This article follows on from previous blog What are PDF ‘readonly’ text fields?
In that article I introduced ReadOnly text fields and explained that ‘ReadOnly Text Fields within a PDF are not truly read only. This article expands on some issues and explains how our PDF Viewer handles these quirks and makes use of the features on readonly text fields?
JPedal makes the textfields readonly by using JButtons to display them. This also allows us to use our superior PDF font engine to display the form as close as possible to the way Adobe Acrobat does.
The problems comes when the value gets changed, as now the Appearance Object associated to the form is no longer valid.
This requires some careful manipulation of the image display stream so that the text still appears as close as we can get it to Adobe Acrobat.
So the fact that ReadOnly text field are not totally readonly introduces a number of issues which have to be carefully worked around. Have you encountered any problems like this?
Are you a Developer working with PDF files?
Our developers guide contains a large number of technical posts to help you understand the PDF file Format.
Find out more about our software for Developers
|Convert PDF to HTML5 or SVG|
|Convert AcroForms and XFA to HTML5|
|Java PDF SDK for working with PDF files|