[jira] [Commented] (PDFBOX-2648) Preflight does not check CIDSet contents

["Petras (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PDFBOX-2648?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14702725#comment-14702725 ] 

Petras commented on PDFBOX-2648:
--------------------------------

As stated in PDF/A-1 specification:
{quote}
For all *CIDFont* subsets referenced within a conforming file, the font descriptor dictionary shall include a
*CIDSet* stream identifying which CIDs are present in the embedded *CIDFont* file.
{quote}

PDF/A-2 (and PDF/A-3) makes *CIDSet* optional but specifies the requirement for *CIDSet* more detailed:
{quote}
If the *FontDescriptor* dictionary of an embedded CID font contains a *CIDSet* stream, then it shall identify all CIDs which are present in the font program, regardless of whether a CID in the font is referenced or used by the PDF or not.
{quote}
 
Anyway, for both requirements it is not clear how to correctly generate CIDSet or verify it, when TrueType font program is used as part of  a CIDFont (of *CIDFontType2* subtype). There is no such thing as CID in TrueType, which has GIDs. Therefore in PDF for glyph selection *CIDToGIDMap* must be used. That means it is impossible to verify that *CIDSet* does identify all CIDs, that are present in font program, as CIDs are not present in TrueType font at all. Should I understood this requirement as:
* CIDSet shall identify all CIDs that are mapped in CIDToGIDMap? If so, then in case of *Identity* value, *CIDSet* should identify all glyph indexes which are present in TrueType font, shouldn't it?

Maybe I'm missing something? 

I asked this question in Adobe Community forum, no replies received yet. What is your opinion, how Preflight should validate CIDSet for TrueType font program?

> Preflight does not check CIDSet contents
> ----------------------------------------
>
>                 Key: PDFBOX-2648
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-2648
>             Project: PDFBox
>          Issue Type: Bug
>          Components: Preflight
>    Affects Versions: 2.0.0
>            Reporter: Tilman Hausherr
>             Fix For: 2.1.0
>
>
> As correctly observed by [~zuki_ebetsu]:
> {quote}preflight seems to check only the presence of the stream{quote}
> So we need to check the contents too, somehow. At the very least, that would be the length. Next thing would be to verify that the bits correspond to the CIDs that are present.



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