PdfSmartCopy is copying the contents at the bottom (footer) of the new PDF file

Question

I have a function which is cropping the specific part of the pdf file and adding it into the new Pdf file but the main problem that i am getting is that it is showing the cropped part of the page into the bottom (footer) of the newly created pdf file. Here is the code..

public static void CropPdfFile(string sourceFilePath, string outputFilePath)
{
    // Allows PdfReader to read a pdf document without the owner's password
    PdfReader.unethicalreading = true;

    // Reads the PDF document
    using (PdfReader pdfReader = new PdfReader(sourceFilePath))
    {
        // Set which part of the source document will be copied.
        // PdfRectangel(bottom-left-x, bottom-left-y, upper-right-x, upper-right-y)

        PdfRectangle rect = new PdfRectangle(0f, 9049.172f, 594.0195f, 700.3f);

        using (var output = new FileStream(outputFilePath, FileMode.CreateNew, FileAccess.Write))
        {
            // Create a new document
            using (Document doc = new Document())
            {

                // Make a copy of the document
                PdfSmartCopy smartCopy = new PdfSmartCopy(doc, output);

                // Open the newly created document
                doc.Open();              

                // Loop through all pages of the source document
                for (int i = 4; i <= pdfReader.NumberOfPages; i++)
                {
                    // Get a page
                    var page = pdfReader.GetPageN(i);

                    // Apply the rectangle filter we created
                      page.Put(PdfName.CROPBOX, rect);
                      page.Put(PdfName.MEDIABOX, rect);

                    // Copy the content and insert into the new document

                      smartCopy.SetLinearPageMode();

                    var copiedPage = smartCopy.GetImportedPage(pdfReader, i);
                    smartCopy.AddPage(copiedPage);

                }

                // Close the output document
                doc.Close();
            }
        }
    }

Please help me to solve this..

Answer 1

The size of a PDF page (expressed in user units) depends on the value of the mediabox. For instance: The media box of an A4 page is usually defined like this [0 0 595 842]

In this case, the origin of the coordinate system (0, 0) coincides with the lower-left corner. The coordinate of the upper right corner is (595, 842).

Another possible value for an A4 page would be [0 842 595 1684]. Same width (595 user units), same height (1684 - 842 = 842 user units), but the lower-left corner now has the coordinate (0, 842) and the coordinate of the upper-right corner is (595, 1684).

You write that you create a PdfRectangle using these parameters: (bottom-left-x, bottom-left-y, upper-right-x, upper-right-y). However, you're using these hard-coded values: 0f, 9049.172f, 594.0195f, 700.3f.

Your lower-left-y (9049.172) is at a higher position than your upper-right-y (700.3). This doesn't really make sense. Hence: you should consider changing that value to something that does make sense. What value that should be, is a question only you can answer since only you know the value of the MediaBox of the file you want to crop.

In your comment, you explain that your PDF is an A4 page. You can check this by using the PdfReader method named getPageSize(). If you want to crop the page so that you only see the header of your document, you need to use something like this:

PdfRectangle rect = new PdfRectangle(0f, 842 - x, 595, 842);

Where x is the height of the header. For instance, if the header is 100 user units, then you'd need:

PdfRectangle rect = new PdfRectangle(0f, 742, 595, 842);

It is unclear why you're always talking about 100px. If you want to convert pixels to points, please read Convert Pixels to Points

Using the formula mentioned there 100 pixels equals 75 points.