readPage method

Future<RitoPageRecords> readPage(RitoPreparedArtifact prepared, int pageIndex)

What page pageIndex of prepared holds for a host: its interaction targets, semantic outline, text and text runs. An artifact carries only its pages' index and size; the engine builds these when a host first asks, the way a browser hit-tests the fragments it painted when a pointer arrives. Hit-test a tap with RitoHitResolver over the records of the pages it may land on.

Implementation

Future<RitoPageRecords> readPage(
  RitoPreparedArtifact prepared,
  int pageIndex,
) async {
  _requireOpen();
  final artifact = prepared.artifact;
  _requireLiveArtifact(artifact);
  if (!artifact.pages.any((page) => page.pageIndex == pageIndex)) {
    throw ArgumentError.value(
      pageIndex,
      'pageIndex',
      'is not a page of the artifact',
    );
  }
  late final RitoPageRecords records;
  try {
    records = await gateway.readPage(
      sessionId: sessionId,
      artifactId: artifact.artifactId,
      pageIndex: pageIndex,
    );
  } on RitoNativeSessionInvalidatedException catch (error, stackTrace) {
    return _failClosedAfterCleanupFailure(
      requestId: error.requestId,
      cleanupError: error,
      cleanupStackTrace: stackTrace,
    );
  }
  _requireOpen();
  if (records.artifactId != artifact.artifactId ||
      records.pageIndex != pageIndex) {
    throw StateError('Page records ownership does not match the artifact.');
  }
  return records;
}