luojigou_battle/packages/widget/lib/src/battle_layout.dart

import 'package:flutter/widgets.dart';
import 'package:widget/src/constant.dart';

import 'battle_background.dart';
import 'battle_foreground.dart';

enum _BattleSlot {
  background,
  card,
  foreground,
  topRightLogo,
  bottomLeftLogo,
  bottomRightLogo,
  button,
}

class _BattleLayoutDelegate extends MultiChildLayoutDelegate {
  @override
  void performLayout(Size size) {
    final constraints = BoxConstraints.loose(size);

    double boardWidth = size.width * kBoardWidthAspectRatio;
    double boardHeight = size.height * kBoardHeightAspectRatio;
    final boardConstraints = BoxConstraints.loose(Size(boardWidth, boardHeight));
    layoutChild(_BattleSlot.background, boardConstraints);
    positionChild(_BattleSlot.background, Offset(size.width - boardWidth, size.height - boardHeight));
    layoutChild(_BattleSlot.foreground, boardConstraints);
    positionChild(_BattleSlot.foreground, Offset(size.width - boardWidth, size.height - boardHeight));

    double cardWidth = size.width * kCardWidthAspectRatio;
    double cardHeight = size.height * kCardHeightAspectRatio;
    double leftPadding = size.width * kLeftBorderAspectRatio;
    double coverPadding = size.width * kCardCoverAspectRatio;
    final cardConstraints = BoxConstraints.loose(Size(cardWidth, cardHeight));
    layoutChild(_BattleSlot.card, cardConstraints);
    positionChild(_BattleSlot.card, Offset(leftPadding - coverPadding, 0));

    layoutChild(_BattleSlot.button, boardConstraints);
    positionChild(_BattleSlot.button, Offset(size.width - boardWidth, size.height - boardHeight));

  }

  @override
  bool shouldRelayout(_BattleLayoutDelegate oldDelegate) => false;
}

class BattleBoard extends StatefulWidget {
  final Widget card;
  final Widget button;

  const BattleBoard({
    super.key,
    required this.card,
    required this.button,
  });

  @override
  State<BattleBoard> createState() => _BattleBoardState();
}

class _BattleBoardState extends State<BattleBoard> {
  void _addWithSlot(List<LayoutId> children, _BattleSlot slot, Widget child) {
    children.add(LayoutId(id: slot, child: child));
  }

  @override
  Widget build(BuildContext context) {
    List<LayoutId> children = <LayoutId>[];

    const Widget foreground = BattleForeground();
    const Widget background = BattleBackground();

    children.add(LayoutId(id: _BattleSlot.background, child: background));
    children.add(LayoutId(id: _BattleSlot.card, child: widget.card));
    children.add(LayoutId(id: _BattleSlot.foreground, child: foreground));
    children.add(LayoutId(id: _BattleSlot.button, child: widget.button));

    return Center(
      child: AspectRatio(
        aspectRatio: kTextureAspectRatio,
        child: CustomMultiChildLayout(
          delegate: _BattleLayoutDelegate(),
          children: children,
        ),
      ),
    );
  }
}