Android滑动组件悬浮固定在顶部效果
作者:ganshenml
这篇文章主要为大家详细介绍了Android滑动组件悬浮固定在顶部效果,文中示例代码介绍的非常详细,具有一定的参考价值,感兴趣的小伙伴们可以参考一下
本文实例为大家分享了Android滑动组件悬浮固定在顶部效果的具体代码,供大家参考,具体内容如下
要想实现的效果是如下:
场景:有些时候是内容中间的组件当滑动至顶部的时候固定显示在顶部。
实现的思路:
1.目标组件(button)有两套,放在顶部和内容中间;
2.当内容中间的组件滑动至顶部栏位置时控制显示/隐藏顶部和中间的组件(涉及到组件获取在屏幕的位置知识点);
activity代码:
public class MainActivity extends AppCompatActivity implements ObservableScrollView.ScrollViewListener { private ObservableScrollView scrollView; private Button topBtn1, topBtn2, middleBtn1, middleBtn2; private View topPanel, middlePanel; private int topHeight; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initViews(); initListeners(); } @Override public void onWindowFocusChanged(boolean hasFocus) { super.onWindowFocusChanged(hasFocus); Rect frame = new Rect(); getWindow().getDecorView().getWindowVisibleDisplayFrame(frame); int statusBarHeight = frame.top;//状态栏高度 int titleBarHeight = getWindow().findViewById(Window.ID_ANDROID_CONTENT).getTop();//标题栏高度 topHeight = titleBarHeight + statusBarHeight; } private void initViews() { scrollView = (ObservableScrollView) findViewById(R.id.scrollView); topPanel = findViewById(R.id.topPanel); topBtn1 = (Button) topPanel.findViewById(R.id.button1); topBtn2 = (Button) topPanel.findViewById(R.id.button2); middlePanel = findViewById(R.id.middlePanel); middleBtn1 = (Button) middlePanel.findViewById(R.id.button1); middleBtn2 = (Button) middlePanel.findViewById(R.id.button2); } private void initListeners() { topBtn1.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { middleBtn1.setBackgroundColor(Color.WHITE); topBtn1.setBackgroundColor(Color.WHITE); } }); middleBtn1.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { middleBtn1.setBackgroundColor(Color.BLUE); topBtn1.setBackgroundColor(Color.BLUE); } }); scrollView.setScrollViewListener(this); } @Override public void onScrollChanged(ObservableScrollView scrollView, int x, int y, int oldx, int oldy) { int[] location = new int[2]; middleBtn1.getLocationOnScreen(location); int locationY = location[1]; Log.e("locationY", locationY + " " + "topHeight的值是:" + topHeight); if (locationY <= topHeight && (topPanel.getVisibility() == View.GONE || topPanel.getVisibility() == View.INVISIBLE)) { topPanel.setVisibility(View.VISIBLE); } if (locationY > topHeight && topPanel.getVisibility() == View.VISIBLE) { topPanel.setVisibility(View.GONE); } } }
要点解析:
1.在onWindowFocusChanged()方法中获取屏幕状态栏和标题栏的高度(在onCreate()方法中是获取是0);
2.因为布局中的ScrollView的onScrollChangeListener()方法低版本API不支持——>所以activity实现了自定义ScrollView中的onScrollChanged()接口方法——>在此方法中实现组件的显示/隐藏;
自定义ScrollView的代码:
public class ObservableScrollView extends ScrollView { private ScrollViewListener scrollViewListener = null; public ObservableScrollView(Context context) { super(context); } public ObservableScrollView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } public ObservableScrollView(Context context, AttributeSet attrs) { super(context, attrs); } public void setScrollViewListener(ScrollViewListener scrollViewListener) { this.scrollViewListener = scrollViewListener; } @Override protected void onScrollChanged(int x, int y, int oldx, int oldy) { super.onScrollChanged(x, y, oldx, oldy); if (scrollViewListener != null) { scrollViewListener.onScrollChanged(this, x, y, oldx, oldy); } } public interface ScrollViewListener { void onScrollChanged(ObservableScrollView scrollView, int x, int y, int oldx, int oldy); } }
然后是布局文件:
<?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.example.administrator.slideholdapp.MainActivity"> <com.example.administrator.slideholdapp.ObservableScrollView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/scrollView"> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical"> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginBottom="30dp" android:text="@string/content" /> <include android:id="@+id/middlePanel" layout="@layout/middle_item_layout"></include> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="30dp" android:text="@string/content" /> </LinearLayout> </com.example.administrator.slideholdapp.ObservableScrollView> <include android:id="@+id/topPanel" layout="@layout/middle_item_layout" android:visibility="gone"/> </FrameLayout>
更多关于滑动功能的文章,请点击专题: 《Android滑动功能》
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持脚本之家。