Created
July 8, 2019 13:06
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添加一个半透明"引导"
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import 'package:flutter/material.dart'; | |
class Mask extends StatefulWidget { | |
final Function onTap; | |
final Rect rect; | |
const Mask({Key key, this.onTap, this.rect}) : super(key: key); | |
@override | |
_MaskState createState() => _MaskState(); | |
} | |
class _MaskState extends State<Mask> { | |
@override | |
Widget build(BuildContext context) { | |
return GestureDetector( | |
onTap: widget.onTap, | |
child: Stack( | |
children: <Widget>[ | |
ClipPath( | |
child: Container( | |
width: double.infinity, | |
height: double.infinity, | |
color: Colors.black.withOpacity(0.5), | |
), | |
clipper: getClip(), | |
), | |
GestureDetector( | |
behavior: HitTestBehavior.opaque, | |
child: Container( | |
width: widget.rect.width, | |
height: widget.rect.height, | |
margin: EdgeInsets.only( | |
left: widget.rect.left, | |
top: widget.rect.top, | |
), | |
), | |
onTap: widget.onTap, | |
), | |
], | |
), | |
); | |
} | |
CustomClipper<Path> getClip() { | |
return MyClipper(widget.rect); | |
} | |
} | |
class MyClipper extends CustomClipper<Path> { | |
Rect rect; | |
MyClipper(this.rect); | |
@override | |
Path getClip(Size size) { | |
print(size); | |
return Path() | |
..addRect(Rect.fromLTRB(0, 0, size.width, rect.top)) | |
..addRect(Rect.fromLTRB(0, 0, rect.left, size.height)) | |
..addRect(Rect.fromLTRB(rect.right, 0, size.width, size.height)) | |
..addRect(Rect.fromLTRB(0, rect.bottom, size.width, size.height)); | |
} | |
@override | |
bool shouldReclip(CustomClipper<Path> oldClipper) { | |
return true; | |
} | |
} | |
void showMask(GlobalKey key) { | |
var rect = findGlobalRect(key); | |
final overlay = Overlay.of(key.currentContext); | |
OverlayEntry entry; | |
entry = OverlayEntry(builder: (BuildContext context) { | |
return Mask( | |
rect: rect, | |
onTap: () { | |
entry.remove(); | |
}, | |
); | |
}); | |
overlay.insert(entry); | |
} | |
Rect findGlobalRect(GlobalKey key) { | |
RenderBox renderObject = key.currentContext?.findRenderObject(); | |
if (renderObject == null) { | |
return null; | |
} | |
var globalOffset = renderObject?.localToGlobal(Offset.zero); | |
if (globalOffset == null) { | |
return null; | |
} | |
var bounds = renderObject.paintBounds; | |
bounds = bounds.translate(globalOffset.dx, globalOffset.dy); | |
return bounds; | |
} |
Author
CaiJingLong
commented
Jul 8, 2019
需要配合GlobalKey使用
可以结合首帧监听或延迟几百毫秒使用
上面截图对应例子:
main.dart
import 'package:flutter/material.dart';
import 'guide_mask.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
// This widget is the home page of your application. It is stateful, meaning
// that it has a State object (defined below) that contains fields that affect
// how it looks.
// This class is the configuration for the state. It holds the values (in this
// case the title) provided by the parent (in this case the App widget) and
// used by the build method of the State. Fields in a Widget subclass are
// always marked "final".
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
// This call to setState tells the Flutter framework that something has
// changed in this State, which causes it to rerun the build method below
// so that the display can reflect the updated values. If we changed
// _counter without calling setState(), then the build method would not be
// called again, and so nothing would appear to happen.
_counter++;
});
}
var key = GlobalKey();
@override
void initState() {
super.initState();
Future.delayed(Duration(seconds: 1), () {
showMask(key);
});
}
@override
Widget build(BuildContext context) {
// This method is rerun every time setState is called, for instance as done
// by the _incrementCounter method above.
//
// The Flutter framework has been optimized to make rerunning build methods
// fast, so that you can just rebuild anything that needs updating rather
// than having to individually change instances of widgets.
return Scaffold(
appBar: AppBar(
// Here we take the value from the MyHomePage object that was created by
// the App.build method, and use it to set our appbar title.
title: Text(widget.title),
),
body: Center(
// Center is a layout widget. It takes a single child and positions it
// in the middle of the parent.
child: Column(
// Column is also layout widget. It takes a list of children and
// arranges them vertically. By default, it sizes itself to fit its
// children horizontally, and tries to be as tall as its parent.
//
// Invoke "debug painting" (press "p" in the console, choose the
// "Toggle Debug Paint" action from the Flutter Inspector in Android
// Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
// to see the wireframe for each widget.
//
// Column has various properties to control how it sizes itself and
// how it positions its children. Here we use mainAxisAlignment to
// center the children vertically; the main axis here is the vertical
// axis because Columns are vertical (the cross axis would be
// horizontal).
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.display1,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
key: key,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
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