flutter - 参数类型“_ProfileImageState”不能分配给参数类型“TickerProvider”

Question

主要目标是允许用户从图库/相机中选择图像，但为了使事情看起来不错，使用了一些动画并设计了整个图像选择对话框

class _ProfileImageState extends State<ProfileImage>{

      @override

      File _image;

      //ImagePickerHandler imagePicker;

      @override
      void initState() {

        super.initState();
//initiating to start so that transition from one state to another is smooth
 
        var _controller = new AnimationController(
          vsync: this,
          duration: const Duration(milliseconds: 500),
        );


        imagePicker=new ImagePickerHandler(this.userImage(_image));


      }

Answer 1

您需要使用SingleTickerProviderStateMixinmixin 来this用作 vsync 参数。您可以通过使用with关键字来实现此目的，方法如下：

class _ProfileImageState extends State<ProfileImage> with SingleTickerProviderStateMixin {

      @override

      File _image;

      //ImagePickerHandler imagePicker;

      @override
      void initState() {

        super.initState();
 
        var _controller = new AnimationController(
          vsync: this,
          duration: const Duration(milliseconds: 500),
        );


        imagePicker=new ImagePickerHandler(this.userImage(_image));


      }```