Why you cannot combine Direct Access and Standard Functions

A selection of Foxit Quick PDF Library features can be accessed through Direct Access (DA) functions. The names of DA functions are similar to those of their equivalent standard functions, but begin the the prefix “DA”.

Direct Access functions require significantly less memory than standard functions. While standard functions load entire PDF files into memory, DA functions work with PDF files directly on the disk. As such, DA functions load only what is necessary to perform the required tasks into memory, which makes them much less resource-intensive than standard functions. The DA functions were originally added to the library to make working with large PDFs easier. Depending on circumstances, using the standard functions with large PDFs can consume a lot of memory, which can potentially choke workflows.

Since not all of the SDK’s functionality can be accessed via DA functions, it might be tempting to combine standard functions with DA functions when building a complete solution. Unfortunately, this is impossible, due to the fundamental differences in the way the two types of functions work with PDF files — i.e., with standard functions loading PDFs into memory and DA functions working directly with PDFs on the disk.

As a result of this difference, attempting to use the DA and standard functions together will mean that the functions will not work correctly.

A full listing of all Foxit Quick PDF Library’s Direct Access functions can be found in the page dedicated to the Direct Access function group.

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