capturePng function
Implementation
Future<Uint8List> capturePng(GlobalKey globalKey) async {
RenderRepaintBoundary boundary =
globalKey.currentContext!.findRenderObject() as RenderRepaintBoundary;
ui.Image image = await boundary.toImage();
ByteData byteData =
(await (image.toByteData(format: ui.ImageByteFormat.png)))!;
Uint8List pngBytes = byteData.buffer.asUint8List();
return pngBytes;
}