我需要分析pdf文件的路径数据，并用itext7来操纵内容。操作包括删除/替换和着色。
我可以使用以下代码分析图形：
public class ContentParsing {
public static void main(String[] args) throws IOException {
new ContentParsing().inspectPdf("testdata/test.pdf");
}
public void inspectPdf(String path) throws IOException {
File file = new File(path);
PdfDocument pdf = new PdfDocument(new PdfReader(file.getAbsolutePath()));
PdfDocumentContentParser parser = new PdfDocumentContentParser(pdf);
for (int i=1; i<=pdf.getNumberOfPages(); i++) {
parser.processContent(i, new PathEventListener());
}
pdf.close();
}
}
public class PathEventListener implements IEventListener {
public void eventOccurred(IEventData eventData, EventType eventType) {
PathRenderInfo pathRenderInfo = (PathRenderInfo) eventData;
for ( Subpath subpath : pathRenderInfo.getPath().getSubpaths() ) {
for ( IShape segment : subpath.getSegments() ) {
// Here goes some path analysis code
System.out.println(segment.getBasePoints());
}
}
}
public Set<EventType> getSupportedEvents() {
Set<EventType> supportedEvents = new HashSet<EventType>();
supportedEvents.add(EventType.RENDER_PATH);
return supportedEvents;
}
}
现在，操纵事物并将它们写回PDF的方法是什么？我是否必须构建一个全新的PDF文档，并以操纵形式复制所有内容，还是可以直接操纵读取PDF数据？
现在，操纵事物并将它们写回PDF的方法是什么？我是否必须构建一个全新的PDF文档，并以操纵形式复制所有内容，还是可以直接操纵读取PDF数据？
本质上，您正在寻找一个类，它不仅在解析PDF内容流并像PdfCanvasProcessor一样向其中的指示发出信号（您使用的PdfDocumentContentParser只是PdfCanvasProcessor的非常薄的包装器），还可以创建内容流。重新带有指示您向前回到的指示。
通用内容流编辑器类
对于Itext 5.5.x，可以在此答案中找到此类内容流编辑器类的概念验证（Java版本在答案文本中有点远）。
这是ITEXT 7：
的概念证明的端口public class PdfCanvasEditor extends PdfCanvasProcessor
{
/**
* This method edits the immediate contents of a page, i.e. its content stream.
* It explicitly does not descent into form xobjects, patterns, or annotations.
*/
public void editPage(PdfDocument pdfDocument, int pageNumber) throws IOException
{
if ((pdfDocument.getReader() == null) || (pdfDocument.getWriter() == null))
{
throw new PdfException("PdfDocument must be opened in stamping mode.");
}
PdfPage page = pdfDocument.getPage(pageNumber);
PdfResources pdfResources = page.getResources();
PdfCanvas pdfCanvas = new PdfCanvas(new PdfStream(), pdfResources, pdfDocument);
editContent(page.getContentBytes(), pdfResources, pdfCanvas);
page.put(PdfName.Contents, pdfCanvas.getContentStream());
}
/**
* This method processes the content bytes and outputs to the given canvas.
* It explicitly does not descent into form xobjects, patterns, or annotations.
*/
public void editContent(byte[] contentBytes, PdfResources resources, PdfCanvas canvas)
{
this.canvas = canvas;
processContent(contentBytes, resources);
this.canvas = null;
}
/**
* <p>
* This method writes content stream operations to the target canvas. The default
* implementation writes them as they come, so it essentially generates identical
* copies of the original instructions the {@link ContentOperatorWrapper} instances
* forward to it.
* </p>
* <p>
* Override this method to achieve some fancy editing effect.
* </p>
*/
protected void write(PdfCanvasProcessor processor, PdfLiteral operator, List<PdfObject> operands)
{
PdfOutputStream pdfOutputStream = canvas.getContentStream().getOutputStream();
int index = 0;
for (PdfObject object : operands)
{
pdfOutputStream.write(object);
if (operands.size() > ++index)
pdfOutputStream.writeSpace();
else
pdfOutputStream.writeNewLine();
}
}
//
// constructor giving the parent a dummy listener to talk to
//
public PdfCanvasEditor()
{
super(new DummyEventListener());
}
//
// Overrides of PdfContentStreamProcessor methods
//
@Override
public IContentOperator registerContentOperator(String operatorString, IContentOperator operator)
{
ContentOperatorWrapper wrapper = new ContentOperatorWrapper();
wrapper.setOriginalOperator(operator);
IContentOperator formerOperator = super.registerContentOperator(operatorString, wrapper);
return formerOperator instanceof ContentOperatorWrapper ? ((ContentOperatorWrapper)formerOperator).getOriginalOperator() : formerOperator;
}
//
// members holding the output canvas and the resources
//
protected PdfCanvas canvas = null;
//
// A content operator class to wrap all content operators to forward the invocation to the editor
//
class ContentOperatorWrapper implements IContentOperator
{
public IContentOperator getOriginalOperator()
{
return originalOperator;
}
public void setOriginalOperator(IContentOperator originalOperator)
{
this.originalOperator = originalOperator;
}
@Override
public void invoke(PdfCanvasProcessor processor, PdfLiteral operator, List<PdfObject> operands)
{
if (originalOperator != null && !"Do".equals(operator.toString()))
{
originalOperator.invoke(processor, operator, operands);
}
write(processor, operator, operands);
}
private IContentOperator originalOperator = null;
}
//
// A dummy event listener to give to the underlying canvas processor to feed events to
//
static class DummyEventListener implements IEventListener
{
@Override
public void eventOccurred(IEventData data, EventType type)
{ }
@Override
public Set<EventType> getSupportedEvents()
{
return null;
}
}
}
（pdfcanvaseitor.java）
ITEXT 5答案中的解释仍然适用，解析框架从Itext 5.5.5.x到Itext7.0.x。
并没有太大变化。用法示例
不幸的是，您用非常模糊的术语撰写了有关您要如何更改内容的方式。因此，我只是移植了一些使用原始ITEXT 5内容流编辑器类的ITEXT 5样本：
去除水印
这些是此答案中用例的端口。
testRemoveBoldMTTextDocument
此示例将所有文本写入字体，其名称以" boldmt"结尾：
try ( InputStream resource = getClass().getResourceAsStream("document.pdf");
PdfReader pdfReader = new PdfReader(resource);
OutputStream result = new FileOutputStream(new File(RESULT_FOLDER, "document-noBoldMTText.pdf"));
PdfWriter pdfWriter = new PdfWriter(result);
PdfDocument pdfDocument = new PdfDocument(pdfReader, pdfWriter) )
{
PdfCanvasEditor editor = new PdfCanvasEditor()
{
@Override
protected void write(PdfCanvasProcessor processor, PdfLiteral operator, List<PdfObject> operands)
{
String operatorString = operator.toString();
if (TEXT_SHOWING_OPERATORS.contains(operatorString))
{
if (getGraphicsState().getFont().getFontProgram().getFontNames().getFontName().endsWith("BoldMT"))
return;
}
super.write(processor, operator, operands);
}
final List<String> TEXT_SHOWING_OPERATORS = Arrays.asList("Tj", "'", """, "TJ");
};
for (int i = 1; i <= pdfDocument.getNumberOfPages(); i++)
{
editor.editPage(pdfDocument, i);
}
}
（editPageContent.java测试方法testRemoveBoldMTTextDocument）
testRemoveBigTextDocument
此示例丢弃所有带有大字体大小的文本：
try ( InputStream resource = getClass().getResourceAsStream("document.pdf");
PdfReader pdfReader = new PdfReader(resource);
OutputStream result = new FileOutputStream(new File(RESULT_FOLDER, "document-noBigText.pdf"));
PdfWriter pdfWriter = new PdfWriter(result);
PdfDocument pdfDocument = new PdfDocument(pdfReader, pdfWriter) )
{
PdfCanvasEditor editor = new PdfCanvasEditor()
{
@Override
protected void write(PdfCanvasProcessor processor, PdfLiteral operator, List<PdfObject> operands)
{
String operatorString = operator.toString();
if (TEXT_SHOWING_OPERATORS.contains(operatorString))
{
if (getGraphicsState().getFontSize() > 100)
return;
}
super.write(processor, operator, operands);
}
final List<String> TEXT_SHOWING_OPERATORS = Arrays.asList("Tj", "'", """, "TJ");
};
for (int i = 1; i <= pdfDocument.getNumberOfPages(); i++)
{
editor.editPage(pdfDocument, i);
}
}
（editpagecontent.java测试方法testRemoveBigTextDocument）
文本颜色更改
这是此答案中用例的端口。
testChangeBlackTextToGreenDocument
此示例将黑色文本的颜色更改为绿色。
try ( InputStream resource = getClass().getResourceAsStream("document.pdf");
PdfReader pdfReader = new PdfReader(resource);
OutputStream result = new FileOutputStream(new File(RESULT_FOLDER, "document-blackTextToGreen.pdf"));
PdfWriter pdfWriter = new PdfWriter(result);
PdfDocument pdfDocument = new PdfDocument(pdfReader, pdfWriter) )
{
PdfCanvasEditor editor = new PdfCanvasEditor()
{
@Override
protected void write(PdfCanvasProcessor processor, PdfLiteral operator, List<PdfObject> operands)
{
String operatorString = operator.toString();
if (TEXT_SHOWING_OPERATORS.contains(operatorString))
{
if (currentlyReplacedBlack == null)
{
Color currentFillColor = getGraphicsState().getFillColor();
if (Color.BLACK.equals(currentFillColor))
{
currentlyReplacedBlack = currentFillColor;
super.write(processor, new PdfLiteral("rg"), Arrays.asList(new PdfNumber(0), new PdfNumber(1), new PdfNumber(0), new PdfLiteral("rg")));
}
}
}
else if (currentlyReplacedBlack != null)
{
if (currentlyReplacedBlack instanceof DeviceCmyk)
{
super.write(processor, new PdfLiteral("k"), Arrays.asList(new PdfNumber(0), new PdfNumber(0), new PdfNumber(0), new PdfNumber(1), new PdfLiteral("k")));
}
else if (currentlyReplacedBlack instanceof DeviceGray)
{
super.write(processor, new PdfLiteral("g"), Arrays.asList(new PdfNumber(0), new PdfLiteral("g")));
}
else
{
super.write(processor, new PdfLiteral("rg"), Arrays.asList(new PdfNumber(0), new PdfNumber(0), new PdfNumber(0), new PdfLiteral("rg")));
}
currentlyReplacedBlack = null;
}
super.write(processor, operator, operands);
}
Color currentlyReplacedBlack = null;
final List<String> TEXT_SHOWING_OPERATORS = Arrays.asList("Tj", "'", """, "TJ");
};
for (int i = 1; i <= pdfDocument.getNumberOfPages(); i++)
{
editor.editPage(pdfDocument, i);
}
}
（EditPageContent.java测试方法testChangeBlackTextToGreenDocument）