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https://issues.apache.org/jira/browse/PDFBOX-4793?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Christian Appl updated PDFBOX-4793:
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Attachment: screenshot-5.png
> Questionable fallback font for some embedded chinese fonts
> ----------------------------------------------------------
>
> Key: PDFBOX-4793
> URL: https://issues.apache.org/jira/browse/PDFBOX-4793
> Project: PDFBox
> Issue Type: Bug
> Components: Rendering
> Affects Versions: 2.0.18
> Reporter: Christian Appl
> Priority: Major
> Attachments: image-2020-03-04-09-49-42-323.png,
> image-2020-03-04-09-58-01-055.png, image-2020-03-04-10-09-25-343.png,
> image-2020-03-04-10-31-03-065.png, pdf_font-zhcn.pdf, screenshot-2.png,
> screenshot-3.png, screenshot-4.png, screenshot-5.png
>
>
> *Issue:*
> I tried to render PDFs, that contain embedded chinese fonts. Neither the PDF
> Debugger, nor printouts of the document (PDFPrintable), nor the PDFRenderer
> can display/render the chinese glyphs correctly and will render placeholders
> instead.
> *Assumptions:*
> I assume, that said embedded fonts are incomplete and don't contain all
> glyphs, that would be required to render the text properly and therefore
> PDFbox attempts to use the previously determined fallback font. (!?)
> !image-2020-03-04-09-49-42-323.png!
> !image-2020-03-04-09-58-01-055.png!
> And fails to find the glyphs in said fallback font.
> Which is not surprising, as the Fallback font "MalgunGothic-Semilight"
> (Windows standard font) does not contain chinese characters.
> !image-2020-03-04-10-09-25-343.png!
> *Debugging:*
> I tried to understand how the fallback font is determined and what could be
> done to solve this problem on my end. But I was unable to find a satisfying
> solution.
> My best guess so far is, that the CIDFontMapping (FontMapperImpl) is to blame
> for determining an unfit fallback font.
> Although it seems to check, whether required codepages are contained in a
> fallback font, it still does rank the Malgun font as the topscorer and best
> substitute font, even though it does clearly not contain all required
> codepages.
> *My opinion:*
> This is troubling, as better fit fonts exist and could have been selected.
> (ie.: Adobe Stong Std) And are indeed included in the CIDFontMapping, but
> seemingly are scoring lower for some reason.
> *Further information:*
> I can not disclose the document in question, however I found a document
> (pdf_font-zhcn.pdf) in another issue (PDFBOX-3132), that can be used to
> reproduce the issue (ie.: by dropping it into the PDF Debugger)
> !image-2020-03-04-10-31-03-065.png!
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