Q: We want to integrate a background image (a logo) on every page at
its bottom. The logo shall always be behind the text.
---
A:
In PDFNet there are several ways to append new content to existing
pages. Probably the simples approach is to use ElementWriter as
illustrated in the following FAQ:
http://www.pdftron.com/net/faq.html#how_watermark.
Starting with PDFNet SDK v.3.6 ElementWriter.Begin() method has couple
of additional options:
---
- background: An optional flag indicating whether the new content
should be added as a foreground or background layer to the existing
page. If background is 'true', the graphics will be added in a
background layer. By default, the new content will appear on top of the
existing graphics.
- compress: An optional flag indicating whether the page content stream
should be compressed. This may be useful for debugging content streams.
Also some applications need to do a clear text search on strings in the
PDF files. By default, all content streams are compressed.
----
So, the simplest approach to add an image to an existing page as a
background layer is as follows:
ElementWriter writer = new ElementWriter();
ElementBuilder eb = new ElementBuilder();
// Create a new page content stream.
writer.Begin(old_page, true); // <-- 'true' means: add new content as
a background layer.
Image img = Image.Create(doc, "c:/peppers.jpg");
Element element = eb.CreateImage(img, new Matrix2D(200, 0, 0, 250, 50,
500));
writer.WriteElement(element);
... add other background graphics
writer.End();