如何在合并时删除空格

Question

我有一些代码需要3个不同的PDF字节数组并将其合并。这段代码很棒。（某些人）遇到的问题是，即使PDF仅包含4英寸的内容，每个PDF仍被视为整页（如果打印的话），因此垂直留有7英寸的空白。然后，中间文档被放入，并且末尾可能有也可能没有垂直空白。然后，页脚也会放在自己的页面上。这是代码：byte[] Bytes = rv.LocalReport.Render("PDF", null, out MimeType, out Encoding, out Extension, out StreamIDs, out Warnings);List<byte[]> MergeSets = // This is filled prior to this code// Append any other pages to this primary letterif (MergeSets.Count > 0) {  MemoryStream ms = new MemoryStream();  Document document = new Document();  PdfCopy copy = new PdfCopy(document, ms);  document.Open();  PdfImportedPage page;  PdfReader reader = new PdfReader(Bytes); // read the generated primary Letter  int pages = reader.NumberOfPages;  for (int i = 0; i < pages; ) {    page = copy.GetImportedPage(reader, ++i);    copy.AddPage(page);  } // foreach of the pages in the Cover Letter  // Now append the merge sets  foreach (byte[] ba in MergeSets) {    reader = new PdfReader(ba);    pages = reader.NumberOfPages;    for (int i = 0; i < pages; ) {      page = copy.GetImportedPage(reader, ++i);      copy.AddPage(page);    } // foreach of the pages in the current merge set  } // foreach of the sets of data  document.Close();  ServerSaved = SaveGeneratedLetter(ms.GetBuffer(), DateTime.Now.Year, hl.LetterName, SaveName);} // if there is anything to merge当我合并每个页面以剪切/删除/擦除每个pdf末尾的垂直空白时，有没有一种方法可以使它显示为一个无缝文档？

Answer 1

我已经将@mkl的代码转换为C＃，就在这里。

工具类：

public class PdfVeryDenseMergeTool {

  private Rectangle PageSize;

  private float TopMargin;

  private float BottomMargin;

  private float Gap;

  private Document Document = null;

  private PdfWriter Writer = null;

  private float YPosition = 0;

  public PdfVeryDenseMergeTool(Rectangle size, float top, float bottom, float gap) {

    this.PageSize = size;

    this.TopMargin = top;

    this.BottomMargin = bottom;

    this.Gap = gap;

  } // PdfVeryDenseMergeTool

  public void Merge(MemoryStream outputStream, List<PdfReader> inputs) {

    try {

      this.OpenDocument(outputStream);

      foreach (PdfReader reader in inputs) {

        this.Merge(reader);

      } // foreach of the PDF files to merge

    } finally {

      this.CloseDocument();

    } // try-catch-finally

  } // Merge

  public void OpenDocument(MemoryStream outputStream) {

    this.Document = new Document(PageSize, 36, 36, this.TopMargin, this.BottomMargin);

    this.Writer = PdfWriter.GetInstance(Document, outputStream);

    this.Document.Open();

    this.NewPage();

  } // OpenDocument

  public void CloseDocument() {

    try {

      this.Document.Close();

    } finally {

      this.Document = null;

      this.Writer = null;

      this.YPosition = 0;

    } // try-finally

  } // CloseDocument

  public void NewPage() {

    this.Document.NewPage();

    this.YPosition = PageSize.GetTop(this.TopMargin);

  } // Merge

  public void Merge(PdfReader reader) {

    PdfReaderContentParser parser = new PdfReaderContentParser(reader);

    for (int pageIndex = 1; pageIndex <= reader.NumberOfPages; pageIndex++) {

      this.Merge(reader, parser, pageIndex);

    } // foreach of the pages of the current PDF

  } // Merge

  public void Merge(PdfReader reader, PdfReaderContentParser parser, int pageIndex) {

    PdfImportedPage importedPage = Writer.GetImportedPage(reader, pageIndex);

    PdfContentByte directContent = Writer.DirectContent;

    PageVerticalAnalyzer finder = parser.ProcessContent(pageIndex, new PageVerticalAnalyzer());

    if (finder.VerticalFlips.Count < 2)

      return;

    Rectangle pageSizeToImport = reader.GetPageSize(pageIndex);

    int startFlip = finder.VerticalFlips.Count - 1;

    bool first = true;

    while (startFlip > 0) {

      if (!first)

        this.NewPage();

      float freeSpace = this.YPosition - PageSize.GetBottom(BottomMargin);

      int endFlip = startFlip + 1;

      while ((endFlip > 1) && (finder.VerticalFlips[startFlip] - finder.VerticalFlips[endFlip - 2] < freeSpace))

        endFlip -= 2;

      if (endFlip < startFlip) {

        float height = finder.VerticalFlips[startFlip] - finder.VerticalFlips[endFlip];

        directContent.SaveState();

        directContent.Rectangle(0, this.YPosition - height, pageSizeToImport.Width, height);

        directContent.Clip();

        directContent.NewPath();

        this.Writer.DirectContent.AddTemplate(importedPage, 0, this.YPosition - (finder.VerticalFlips[startFlip] - pageSizeToImport.Bottom));

        directContent.RestoreState();

        this.YPosition -= height + this.Gap;

        startFlip = endFlip - 1;

      } else if (!first) {

        throw new ArgumentException(string.Format("Page {0} content too large", pageIndex));

      } // if

      first = false;

    } // while

  } // Merge

} // PdfVeryDenseMergeTool

RenderListener类：

修复了1行代码及其工作：请参见代码中的注释

public class PageVerticalAnalyzer : IRenderListener {

  public PageVerticalAnalyzer() { }

  public List<float> VerticalFlips = new List<float>();

  public void AddVerticalUseSection(float from, float to) {

    if (to < from) {

      float temp = to;

      to = from;

      from = temp;

    }

    int i = 0;

    int j = 0;

    for (i = 0; i < VerticalFlips.Count; i++) {

      float flip = VerticalFlips[i];

      if (flip < from)

        continue;

      for (j = i; j < VerticalFlips.Count; j++) {

        flip = VerticalFlips[j];

        if (flip < to)

          continue;

        break;

      }

      break;

    } // foreach of the vertical flips

    bool fromOutsideInterval = i % 2 == 0;

    bool toOutsideInterval = j % 2 == 0;

    while (j-- > i)

      VerticalFlips.RemoveAt(j); // This was the problem line with just .Remove(j)

    if (toOutsideInterval)

      VerticalFlips.Insert(i, to);

    if (fromOutsideInterval)

      VerticalFlips.Insert(i, from);

  } // AddVerticalUseSection

  public void BeginTextBlock() { /* Do nothing */  }

  public void EndTextBlock() { /* Do nothing */ }

  public void RenderImage(ImageRenderInfo renderInfo) {

    Matrix ctm = renderInfo.GetImageCTM();

    List<float> YCoords = new List<float>(4) { 0, 0, 0, 0 };

    for (int x = 0; x < 2; x++) {

      for (int y = 0; y < 2; y++) {

        Vector corner = new Vector(x, y, 1).Cross(ctm);

        YCoords[2 * x + y] = corner[Vector.I2];

      }

    }

    YCoords.Sort();

    AddVerticalUseSection(YCoords[0], YCoords[3]);

  } // RenderImage

  public void RenderText(TextRenderInfo renderInfo) {

    LineSegment ascentLine = renderInfo.GetAscentLine();

    LineSegment descentLine = renderInfo.GetDescentLine();

    List<float> YCoords = new List<float>(4) {

      ascentLine.GetStartPoint()[Vector.I2],

      ascentLine.GetEndPoint()[Vector.I2],

      descentLine.GetStartPoint()[Vector.I2],

      descentLine.GetEndPoint()[Vector.I2],

    };

    YCoords.Sort();

    AddVerticalUseSection(YCoords[0], YCoords[3]);

  } // RenderText

} // PageVericalAnalyzer

收集文件并运行该工具的代码：

public void TestMergeDocuments() {

  PdfVeryDenseMergeTool tool = new PdfVeryDenseMergeTool(iTextSharp.text.PageSize.A4, 18, 18, 10);

  List<byte[]> Files = new List<byte[]>();

  // Code to load each of the 3 files I need into this byte array list

  using (MemoryStream ms = new MemoryStream()) {

    List<PdfReader> files = new List<PdfReader>();

    foreach (byte[] ba in Files) {

      files.Add(new PdfReader(ba));

    } // foreach of the sets of data

    tool.Merge(ms, files);

    // Save the file using: ms.GetBuffer()

  } // using the memory stream

} // TestMergeDocuments

Answer 2

下面的示例工具一直沿着工具的想法实现PdfDenseMergeTool，从这个答案，其中OP曾评论是如此接近到什么[他] NEED 秒。就像PdfDenseMergeTool此工具在Java / iText中实现一样，我比C＃/ iTextSharp更能在家中使用。由于OP 已转换 PdfDenseMergeTool为C＃/ iTextSharp，因此在此处翻译此工具也不会有太大问题。

PdfVeryDenseMergeTool

该工具类似于PdfDenseMergeTool从多个PdfReader实例中获取页面的页面内容，并尝试密集地合并它们，即，如果有足够的可用空间，则将多个源页面的内容放到单个目标页面上。与以前的工具相比，该工具甚至可以拆分源页面内容，以实现更密集的合并。

就像其他工具一样，PdfVeryDenseMergeTool它不考虑矢量图形，因为iText（Sharp）解析API仅转发文本和位图图像

该PdfVeryDenseMergeTool拆分源的网页，无法完全贴合到目标页面，在未通过文字的字形或位图图形的边框相交的水平线。

工具类：

public class PdfVeryDenseMergeTool

{

    public PdfVeryDenseMergeTool(Rectangle size, float top, float bottom, float gap)

    {

        this.pageSize = size;

        this.topMargin = top;

        this.bottomMargin = bottom;

        this.gap = gap;

    }

    public void merge(OutputStream outputStream, Iterable<PdfReader> inputs) throws DocumentException, IOException

    {

        try

        {

            openDocument(outputStream);

            for (PdfReader reader: inputs)

            {

                merge(reader);

            }

        }

        finally

        {

            closeDocument();

        }

    }

    void openDocument(OutputStream outputStream) throws DocumentException

    {

        final Document document = new Document(pageSize, 36, 36, topMargin, bottomMargin);

        final PdfWriter writer = PdfWriter.getInstance(document, outputStream);

        document.open();

        this.document = document;

        this.writer = writer;

        newPage();

    }

    void closeDocument()

    {

        try

        {

            document.close();

        }

        finally

        {

            this.document = null;

            this.writer = null;

            this.yPosition = 0;

        }

    }

    void newPage()

    {

        document.newPage();

        yPosition = pageSize.getTop(topMargin);

    }

    void merge(PdfReader reader) throws IOException

    {

        PdfReaderContentParser parser = new PdfReaderContentParser(reader);

        for (int page = 1; page <= reader.getNumberOfPages(); page++)

        {

            merge(reader, parser, page);

        }

    }

    void merge(PdfReader reader, PdfReaderContentParser parser, int page) throws IOException

    {

        PdfImportedPage importedPage = writer.getImportedPage(reader, page);

        PdfContentByte directContent = writer.getDirectContent();

        PageVerticalAnalyzer finder = parser.processContent(page, new PageVerticalAnalyzer());

        if (finder.verticalFlips.size() < 2)

            return;

        Rectangle pageSizeToImport = reader.getPageSize(page);

        int startFlip = finder.verticalFlips.size() - 1;

        boolean first = true;

        while (startFlip > 0)

        {

            if (!first)

                newPage();

            float freeSpace = yPosition - pageSize.getBottom(bottomMargin);

            int endFlip = startFlip + 1;

            while ((endFlip > 1) && (finder.verticalFlips.get(startFlip) - finder.verticalFlips.get(endFlip - 2) < freeSpace))

                endFlip -=2;

            if (endFlip < startFlip)

            {

                float height = finder.verticalFlips.get(startFlip) - finder.verticalFlips.get(endFlip);

                directContent.saveState();

                directContent.rectangle(0, yPosition - height, pageSizeToImport.getWidth(), height);

                directContent.clip();

                directContent.newPath();

                writer.getDirectContent().addTemplate(importedPage, 0, yPosition - (finder.verticalFlips.get(startFlip) - pageSizeToImport.getBottom()));

                directContent.restoreState();

                yPosition -= height + gap;

                startFlip = endFlip - 1;

            }

            else if (!first) 

                throw new IllegalArgumentException(String.format("Page %s content sections too large.", page));

            first = false;

        }

    }

    Document document = null;

    PdfWriter writer = null;

    float yPosition = 0; 

    final Rectangle pageSize;

    final float topMargin;

    final float bottomMargin;

    final float gap;

}

（PdfVeryDenseMergeTool.java）

该工具利用了RenderListener与iText解析器API一起使用的自定义：

public class PageVerticalAnalyzer implements RenderListener

{

    @Override

    public void beginTextBlock() { }

    @Override

    public void endTextBlock() { }

    /*

     * @see RenderListener#renderText(TextRenderInfo)

     */

    @Override

    public void renderText(TextRenderInfo renderInfo)

    {

        LineSegment ascentLine = renderInfo.getAscentLine();

        LineSegment descentLine = renderInfo.getDescentLine();

        float[] yCoords = new float[]{

                ascentLine.getStartPoint().get(Vector.I2),

                ascentLine.getEndPoint().get(Vector.I2),

                descentLine.getStartPoint().get(Vector.I2),

                descentLine.getEndPoint().get(Vector.I2)

        };

        Arrays.sort(yCoords);

        addVerticalUseSection(yCoords[0], yCoords[3]);

    }

    /*

     * @see RenderListener#renderImage(ImageRenderInfo)

     */

    @Override

    public void renderImage(ImageRenderInfo renderInfo)

    {

        Matrix ctm = renderInfo.getImageCTM();

        float[] yCoords = new float[4];

        for (int x=0; x < 2; x++)

            for (int y=0; y < 2; y++)

            {

                Vector corner = new Vector(x, y, 1).cross(ctm);

                yCoords[2*x+y] = corner.get(Vector.I2);

            }

        Arrays.sort(yCoords);

        addVerticalUseSection(yCoords[0], yCoords[3]);

    }

    /**

     * This method marks the given interval as used.

     */

    void addVerticalUseSection(float from, float to)

    {

        if (to < from)

        {

            float temp = to;

            to = from;

            from = temp;

        }

        int i=0, j=0;

        for (; i<verticalFlips.size(); i++)

        {

            float flip = verticalFlips.get(i);

            if (flip < from)

                continue;

            for (j=i; j<verticalFlips.size(); j++)

            {

                flip = verticalFlips.get(j);

                if (flip < to)

                    continue;

                break;

            }

            break;

        }

        boolean fromOutsideInterval = i%2==0;

        boolean toOutsideInterval = j%2==0;

        while (j-- > i)

            verticalFlips.remove(j);

        if (toOutsideInterval)

            verticalFlips.add(i, to);

        if (fromOutsideInterval)

            verticalFlips.add(i, from);

    }

    final List<Float> verticalFlips = new ArrayList<Float>();

}

（PageVerticalAnalyzer.java）

它的用法如下：

PdfVeryDenseMergeTool tool = new PdfVeryDenseMergeTool(PageSize.A4, 18, 18, 5);

tool.merge(output, inputs);

（VeryDenseMerging.java）

适用于OP的样本文件

标题.pdf

身体.pdf

页脚.pdf

它产生

如果将目标文档页面尺寸定义为A5横向：

PdfVeryDenseMergeTool tool = new PdfVeryDenseMergeTool(new RectangleReadOnly(595,421), 18, 18, 5);

tool.merge(output, inputs);

（VeryDenseMerging.java）

它生成此：

谨防！这仅是概念的证明，并未考虑所有可能性。例如，没有正确处理“旋转”值不重要的源页面或目标页面的情况。因此，它还没有准备好用于生产。

当前（5.5.6 SNAPSHOT）iText版本的改进

当前面向5.5.6的iText开发版本增强了解析器功能，还可以向矢量图形发出信号。因此，我扩展了PageVerticalAnalyzer，以利用此功能：

public class PageVerticalAnalyzer implements ExtRenderListener

{

    @Override

    public void beginTextBlock() { }

    @Override

    public void endTextBlock() { }

    @Override

    public void clipPath(int rule) { }

    ...

    static class SubPathSection

    {

        public SubPathSection(float x, float y, Matrix m)

        {

            float effectiveY = getTransformedY(x, y, m);

            pathFromY = effectiveY;

            pathToY = effectiveY;

        }

        void extendTo(float x, float y, Matrix m)

        {

            float effectiveY = getTransformedY(x, y, m);

            if (effectiveY < pathFromY)

                pathFromY = effectiveY;

            else if (effectiveY > pathToY)

                pathToY = effectiveY;

        }

        float getTransformedY(float x, float y, Matrix m)

        {

            return new Vector(x, y, 1).cross(m).get(Vector.I2);

        }

        float getFromY()

        {

            return pathFromY;

        }

        float getToY()

        {

            return pathToY;

        }

        private float pathFromY;

        private float pathToY;

    }

    /*

     * Beware: The implementation is not correct as it includes the control points of curves

     * which may be far outside the actual curve.

     * 

     * @see ExtRenderListener#modifyPath(PathConstructionRenderInfo)

     */

    @Override

    public void modifyPath(PathConstructionRenderInfo renderInfo)

    {

        Matrix ctm = renderInfo.getCtm();

        List<Float> segmentData = renderInfo.getSegmentData();

        switch (renderInfo.getOperation())

        {

        case PathConstructionRenderInfo.MOVETO:

            subPath = null;

        case PathConstructionRenderInfo.LINETO:

        case PathConstructionRenderInfo.CURVE_123:

        case PathConstructionRenderInfo.CURVE_13:

        case PathConstructionRenderInfo.CURVE_23:

            for (int i = 0; i < segmentData.size()-1; i+=2)

            {

                if (subPath == null)

                {

                    subPath = new SubPathSection(segmentData.get(i), segmentData.get(i+1), ctm);

                    path.add(subPath);

                }

                else

                    subPath.extendTo(segmentData.get(i), segmentData.get(i+1), ctm);

            }

            break;

        case PathConstructionRenderInfo.RECT:

            float x = segmentData.get(0);

            float y = segmentData.get(1);

            float w = segmentData.get(2);

            float h = segmentData.get(3);

            SubPathSection section = new SubPathSection(x, y, ctm);

            section.extendTo(x+w, y, ctm);

            section.extendTo(x, y+h, ctm);

            section.extendTo(x+w, y+h, ctm);

            path.add(section);

        case PathConstructionRenderInfo.CLOSE:

            subPath = null;

            break;

        default:

        }

    }

    /*

     * @see ExtRenderListener#renderPath(PathPaintingRenderInfo)

     */

    @Override

    public Path renderPath(PathPaintingRenderInfo renderInfo)

    {

        if (renderInfo.getOperation() != PathPaintingRenderInfo.NO_OP)

        {

            for (SubPathSection section : path)

                addVerticalUseSection(section.getFromY(), section.getToY());

        }

        path.clear();

        subPath = null;

        return null;

    }

    List<SubPathSection> path = new ArrayList<SubPathSection>();

    SubPathSection subPath = null;

    ...

}

（PageVerticalAnalyzer.java）

一个简单的测试（VeryDenseMerging.java方法testMergeOnlyGraphics）合并这些文件

但是，再次提防：这仅仅是概念的证明。尤其modifyPath()需要改进，实现方式不正确，因为它包括可能远远超出实际曲线的曲线控制点。