Flutter 实现酷炫的3D效果示例代码_Android

此文讲解3个酷炫的3d动画效果。

下面是要实现的效果：

flutter 中3d效果是通过 transform 组件实现的，没有变换效果的实现：

class transformdemo extends statelesswidget {
 @override
 widget build(buildcontext context) {
 return scaffold(
 appbar: appbar(
 title: text('3d 变换demo'),
 ),
 body: container(
 alignment: alignment.center,
 color: colors.white,
 child: text('3d 变换demo'),
 ),
 );
 }
}

通过 gesturedetector 组件添加滑动事件监听：

@override
widget build(buildcontext context) {
 return scaffold(
 appbar: appbar(
 title: text('3d 变换demo'),
 ),
 body: gesturedetector(
 onpanupdate: (details) {
 print('$details');
 },
 child: container(
 alignment: alignment.center,
 color: colors.white,
 child: text('3d 变换demo'),
 ),
 ),
 );
}

添加 transform 对组件进入旋转：

@override
widget build(buildcontext context) {
 return transform(
 transform: matrix4.identity()
 ..setentry(3, 2, 0.001)
 ..rotatex(pi/6)
 ..rotatey(pi/6),
 alignment: alignment.center,
 child: scaffold(
 appbar: appbar(
  title: text('3d 变换demo'),
 ),
 body: gesturedetector(
  onpanupdate: (details) {
  },
  child: container(
  alignment: alignment.center,
  color: colors.white,
  child: text('3d 变换demo'),
  ),
 ),
 ));
}

将滑动的偏移和旋转进行关联：

class transformdemo extends statefulwidget {
 @override
 _transformdemostate createstate() => _transformdemostate();
}

class _transformdemostate extends state<transformdemo> {
 double _rotatex = .0;
 double _rotatey = .0;

 @override
 widget build(buildcontext context) {
 return transform(
 transform: matrix4.identity()
  ..rotatex(_rotatex)
  ..rotatey(_rotatey),
 alignment: alignment.center,
 child: scaffold(
  appbar: appbar(
  title: text('3d 变换demo'),
  ),
  body: gesturedetector(
  onpanupdate: (details) {
  setstate(() {
  _rotatex += details.delta.dy * .01;
  _rotatey += details.delta.dx * -.01;
  });
  },
  child: container(
  alignment: alignment.center,
  color: colors.white,
  child: text('3d 变换demo'),
  ),
  ),
 ));
 }
}

基本已经实现了3d效果，但效果比较生硬，尤其垂直方向旋转的时候远点和近点在屏幕上的宽度是一样，

添加近大远小的效果：

transform(
 transform: matrix4.identity()
 ..setentry(3, 2, 0.001)
 ..rotatex(_rotatex)
 ..rotatey(_rotatey),
 ...

翻书效果

上面的效果类似于翻书的效果。

实现的原理：

将图片左右切割为两部分，两张图片共分割为4个新的组件，如下图，分别为1、2、3、4

代码实现：

_child1 = cliprect(
 child: align(
 alignment: alignment.centerleft,
 widthfactor: 0.5,
 child: child1,
 ),
);
_child2 = cliprect(
 child: align(
 alignment: alignment.centerright,
 widthfactor: 0.5,
 child: child1,
 ),
);

_child3 = cliprect(
 child: align(
 alignment: alignment.centerleft,
 widthfactor: 0.5,
 child: child2,
 ),
);

_child4 = cliprect(
 child: align(
 alignment: alignment.centerright,
 widthfactor: 0.5,
 child: child2,
 ),
);

将第一张图片放在第二种图片的上面，先旋转组件2 从 0度到 90度，然后再旋转组件3 从 -90度到0度，代码实现：

row(
 mainaxisalignment: mainaxisalignment.center,
 children: <widget>[
 stack(
 children: [
 _child1,
 transform(
  alignment: alignment.centerright,
  transform: matrix4.identity()
  ..setentry(3, 2, 0.001)
  ..rotatey(_animation1.value),
  child: _child3,
 ),
 ],
 ),
 container(
 width: 3,
 color: colors.white,
 ),
 stack(
 children: [
 _child4,
 transform(
  alignment: alignment.centerleft,
  transform: matrix4.identity()
  ..setentry(3, 2, 0.001)
  ..rotatey(_animation.value),
  child: _child2,
 )
 ],
 )
 ],
)

动画控制器设置：

@override
void initstate() {
 init();
 _controller =
 animationcontroller(vsync: this, duration: duration(seconds: 5))
 ..addlistener(() {
  setstate(() {});
 });
 _animation = tween(begin: .0, end: pi / 2)
 .animate(curvedanimation(parent: _controller, curve: interval(.0, .5)));
 _animation1 = tween(begin: -pi / 2, end: 0.0).animate(
 curvedanimation(parent: _controller, curve: interval(.5, 1.0)));
 _controller.forward();
 super.initstate();
}

其中 child1, child2为两种图片，代码如下：

_flipupdemostate(
 container(
 width: 300,
 height: 400,
 child: image.asset(
 'assets/images/b.jpg',
 fit: boxfit.cover,
 ),
 ),
 container(
 width: 300,
 height: 400,
 child: image.asset(
 'assets/images/c.jpeg',
 fit: boxfit.cover,
 ),
 ))

最后生成的效果就是开始的翻书效果。

上面是左右翻页效果，同理换成上下翻页效果：

@override
widget build(buildcontext context) {
 return scaffold(
 appbar: appbar(),
 body: column(
 mainaxisalignment: mainaxisalignment.center,
 children: <widget>[
 stack(
  children: [
  _upperchild1,
  transform(
  alignment: alignment.bottomcenter,
  transform: matrix4.identity()
  ..setentry(3, 2, 0.003)
  ..rotatex(_animation1.value),
  child: _upperchild2,
  ),
  ],
 ),
 sizedbox(
  height: 2,
 ),
 stack(
  children: [
  _lowerchild2,
  transform(
  alignment: alignment.topcenter,
  transform: matrix4.identity()
  ..setentry(3, 2, 0.003)
  ..rotatex(_animation.value),
  child: _lowerchild1,
  )
  ],
 )
 ],
 ),
 );
}