我正在尝试用PageView在Flutter中实现一个自定义的BottomNavigationBar,用于在同一支架中包含有状态小部件的不同页面之间滑动。
虽然我可以点击navbar并更改页面,但我无法在更改指示所选页面的icon_button的颜色的同时实现pageview滑动手势。我能够完美地使用BottomNavigationBarItem来完成此操作,但我想使用自定义设计。
包含不同Icon_buttons的Stack小部件是否可以转换为BottomNavigationBarItem,这样我们就可以使用onTap和currentindex函数来使其更简单?出路何在?
import 'package:app/screens/screens.dart';
import 'package:flutter/material.dart';
class AppBottomNav extends StatefulWidget {
AppBottomNav({Key key}) : super(key: key);
@override
_AppBottomNavState createState() => _AppBottomNavState();
}
class _AppBottomNavState extends State<AppBottomNav> {
int currentIndex = 0;
var pages = [HomeScreen(), HistoryScreen(), ScanScreen(),
BleConnectionScreen(), AccountScreen()];
var _appPageController = PageController();
setBottomBarIndex(index) {
setState(() {
currentIndex = index;
});
}
@override
Widget build(BuildContext context) {
final Size size = MediaQuery.of(context).size;
return Scaffold(
backgroundColor: Colors.white.withAlpha(100),
body: PageView(
scrollDirection: Axis.horizontal,
children: pages,
onPageChanged: (index) {
setState(() {
currentIndex = index;
});
},
controller: _appPageController,
),
bottomNavigationBar:
Stack(
children: [
Positioned(
bottom: 0,
left: 0,
child: Container(
width: size.width,
height: 80,
child: Stack(
overflow: Overflow.visible,
children: [
CustomPaint(
size: Size(size.width, 80),
painter: BNBCustomPainter(),
),
Center(
heightFactor: 0.6,
child: FloatingActionButton(backgroundColor: Colors.green[700],
child: Icon(Icons.search), // Analyze Button
elevation: 0.1,
onPressed: () {}),
),
Container(
width: size.width,
height: 80,
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
IconButton(
icon: Icon(
Icons.home,
color: currentIndex == 0 ? Colors.green[700] : Colors.grey.shade400,
),
onPressed: () {
setBottomBarIndex(0);
},
splashColor: Colors.white,
),
IconButton(
icon: Icon(
Icons.history,
color: currentIndex == 1 ? Colors.green[700] : Colors.grey.shade400,
),
onPressed: () {
setBottomBarIndex(1);
}),
Container(
width: size.width * 0.20,
),
IconButton(
icon: Icon(
Icons.bluetooth,
color: currentIndex == 2 ? Colors.green[700] : Colors.grey.shade400,
),
onPressed: () {
setBottomBarIndex(2);
}),
IconButton(
icon: Icon(
Icons.account_circle,
color: currentIndex == 3 ? Colors.green[700] : Colors.grey.shade400,
),
onPressed: () {
setBottomBarIndex(3);
}),
],
),
)
],
),
),
)
],
),
);
}
void _onTappedBar(int value) {
setState(() {
currentIndex = value;
});
_appPageController.jumpToPage(value);
}
}
class BNBCustomPainter extends CustomPainter {
@override
void paint(Canvas canvas, Size size) {
Paint paint = new Paint()
..color = Colors.white
..style = PaintingStyle.fill;
Path path = Path();
path.moveTo(0, 20); // Start
path.quadraticBezierTo(size.width * 0.20, 0, size.width * 0.35, 0);
path.quadraticBezierTo(size.width * 0.40, 0, size.width * 0.40, 20);
path.arcToPoint(Offset(size.width * 0.60, 20), radius: Radius.circular(20.0), clockwise: false);
path.quadraticBezierTo(size.width * 0.60, 0, size.width * 0.65, 0);
path.quadraticBezierTo(size.width * 0.80, 0, size.width, 20);
path.lineTo(size.width, size.height);
path.lineTo(0, size.height);
path.lineTo(0, 20);
canvas.drawShadow(path, Colors.black, 5, true);
canvas.drawPath(path, paint);
}
@override
bool shouldRepaint(CustomPainter oldDelegate) {
return false;
}
}
您可以在下面复制、粘贴、运行完整代码
步骤1:您可以在BottomNavigationBar
中删除堆栈
和定位
并且只使用容器
步骤2:SetBottomBarindex
使用_AppPageController.AnimateTopage
代码段
bottomNavigationBar: Container(
width: size.width,
height: 80,
child: Stack(
//overflow: Overflow.visible,
children: [
CustomPaint(
...
setBottomBarIndex(index) {
setState(() {
currentIndex = index;
});
_appPageController.animateToPage(index,
duration: Duration(milliseconds: 500), curve: Curves.ease);
}
工作演示
完整代码
import 'package:flutter/material.dart';
class AppBottomNav extends StatefulWidget {
AppBottomNav({Key key}) : super(key: key);
@override
_AppBottomNavState createState() => _AppBottomNavState();
}
class _AppBottomNavState extends State<AppBottomNav> {
int currentIndex = 0;
var pages = [
HomeScreen(),
HistoryScreen(),
ScanScreen(),
BleConnectionScreen(),
AccountScreen()
];
var _appPageController = PageController();
setBottomBarIndex(index) {
setState(() {
currentIndex = index;
});
_appPageController.animateToPage(index,
duration: Duration(milliseconds: 500), curve: Curves.ease);
}
@override
Widget build(BuildContext context) {
final Size size = MediaQuery.of(context).size;
return Scaffold(
backgroundColor: Colors.white.withAlpha(100),
body: PageView(
scrollDirection: Axis.horizontal,
children: pages,
onPageChanged: (index) {
setState(() {
currentIndex = index;
});
},
controller: _appPageController,
),
bottomNavigationBar: Container(
width: size.width,
height: 80,
child: Stack(
//overflow: Overflow.visible,
children: [
CustomPaint(
size: Size(size.width, 80),
painter: BNBCustomPainter(),
),
Center(
heightFactor: 0.6,
child: FloatingActionButton(
backgroundColor: Colors.green[700],
child: Icon(Icons.search), // Analyze Button
elevation: 0.1,
onPressed: () {}),
),
Container(
width: size.width,
height: 80,
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
IconButton(
icon: Icon(
Icons.home,
color: currentIndex == 0
? Colors.green[700]
: Colors.grey.shade400,
),
onPressed: () {
setBottomBarIndex(0);
},
splashColor: Colors.white,
),
IconButton(
icon: Icon(
Icons.history,
color: currentIndex == 1
? Colors.green[700]
: Colors.grey.shade400,
),
onPressed: () {
setBottomBarIndex(1);
}),
Container(
width: size.width * 0.20,
),
IconButton(
icon: Icon(
Icons.bluetooth,
color: currentIndex == 2
? Colors.green[700]
: Colors.grey.shade400,
),
onPressed: () {
setBottomBarIndex(2);
}),
IconButton(
icon: Icon(
Icons.account_circle,
color: currentIndex == 3
? Colors.green[700]
: Colors.grey.shade400,
),
onPressed: () {
setBottomBarIndex(3);
}),
],
),
)
],
),
),
);
}
void _onTappedBar(int value) {
setState(() {
currentIndex = value;
});
_appPageController.jumpToPage(value);
}
}
class BNBCustomPainter extends CustomPainter {
@override
void paint(Canvas canvas, Size size) {
Paint paint = new Paint()
..color = Colors.white
..style = PaintingStyle.fill;
Path path = Path();
path.moveTo(0, 20); // Start
path.quadraticBezierTo(size.width * 0.20, 0, size.width * 0.35, 0);
path.quadraticBezierTo(size.width * 0.40, 0, size.width * 0.40, 20);
path.arcToPoint(Offset(size.width * 0.60, 20),
radius: Radius.circular(20.0), clockwise: false);
path.quadraticBezierTo(size.width * 0.60, 0, size.width * 0.65, 0);
path.quadraticBezierTo(size.width * 0.80, 0, size.width, 20);
path.lineTo(size.width, size.height);
path.lineTo(0, size.height);
path.lineTo(0, 20);
canvas.drawShadow(path, Colors.black, 5, true);
canvas.drawPath(path, paint);
}
@override
bool shouldRepaint(CustomPainter oldDelegate) {
return false;
}
}
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: AppBottomNav(),
);
}
}
class ScanScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Container(
child: Center(
child: Text(
"Scan",
style: TextStyle(color: Colors.green),
)));
}
}
class HistoryScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Center(child: Text("History"));
}
}
class HomeScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Center(child: Container(color: Colors.blue, child: Text("Home")));
}
}
class AccountScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Center(child: Text("Account"));
}
}
class BleConnectionScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Center(child: Text("BleConnection"));
}
}
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