Flutter：长按图片可以像 Instagram 一样放大预览
所以我目前有一个图片网格，我想从 instagram 实现一个功能：如果你长按其中一张图片，你会在屏幕中间看到那张图片的更大版本。如果您停止按下，图像就会消失。
我真的不需要代码，但我只是想不出我应该使用哪些小部件。
可能有这样的包吗？如果不是，那么我如何使用 Flutter 标准小部件来做到这一点？也许使用出现在 longPress 上的对话框？
这是经过改进的 vewrsion，它类似于具有模糊背景的 Instagram 完全相同的用户体验。
我们可以使用Stateful Widget,Stack和的组合来实现这一点BackdropFliter，这是示例代码 -
import 'dart:ui';
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Counter Demo',
theme: ThemeData.light(),
home: Scaffold(
appBar: AppBar(
backgroundColor: Colors.blueGrey,
centerTitle: true,
title: Text("Demo App"),
),
body: Stacked(),
),
);
}
}
class Stacked extends StatefulWidget {
@override
_StackedState createState() => _StackedState();
}
class _StackedState extends State<Stacked> {
final List<String> images = [
"1.jpg",
"2.jpg",
"3.jpg",
"4.jpg",
"5.jpg",
"6.jpg",
"7.jpg",
"8.jpg",
"9.jpg",
"10.jpg",
];
bool _showPreview = false;
String _image = "assets/images/1.jpg";
@override
Widget build(BuildContext context) {
return SafeArea(
child: Stack(
children: [
GridView.builder(
itemCount: images.length,
gridDelegate:
SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2),
itemBuilder: (BuildContext context, int index) {
return GestureDetector(
onLongPress: () {
setState(() {
_showPreview = true;
_image = "assets/images/${images[index]}";
});
},
onLongPressEnd: (details) {
setState(() {
_showPreview = false;
});
},
child: Padding(
padding: const EdgeInsets.all(4.0),
child: Card(
elevation: 4,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(5.0),
),
clipBehavior: Clip.hardEdge,
child: Image.asset("assets/images/${images[index]}"),
),
),
);
},
),
if (_showPreview) ...[
BackdropFilter(
filter: ImageFilter.blur(
sigmaX: 5.0,
sigmaY: 5.0,
),
child: Container(
color: Colors.white.withOpacity(0.6),
),
),
Container(
child: Center(
child: ClipRRect(
borderRadius: BorderRadius.circular(10.0),
child: Image.asset(
_image,
height: 300,
width: 300,
),
),
),
),
],
],
));
}
}
这只是一个基线示例，您可以修改它以实现您想要的行为的无限可能性。
另一种简单的方法是我们可以使用 StatefulWidget 和 IndexedStack 来构建它——
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Counter Demo',
theme: ThemeData.light(),
home: Scaffold(
appBar: AppBar(
backgroundColor: Colors.blueGrey,
centerTitle: true,
title: Text("Demo App"),
),
body: Body(),
),
);
}
}
class Body extends StatefulWidget {
@override
_BodyState createState() => _BodyState();
}
class _BodyState extends State<Body> {
final List<String> images = [
"1.jpg",
"2.jpg",
"3.jpg",
"4.jpg",
"5.jpg",
"6.jpg",
"7.jpg",
"8.jpg",
"9.jpg",
"10.jpg",
];
int _index = 0;
String _image = "assets/images/1.jpg";
@override
Widget build(BuildContext context) {
return SafeArea(
child: IndexedStack(
index: _index,
children: [
GridView.builder(
itemCount: images.length,
gridDelegate:
SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2),
itemBuilder: (BuildContext context, int index) {
return GestureDetector(
onLongPress: () {
setState(() {
_index = 1;
_image = "assets/images/${images[index]}";
});
},
onLongPressEnd: (details) {
setState(() {
_index = 0;
});
},
child: Padding(
padding: const EdgeInsets.all(4.0),
child: Card(
elevation: 4,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(5.0),
),
clipBehavior: Clip.hardEdge,
child: Image.asset("assets/images/${images[index]}"),
),
),
);
},
),
Container(
decoration: BoxDecoration(
color: Colors.white.withOpacity(0.2),
),
child: Center(
child: ConstrainedBox(
constraints: BoxConstraints(
maxHeight: 400,
maxWidth: 400,
),
child: Image.asset(
_image,
),
),
),
)
],
),
);
}
}
您可以在此处检查上述代码的输出。
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