TPDFlibRangeAvailabilityEvent

Data types, Document management, Progressive loading

Description

Reports whether a complete absolute byte range is already present in progressive storage without fetching it

TPDFlibRangeAvailabilityEvent= Function(Sender: TObject;
  Offset: Int64; Count: LongInt): Integer Of Object;

Sender	The `TPDFlib` instance that owns the callback-backed document
Offset	The absolute zero-based start offset
Count	The number of consecutive bytes being tested

0	One or more requested bytes are not yet present
Nonzero	Every requested byte can be read immediately without transport or blocking I/O

The callback is a status probe and must not fetch data, wait for a download or call back into the same range source

Results should progress monotonically as storage fills; cached bytes remain available even if the callback later reports zero

The callback target and backing storage must remain valid until the loaded document is closed