How to save text markup annotations in the Flutter PDF Viewer (SfPdfViewer) so that they appear again when reopened.

[minhto2811]

Use case

In the Flutter PDF Viewer (SfPdfViewer), users can add text markup annotations (such as highlights, underlines, and strikethroughs) to a document. To ensure these annotations persist after the app is closed and reopened, it is necessary to save the annotations data separately. Later, when the document is loaded again, the saved annotations must be re-imported into the viewer so they reappear as before.

Proposal

Support saving and restoring text markup annotations in the Flutter PDF Viewer (SfPdfViewer), allowing users to view previously added annotations when reopening the document.

[immankumarsync]

Hi @minhto2811,

We can save the annotation made in the PDF document using the PdfViewerController.saveDocument method.

You can use the bytes obtained from this method to replace the document from the original location.
Please try with the attached sample to achieve your requirement.

sfpdfviewer_gh2332.zip

[minhto2811]

I followed your instructions, but the saveDocument() function returns an empty array.

[minhto2811]

I followed your instructions, but the saveDocument() function returns an empty array.

[immankumarsync]

Hi @minhto2811,
We suspect that the PdfViewerController is not attached to the SfPdfViewer widget. Could you please check add the PdfViewerController property referring the below code snippet?

[minhto2811]

Update: I just tried again and it works. As you said, it wasn't attached to the view. Sorry for the inconvenience, and sincerely thank you for your support.

---

I'm certain that the PdfViewerController is attached to the SfPdfViewer widget — the debug values confirm that. Here's the relevant part of my code:

class PdfView extends StatelessWidget {
  const PdfView(
      {super.key,
      required this.path,
      required this.initialPageNumber,
      this.onPageChanged,
      required this.key1,
      this.onHyperlinkClicked,
      required this.controller});

  final String path;
  final int initialPageNumber;
  final void Function(PdfPageChangedDetails)? onPageChanged;
  final GlobalKey<SfPdfViewerState> key1;
  final Function(PdfHyperlinkClickedDetails)? onHyperlinkClicked;
  final PdfViewerController controller;



  @override
  Widget build(BuildContext context) {
    return SfPdfViewer.file(
      key: key1,
      File(path),
      initialPageNumber: initialPageNumber,
      onPageChanged: onPageChanged,
      onHyperlinkClicked: onHyperlinkClicked,
      controller: controller,
      canShowPageLoadingIndicator: false,
    );
  }
}