Save PDF files in C#

Incremental to Stream

If you have a large PDF document in a Stream object and you want to modify only a small part of that PDF, use the SaveToFileInc method of the GdPicturePDF class. This method enables the content of the PDF document to be updated incrementally without rewriting it entirely. As a result, small changes to a larger PDF document are saved faster.

The following code draws a black rectangle on the first page of a PDF document and saves it incrementally to a stream:

using GdPicturePDF gdPicturePDF = new GdPicturePDF();
// Create a `Stream` object from a PDF document.
Stream streamPDF = new FileStream(@"C:\temp\source.pdf", FileMode.Open);
// Load a PDF document from the stream.
gdPicturePDF.LoadFromStream(streamPDF);
// Select the first page.
gdPicturePDF.SelectPage(1);
// Set the fill color to black.
gdPicturePDF.SetFillColor(0, 0, 0);
// Draw a filled rectangle on the entire page.
gdPicturePDF.DrawRectangle(
    Left: 0, Top: 0,
    Width: gdPicturePDF.GetPageWidth(),
    Height: gdPicturePDF.GetPageHeight(),
    Fill: true,
    Stroke: false);
// Save the PDF document incrementally.
gdPicturePDF.SaveToStreamInc(streamPDF);