页面跳转动画是在开发中经常需要使用到的，根据经验撸了一个动画路由类： AnimationPageRoute.
BUG: 出事了，请暂停使用该路由！经验证发现该路由在页面切出去然后再返回，会导致ExitPage对象的类中的initState（原只会执行一次生命周期），didDependencesChanged重复执行多次！显然这不是我们要的效果！因为往往我们会在initState执行网络调用等一类的操作，如此以来就会导致页面多次调用网络请求等初始化操作
注意：文章最下方有一种另类解决方案！
使用事项：
1.exitPage 可忽略对象，如果不传，则只执行enterPage的动画；
2.exitPage 对象应该是指一个完整的Page页面，不可为某一个部件，否则动画会很怪异；
import 'package:flutter/material.dart';
enum AnimationType {
/// 从右到左的滑动
SlideRL,
/// 从左到右的滑动
SlideLR,
/// 从上到下的滑动
SlideTB,
/// 从下到上的滑动
SlideBT,
/// 透明过渡
Fade,
}
class AnimationPageRoute extends PageRouteBuilder {
/// 进入的页面
Widget enterPage;
/// 退出的页面
Widget exitPage;
AnimationPageRoute({
@required this.enterPage,
this.exitPage,
AnimationType animationType = AnimationType.SlideRL,
Duration transitionDuration = const Duration(milliseconds: 300),
bool opaque = true,
bool barrierDismissible = false,
Color barrierColor,
String barrierLabel,
bool maintainState = true,
}) : assert(enterPage != null, '参数[enterPage]不能为空!'),
super(
transitionDuration: transitionDuration,
pageBuilder: (BuildContext context, Animation<double> animation,
Animation<double> secondaryAnimation) =>
enterPage,
transitionsBuilder: (BuildContext context,
Animation<double> animation,
Animation<double> secondaryAnimation,
Widget child) =>
_getAnimation(enterPage, exitPage, animation,
animationType: animationType),
opaque: opaque,
barrierColor: barrierColor,
barrierLabel: barrierLabel,
maintainState: maintainState,
);
static Widget _getAnimation(
Widget enterPage, Widget exitPage, Animation<double> animation,
{AnimationType animationType = AnimationType.SlideRL}) {
List<Widget> _animationWidgets = <Widget>[];
if (animationType == AnimationType.Fade) {
_animationWidgets.addAll([
if (exitPage != null)
FadeTransition(
opacity: Tween<double>(begin: 1, end: 0).animate(animation),
child: exitPage),
FadeTransition(
opacity: Tween<double>(begin: 0, end: 1).animate(animation),
child: enterPage)
]);
} else {
Offset oBegin, oEnd, iBegin, iEnd;
if (animationType == AnimationType.SlideBT) {
oBegin = Offset.zero;
oEnd = Offset(0, -1);
iBegin = Offset(0, 1);
iEnd = Offset.zero;
} else if (animationType == AnimationType.SlideTB) {
oBegin = Offset.zero;
oEnd = Offset(0, 1);
iBegin = Offset(0, -1);
iEnd = Offset.zero;
} else if (animationType == AnimationType.SlideLR) {
oBegin = Offset.zero;
oEnd = Offset(1, 0);
iBegin = Offset(-1, 0);
iEnd = Offset.zero;
} else {
oBegin = Offset.zero;
oEnd = Offset(-1, 0);
iBegin = Offset(1, 0);
iEnd = Offset.zero;
}
_animationWidgets.addAll([
if (exitPage != null)
SlideTransition(
position:
Tween<Offset>(begin: oBegin, end: oEnd).animate(animation),
child: exitPage),
SlideTransition(
position:
Tween<Offset>(begin: iBegin, end: iEnd).animate(animation),
child: enterPage)
]);
}
return Stack(children: _animationWidgets);
}
}
一种另类的解决这种问题的方案
使用RenderPaintBoundary把当前页面图像绘制出来，然后设置它为exitPage，方法如下：
final GlobalKey _repaintBoundaryKey = GlobalKey();
Future<Image> getScreenImage() async {
RenderRepaintBoundary renderRepaintBoundary =
_repaintBoundaryKey.currentContext.findRenderObject();
UI.Image image = await renderRepaintBoundary.toImage();
return Image.memory((await image.toByteData(format: UI.ImageByteFormat.png))
.buffer
.asUint8List());
}
@override
Widget build(BuildContext context) => RepaintBoundary(
key: _repaintBoundaryKey,
child: Scaffold(
backgroundColor: const Color(0xfff5f5f5),
appBar: _buildAppBar(),
body: _buildContentView()));
优化之路，使用Mixin
import 'dart:ui' as Ui;
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'package:yunnan_season/core/route/animation_page_route.dart';
/// 使用[AnimationPageRoute]需要调用该Mixin
mixin AnimationPageProviderMixin {
/// 绘制面板关联的GlobalKey对象
final GlobalKey _repaintBoundaryKey = GlobalKey();
/// 获取绘制面板中的图像
Future<RawImage> getUiDrawingImage() async {
if (_repaintBoundaryKey == null)
throw Exception('错误：调用该方法前请使用[drawingPad]方法！');
RenderRepaintBoundary renderBoundary =
_repaintBoundaryKey.currentContext.findRenderObject();
return RawImage(
image: (await renderBoundary.toImage(
pixelRatio: Ui.window.devicePixelRatio)),
filterQuality: FilterQuality.high);
}
/// 绘画面板
Widget drawingPad(Widget child) =>
RepaintBoundary(key: _repaintBoundaryKey, child: child);
/// 动画路由对象
AnimationPageRoute<T> animationPageRoute<T>(
Widget nextPage,
Widget currentPage, {
Duration duration = const Duration(milliseconds: 400),
AnimationType type = AnimationType.SlideRL,
}) =>
AnimationPageRoute<T>(
enterPage: nextPage,
exitPage: currentPage,
transitionDuration: duration,
animationType: type);
}
使用实例：
void _startWithDrawMainPage() async => Navigator.push(context,
animationPageRoute(WithDrawMainPage(), (await getUiDrawingImage())));
@override
Widget build(BuildContext context) => drawingPad(Scaffold(
backgroundColor: const Color(0xfff5f5f5),
appBar: _buildAppBar(),
body: _buildContentView()));
哈哈，暂时就这样，希望能帮到各位看客！
再次经过多方研究和求证，发现路由页面的切换动画加上CurvedAnimation会生动很多，而且还不会造成异常。因为以前方案都存在缺陷，甚至是报错。经过多次求证，有了如下代码：
简要说明：动画类似iOS的切换动画，ExitPage也具有离开时的动画(但以下代码暂且只提供SlideRL和SlideLR的动画）。更多效果，请研究CurvedAnimation。
// import 'dart:ui' as Ui;
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
final Tween<double> _tweenFade = Tween<double>(begin: 0, end: 1.0);
final Tween<Offset> _primaryTweenSlideFromBottomToTop =
Tween<Offset>(begin: const Offset(0.0, 1.0), end: Offset.zero);
// final Tween<Offset> _secondaryTweenSlideFromBottomToTop =
// Tween<Offset>(begin: Offset.zero, end: const Offset(0.0, -1.0));
final Tween<Offset> _primaryTweenSlideFromTopToBottom =
Tween<Offset>(begin: const Offset(0.0, -1.0), end: Offset.zero);
// final Tween<Offset> _secondaryTweenSlideFromTopToBottom =
// Tween<Offset>(begin: Offset.zero, end: const Offset(0.0, 1.0));
final Tween<Offset> _primaryTweenSlideFromRightToLeft =
Tween<Offset>(begin: const Offset(1.0, 0.0), end: Offset.zero);
final Tween<Offset> _secondaryTweenSlideFromRightToLeft =
Tween<Offset>(begin: Offset.zero, end: const Offset(-1.0, 0.0));
final Tween<Offset> _primaryTweenSlideFromLeftToRight =
Tween<Offset>(begin: const Offset(-1.0, 0.0), end: Offset.zero);
final Tween<Offset> _secondaryTweenSlideFromLeftToRight =
Tween<Offset>(begin: Offset.zero, end: const Offset(1.0, 0.0));
/// 动画类型枚举，`SlideRL`,`SlideLR`,`SlideTB`, `SlideBT`, `Fade`
enum AnimationType {
/// 从右到左的滑动
SlideRL,
/// 从左到右的滑动
SlideLR,
/// 从上到下的滑动
SlideTB,
/// 从下到上的滑动
SlideBT,
/// 透明过渡
Fade,
}
class AnimationPageRoute<T> extends PageRoute<T> {
AnimationPageRoute({
@required this.builder,
this.isExitPageAffectedOrNot = true,
this.animationType = AnimationType.SlideRL,
RouteSettings settings,
this.maintainState = true,
bool fullscreenDialog = false,
}) : assert(builder != null),
assert(isExitPageAffectedOrNot != null),
assert(animationType != null),
assert(maintainState != null),
assert(fullscreenDialog != null),
assert(opaque),
super(settings: settings, fullscreenDialog: fullscreenDialog);
final WidgetBuilder builder;
/// 该参数只针对当[AnimationType]为[SlideLR]或[SlideRL]新页面及当前页面动画均有效
final bool isExitPageAffectedOrNot;
final AnimationType animationType;
@override
final bool maintainState;
@override
Duration get transitionDuration => const Duration(milliseconds: 1000);
@override
Color get barrierColor => null;
@override
String get barrierLabel => null;
@override
bool canTransitionTo(TransitionRoute<dynamic> nextRoute) =>
nextRoute is AnimationPageRoute && !nextRoute.fullscreenDialog;
@override
Widget buildPage(BuildContext context, Animation<double> animation,
Animation<double> secondaryAnimation) {
final Widget result = builder(context);
assert(() {
if (result == null) {
throw FlutterError.fromParts(<DiagnosticsNode>[
ErrorSummary(
'The builder for route "${settings.name}" returned null.'),
ErrorDescription('Route builders must never return null.')
]);
}
return true;
}());
return Semantics(
scopesRoute: true, explicitChildNodes: true, child: result);
}
@override
Widget buildTransitions(BuildContext context, Animation<double> animation,
Animation<double> secondaryAnimation, Widget child) {
if (animationType == AnimationType.Fade)
FadeTransition(
opacity: CurvedAnimation(
parent: animation,
curve: Curves.linearToEaseOut,
reverseCurve: Curves.easeInToLinear,
).drive(_tweenFade),
child: child);
final TextDirection textDirection = Directionality.of(context);
Tween<Offset> primaryTween = _primaryTweenSlideFromRightToLeft,
secondTween = _secondaryTweenSlideFromRightToLeft;
Cubic curve = Curves.linearToEaseOut, reverseCurve = Curves.easeInToLinear;
if (animationType == AnimationType.SlideBT) {
primaryTween = _primaryTweenSlideFromBottomToTop;
} else if (animationType == AnimationType.SlideTB) {
primaryTween = _primaryTweenSlideFromTopToBottom;
} else if (animationType == AnimationType.SlideLR) {
primaryTween = _primaryTweenSlideFromLeftToRight;
secondTween = _secondaryTweenSlideFromLeftToRight;
curve = Curves.fastOutSlowIn;
reverseCurve = Curves.easeOutCubic;
}
Widget enterAnimWidget = SlideTransition(
position: CurvedAnimation(
parent: animation,
curve: curve,
reverseCurve: reverseCurve,
).drive(primaryTween),
textDirection: textDirection,
child: child);
if (isExitPageAffectedOrNot != true ||
([AnimationType.SlideTB, AnimationType.SlideBT]
.contains(animationType))) return enterAnimWidget;
return SlideTransition(
position: CurvedAnimation(
parent: secondaryAnimation,
curve: curve,
reverseCurve: reverseCurve,
).drive(secondTween),
textDirection: textDirection,
child: enterAnimWidget);
}
@override
String get debugLabel => '${super.debugLabel}(${settings.name})';
}
