Incorrect direction of extracted Arabic Text
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Key: PDFBOX-377
URL: https://issues.apache.org/jira/browse/PDFBOX-377
Project: PDFBox
Issue Type: Bug
Components: Text extraction
Affects Versions: 0.8.0-incubator
Reporter: Brian Carrier
Arabic text (and other right to left languages) is stored in presentation
format in PDF files, which is the opposite of the logical order that Arabic
text is typically stored. Arabic text is typically stored such that the first
byte is for the right-most character, but the output of PDFBox has the first
byte always being the left-most character.
Further, PDF files typically store the presentation form of Arabic characters
instead the more general form. For example, U+FB50 instead of U+0671. The
presentation form is not supposed to be stored in the logical form, but PDFBox
does not normalize them out.
The attached patch solves both of these problems using the ICU4J library
(http://www.icu-project.org/). It identifies the dominant text direction of
each page and reverses the order of each line (only if any right to left text
exists). It then normalizes the text to remove the presentation forms.
An example file is attached. Without the patch, the following is (incorrectly)
produced:
Hello ﺪﻤﺤﻣ World.
With the patch, the following is (correctly) produced:
Hello محمد World.
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