onLayoutChange()被调用太多次 [英] onLayoutChange() called too many times

问题描述

视图初始化后，我尝试更新缩略图图像并知道其大小

I am trying to update a thumbnail image once the view is initialized and knows its sizes

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
       View pagerView = inflater.inflate(R.layout.fragment_reference, container, false);
       ......
        mPhotoView = pagerView.findViewById(R.id.reference_photo);
        mPhotoView.addOnLayoutChangeListener((v, left, top, right, bottom, oldLeft, oldTop, oldRight, oldBottom) -> {
        Log.d(TAG,"Reference Pager PhotoView Layout Change."+" left: "+left+" top: "+top+" right: "+right+ " bottom: "+bottom);
        updatePhotoView();
    });
       ......
}

但是 Logcat 显示它已被连续调用四次:

but Logcat shows it has been called four times in a row:

Reference Pager PhotoView Layout Change. left: 0 top: 0 right: 720 bottom: 436
Reference Pager PhotoView Layout Change. left: 0 top: 0 right: 720 bottom: 436
Skipped 59 frames!  The application may be doing too much work on its main thread.
Reference Pager PhotoView Layout Change. left: 0 top: 0 right: 720 bottom: 436
Reference Pager PhotoView Layout Change. left: 0 top: 0 right: 720 bottom: 436

什么原因导致这种情况发生?如何避免这种情况?

What causes that to happen? How do I avoid that?

推荐答案

什么原因导致这种情况发生?

What causes that to happen?

您从未删除侦听器.这导致多次调用 onLayoutChange().在视图上调用 removeOnLayoutChangeListener()，如下所示:

You never removed the listener. This results in onLayoutChange() being invoked multiple times. Call removeOnLayoutChangeListener() on the view as follows:

mPhotoView.addOnLayoutChangeListener((v, left, top, right, bottom, oldLeft, oldTop, oldRight, oldBottom) -> {
    v.removeOnLayoutChangeListener(this);  // this prevents the callback to be invoked multiple times
    Log.d(TAG,"Reference Pager PhotoView Layout Change."+" left: "+left+" top: "+top+" right: "+right+ " bottom: "+bottom);
    updatePhotoView();
});

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