我想在一个透明的对话框中用flutter显示一个图像。我把opaque设置为false并使用了MaterialType.transparency。当我打开对话框时，背景是黑色的。

class ShowProfileImage extends ModalRoute<void> {
  final String url;

  @override
  Duration get transitionDuration => Duration(milliseconds: 500);

  @override
  bool get opaque => false;

  @override
  bool get barrierDismissible => false;

  @override
  Color get barrierColor => Colors.black;

  @override
  String get barrierLabel => null;

  @override
  bool get maintainState => true;

  VoidCallback onDeleteImage;

  ShowProfileImage(String this.url);

  @override
  Widget buildPage(
    BuildContext context,
    Animation<double> animation,
    Animation<double> secondaryAnimation,
  ) {
    // This makes sure that text and other content follows the material style
    return Material(
      type: MaterialType.transparency,
      // make sure that the overlay content is not cut off
      child: SafeArea(
        child: InkWell(
            onTap: () => Navigator.of(context).pop(),
            child: Container(
                height: double.infinity,
                width: double.infinity,
                color: Colors.transparent,
                child: Center(
                    child: Container(
                        width: 300,
                        child: Image(image: NetworkImageWithRetry(url)))))),
      ),
    );
  }
}