Compare two PDF files in C# windows application

Deva Subbu

Hi,

I am looking for the components which will compare two PDF files( with text and image) and show the difference highlighted in the PDF... let me know if there is any third party tools that can be integrated with my dot net code.

i have referred few links but its a separate application itself cannot integrate with my application.

Thanks

Dev

4 Replies

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Atir Tahir7y ago
As you are looking for a component/API that could be integrated in your existing C# applicaiton? You must try out GroupDocs.Comparison for .NET https://products.groupdocs.com/comparison/net.
Below code will show how easy it is to do document comparison:
//Source and target files to be compared
string source = @"source.pdf";
string target = @"target.pdf";
Comparer comparer = new Comparer();
//Compare two documents
ICompareResult result = comparer.Compare(source, target, new ComparisonSettings());
result.SaveDocument("output path", "output name");
This API is totally UI-Agnostic and could be integrated in any .NET application (console/web/windows form etc).
Maniteja Vegi8y ago
public static void CompareTwoPDF(string FirstPDF, string SecondPDF)
{
if (File.Exists(FirstPDF) && File.Exists(SecondPDF))
{
PdfReader reader = new PdfReader(FirstPDF);
for (int page = 1; page <= reader.NumberOfPages; page++)
{
ITextExtractionStrategy strategy = new SimpleTextExtractionStrategy();
FirstFile += PdfTextExtractor.GetTextFromPage(reader, page, strategy);
}
PdfReader reader1 = new PdfReader(SecondPDF);
for (int page = 1; page <= reader.NumberOfPages; page++)
{
ITextExtractionStrategy strategy = new SimpleTextExtractionStrategy();
SecondFile += PdfTextExtractor.GetTextFromPage(reader1, page, strategy);
}
}
else
{
Console.WriteLine("Files does not exist.");
}

List File1diff;
List File2diff;
IEnumerable file1 = FirstFile.Trim().Split('\r', '\n');
IEnumerable file2 = SecondFile.Trim().Split('\r', '\n');
File1diff = file1.ToList();
File2diff = file2.ToList();

if (file2.Count() > file1.Count())
{
Console.WriteLine("File 1 has less number of lines than File 2.");
for (int i = 0; i < File1diff.Count; i++)
{
if (!File1diff[i].Equals(File2diff[i]))
{
Console.WriteLine("File 1 content: " + File1diff[i] + "\r\n" + "File 2 content: " + File2diff[i]);
}

}

for (int i = File1diff.Count; i < File2diff.Count; i++)
{
Console.WriteLine("File 2 extra content: " + File2diff[i]);
}

}
else if (file2.Count() < file1.Count())
{
Console.WriteLine("File 2 has less number of lines than File 1.");

for (int i = 0; i < File2diff.Count; i++)
{
if (!File1diff[i].Equals(File2diff[i]))
{
Console.WriteLine("File 1 content: " + File1diff[i] + "\r\n" + "File 2 content: " + File2diff[i]);
}

}

for (int i = File2diff.Count; i < File1diff.Count; i++)
{
Console.WriteLine("File 1 extra content: " + File1diff[i]);
}
}
else
{
Console.WriteLine("File 1 and File 2, both are having same number of lines.");

for (int i = 0; i < File1diff.Count; i++)
{
if (!File1diff[i].Equals(File2diff[i]))
{
Console.WriteLine("File 1 content: " + File1diff[i] + "\r\n" + "File 2 Content: " + File2diff[i]);
}

}

}

}
Maen Badwan9y ago
LEADTOOLS.PDFDocument class provides the ability to parse all objects (Text, images, hyperlinks, etc.) using the ParsePages method, which returns the bounds (location) for each parsed object along with the object itself (text or image).
After parsing the object, you can extract them to external file on disk (or memory) and apply your own comparison algorithm or criteria with the conditions that you want.
The following link provides more details about the PDFDocument.ParsePages method:
https://www.leadtools.com/help/leadtools/v19/dh/pdf/leadtools.pdf~leadtools.pdf.pdfdocument~parsepages.html

Note that LEADTOOLS has image processing functions that can help in the case of image comparison feature.
Disclaimer: I am an employee of this library.
Mangesh G9y ago
public bool ComparePDFs(string file1, string file2)
{
if (!File.Exists(file2))
return false;

int i;
string f1 = File.ReadAllText(file1);
string f2 = File.ReadAllText(file2);

if (f1.Length != f2.Length)
return false;

// Remove PDF ID from file1
i = f1.LastIndexOf("/ID [<");
if (i < 0)
Console.WriteLine("Error: File is not a valid PDF file: " + file1);
else
f1 = f1.Substring(0, i) + f1.Substring(i + 75);

// Remove PDF ID from file2
i = f2.LastIndexOf("/ID [<");
if (i < 0)
Console.WriteLine("Error: File is not a valid PDF file: " + file2);
else
f2 = f2.Substring(0, i) + f2.Substring(i + 75);

return f1 == f2;
}