android 根据滑动隐藏或显示导航 类似手机QQ好友个人信息

//重写ScrollView


public class NotifyingScrollView extends ScrollView {
     /**
     * @author Cyril Mottier
     */
    public interface OnScrollChangedListener {
        void onScrollChanged(ScrollView who, int l, int t, int oldl, int oldt);
    }

    private OnScrollChangedListener mOnScrollChangedListener;

    public NotifyingScrollView(Context context) {
        super(context);
    }

    public NotifyingScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

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

    @Override
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        super.onScrollChanged(l, t, oldl, oldt);
        if (mOnScrollChangedListener != null) {
            mOnScrollChangedListener.onScrollChanged(this, l, t, oldl, oldt);
        }
    }

    public void setOnScrollChangedListener(OnScrollChangedListener listener) {
        mOnScrollChangedListener = listener;
    }

}

 <你的项目路径.NotifyingScrollView
            android:id="@id/sv_personal"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/layout_bg"
            android:scrollbars="none" >
    
 <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="@color/layout_bg"
                android:orientation="vertical" >
你要显示的内容
</LinearLayout>
        </你的项目路径.NotifyingScrollView>

NotifyingScrollView sv_personal=(NotifyingScrollView)findViewById(R.id.sv_personal);
sv_personal.setOnScrollChangedListener(mOnScrollChangedListener);



private NotifyingScrollView.OnScrollChangedListener mOnScrollChangedListener = new NotifyingScrollView.OnScrollChangedListener() {
public void onScrollChanged(ScrollView who, int l, int t, int oldl, int oldt) {
int Height=Utility.dip2px(context, 130);
float ratio =Math.max(Math.min(1, t/Height), 0);
//导航控件
linar_top.setAlpha(ratio* 255);
}
};