luojigou_thinking_core/example/lib/demo/demo2.dart

import 'dart:ui';

import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

class Demo2 extends StatefulWidget {
  const Demo2({Key? key}) : super(key: key);

  @override
  State<Demo2> createState() => _Demo2State();
}

class _Demo2State extends State<Demo2> {
  late ScrollController _scrollController;

  @override
  void initState() {
    super.initState();
    _scrollController = ScrollController();
  }

  @override
  Widget build(BuildContext context) {
    return Row(
      children: [
        ColoredBox(
          color: const Color(0xFFC8DDFF),
          child: SizedBox(
            width: 55,
            child: ListView.builder(
              itemBuilder: (context, index) {
                return CustomPaint(
                  painter: index == 2 ? _Painter() : null,
                  child: SizedBox(
                    width: double.infinity,
                    height: 100,
                    child: Center(child: Text("Hello $index")),
                  ),
                );
              },
            ),
          ),
        ),
        Expanded(
          child: Column(
            children: [
              Expanded(
                child: Container(
                  color: Colors.yellow,
                ),
              ),
              const Expanded(
                child: TestWidget(
                  child: TestWidget(),
                ),
              ),
              Expanded(
                child: Container(
                  color: Colors.lightGreen,
                ),
              ),
              Expanded(
                child: Container(
                  color: Colors.redAccent,
                ),
              ),
            ],
          ),
        ),
      ],
    );
  }
}

const double _width = 18.74;
const double _height = 158.41;

class _Painter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    canvas.drawCircle(
      Offset(size.width - 5 - 2, size.height / 2),
      2,
      Paint()..color = Colors.green,
    );

    var path = Path();
    path.reset();
    path.moveTo(size.width, size.height / 2 - 20);
    path.lineTo(size.width + 20, size.height / 2);
    path.lineTo(size.width, size.height / 2 + 20);
    path.close();

    canvas.drawPath(
      path,
      Paint()
        ..color = Colors.blue
        ..style = PaintingStyle.fill,
    );
    // canvas.drawRect(Offset.zero & size, Paint()..color = Colors.green);
  }

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

class TestWidget extends SingleChildRenderObjectWidget {
  const TestWidget({
    Key? key,
    Widget? child,
  }) : super(key: key, child: child);

  @override
  RenderObject createRenderObject(BuildContext context) {
    return _RenderTest();
  }
}

class _RenderTest extends RenderBox with RenderObjectWithChildMixin<RenderBox> {
  @override
  void performLayout() {
    child?.layout(constraints.deflate(const EdgeInsets.all(20)));
    size = constraints.constrain(Size.infinite);
  }

  @override
  Size computeDryLayout(BoxConstraints constraints) {
    return constraints.constrain(Size.infinite);

    Listener listener;
  }

  @override
  void paint(PaintingContext context, Offset offset) {
    super.paint(context, offset);
    Color color;
    if (parent is _RenderTest) {
      if (_touchOffset != null) {
        color = Colors.black;
      } else {
        color = Colors.red;
      }
    } else {
      if (_touchOffset != null) {
        color = Colors.tealAccent;
      } else {
        color = Colors.deepPurple;
      }
    }

    context.canvas.drawRect(offset & size, Paint()
      ..color = color);
    if (child != null) {
      context.paintChild(child!, offset);
    }
  }

  @override
  bool hitTestChildren(BoxHitTestResult result, {required Offset position}) {
    if(child != null){
      return child!.hitTest(result, position: position);
    }
    return super.hitTestChildren(result, position: position);
  }

  @override
  bool hitTestSelf(Offset position) => size.contains(position);

  Offset? _touchOffset;

  GestureRecognizer gestureDetector = TapGestureRecognizer()
    ..onTap = () {
      debugPrint("TapGestureRecognizer onTap");
    }
    ..onTapDown = (details) {
      debugPrint("TapGestureRecognizer onTapDown");
    }
    ..onTapUp = (details) {
      debugPrint("TapGestureRecognizer onTapUp");
    }
    ..onTapCancel = () {
      debugPrint("TapGestureRecognizer onTapCancel");
    };

  @override
  void handleEvent(PointerEvent event, covariant HitTestEntry entry) {
    debugPrint(event.runtimeType.toString());
    debugPrint(event.position.toString());
    if (event is PointerDownEvent) {
      _touchOffset = event.localPosition;
      gestureDetector.addPointer(event);
    } else if (event is PointerMoveEvent) {
      _touchOffset = event.localPosition;
    } else {
      _touchOffset = null;
    }

    markNeedsPaint();
  }
}