如何在合并时删除空格
How To Remove Whitespace on Merge
我有一些代码采用 3 个不同的 PDF 字节数组并将它们合并。这段代码效果很好。 （某些人）遇到的问题是每个 PDF 都被认为是整页（如果打印的话），即使上面只有 4 英寸的内容，因此垂直留下 7 英寸的白色 space。然后中间文档被放入，最后可能有也可能没有垂直白色 space。然后页脚也会放在自己的页面上。
代码如下：
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 letter
if (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
当我将每个页面合并到每个 pdf 末尾的 clip/remove/erase 垂直白色 space 时，有没有办法让它显示为一个无缝文档？
UPDATE:
Here are some sample .pdf files I am trying to merge.
UPDATE 2: USING THE ANSWER:
I have converted @mkl's code to C# and here it is.
The tool class:
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
The RenderListener class:
UPDATE 3: FIXED 1 LINE OF CODE AND IT WORKS: See comment in code
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
Code to gather files and run the tool:
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
下面的示例工具是按照工具PdfDenseMergeTool的思想从 which the OP has commented to be SO close to what [he] NEEDs. Just like PdfDenseMergeTool this tool here is implemented in Java/iText which I'm more at home with than C#/iTextSharp. As the OP PdfDenseMergeTool到C#/iTextSharp实现的，在这里翻译这个工具也应该问题不大。
PdfVeryDenseMergeTool
此工具类似于 从多个 PdfReader 实例中获取页面的页面内容并尝试将它们密集合并，即将多个源页面的内容放在一个目标页面上，如果有足够的免费 space 来这样做。与早期的工具相比，此工具甚至可以拆分源页面内容以允许更密集的合并。
就像其他工具一样，PdfVeryDenseMergeTool 不考虑矢量图形，因为 iText(Sharp) 解析 API 只转发文本和位图图像
PdfVeryDenseMergeTool 在不与文本字形或位图图形的边界框相交的水平线上拆分不完全适合目标页面的源页面。
工具class:
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;
}
此工具使用自定义 RenderListener 与 iText 解析器一起使用 API:
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>();
}
它是这样使用的：
PdfVeryDenseMergeTool tool = new PdfVeryDenseMergeTool(PageSize.A4, 18, 18, 5);
tool.merge(output, inputs);
应用于 OP 的示例文档
Header.pdf
Body.pdf
Footer.pdf
它生成
如果将目标文档页面大小定义为 A5 横向：
PdfVeryDenseMergeTool tool = new PdfVeryDenseMergeTool(new RectangleReadOnly(595,421), 18, 18, 5);
tool.merge(output, inputs);
它生成这个：
当心！ 这只是概念验证，并未考虑所有可能性。例如。具有重要 Rotate 值的源页面或目标页面的情况未得到正确处理。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
当前的 iText 开发版本 5.5.6 增强了解析器功能，也可以表示矢量图形。因此，我扩展了 PageVerticalAnalyzer 以利用它：
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;
...
}
一个简单的测试（VeryDenseMerging.java方法testMergeOnlyGraphics）合并这些文件
进入这个：
但再次注意：这仅仅是概念验证。特别是modifyPath()需要改进，实现不正确，因为它包含了可能远离实际曲线的曲线控制点。
我有一些代码采用 3 个不同的 PDF 字节数组并将它们合并。这段代码效果很好。 （某些人）遇到的问题是每个 PDF 都被认为是整页（如果打印的话），即使上面只有 4 英寸的内容，因此垂直留下 7 英寸的白色 space。然后中间文档被放入，最后可能有也可能没有垂直白色 space。然后页脚也会放在自己的页面上。
代码如下：
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 letter
if (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
当我将每个页面合并到每个 pdf 末尾的 clip/remove/erase 垂直白色 space 时，有没有办法让它显示为一个无缝文档？
UPDATE: Here are some sample .pdf files I am trying to merge.
UPDATE 2: USING THE ANSWER:
I have converted @mkl's code to C# and here it is.
The tool class:
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
The RenderListener class:
UPDATE 3: FIXED 1 LINE OF CODE AND IT WORKS: See comment in code
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
Code to gather files and run the tool:
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
下面的示例工具是按照工具PdfDenseMergeTool的思想从PdfDenseMergeTool this tool here is implemented in Java/iText which I'm more at home with than C#/iTextSharp. As the OP PdfDenseMergeTool到C#/iTextSharp实现的，在这里翻译这个工具也应该问题不大。
PdfVeryDenseMergeTool
此工具类似于 PdfReader 实例中获取页面的页面内容并尝试将它们密集合并，即将多个源页面的内容放在一个目标页面上，如果有足够的免费 space 来这样做。与早期的工具相比，此工具甚至可以拆分源页面内容以允许更密集的合并。
就像其他工具一样，PdfVeryDenseMergeTool 不考虑矢量图形，因为 iText(Sharp) 解析 API 只转发文本和位图图像
PdfVeryDenseMergeTool 在不与文本字形或位图图形的边界框相交的水平线上拆分不完全适合目标页面的源页面。
工具class:
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; }
此工具使用自定义 RenderListener 与 iText 解析器一起使用 API:
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>(); }
它是这样使用的：
PdfVeryDenseMergeTool tool = new PdfVeryDenseMergeTool(PageSize.A4, 18, 18, 5); tool.merge(output, inputs);
应用于 OP 的示例文档
Header.pdf
Body.pdf
Footer.pdf
它生成
如果将目标文档页面大小定义为 A5 横向：
PdfVeryDenseMergeTool tool = new PdfVeryDenseMergeTool(new RectangleReadOnly(595,421), 18, 18, 5); tool.merge(output, inputs);
它生成这个：
当心！ 这只是概念验证，并未考虑所有可能性。例如。具有重要 Rotate 值的源页面或目标页面的情况未得到正确处理。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
当前的 iText 开发版本 5.5.6 增强了解析器功能，也可以表示矢量图形。因此，我扩展了 PageVerticalAnalyzer 以利用它：
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; ... }
一个简单的测试（VeryDenseMerging.java方法testMergeOnlyGraphics）合并这些文件
进入这个：
但再次注意：这仅仅是概念验证。特别是modifyPath()需要改进，实现不正确，因为它包含了可能远离实际曲线的曲线控制点。