安卓 : Hide RelativeLayout with animationwhen scroll down/up listview

Question

我尝试实现一个动画来隐藏 ListView 上方的 relativeLayout。我想要这种行为:

• 向下滚动时:隐藏 RelativeLayout
• 向上滚动:仅当我在顶部时才显示 RelativeLayout

我创建的以下代码有效，但有 2 个问题:

1. 当我向下滚动或向上滚动时，如果我位于 ListView 的顶部，则相关布局会闪烁。为了隐藏这次攀登，我必须进行一次快速滚动。 => 我的代码有问题，可能是在 listIsAtTop() 函数上？
2. 第二个问题，我没有动画。我使用 setVisivility(VISIBLE 或 GONE) 来显示或隐藏 relativeLayout。它不是用户友好的，不是吗？ :) 我不知道如何添加一点翻译动画来隐藏和显示这个 relativeLayout。

在 Account_Activity 类的 onCreate() 中:

list = (com.app.frisbeee.account_view.CustomListView)findViewById(R.id.accountview_listview);
adapter = new Account_view_custom_adapter(Account_view_act.this, annoncesList);
            list.setAdapter(adapter);
            adapter.notifyDataSetChanged();
            registerForContextMenu(list);

            list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    list.showContextMenuForChild(view);   
                }
            });

            list.setOnDetectScrollListener(new OnDetectScrollListener() {
                @Override
                public void onUpScrolling() {
                    /* do something */
                    Log.d("INFO", "UPPPPPPPPPPP");
                    if (listIsAtTop()) {
                        RelativeLayout relative1 = (RelativeLayout) findViewById(R.id.relative1);
                        relative1.setVisibility(View.VISIBLE);
                    }
                }

                @Override
                public void onDownScrolling() {
                    /* do something */
                    Log.d("INFO", "DOWNNNNNNNN");
                    if (!listIsAtTop()) {
                        RelativeLayout relative1 = (RelativeLayout) findViewById(R.id.relative1);
                        relative1.setVisibility(View.GONE);
                    }

                }
            });

        }

listIsAtTop 函数代码:

private boolean listIsAtTop()   {   
        if (list.getChildCount() == 0) {
            return true;
        }
        return list.getFirstVisiblePosition() == 0 && (list.getChildCount() == 0 || list.getChildAt(0).getTop() == 0);
    }

CustomListView 用于检测向上和向下滚动:

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.AbsListView;

public class CustomListView extends android.widget.ListView {

    private OnScrollListener onScrollListener;
    private OnDetectScrollListener onDetectScrollListener;

    public CustomListView(Context context) {
        super(context);
        onCreate(context, null, null);
    }

    public CustomListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        onCreate(context, attrs, null);
    }

    public CustomListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        onCreate(context, attrs, defStyle);
    }

    private void onCreate(Context context, AttributeSet attrs, Integer defStyle) {
        setListeners();
    }

    private void setListeners() {
        super.setOnScrollListener(new OnScrollListener() {

            private int oldTop;
            private int oldFirstVisibleItem;

            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {
                if (onScrollListener != null) {
                    onScrollListener.onScrollStateChanged(view, scrollState);
                }
            }

            @Override
            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
                if (onScrollListener != null) {
                    onScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
                }

                if (onDetectScrollListener != null) {
                    onDetectedListScroll(view, firstVisibleItem);
                }
            }

            private void onDetectedListScroll(AbsListView absListView, int firstVisibleItem) {
                View view = absListView.getChildAt(0);
                int top = (view == null) ? 0 : view.getTop();

                if (firstVisibleItem == oldFirstVisibleItem) {
                    if (top > oldTop) {
                        onDetectScrollListener.onUpScrolling();
                    } else if (top < oldTop) {
                        onDetectScrollListener.onDownScrolling();
                    }
                } else {
                    if (firstVisibleItem < oldFirstVisibleItem) {
                        onDetectScrollListener.onUpScrolling();
                    } else {
                        onDetectScrollListener.onDownScrolling();
                    }
                }

                oldTop = top;
                oldFirstVisibleItem = firstVisibleItem;
            }
        });
    }

    @Override
    public void setOnScrollListener(OnScrollListener onScrollListener) {
        this.onScrollListener = onScrollListener;
    }

    public void setOnDetectScrollListener(OnDetectScrollListener onDetectScrollListener) {
        this.onDetectScrollListener = onDetectScrollListener;
    }
}

Answer 1

对 listIsAtTop() 函数试试这个:

private boolean listIsAtTop()   {   
    if(listView.getChildCount() == 0) return true;
    return listView.getChildAt(0).getTop() == 0;
}

关于滑动动画:

slide_down.xml 代码:

<set xmlns:android="http://schemas.android.com/apk/res/android">  
    <translate android:fromXDelta="0" android:fromYDelta="-1000" android:duration="1500"/>
</set>

slide_up.xml 代码:

<set xmlns:android="http://schemas.android.com/apk/res/android">  
    <translate android:fromXDelta="0" android:fromYDelta="1000" android:duration="1500"/>
</set>

然后在onCreate方法中加载动画:

Animation slideUp = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.slide_up);

然后将它附加到您的 RelativeLayout:

relative1.startAnimation(slideUp);

希望这对您有所帮助:)