THPDFRandomAccessSource.ReadAtCancellable Method

Reads bytes at Offset while observing a cancellation token before and after the underlying read

Declaration

function ReadAtCancellable(Offset: Int64; var Buffer; Count: Longint;
  CancellationToken: THPDFCancellationToken): Longint; virtual;

HPDFDoc

Name	Purpose
`Offset`	Zero-based byte offset to read from
`Buffer`	Untyped buffer that receives the bytes
`Count`	Maximum number of bytes to read
`CancellationToken`	Token polled for cancellation, or nil to read without cancellation checks

Number of bytes read, as reported by ReadAt

The base implementation raises the cancellation exception before and after ReadAt when the token is signaled
Override in slow sources such as network or archive-backed inputs to poll the token between transport chunks
Deterministic replay wraps this method so recorded runs reproduce the same cancellation decisions