回调函数 应用

定义函数

getFiles(DirNode dir) {

print("getFiles");

files = [];

var list = FileProvider.listFiles(Directory(dir.path));


files.addall(list);

}

定义回调函数 的引用 方便传递函数

void Function(DirNode) onGetFiles;

在 点击事件中调用 回调函数

if (onGetFiles != null) {

print("object");

onGetFiles!(node);

}

},

关联回调函数和 函数体

Widget leftPanel(ExpandedTileController? controller){

var tile = RecursiveExpandedTile(_currentDir!, (DirNode dir) {

getFiles(dir);

}, hideHeadOnFirstCall: true, controller: controller);


return Container(

alignment: Alignment.topLeft,

width: _showLeftPanel ? width : 0,

child:  tile,

);

}

class RecursiveExpandedTile extends StatelessWidget {

final DirNode node;

final bool hideHeadOnFirstCall;

ExpandedTileController? controller;

void Function(DirNode) onGetFiles;

  

RecursiveExpandedTile(

this.node,

this.onGetFiles, {

this.hideHeadOnFirstCall = false,

this.controller,

});


@override

Widget build(BuildContext context) {

final tileController =

controller ?? ExpandedTileController(isExpanded: false);

return ExpandedTile(

enabled: false,

hiddenHead: hideHeadOnFirstCall,

isExpanded: controller != null ? true : false,

onTap: () {

print("dirNode.name: ${node.name}");

if (onGetFiles != null) {

print("object");

onGetFiles!(node);

}

},

title: Text(node.name),

leading: node.children.isNotEmpty ? null : Container(),

content: Column(

children: node.children

?.map((child) => RecursiveExpandedTile(child, onGetFiles))

?.toList() ??

[],

),

controller: tileController,

);

}

}