I have been looking at some Annotation issues and came across an interesting feature in a sample PDF file. I viewed it in Acrobat’s viewer and saw the following.
It is a freetext annotation with an AP object to define how it appears. It was not appearing in our PDF viewer so I dug down and found we were not reading the AP object (number 22). Then I opened up the raw PDF file to see why, which is where it gets very interesting…
The PDF only contains 21 objects and there is no AP object attached to the Annotation. The object that I am seeing in Adobe Acrobat is actually a ‘synthetic’ object created by Adobe – it does not exist in the file. So does it really exist?
This post is part of our “Understanding the PDF File Format” series. In each article, we discuss a PDF feature, bug, gotcha or tip. If you wish to learn more about PDF, we have 13 years worth of PDF knowledge and tips, so click here to visit our series index!
IDRsolutions develop a Java PDF library, a PDF forms to HTML5 converter, a PDF to HTML5 or SVG converter and a Java Image Library that doubles as an ImageIO replacement. On the blog our team post about anything interesting they learn about.