PDFsharp & MigraDoc Foundation

       
static public int ScalePagesSimple(string fn, PageSize pageSize, double scale)
        {
            if (scale >= 1.0)  // 1.0 means nothing to do, larger isn't supported here
            {
                return 0;
            }

            int scaledPagesCount = 0;

            var dir = System.IO.Path.GetDirectoryName(fn);
            var originalFilenameNoPath = System.IO.Path.GetFileName(fn);
            var backupFilename = System.IO.Path.GetFileNameWithoutExtension(fn) + "_beforescale.PDF";
            var backupFilePath = System.IO.Path.Combine(new string[] { dir, backupFilename });

            // backup the original file then delete it.
            if (File.Exists(backupFilePath)) File.Delete(backupFilePath);
            System.IO.File.Copy(fn, backupFilePath);

            var o = PdfReader.Open(fn, PdfDocumentOpenMode.Modify);

            // load the original document
            var inpPdfForm = XPdfForm.FromFile(fn);

            // scale each page into the output document
            for (int thisPageNumber = 0; thisPageNumber < o.PageCount; thisPageNumber++)
            {
                scaledPagesCount++;
                var inpPage = o.Pages[thisPageNumber];

                // calculate the center point on the page; unsure if this is necessary
                var newXcenter = inpPage.Width.Point / 2;
                var newYcenter = inpPage.Height.Point / 2;

                // Associate a graphics context with the designated output page,  indicating that the graphics
                // context will overwrite existing content (Replace) taken from the inpPage.
                // Then specify scaling to apply to everything drawn in the context.
                XGraphics gfx = XGraphics.FromPdfPage(inpPage, XGraphicsPdfPageOptions.Replace);
                gfx.ScaleAtTransform(scale, scale, newXcenter, newYcenter);

                // Construct a rectangle with dimensions of the page
                XRect pageRect = new XRect(0, 0, inpPage.Width.Point, inpPage.Height.Point);

                // convert the input page to a graphic and then draw it on the page.
                inpPdfForm.PageNumber = thisPageNumber + 1; // pdf forms are 1-based
                XImage inpImg = inpPdfForm;

                // Render the image of the current page in the PDF into the scaled rectange and draw it into
                // the graphics context.
                gfx.DrawImage(inpImg, 0, 0);
            }
            o.Save(fn);
           
            return scaledPagesCount;
        }

page.Orientation = PageOrientation.Portrait;