buildModalBarrier method

@override Widget buildModalBarrier()

Build the barrier for this ModalRoute, subclasses can override this method to create their own barrier with customized features such as color or accessibility focus size.

See also:

• ModalBarrier, which is typically used to build a barrier.
• ModalBottomSheetRoute, which overrides this method to build a customized barrier.

Implementation

@override
Widget buildModalBarrier() {
  if (barrierColor.alpha != 0 && !offstage) {
    // 如果 barrierColor 或 offstage 更新，则调用 changedInternalState
    assert(barrierColor != barrierColor.withOpacity(0.0));
    final Animation<Color?> color = animation!.drive(
      ColorTween(
        begin: barrierColor.withOpacity(0.0),
        end: barrierColor, // 如果 barrierColor 更新，则调用 changedInternalState
      ).chain(
        CurveTween(curve: barrierCurve),
      ), // 如果 barrierCurve 更新，则调用 changedInternalState
    );
    return AnimatedModalBarrier(
      color: color,
      dismissible: barrierDismissible,
      // 如果 barrierDismissible 更新，则调用 changedInternalState
      semanticsLabel: barrierLabel,
      // 如果 barrierLabel 更新，则调用 changedInternalState
      barrierSemanticsDismissible: semanticsDismissible,
      clipDetailsNotifier: _clipDetailsNotifier,
      semanticsOnTapHint: barrierOnTapHint,
    );
  } else {
    return ModalBarrier(
      dismissible: barrierDismissible,
      // 如果 barrierDismissible 更新，则调用 changedInternalState
      semanticsLabel: barrierLabel,
      // 如果 barrierLabel 更新，则调用 changedInternalState
      barrierSemanticsDismissible: semanticsDismissible,
      clipDetailsNotifier: _clipDetailsNotifier,
      semanticsOnTapHint: barrierOnTapHint,
    );
  }
}