that contains selected fonts from the existing test files. These embedded fonts are used for all the different if conditions in this PR for dealing with font flags, as well as one font that apparently does not include a cmap. This PR raises a KeyError in that case.
This PR is a small part of #3652 and it includes all work from #3602. I created it to make review more manageable. It should be ready as is!