Peter Williams 88fda44e0a
Text extraction code for columns. (#366)
* Fixed filename:page in logging

* Got CMap working for multi-rune entries

* Treat CMap entries as strings instead of runes to handle multi-byte encodings.

* Added a test for multibyte encoding.

* First version of text extraction that recognizes columns

* Added an expanation of the text columns code to README.md.

* fixed typos

* Abstracted textWord depth calculation. This required change textMark to *textMark in a lot of code.

* Added function comments.

* Fixed text state save/restore.

* Adjusted inter-word search distance to make paragrah division work for thanh.pdf

* Got text_test.go passing.

* Reinstated hyphen suppression

* Handle more cases of fonts not being set in text extraction code.

* Fixed typo

* More verbose logging

* Adding tables to text extractor.

* Added tests for columns extraction.

* Removed commented code

* Check for textParas that are on the same line when writing out extracted text.

* Absorb text to the left of paras into paras e.g. Footnote numbers

* Removed funny character from text_test.go

* Commented out a creator_test.go test that was broken by my text extraction changes.

* Big changes to columns text extraction code for PR.

Performance improvements in several places.
Commented code.

* Updated extractor/README

* Cleaned up some comments and removed a panic

* Increased threshold for truncating extracted text when there is no license 100 -> 102.

This is a workaround to let a test in creator_test.go pass.

With the old text extraction code the following extracted text was 100 chars. With the new code it
is 102 chars which looks correct.

"你好\n你好你好你好你好\n河上白云\n\nUnlicensed UniDoc - Get a license on https://unidoc.io\n\n"

* Improved an error message.

* Removed irrelevant spaces

* Commented code and removed unused functions.

* Reverted PdfRectangle changes

* Added duplicate text detection.

* Combine diacritic textMarks in text extraction

* Reinstated a diacritic recombination test.

* Small code reorganisation

* Reinstated handling of rotated text

* Addressed issues in PR review

* Added color fields to TextMark

* Updated README

* Reinstated the disabled tests I missed before.

* Tightened definition for tables to prevent detection of tables where there weren't any.

* Compute line splitting search range based on fontsize of first word in word bag.

* Use errors.Is(err, core.ErrNotSupported) to distinguish unsupported font errorrs.

See https://blog.golang.org/go1.13-errors

* Fixed some naming and added some comments.

* errors.Is -> xerrors.Is and %w -> %v for go 1.12 compatibility

* Removed code that doesn't ever get called.

* Removed unused test
2020-06-30 19:33:10 +00:00
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