java - PDFBOX 2.0 : How can I scale large page sizes to letter?

Question

我正在使用 pdfbox 2.0.21 来(物理地)打印可能具有混合页面尺寸的 PDF 文件，包括非标准尺寸，例如 8.7"x11.3"，它可以在不缩放的情况下打印在合法尺寸或更大的纸张上。 pdf 由许多不同的员工以不同的方式创建(Acrobat DC，从 Word 保存，打印到 pdf，由我们的文档系统生成......)并发送给我的团队打印和邮寄。该卷不允许我们单独检查它们，最终我们将我们的应用程序指向一个文件夹，它会打印那里的所有内容。我更愿意创建一个 PrinterJob 或 PDFPageable 来根据需要自动缩放所有页面，但无法让它工作。

public class PDPrn {
  public static void main(String[] args) {
    try (PDDocument pdf = PDDocument.load(new File("foo.pdf"))) {
      PrinterJob job = PrinterJob.getPrinterJob();
      Paper paper = new Paper();
      Paper.setSize(612, 792); // letter size
      paper.setImageableArea(36, 36, paper.getWidth() - 72, paper.getHeight() - 72); // 0.5in margins
      PageFormat format = new PageFormat();
      format.setPaper(paper);
      PDFPageable pageable = new PDFPageable(pdf);

      //doesn't scale down pages
      //printer will ask for legal and cutoff bottom when forced to use letter
      pageable.append(new PDFPrintable(pdf, Scaling.SCALE_TO_FIT), format);

      job.setPageable(pageable);
      try {
        job.print();
      } catch (PrinterException pe) {
      }
      pdf.close();
    } catch (IOException ioe) {
    }
  }
}

我尝试遍历每个页面并直接缩小任何大于字母的内容，但失败了，但这会以令人费解的方式在页面上四处移动内容。

public class PDPrn {
  public static void main(String[] args) {
    try (PDDocument pdf = PDDocument.load(new File("foo.pdf"))) {
      PrinterJob job = PrinterJob.getPrinterJob();
      PDFPageable pageable = new PDFPageable(pdf);
      PDPageTree tree = pdf.getDocumentCatalog().getPages();
      Iterator<PDPage> iterator = tree.iterator();
      while (iterator.hasNext()) {
        PDPage page = iterator.next();
        if (page.getMediaBox().getWidth() !=612 || page.getMediaBox().getHeight() != 792) {
          PDPageContentStream contentStream = new PDPageContentStream(pdf, page,
            PDPageContentStream.AppendMode.PREPEND, false);

          //these are the wrong scaling factors but they do shrink oversized pages
          //however the shrunk content is moved far down the page and runs off the bottom
          //printer still asks for legal and cuts off bottom when forced to use letter
          //edit: these floats should probably be smaller
          //to account for margins, but the result is still
          //offset significantly below the upper left
          contentStream.transform(Matrix.getScaleInstance(612f / page.getMediaBox().getWidth(),
            792f / page.getMediaBox().getHeight()));

          //round figures, a large positive Y moves the content upward
          //but not cleanly to the upper left
          //whereas a large negative Y moves the content down and cuts off the bottom
          //but does print on letter without the printer complaining about size
          contentStream.transform(Matrix.getTransformInstance(0f, 250f);
          contentStream.close();
        }
      }
      job.setPageable(pageable);
      try {
        job.print();
      } catch (PrinterException pe) {
      }
      pdf.close();
    } catch (IOException ioe) {
    }
  }
}

使用具有 MediaName、MediaSizeName 和 MediaTray 常量的各种组合的属性集也不会导致减少，打印机会停止并要求使用 legal 纸张，并在被迫打印字母时切掉底部。

如何使用 pdfbox 2.0 在打印时将单个超大页面正确缩小为字母大小？

编辑:通过将页面的 MediaBox 设置为 PDRectangle.LETTER，我能够确保打印机不会要求提供合法纸张，并且左下角的内容流源可见。现在只需要使用正确的数学方法来获取比例因子并可能影响边距，使用 ImageableArea 或 CropBox？

public class PDPrn {
  public static void main(String[] args) {
    try (PDDocument pdf = PDDocument.load(new File("foo.pdf"))) {
      PrinterJob job = PrinterJob.getPrinterJob();
      PDFPageable pageable = new PDFPageable(pdf);
      PDPageTree tree = pdf.getDocumentCatalog().getPages();
      Iterator<PDPage> iterator = tree.iterator();
      while (iterator.hasNext()) {
        PDPage page = iterator.next();
        if (page.getMediaBox().getWidth() !=612 || page.getMediaBox().getHeight() != 792) {
          PDPageContentStream contentStream = new PDPageContentStream(pdf, page,
            PDPageContentStream.AppendMode.PREPEND, false);

          //these are the wrong scaling factors but they do shrink oversized pages
          contentStream.transform(Matrix.getScaleInstance(0.5f,0.5f));
          page.setMediaBox(PDRectangle.LETTER); // make the page letter size with shrunk content origin in lower left
          contentStream.close();
        }
      }
      job.setPageable(pageable);
      try {
        job.print();
      } catch (PrinterException pe) {
      }
      pdf.close();
    } catch (IOException ioe) {
    }
  }
}

Answer 1

设置新的 MediaBox 大小确实足以将缩放后的内容流推送到较小的页面中。比较源宽度/高度和目标宽度/高度的红利让我找到一个合适的比例因子应用于两侧，保持纵横比。页面本身产生的边距看起来可以接受我们的使用，所以我现在不担心精细控制，只需将纸张设置为 0 边距并放手。 PDFPrintable 构造函数中的 SHRINK_TO_FIT 似乎没有做任何事情，我不确定它在什么情况下会起作用。

public class PDPrn {
  public static void main(String[] args) {
    try (PDDocument pdf = PDDocument.load(new File("foo.pdf"))) {
      PrinterJob job = PrinterJob.getPrinterJob();
      PDPageTree tree = pdf.getDocumentCatalog().getPages();
      Iterator<PDPage> iterator = tree.iterator();
      while (iterator.hasNext()) {
        PDPage page = iterator.next();
        if (page.getMediaBox().getWidth() > 612 || page.getMediaBox().getHeight() > 792) {
          float fWidth = 612f / page.getMediaBox().getWidth();
          float fHeight = 792f / page.getMediaBox().getHeight();
          float factor = 0f;
          if (fWidth > fHeight) {
            factor = fHeight;
          } else {
            factor = fWidth;
          }
          PDPageContentStream contentStream = new PDPageContentStream(pdf, page,
            PDPageContentStream.AppendMode.PREPEND, false);
          contentStream.transform(Matrix.getScaleInstance(factor, factor));
          contentStream.close();
          page.setMediaBox(PDRectangle.LETTER);
        }
      }
      Paper paper = new Paper();
      paper.setSize(612, 792);
      paper.setImageableArea(0, 0, 612, 792);
      PageFormat pageFormat = new PageFormat();
      pageFormat.setPaper(paper);
      Book book = new Book();
      book.append(new PDFPrintable(pdf, Scaling.SHRINK_TO_FIT), pageFormat, pdf.getNumberOfPages());
      job.setPageable(book);
      try {
        job.print();
      } catch (PrinterException pe) {
      }
      pdf.close();
    } catch (IOException ioe) {
    }
  }
}