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To convert my html to pdf i use itext7's API convertToDocument, passing parameters the template's ByteArrayInputStream, the PDFDocument and convertProperties.

relevant code snippet:

HtmlConverter.convertToDocument(new ByteArrayInputStream(templateWritten), pdfDocument, converterProps);

As docs says, if I set baseURI of convertProperties there is no problem, but if I set PDF fonts this error shows up when the are many concurrent calls:

"Pdf indirect object belongs to other PDF document. Copy object to current pdf document.”

creation of convert properties

private ConverterProperties addResourcesForInitiative(String templateKey, FontProvider fontProvider) {
//        CustomDefaultFontProvider cdfp = new CustomDefaultFontProvider();
        ConverterProperties converterprops = new ConverterProperties();
//        converterprops.setFontProvider(fontProvider);
        converterprops.setBaseUri(ConfigurationManager.getParamValue("resource.path") + templateKey + "/resources/");
        log.info("Properties for conversione are setted. Url of folder loaded " + converterprops.getBaseUri());
        return converterprops;
    }

the object is created each call before convertToDocument API

am I missing something?

thanks all for your help

stecava
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1 Answers1

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I experienced the same problem. It is related to (but not a duplicate of) Itext7 generate pdf with Exception "Pdf indirect object belongs to other PDF document. Copy object to current pdf document."

What I didn't understand about iText 7 at first, is that you have a FontProgram and a PdfFont.

  • FontProgram is a class that contains all the information that iText needs to use a font program. It can be reused in a process that creates many different PDF files.
  • PdfFont is a class that uses FontProgram in the context of a single document. Each PdfFont object belongs to exactly one PdfDocument.

If you try to use a PdfFont object to create another document, you get the error "Pdf indirect object belongs to other PDF document. Copy object to current pdf document."

In other words: you can't just reuse PdfFont objects, only FontProgram objects. This can be a problem when reusing ConverterProperties (or a FontProvider). The trick is not to cache PdfFont objects in a FontProvider, but cache the FontProgram instead.

As this is very confusing, I have asked the iText 7 development team to fix this. When I look at the closed ticketing system, I can see that the documentation will be fixed, and that efforts will be done with respect to the ConverterProperties. This means that you'll see improvements in the next version.

In the meantime, I have fixed this for myself by changing the way I use a FontProvider and ConverterProperties. New instances of PdfFont have to be created for every new document, and I understand why: PdfFont keeps track of the characters that are used in a specific document, and uses that information to create a font subset. That subset is different for every document; hence every document needs a different PdfFont instance.

I will add a reference to this question in the tickets about this topic.

Bruno Lowagie
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