java - 如何使pdf导入的页面大小相同

Question

我正在使用 java 中的 iTextPdf 从其他 pdf 文件创建一个合并的 pdf。一些 PDF 文件的页面尺寸非常大 (3200x2432)。结果，当用户滚动浏览文档时，较小的页面看起来像缩略图。

如何缩放 PdfImported 页面以确保它们的大小相同？

TIA

已解决：通过切换到 PdfWriter 而不是 PdfCopy。

新代码：

public static boolean CollecPdfs(Vector<File> pdfFiles, OutputStream pdfOutputStream)
{
    try
    {

        Rectangle r=PageSize.LETTER;
// create intermediate output pdf in memory for new pages
        Document odoc=new Document(r);
        PdfWriter writer=PdfWriter.getInstance(odoc, pdfOutputStream);
        odoc.open();
// add documents
        for(File pdfFile : pdfFiles)
        {
            PdfReader reader=null;
            try
            {
                FileInputStream is=new FileInputStream(pdfFile);
                reader=new PdfReader(is);
                int pgs=reader.getNumberOfPages();
                PdfContentByte canvas=writer.getDirectContent();
                for(int i=0; i<pgs;)
                {
                    PdfImportedPage pg=writer.getImportedPage(reader, ++i);
                    float ws=PageSize.LETTER.getWidth()/pg.getWidth();
                    float hs=PageSize.LETTER.getHeight()/pg.getHeight();
                    canvas.addTemplate(pg, 
                            ws, 0, 0, 
                            hs, 0, 0);
                    odoc.newPage();
                }
            }
            catch(ClientAbortException cex)
            {

            }
        }
        odoc.close();
    }
    catch(Exception e)
    {
        ExceptionRpt.sendStackTrace(e);
        return false;
    }
    return true;
}

旧代码：

public static boolean CollecPdfs(Vector<File> pdfFiles, OutputStream pdfOutputStream)
{
    try
    {

        Rectangle r=PageSize.LETTER;
        Document odoc=new Document(r);
        PdfCopy copy=new PdfCopy(odoc, pdfOutputStream);
        odoc.open();
        for(File pdfFile : pdfFiles)
        {
            PdfReader reader=null;
            try
            {
                FileInputStream is=new FileInputStream(pdfFile);
                reader=new PdfReader(is);
                int pgs=reader.getNumberOfPages();
                for(int i=0; i<pgs;)
                {
                    PdfImportedPage pg=copy.getImportedPage(reader, ++i);
                    copy.addPage(pg);
                }
            }
            catch(ClientAbortException cex)
            {

            }
            copy.freeReader(reader);
        }
        odoc.close();
        copy.close();
    }
    catch(Exception e)
    {
        ExceptionRpt.sendStackTrace(e);
        return false;
    }
    return true;
}

Answer 1

您需要在 PDF 页面属性中进行以下更改：

单页显示 - 适合页面

Answer 2

我也有同样的问题。经过一番研究，我终于解决了这个问题。

 FileInputStream pdfInput = new FileInputStream(pdf);
        PdfReader pdfReader = new PdfReader(pdfInput);
        for (int index = 1; index <= pdfReader.getNumberOfPages(); index++) {
            main.newPage();
            PdfImportedPage page = pdfWriter.getImportedPage(pdfReader,
                index);
            Rectangle pagesize = pdfReader.getPageSizeWithRotation(index);
            float oWidth = pagesize.getWidth();
            float oHeight = pagesize.getHeight();
            float scale = getScale(oWidth, oHeight);
            float scaledWidth = oWidth * scale;
            float scaledHeight = oHeight * scale;
            int rotation = pdfReader.getPageRotation(index);

            AffineTransform transform = new AffineTransform(scale, 0, 0, scale, 0, 0);
            switch (rotation) {
                case 0:
                    cb.addTemplate(page, transform);
                    break;
                case 90:
                    AffineTransform rotate90 = new AffineTransform(0, -1f, 1f, 0, 0, scaledHeight);
                    rotate90.concatenate(transform);
                    cb.addTemplate(page, rotate90);
                    break;
                case 180:
                    AffineTransform rotate180 = new AffineTransform(-1f, 0, 0, -1f, scaledWidth,
                        scaledHeight);
                    rotate180.concatenate(transform);
                    cb.addTemplate(page, rotate180);
                    break;
                case 270:
                    AffineTransform rotate270 = new AffineTransform(0, 1f, -1f, 0, scaledWidth, 0);
                    rotate270.concatenate(transform);
                    cb.addTemplate(page, rotate270);
                    break;
                default:
                    cb.addTemplate(page, scale, 0, 0, scale, 0, 0);
            }
        }

private static float getScale(float width, float height) {
    float scaleX = PageSize.A4.getWidth() / width;
    float scaleY = PageSize.A4.getHeight() / height;
    return width > height ? Math.min(scaleX, scaleY) : Math.max(scaleX,
        scaleY);
}