flutter-fqreader/lib/scan_view.dart

part of fqreader;

class ScanView extends StatefulWidget {
  /**
   * 扫描事件
   */
  final ScanEvent onScan;

  /**
   * 扫描区域大小
   */
  final Size scanSize;


  /**
   * 图片大小
   */
  final Size pictureSize;
  /**
   * ScanView控件大小
   */
  final Size viewSize;


  /**
   * 扫描框的位置(位于图片)
   */
  final Alignment scanAilgn;

  /**
   * view的位置(位于图片)
   */
  final Alignment viewAilgn;

  /**
   * 屏幕分辨率
   */
  final double devicePixelRatio;

  /**
   * 是否立即扫描
   */
  final bool autoScan;

  /**
   * 是否连续扫描
   */
  final bool continuityScan;

  /**
   * 连续扫描间隔
   */
  final Duration scanInterval;

  /**
   *  扫描的条码类型
   */
  final List<ScanType> scanType;

  const ScanView(
      {Key key,
      this.onScan,
      @required this.viewSize,
      @required this.pictureSize,
      @required this.scanSize,
      this.scanAilgn = Alignment.topLeft,
      this.viewAilgn = Alignment.topLeft,
      @required this.devicePixelRatio,
      this.scanType = const [ScanType.ALL],
      this.autoScan = true,
      this.continuityScan = false,
      this.scanInterval = const Duration(milliseconds: 500)})
      : super(key: key);

  @override
  State<StatefulWidget> createState() => ScanViewState();
}

class ScanViewState extends State<ScanView> {
  int _textureId;
  StreamSubscription _readySubscription;
  Size _cameraSize;

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    if(widget.autoScan){
      this.startScan();
    }
  }

  @override
  Widget build(BuildContext context) {
    return _textureId != null
        ? new _ScanViewTexture(
            textureId: _textureId,
            cameraSize: _cameraSize,
            viewRect: _getViewRect(_cameraSize, widget.viewSize, widget.viewAilgn),
          )
        : new Container();
  }

  Rect _getViewRect(Size cameraSize, Size viewSize, Alignment alignment)
  {
    var offset = cameraSize - viewSize;
    return alignment.alongOffset(offset) & viewSize;
  }


  @override
  void deactivate() {
    // TODO: implement deactivate
    super.deactivate();
    _readySubscription.cancel();
    Fqreader._release();
  }

  /**
   * 开始扫描
   */
  Future startScan() async {
    if (this._textureId == null) {
      var initResult = await Fqreader._initView(
          viewSize: widget.pictureSize,
          devicePixelRatio: widget.devicePixelRatio,
          scanType: widget.scanType);
      _cameraSize = initResult.cameraSize;
      _textureId = initResult.textureID;
      Fqreader._setScanRect(_getViewRect(_cameraSize, widget.scanSize, widget.scanAilgn), widget.devicePixelRatio);
      _readySubscription = new EventChannel('fqreader/scanEvents$_textureId')
          .receiveBroadcastStream()
          .listen(_listener);
      setState(() {
        
      });
    }
    await Fqreader._startScan();
  }

  /**
   * 暂停扫描
   */
  Future stopScan() async {
    await Fqreader._stopScan();
  }

  /**
   * 开灯
   */
  Future turnOn() async {
    await Fqreader._turnOn();
  }

  /**
   * 关灯
   */
  Future turnOff() async {
    await Fqreader._turnOff();
  }

  Future release() async {
    this._textureId = null;
    Fqreader._release();
  }

  void _listener(dynamic value) {
    if (widget != null) {
      if (!widget.continuityScan) //是否连续扫描
      {
        Fqreader._stopScan();
      }

      var result = ScanResult(
        scanType: _parseScanType(value['scanType']),
        data: value['data'],
      );
      widget.onScan(result).then((result) {
        if (widget.continuityScan && result) {
          Future.delayed(widget.scanInterval, () {
            Fqreader._startScan();
          });
        } else {
          Fqreader._stopScan();
        }
      });
    }
  }
}

class _ScanViewTexture extends LeafRenderObjectWidget {
  final Size cameraSize;
  final Rect viewRect;

  /// Creates a widget backed by the texture identified by [textureId].
  const _ScanViewTexture({
    Key key,
   @required  this.cameraSize,
   @required  this.viewRect,
    @required this.textureId,
  })  : assert(textureId != null),
        super(key: key);

  /// The identity of the backend texture.
  final int textureId;

  @override
  _ScanViewTextureBox createRenderObject(BuildContext context) =>
      _ScanViewTextureBox(textureId: textureId, cameraSize: cameraSize, viewRect: viewRect);

  @override
  void updateRenderObject(
      BuildContext context, _ScanViewTextureBox renderObject) {
    renderObject.textureId = textureId;
    renderObject.cameraSize = cameraSize;
    renderObject.viewRect = viewRect;
  }
}

class _ScanViewTextureBox extends RenderBox {
  /// Creates a box backed by the texture identified by [textureId].
  _ScanViewTextureBox({@required int textureId, @required Size cameraSize,@required  Rect viewRect})
      : assert(textureId != null),
       assert(viewRect != null),
       assert(cameraSize != null),
        _textureId = textureId,
        _cameraSize = cameraSize,
        _viewRect = viewRect;

  /// The identity of the backend texture.
  int get textureId => _textureId;
  int _textureId;
  set textureId(int value) {
    assert(value != null);
    if (value != _textureId) {
      _textureId = value;
      markNeedsPaint();
    }
  }

  Size get cameraSize => _cameraSize;
  Size _cameraSize;
  set cameraSize(Size value) {
    assert(value != null);
    if (value != _cameraSize) {
      _cameraSize = value;
      markNeedsPaint();
    }
  }

  Rect get viewRect => _viewRect;
  Rect _viewRect;
  set viewRect(Rect value) {
    assert(value != null);
    if (value != _viewRect) {
      _viewRect = value;
      markNeedsPaint();
    }
  }
  @override
  bool get sizedByParent => true;

  @override
  bool get alwaysNeedsCompositing => true;

  @override
  bool get isRepaintBoundary => true;

  @override
  void performResize() {
    size = viewRect.size;
  }

  @override
  bool hitTestSelf(Offset position) => true;

  @override
  void paint(PaintingContext context, Offset offset) {
    if (_textureId == null) return;
    // context.addLayer(TextureLayer(
    //   rect: Rect.fromLTWH(offset.dx, offset.dy, _viewSize.width, _viewSize.height),
    //   textureId: _textureId,
    // ));
    print(_cameraSize);
    context.pushClipRect(
        needsCompositing, offset, viewRect,
        (PaintingContext context, Offset offset) {
      context.addLayer(TextureLayer(
        rect: Rect.fromLTWH(
            offset.dx, offset.dy, _cameraSize.width, _cameraSize.height),
        textureId: _textureId,
      ));
    });
  }
}