XfaBStrHelpersAvailable 函数

Returns True when XFA BSTR helper exports are present in the loaded PDFium DLL.

XFA support requires a special PDFium build with FPDFXFA_* exports; without it, XFA documents render as the static fallback only.

Class function; checks the DLL for the symbols at runtime.

• Treat the value as immutable for the lifetime of the open document — reopening the file or changing pages may yield a different result.
• Surface this value in your UI to drive feature toggles (for example, disable accessibility export when IsTagged is False).
• All scalar boolean / type properties on TPdf are inexpensive O(1) reads.