之前经常在网上看到这种效果，猜想是滚动listview来改变标题栏的颜色，担心感觉那个应用的比较少，今天项目里需要这样的效果，我就想用scrollview来实现一下，废话少说，上图为要实现的效果(网易考拉商品详情页)。
直接上代码：
核心类GradationScrollView
/** * @author 程龙 * @data 2018/12/21 * 带滚动监听的scrollview */ public class GradationScrollView extends ScrollView { public interface ScrollViewListener { void onScrollChanged(GradationScrollView scrollView, int x, int y, int oldx, int oldy); } private ScrollViewListener scrollViewListener = null; public GradationScrollView(Context context) { super(context); } public GradationScrollView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } public GradationScrollView(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); } } }
具体使用(MainActivity.java)
public class MainActivity extends Activity implements ScrollViewListener{ private ObservableScrollView scrollView; private ListView listView; private ImageView imageView; private TextView textView; private int imageHeight; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); scrollView = (ObservableScrollView) findViewById(R.id.scrollview); listView = (ListView) findViewById(R.id.listview); imageView = (ImageView) findViewById(R.id.imageview); textView = (TextView) findViewById(R.id.textview); initListeners(); initData(); } private void initListeners() { // 获取顶部图片高度后，设置滚动监听 ViewTreeObserver vto = imageView.getViewTreeObserver(); vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() { @Override public void onGlobalLayout() { imageView.getViewTreeObserver().removeGlobalOnLayoutListener( this); imageHeight = imageView.getHeight(); scrollView.setScrollViewListener(MainActivity.this); } }); } private void initData() { ArrayAdapter<String> adapter = new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, getResources().getStringArray(R.array.data)); listView.setAdapter(adapter); } @Override public void onScrollChanged(ObservableScrollView scrollView, int x, int y, int oldx, int oldy) { //这个就是关键方法了，大家可根据实际需要进行编写 if (y <= 0) { textView.setBackgroundColor(Color.argb((int) 0, 227, 29, 26)); } else if (y > 0 && y <= imageHeight) { float scale = (float) y / imageHeight; float alpha = (255 * scale); textView.setBackgroundColor(Color.argb((int) alpha, 227, 29, 26)); } else { textView.setBackgroundColor(Color.argb((int) 255, 227, 29, 26)); } } }
XML(activity_main.xml）
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="${relativePackage}.${activityClass}" > <com.jukopro.titlebarcolor.ObservableScrollView android:id="@+id/scrollview" android:layout_width="match_parent" android:layout_height="match_parent" android:scrollbars="none" > <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" > <ImageView android:id="@+id/imageview" android:layout_width="match_parent" android:layout_height="200dp" android:background="@drawable/zuqiu" /> <com.jukopro.titlebarcolor.MyListview android:id="@+id/listview" android:layout_width="match_parent" android:layout_height="wrap_content" > </com.jukopro.titlebarcolor.MyListview> </LinearLayout> </com.jukopro.titlebarcolor.ObservableScrollView> <TextView android:id="@+id/textview" android:layout_width="match_parent" android:layout_height="48dp" android:gravity="center" android:text="我是标题" android:textSize="18sp" android:textColor="@android:color/white" android:background="#00000000" /> </RelativeLayout>
以上就是该功能实现代码，大家可根据自己需要进行更改。
