Question

我有一个片段，显示输入动画，我按

设置过渡

this.setEnterTransition(transition);

之后我想展示另一个动画。但我需要知道转换动画何时结束才能开始第二个动画。

对于活动，有一个类似onEnterAnimationComplete()的回调，但在Fragment的转换结束时不会调用它。

有没有办法知道何时输入片段的转换结束？

Answer 1

transition.addListener(new Transition.TransitionListener() {
                    @Override
                    public void onTransitionStart(Transition transition) {}

                    @Override
                    public void onTransitionEnd(Transition transition) {}

                    @Override
                    public void onTransitionCancel(Transition transition) {}

                    @Override
                    public void onTransitionPause(Transition transition) {}

                    @Override
                    public void onTransitionResume(Transition transition) {}
                });

                this.setEnterTransition(transition);

Answer 2

如果您有以下设置：

FragmentA使用SharedElementEnterTransition调用FragmentB，如

private final TransitionSet transition = new TransitionSet()
        .addTransition(new ChangeBounds());
//...
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction()
            .replace(R.id.container, fragment, fragment.getClass().getSimpleName());

transaction.addSharedElement(view, view.getTransitionName());
fragment.setSharedElementEnterTransition(transition);
fragment.setSharedElementReturnTransition(transition);
transaction.commit();

在第二个片段中侦听SharedElementTransition的结束。然后你必须在FragmentB的onAttach中获得SharedElementEnterTransition，如：

@Override
public void onAttach(Context context) {
    super.onAttach(context);
    TransitionSet transitionSet = (TransitionSet) getSharedElementEnterTransition();
    if (transitionSet != null) {
        transitionSet.addListener(new Transition.TransitionListener() {
            @Override
            public void onTransitionEnd(@NonNull Transition transition) {
                // remove listener as otherwise there are side-effects
                transition.removeListener(this);
                // do something here
            }

            @Override
            public void onTransitionStart(@NonNull Transition transition) {}
            @Override
            public void onTransitionCancel(@NonNull Transition transition) {}
            @Override
            public void onTransitionPause(@NonNull Transition transition) {}
            @Override
            public void onTransitionResume(@NonNull Transition transition) {}
        });
    }
}

正如this answer的评论中指出的那样，在onAttach（）中没有设置监听器时会出现错误。

如何知道片段何时进入转换结束？

2 个答案: