THPDFRandomAccessSource Class

Abstract base class that lets THotPDF.LoadFromRandomAccessSource load a PDF from any caller-defined seekable byte store without requiring a TStream implementation

Declaration

THPDFRandomAccessSource = class
public
  function GetSize: Int64; virtual; abstract;
  function ReadAt(Offset: Int64; var Buffer;
    Count: Longint): Longint; virtual; abstract;
end;

Unit

HPDFDoc

Members

Name	Purpose
`GetSize`	Returns the stable byte length of the backing store
`ReadAt`	Reads `Count` bytes starting at `Offset` into `Buffer`

Usage notes

Derive a subclass and override both abstract methods to adapt HotPDF to HTTP range requests, database BLOBs, compressed archives, encrypted volumes, or any virtual storage that can supply bytes by offset
GetSize must return a stable, non-negative byte length for the lifetime of the load; HotPDF parses the cross-reference tables and object streams by seeking through this source
ReadAt returns the number of bytes actually transferred (zero through Count); the parser treats a short read at the documented end of file as end-of-stream, not as an error
The source must remain valid whilst the loaded document is in use; pass OwnsSource = True to LoadFromRandomAccessSource to have HotPDF free the source automatically

THPDFRandomAccessSource Class

Declaration

Unit

Members

Usage notes

Related APIs