c# - Change object's color inside existiong PDF with iTextSharp -

major part of job automation of engineering process, have create simple program, compares 2 different version of 1 drawn element, overlapping drawings, in order review differences. drawings represent single sheet pdf files.

• i'm using .net framework , c# 4.5;

• itextsharp library editing pdf files;

• initially, i'm getting 2 files, read them , create third one, contains result;

      var file1 = "file1.pdf";     var file2 = "file2.pdf";     var result = "result.pdf";      using (stream f1stream = new filestream(file1, filemode.open))     using (stream f2stream = new filestream(file2, filemode.open))     using (stream resultstream = new filestream(result, filemode.create, fileaccess.readwrite))     using (pdfreader f2reader = new pdfreader(f2stream))     using (pdfreader f1reader = new pdfreader(f1stream))     {         pdfstamper pdfstamper = new pdfstamper(f1reader, resultstream);          pdfcontentbyte pdfcontentbyte = pdfstamper.getovercontent(1);          var page = pdfstamper.getimportedpage(f2reader, 1);          pdfcontentbyte.addtemplate(page,2,2);          pdfstamper.close();     }  

the code above makes that, few sequential questions arising

• i want change color of elements in result file i.e. elements come 1st drawing in green , others 2nd 1 - in red color. maybe have change color of entities in initial 2 pdfs , merge;
• initial files have layers, , because 2 sequential revision of same construction element , differences between them few, have identical layers. , want have " layerfoo " , " layerfoo@ " in result pdf. maybe have rename layers in 1 the 2 initial pdfs , merge them.

Аll suggestions welcomed including usage of library :)

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--> edit1 big chris haas! absolutely right token type , string value! itextrups great helping tool understanding structure of pdf files. following code taken post pointed me out.

the following statement:

stream.setdata(system.text.encoding.ascii.getbytes(string.join("\n", newbuf.toarray()))); 

updates stream of file ,

using (var fs = new filestream(file2, filemode.create, fileaccess.write, fileshare.none))         {             var stamper = new pdfstamper(reader, fs);             reader.setpagecontent(1,reader.getpagecontent(1));             stamper.close();         } 

the new file created updated stream.

i made 1 simple test file 2 lines, change color , save new file. no problem! after that, tried same simple operation real file, represents real drawing of construction element, result file less half of original , broken. comes mind updated stream saved new file other information inside other containers not saved, it's stream.

because stuck that, continue next step of investigation -> layers wrote code in order available layers in pdf file. try insert more records layers dictionary see happen.

        var resourcesreference = page.get(pdfname.resources) pdfindirectreference;         var resources = pdfreader.getpdfobject(resourcesreference) pdfdictionary;          var propertiesobjhectreferences = resources.get(pdfname.properties);         var properties = pdfreader.getpdfobject(propertiesobjhectreferences) pdfdictionary;         foreach (var property in properties.keys)         {             var layerreference = properties.get(property);             var layerobject = pdfreader.getpdfobject(layerreference) pdfdictionary;             foreach (var key in layerobject.keys)             {                 if (key.tostring()!=pdfname.type.tostring())                 {                     var layername = layerobject.getasstring(key).tounicodestring();                 }             }          } 

if come main goal top of post, tends insert stream , layers first file second in order obtain result file, contains objects previous 2, painted in different colors + layers both.

feel free suggest me another, more simpler , beautiful solution! happy if revise code , correct it! thank much!

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edit 2

i simplify work because lack of time, change color of entities inside 1 pdf , put on background on other.

 const string pdf = "file1.pdf";          var reader = new pdfreader(pdf);         var page = reader.getpagen(1);         var objectreference = page.get(pdfname.contents) pdfindirectreference;         var stream = (prstream)pdfreader.getpdfobject(objectreference);         var streambytes = pdfreader.getstreambytes(stream);         var tokenizer = new prtokeniser(new randomaccessfileorarray(streambytes));          var newbuf = new list<string>();         while (tokenizer.nexttoken())         {             var token = tokenizer.stringvalue;             newbuf.add(token);             if (tokenizer.tokentype == prtokeniser.toktype.other                 && newbuf[newbuf.count - 1].equals("s", stringcomparison.currentcultureignorecase))             {                 newbuf.insert(newbuf.count - 1, "0");                 newbuf.insert(newbuf.count - 1, "1");                 newbuf.insert(newbuf.count - 1, "1");                 newbuf.insert(newbuf.count - 1, "rg");             }         }         var resultstream = string.join("\n", newbuf.toarray());         stream.setdata(system.text.encoding.ascii.getbytes(resultstream));          var file2 = pdf.insert(pdf.length - 4, "result");         using (var fs = new filestream(file2, filemode.create, fileaccess.write, fileshare.none))         {             var stamper = new pdfstamper(reader, fs);             reader.setpagecontent(1, reader.getpagecontent(1));             stamper.close();         } 

result pdf broken , itextrups throws exception when try stream data page.