exportImage method
Generates Uint8List of the ui.Image generated by the renderImage()
method.
Can be converted to image file by writing as bytes.
Implementation
Future<Uint8List?> exportImage() async {
late ui.Image _convertedImage;
// questo fa un mix della foto in back + l'overlay
// final _boundary = _repaintKey.currentContext!.findRenderObject() as RenderRepaintBoundary;
// _convertedImage = await _boundary.toImage(pixelRatio: 3);
//a noi interessa SOLO _image (ns overlay puro)
_convertedImage = await _renderImage();
final byteData = await _convertedImage.toByteData(format: ui.ImageByteFormat.png);
return byteData?.buffer.asUint8List();
}