Coordinate conversion in the Flutter PDF viewer

PDF documents and Flutter views use different coordinate spaces. The PDF coordinate system starts in the bottom-left corner, and y values increase upward. Flutter view coordinates start in the top-left corner, and y values increase downward.

Nutrient Flutter SDK provides coordinate conversion APIs on NutrientController to map between these coordinate spaces on Android and iOS. Refer to the Nutrient controller(opens in a new tab) API reference for details.

Convert view coordinates to PDF coordinates

Use convertViewPointToPdfPoint to convert a point from the view coordinate space to the PDF page coordinate space. The input point uses logical pixel coordinates relative to the upper-left corner of the rendered page:

NutrientDocumentView(
  documentPath: documentPath,
  onControllerReady: (controller) {
    controller.events.documentLoaded.listen((_) async {
      final pdfPoint = await controller.convertViewPointToPdfPoint(
        0, // `pageIndex` (zero-based).
        const Offset(150.0, 300.0),
      );

      print('PDF coordinates: (${pdfPoint.dx}, ${pdfPoint.dy})');
    });
  },
)

Convert PDF coordinates to view coordinates

Use convertPdfPointToViewPoint to convert a point from the PDF page coordinate space to the view coordinate space. The returned Offset uses logical pixel coordinates relative to the upper-left corner of the rendered page.

final viewPoint = await controller.convertPdfPointToViewPoint(
  0, // `pageIndex` (zero-based).
  const Offset(72.0, 720.0),
);

print('View coordinates: (${viewPoint.dx}, ${viewPoint.dy})');

For more information about PDF coordinate spaces, refer to the web coordinate spaces guide.