node_widget.dart

// Copyright 2020 the Dart project authors.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd

import 'package:flutter/material.dart';

import 'builder.dart';
import 'primitives/tree_controller.dart';
import 'primitives/tree_node.dart';

/// Widget that displays one [TreeNode] and its children.
class NodeWidget extends StatefulWidget {
  final TreeNode treeNode;
  final double? indent;
  final double? iconSize;
  final TreeController state;
  final Widget? primaryIcon;
  final Widget? secondaryIcon;

  const NodeWidget({
    Key? key,
    required this.treeNode,
    this.indent,
    required this.state,
    this.iconSize,
    this.primaryIcon,
    this.secondaryIcon,
  }) : super(key: key);

  @override
  _NodeWidgetState createState() => _NodeWidgetState();
}

class _NodeWidgetState extends State<NodeWidget> {
  bool get _isLeaf {
    return widget.treeNode.children == null || widget.treeNode.children!.isEmpty;
  }

  bool get _isExpanded {
    return widget.state.isNodeExpanded(widget.treeNode.key!);
  }

  @override
  Widget build(BuildContext context) {
    var icon = _isLeaf
        ? null
        : _isExpanded
            ? widget.secondaryIcon ?? Icon(Icons.expand_more)
            : widget.primaryIcon ?? Icon(Icons.chevron_right);

    var onIconPressed = _isLeaf ? null : () => setState(() => widget.state.toggleNodeExpanded(widget.treeNode.key!));

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Row(
          children: [
            Material(
              child: InkWell(
                borderRadius: BorderRadius.circular(2.00),
                child: SizedBox.square(
                  dimension: widget.iconSize ?? 24.0,
                  child: icon,
                ),
                onTap: onIconPressed,
              ),
            ),
            widget.treeNode.content,
          ],
        ),
        if (_isExpanded && !_isLeaf)
          Padding(
            padding: EdgeInsets.only(left: widget.indent!),
            child: buildNodes(
              widget.treeNode.children!,
              widget.indent,
              widget.state,
              widget.iconSize,
              widget.primaryIcon,
              widget.secondaryIcon,
            ),
          )
      ],
    );
  }
}