一个九宫格图片查看器

Screenshot_1542963454.png

Screenshot_1542963645.png

import 'package:cached_network_image/cached_network_image.dart';

import 'package:flutter/material.dart';

class PictureShow extends StatelessWidget {

final List picList;

PictureShow({this.picList});

Widget build(BuildContext context) {

return Container(

child: GridView.count(

crossAxisCount: picList.length >= 3 ? 3 : picList.length < 2 ? 1 : 2,

children: List.generate(

picList.length,

(index) => GestureDetector(

child: Center(

child: Padding(

padding: const EdgeInsets.all(1.0),

child: CachedNetworkImage(

key: Key(index.toString()),

imageUrl: picList[index],

),

),

),

onTap: () {

Navigator.of(context).push(

NinePicture(picList, index),

);

},

),

),

),

);

}

}

class NinePicture extends PopupRoute {

final String barrierLabel;

final List picList;

final int index;

int startX;

int endX;

NinePicture(this.picList, this.index, {this.barrierLabel});

@override

Duration get transitionDuration => Duration(milliseconds: 2000);

@override

@override

Color get barrierColor => Colors.black54;

@override

bool get barrierDismissible => true;

AnimationController _animationController;

@override

AnimationController createAnimationController() {

assert(_animationController == null);

_animationController =

BottomSheet.createAnimationController(navigator.overlay);

return _animationController;

}

@override

Widget buildPage(BuildContext context, Animation animation,

Animation secondaryAnimation) {

return MediaQuery.removePadding(

removeTop: true,

context: context,

child: GestureDetector(

child: AnimatedBuilder(

animation: animation,

builder: (BuildContext context, Widget child) => GestureDetector(

onTap: () {

Navigator.pop(context);

},

child: _PictureWidget(picList, index),

),

),

),

);

}

}

class _PictureWidget extends StatefulWidget {

final List picList;

final int index;

_PictureWidget(this.picList, this.index);

@override

State createState() {

return _PictureWidgetState();

}

}

class _PictureWidgetState extends State<_picturewidget> {

int startX = 0;

int endX = 0;

int index = 0;

@override

void initState() {

// TODO: implement initState

super.initState();

index = widget.index;

}

@override

Widget build(BuildContext context) {

return new Material(

color: Colors.transparent,

child: new Container(

width: double.infinity,

child: Stack(

children: [

GestureDetector(

child: Center(

child: CachedNetworkImage(

imageUrl: widget.picList[index],

fit: BoxFit.cover,

),

),

onHorizontalDragDown: (detail) {

startX = detail.globalPosition.dx.toInt();

},

onHorizontalDragUpdate: (detail) {

endX = detail.globalPosition.dx.toInt();

},

onHorizontalDragEnd: (detail) {

_getIndex(endX - startX);

setState(() {});

},

onHorizontalDragCancel: () {},

),

Align(

alignment: Alignment.bottomCenter,

child: Row(

mainAxisAlignment: MainAxisAlignment.spaceAround,

children: List.generate(

widget.picList.length,

(i) => GestureDetector(

child: CircleAvatar(

foregroundColor: Theme.of(context).primaryColor,

radius: 8.0,

backgroundColor: index == i

? Theme.of(context).primaryColor

: Colors.white,

),

onTap: () {

setState(() {

startX = endX = 0;

index = i;

});

},

),

).toList(),

),

)

],

),

alignment: Alignment.center,

),

);

}

void _getIndex(int delta) {

if (delta > 50) {

setState(() {

index--;

index = index.clamp(0, widget.picList.length - 1);

});

} else if (delta < 50) {

setState(() {

index++;

index = index.clamp(0, widget.picList.length - 1);

});

}

}

}