SM-N9500_20181221190414_1_1.gif

之前經(jīng)常在網(wǎng)上看到這種效果，猜想是滾動listview來改變標(biāo)題欄的顏色夯缺，擔(dān)心感覺那個應(yīng)用的比較少蚤氏，今天項目里需要這樣的效果，我就想用scrollview來實現(xiàn)一下踊兜，廢話少說竿滨，上圖為要實現(xiàn)的效果(網(wǎng)易考拉商品詳情頁)。

直接上代碼：

核心類GradationScrollView

/**
 *  @author  程龍
 *  @data  2018/12/21
 *  帶滾動監(jiān)聽的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);
        }
    }

}

具體使用(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() {
        // 獲取頂部圖片高度后捏境，設(shè)置滾動監(jiān)聽
        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) {
        //這個就是關(guān)鍵方法了于游，大家可根據(jù)實際需要進(jìn)行編寫
        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="我是標(biāo)題"
        android:textSize="18sp"
        android:textColor="@android:color/white"
        android:background="#00000000" />
 
</RelativeLayout>

以上就是該功能實現(xiàn)代碼，大家可根據(jù)自己需要進(jìn)行更改垫言。