Flutter 嵌套地狱？不存在的，ConstraintLayout 来解救！（四）

7. margin Flutter Web 在线示例
 

margin.png

class MarginExample extends StatelessWidget {
  const MarginExample({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: ConstraintLayout(
        children: [
          Container(
            color: const Color(0xFF005BBB),
          ).applyConstraint(
            size: 50,
            topLeftTo: parent,
            margin: const EdgeInsets.only(
              left: 20,
              top: 100,
            ),
          ),
          Container(
            color: const Color(0xFFFFD500),
          ).applyConstraint(
            size: 100,
            top: sId(-1).bottom,
            right: parent.right.margin(100),
          ),
          Container(
            color: Colors.pink,
          ).applyConstraint(
            size: 50,
            topRightTo: parent.rightMargin(20).topMargin(50),
          ),
        ],
      ),
    );
  }
}

8. 图钉定位 Flutter Web 在线示例
 

pinned_position.gif

class PinnedPositionExampleState extends State<PinnedPositionExample> {
  late Timer timer;
  double angle = 0;

  @override
  void initState() {
    super.initState();
    timer = Timer.periodic(const Duration(milliseconds: 16), (_) {
      setState(() {
        angle++;
      });
    });
  }

  @override
  void dispose() {
    super.dispose();
    timer.cancel();
  }

  @override
  Widget build(BuildContext context) {
    ConstraintId anchor = ConstraintId('anchor');
    return Scaffold(
      appBar: const CustomAppBar(
        title: 'Pinned Position',
        codePath: 'example/pinned_position.dart',
      ),
      body: ConstraintLayout(
        children: [
          Container(
            color: Colors.yellow,
          ).applyConstraint(
            id: anchor,
            size: 200,
            centerTo: parent,
          ),
          Container(
            color: Colors.cyan,
          ).applyConstraint(
            size: 100,
            pinnedInfo: PinnedInfo(
              anchor,
              Anchor(0.2, AnchorType.percent, 0.2, AnchorType.percent),
              Anchor(1, AnchorType.percent, 1, AnchorType.percent),
              angle: angle,
            ),
          ),
          Container(
            color: Colors.orange,
          ).applyConstraint(
            size: 60,
            pinnedInfo: PinnedInfo(
              anchor,
              Anchor(1, AnchorType.percent, 1, AnchorType.percent),
              Anchor(0, AnchorType.percent, 0, AnchorType.percent),
              angle: 360 - angle,
            ),
          ),
          Container(
            color: Colors.black,
          ).applyConstraint(
            size: 60,
            pinnedInfo: PinnedInfo(
              anchor,
              Anchor(0.5, AnchorType.percent, 0.5, AnchorType.percent),
              Anchor(0.5, AnchorType.percent, 0.5, AnchorType.percent),
              angle: angle,
            ),
          ),
          Container(
            decoration: const BoxDecoration(
              color: Colors.red,
              borderRadius: BorderRadius.all(Radius.circular(10)),
            ),
          ).applyConstraint(
            size: 10,
            centerBottomRightTo: anchor,
          ),
          Container(
            decoration: const BoxDecoration(
              color: Colors.red,
              borderRadius: BorderRadius.all(Radius.circular(10)),
            ),
          ).applyConstraint(
            size: 10,
            centerTopLeftTo: anchor,
          ),
          Container(
            decoration: const BoxDecoration(
              color: Colors.red,
              borderRadius: BorderRadius.all(Radius.circular(10)),
            ),
          ).applyConstraint(
            size: 10,
            centerTo: anchor,
          )
        ],
      ),
    );
  }
}

9. 平移 Flutter Web 在线示例
 

translate.gif

class TrackPainter extends CustomPainter {
  Queue<Offset> points = Queue();
  Paint painter = Paint();

  TrackPainter(this.points);

  @override
  void paint(Canvas canvas, Size size) {
    canvas.drawPoints(PointMode.polygon, points.toList(), painter);
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) => true;
}

class TranslateExampleState extends State<TranslateExample> {
  late Timer timer;
  double angle = 0;
  double earthRevolutionAngle = 0;
  Queue<Offset> points = Queue();

  @override
  void initState() {
    super.initState();
    timer = Timer.periodic(const Duration(milliseconds: 16), (_) {
      setState(() {
        angle += 1;
        earthRevolutionAngle += 0.1;
      });
    });
  }

  @override
  void dispose() {
    super.dispose();
    timer.cancel();
  }

  @override
  Widget build(BuildContext context) {
    ConstraintId anchor = ConstraintId('anchor');
    return Scaffold(
      appBar: const CustomAppBar(
        title: 'Translate',
        codePath: 'example/translate.dart',
      ),
      body: ConstraintLayout(
        children: [
          CustomPaint(
            painter: TrackPainter(points),
          ).applyConstraint(
            width: matchParent,
            height: matchParent,
          ),
          Container(
            decoration: const BoxDecoration(
              color: Colors.redAccent,
              borderRadius: BorderRadius.all(Radius.circular(1000)),
            ),
            child: const Text('----'),
            alignment: Alignment.center,
          ).applyConstraint(
            id: cId('sun'),
            size: 200,
            pinnedInfo: PinnedInfo(
              parent,
              Anchor(0.5, AnchorType.percent, 0.5, AnchorType.percent),
              Anchor(0.3, AnchorType.percent, 0.5, AnchorType.percent),
              angle: earthRevolutionAngle * 365 / 25.4,
            ),
          ),
          Container(
            decoration: const BoxDecoration(
              color: Colors.blue,
              borderRadius: BorderRadius.all(Radius.circular(1000)),
            ),
            child: const Text('----'),
            alignment: Alignment.center,
          ).applyConstraint(
            id: cId('earth'),
            size: 100,
            pinnedInfo: PinnedInfo(
              cId('sun'),
              Anchor(0.5, AnchorType.percent, 0.5, AnchorType.percent),
              Anchor(0.5, AnchorType.percent, 0.5, AnchorType.percent),
              angle: earthRevolutionAngle * 365,
            ),
            translate: circleTranslate(
              radius: 250,
              angle: earthRevolutionAngle,
            ),
            translateConstraint: true,
          ),
          Container(
            decoration: const BoxDecoration(
              color: Colors.grey,
              borderRadius: BorderRadius.all(Radius.circular(1000)),
            ),
            child: const Text('----'),
            alignment: Alignment.center,
          ).applyConstraint(
            id: cId('moon'),
            size: 50,
            pinnedInfo: PinnedInfo(
              cId('earth'),
              Anchor(0.5, AnchorType.percent, 0.5, AnchorType.percent),
              Anchor(0.5, AnchorType.percent, 0.5, AnchorType.percent),
              angle: earthRevolutionAngle * 365 / 27.32,
            ),
            translate: circleTranslate(
              radius: 100,
              angle: earthRevolutionAngle * 365 / 27.32,
            ),
            translateConstraint: true,
            paintCallback: (_, __, ____, offset, ______) {
              points.add(offset!);
              if (points.length > 2000) {
                points.removeFirst();
              }
            },
          ),
          Text('Sun rotates ${(earthRevolutionAngle * 365 / 25.4) ~/ 360} times')
              .applyConstraint(
            outTopCenterTo: cId('sun'),
          ),
          Text('Earth rotates ${earthRevolutionAngle * 365 ~/ 360} times')
              .applyConstraint(
            outTopCenterTo: cId('earth'),
          ),
          Text('Moon rotates ${(earthRevolutionAngle * 365 / 27.32) ~/ 360} times')
              .applyConstraint(
            outTopCenterTo: cId('moon'),
          ),
          Container(
            color: Colors.yellow,
          ).applyConstraint(
            id: anchor,
            size: 250,
            centerRightTo: parent.rightMargin(300),
          ),
          Container(
            color: Colors.red,
            child: const Text('pinned translate'),
          ).applyConstraint(
            centerTo: anchor,
            translate: PinnedTranslate(
              PinnedInfo(
                null,
                Anchor(0.5, AnchorType.percent, 0.5, AnchorType.percent),
                null,
                angle: angle,
              ),
            ),
          ),
          Container(
            color: Colors.blue,
            child: const Text('circle translate'),
          ).applyConstraint(
            size: wrapContent,
            centerTo: anchor,
            translate: circleTranslate(
              radius: 100,
              angle: angle,
            ),
          ),
          Container(
            color: Colors.cyan,
            child: const Text('pinned & circle translate'),
          ).applyConstraint(
            centerTo: anchor,
            translate: PinnedTranslate(
              PinnedInfo(
                null,
                Anchor(0.5, AnchorType.percent, 0.5, AnchorType.percent),
                null,
                angle: angle,
              ),
            ) +
                circleTranslate(
                  radius: 150,
                  angle: angle,
                ),
          ),
          Container(
            color: Colors.orange,
            child: const Text('normal translate'),
          ).applyConstraint(
            size: wrapContent,
            outBottomCenterTo: anchor,
            translate: Offset(0, angle / 5),
          )
        ],
      ),
    );
  }
}

文章转自公众号：FlutterFirst