android标题栏颜色渐变效果的实现(标题栏随着scrollview的滚动而变化)

之前也是在网上看到这种效果，不过是滚动listview来改变标题栏的颜色，感觉那个应用的比较少，比如我要滚动scrollview来实现呢，那么问题就来了，废话少说，看一下要实现的效果先(这是在项目应用的效果)。

直接上源代码：

【一、核心类(ObservableScrollView.java)】

package com.jukopro.titlebarcolor;import android.content.Context;import android.util.AttributeSet;import android.widget.ScrollView;/** * 带滚动监听的scrollview * */public class ObservableScrollView extends ScrollView {public interface ScrollViewListener {void onScrollChanged(ObservableScrollView scrollView, int x, int y,int oldx, int oldy);}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;}@Overrideprotected 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);}}}

【二、具体使用(MainActivity.java)】

package com.jukopro.titlebarcolor;import android.app.Activity;import android.graphics.Color;import android.os.Bundle;import android.view.ViewTreeObserver;import android.view.ViewTreeObserver.OnGlobalLayoutListener;import android.widget.ArrayAdapter;import android.widget.ImageView;import android.widget.ListView;import android.widget.TextView;import com.jukopro.titlebarcolor.ObservableScrollView.ScrollViewListener;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() {@Overridepublic 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);}@Overridepublic void onScrollChanged(ObservableScrollView scrollView, int x, int y,int oldx, int oldy) {// TODO Auto-generated method stub// Log.i("TAG", "y--->" + y + "    height-->" + height);if (y <= 0) {textView.setBackgroundColor(Color.argb((int) 0, 227, 29, 26));//AGB由相关工具获得，或者美工提供} else if (y > 0 && y <= imageHeight) {float scale = (float) y / imageHeight;float alpha = (255 * scale);// 只是layout背景透明(仿知乎滑动效果)textView.setBackgroundColor(Color.argb((int) alpha, 227, 29, 26));} else {textView.setBackgroundColor(Color.argb((int) 255, 227, 29, 26));}}}

【二、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>

还不懂的童鞋可以下载源代码：http://download.csdn.net/detail/sinat_21283073/9510052