带有PDFBox的java标记PDF

Question

是否可以使用PDFBox创建带标签的PDF（PDF/UA）？看起来PDFBox有一个API（包org.apache.pdfbox.pdmodel.documentinterchange.taggedpdf），但我找不到任何教程或代码示例

使用下面的代码，我生成了一个包含图像的PDF文件，屏幕阅读器NVDA（在我的例子中）识别它并读取“。。。图形替代说明'。但是，辅助功能检查器PAC 2显示错误：“图像对象未标记”

        PDDocument doc = new PDDocument();
        PDPage page = new PDPage();
        doc.addPage(page);
        PDDocumentCatalog documentCatalog = doc.getDocumentCatalog();

        PDImageXObject pdImage = PDImageXObject.createFromFile(imagePath, doc);
        PDPageContentStream contents = new PDPageContentStream(doc, page);
        contents.drawImage(pdImage, 100, 600, pdImage.getWidth() / 2, pdImage.getHeight() / 2);
        contents.close();

        PDStructureTreeRoot treeRoot = new PDStructureTreeRoot();
        PDStructureElement structureElement = new PDStructureElement(StandardStructureTypes.Figure, treeRoot);
        structureElement.setPage(page);

        PDMarkedContent markedImg = new PDMarkedContent(COSName.IMAGE, new COSDictionary());
        markedImg.addXObject(pdImage);

        structureElement.appendKid(markedImg);
        structureElement.setAlternateDescription("Alternate Description");
        treeRoot.appendKid(structureElement);
        documentCatalog.setStructureTreeRoot(treeRoot);
        // ....
        doc.save(fileName);

你能提供一些关于这个主题的解释或代码示例吗

Answer 1

我举了一个工作示例，演示如何使用PDFBox 2创建可访问的PDF： https://github.com/martinlovell/accessible-pdfbox-example

问题代码中缺少一些东西。标记的内容需要alt文本，我相信您需要标记内容的mcid

示例项目更详细地演示了您需要什么

应该是这样的：

PDPageContentStream contents = new PDPageContentStream(doc, page);

// the content in the stream needs an id
int mcid = 5;
COSDictionary dictionary = new COSDictionary();
dictionary = new COSDictionary();
dictionary(COSName.MCID, mcid);

// wrap image drawing in marked content
contents.beginMarkedContent(COSName.IMAGE, PDPropertyList.create(dictionary));
contents.drawImage(pdImage, 100, 600, pdImage.getWidth() / 2, pdImage.getHeight() / 2);
contents.endMarkedContent();

contents.close();

PDStructureTreeRoot treeRoot = new PDStructureTreeRoot();
documentCatalog.setStructureTreeRoot(treeRoot);
PDStructureElement structureElement = new PDStructureElement(StandardStructureTypes.Figure, treeRoot);
structureElement.setPage(page);
structureElement.setAlternateDescription("Alternate Description");

// Set alt text on marked content for structure.  
// This is the dictionary with the mcid used in beginMarkedContent.
dictionary.setString(COSName.ALT, "Alternate Description");
PDMarkedContent markedImg = new PDMarkedContent(COSName.IMAGE, dictionary);
markedImg.addXObject(pdImage);
structureElement.appendKid(markedImg);