Acrobat/Reader 8: PDFs rendering or behaving differently

If you have upgraded from Adobe Reader 7 or earlier to Adobe Reader 8 or later, you notice some differences in the PDF behavior. For example,

  • Form events not fired in the same order, or with the same frequency (particularly the layout:ready event). As a workaround, you can move the script to another event in Designer (for example, form:ready).
  • Text is shifted or clipped
  • PDF field values are modified (particularly checkbox and radio-button values)
  • Tabbing order is different (read-only fields are included in the tabbing order). As a workaround, set the field property in Designer to “protected” instead of “read-only“.

These differences result from a change in the rendering engine in Adobe Reader 8 and later.  The rendering engine was redeveloped to improve performance of large dynamic forms (100+ pages). The rendering engine in Adobe Reader 8 and later uses direct or AGM rendering. Some of  the changes mentioned above (form events, tabbing order) are side-effects of the rendering engine modifications, and others (text-clipping, field values) are product issues. The side-effects have known workarounds as outlined above, whereas the product issues have been addressed in the subsequent versions of Reader (8.2, and 9.3).

If you encounter other issues not mentioned above, and you want to restore the behavior from Adobe Reader 7, you can use a compatibility flag. The flag instructs the rendering engine to use the legacy engine from version 7.  Place the following flag in the XML source:

<?originalXFAVersion http://www.xfa.org/schema/xfa-template/2.4/LegacyRendering:1?>

VN:F [1.9.22_1171]
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