短视频系统源码，根据手指指令放大或缩小图片

短视频系统源码，根据手指指令放大或缩小图片实现的相关代码
缩放功能

class ScaleAnimatedContent extends StatefulWidget {
  final Widget child;
  final bool show;

  const ScaleAnimatedContent({Key key, this.child, this.show = false})
      : super(key: key);

  @override
  ScaleAnimatedContentState createState() => ScaleAnimatedContentState();
}

class ScaleAnimatedContentState extends State<ScaleAnimatedContent>
    with TickerProviderStateMixin {
  AnimationController animationController;
  Animation<double> animation;

  @override
  void initState() {
    animationController = new AnimationController(
      vsync: this,
      duration: new Duration(milliseconds: 600),
    );

    // animationSlideUp = new Tween(begin: 0.0,end: 1.0).animate(animationController);
    animation = Tween(begin: 0.0, end: 1.0).animate(animationController);

    if (widget.show) {
      animationController.forward();
    }

    super.initState();
  }

  @override
  void didUpdateWidget(ScaleAnimatedContent oldWidget) {
    if (widget != oldWidget) {
      if (widget.show && !oldWidget.show) {
        animationController.forward(from: 0.0);
      } else if (!widget.show) {
        animationController.reverse();
      }
    }
    super.didUpdateWidget(oldWidget);
  }

  @override
  Widget build(BuildContext context) {
    return ScaleTransition(
      scale: animation,
      child: widget.child,
    );
  }

  @override
  void dispose() {
    animationController.dispose();
    super.dispose();
  }
}

滑动效果

class SlideAnimatedContent extends StatefulWidget {
  final Widget child;
  final bool show;

  const SlideAnimatedContent({Key key, this.child, this.show = false})
      : super(key: key);

  @override
  SlideAnimatedContentState createState() => SlideAnimatedContentState();
}

class SlideAnimatedContentState extends State<SlideAnimatedContent>
    with TickerProviderStateMixin {
  AnimationController animationController;
  Animation<Offset> animationSlideUp;

  @override
  void initState() {
    animationController = new AnimationController(
      vsync: this,
      duration: new Duration(milliseconds: 600),
    );

    animationSlideUp = new Tween(
      begin: Offset(0.0, 5.0),
      end: Offset(0.0, 0.0),
    ).animate(CurvedAnimation(parent: animationController, curve: Curves.ease));

    if (widget.show) {
      animationController.forward();
    }

    super.initState();
  }

  @override
  void didUpdateWidget(SlideAnimatedContent oldWidget) {
    if (widget != oldWidget) {
      if (widget.show && !oldWidget.show) {
        animationController.forward(from: 0.0);
      } else if (!widget.show) {
        animationController.reverse();
      }
    }
    super.didUpdateWidget(oldWidget);
  }

  @override
  Widget build(BuildContext context) {
    return SlideTransition(
      position: animationSlideUp,
      child: FadeTransition(
        opacity: animationController,
        child: widget.child,
      ),
    );
  }

  @override
  void dispose() {
    animationController.dispose();
    super.dispose();
  }
}

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