Flutter 添加appBar时绘制的线条发生偏移 Flu

我正在制作一款Ffltter的绘图应用程序.当我把它放在只有家的脚手架上时，我可以正常地画一条线.但问题是，当我添加一个AppBar时，行从顶部向下偏移，它不是我在屏幕上touch 的位置，它与App bar的高度一样向下移动.

这是我的代码.

class HiraganaWriting extends StatefulWidget {
  const HiraganaWriting({Key? key}) : super(key: key);

  @override
  State<HiraganaWriting> createState() => _HiraganaWritingState();
}

class _HiraganaWritingState extends State<HiraganaWriting> {
  final GlobalKey _globalKey = GlobalKey();
  List<DrawnLine> lines = <DrawnLine>[];
  DrawnLine line = DrawnLine([Offset(50, 50)], Colors.black, 5.0);
  Color selectedColor = Colors.black;
  double selectedWidth = 5.0;

  StreamController<List<DrawnLine>> linesStreamController = StreamController<List<DrawnLine>>.broadcast();
  StreamController<DrawnLine> currentLineStreamController = StreamController<DrawnLine>.broadcast();

  String picName = "Hi";

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("AppBar"),
      ),
      body: Container(
        child: Stack(
          children: [
            buildAllPaths(context),
            buildCurrentPath(context),
          ],
        ),
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: [
          BottomNavigationBarItem(icon: Icon(Icons.arrow_back), label: ""),
          BottomNavigationBarItem(icon: Icon(Icons.arrow_back), label: ""),
          BottomNavigationBarItem(icon: Icon(Icons.arrow_back), label: ""),
          BottomNavigationBarItem(icon: Icon(Icons.arrow_back), label: ""),
        ],
      ),
    );
  }

  Widget buildAllPaths(BuildContext context) {
    return RepaintBoundary(
      key: _globalKey,
      child: Container(
        width: MediaQuery.of(context).size.width,
        height: MediaQuery.of(context).size.height,
        color: Colors.transparent,
        padding: EdgeInsets.all(4),
        alignment: Alignment.topLeft,
        child: StreamBuilder<List<DrawnLine>>(
          stream: linesStreamController.stream,
          builder: (context, snapshot) {
            return CustomPaint(
              painter: Sketcher(
                lines: lines,
              ),
            );
          },
        ),
      ),
    );
  }

  Widget buildCurrentPath(BuildContext context) {
    return GestureDetector(
      onPanStart: onPanStart,
      onPanUpdate: onPanUpdate,
      onPanEnd: onPanEnd,
      child: RepaintBoundary(
        child: Container(
          width: MediaQuery.of(context).size.width,
          height: MediaQuery.of(context).size.height,
          padding: EdgeInsets.all(4),
          color: Colors.transparent,
          alignment: Alignment.topLeft,
          child: StreamBuilder<DrawnLine>(
            stream: currentLineStreamController.stream,
            builder: (context, snapshot) {
              return CustomPaint(
                painter: Sketcher(
                  lines: [line],
                ),
              );
            },
          ),
        ),
      ),
    );
  }

  void onPanStart(DragStartDetails details) {
    RenderBox? box = context.findRenderObject() as RenderBox?;
    Offset point = box!.globalToLocal(details.globalPosition);
    line = DrawnLine([point], selectedColor, selectedWidth);
  }

  void onPanUpdate(DragUpdateDetails details) {
    RenderBox? box = context.findRenderObject() as RenderBox?;
    Offset point = box!.globalToLocal(details.globalPosition);

    List<Offset> path = List.from(line.path)..add(point);
    line = DrawnLine(path, selectedColor, selectedWidth);
    currentLineStreamController.add(line);
  }

  void onPanEnd(DragEndDetails details) {
    lines = List.from(lines)..add(line);

    linesStreamController.add(lines);
  }
}

enter image description here个

我试着换了衬垫，或者把Container放进了一个大小的盒子里，...但它的工作方式有误