Android实现水波纹外扩效果的实例代码

微信曾经推出了一个查找附近好友的功能，大致功能是这样的：屏幕上有一个按钮，长按按钮的时候，会有一圈圈水波纹的动画向外扩散，松手后，动画结束。

现在简单来实现这样的一个动画功能：

思路: 主要用到了下面的蓝色的图片，定义三个ImageView，background都设置为蓝色的图片，然后定义一个包括缩放和透明度变化的动画集，然后每隔一段时间，让3个ImageView依次启动这个动画集，看起来就像蓝色的圆圈像水波纹向外扩散一样。

相关实现逻辑如下：

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent" >
 <ImageView
 android:id="@+id/wave1"
 android:layout_width="150dp"
 android:layout_height="150dp"
 android:layout_centerInParent="true"
 android:background="@drawable/wave"
 />
 <ImageView
 android:id="@+id/wave2"
 android:layout_width="150dp"
 android:layout_height="150dp"
 android:layout_centerInParent="true"
 android:background="@drawable/wave"/>
 <ImageView
 android:id="@+id/wave3"
 android:layout_width="150dp"
 android:layout_height="150dp"
 android:layout_centerInParent="true"
 android:background="@drawable/wave" />
 <ImageView
 android:id="@+id/normal"
 android:layout_width="166dp"
 android:layout_height="166dp"
 android:layout_centerInParent="true"
 android:background="@drawable/normal" />
</RelativeLayout>

MainActivity.java

package com.jackie.waveanimation;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.AlphaAnimation;
import android.view.animation.AnimationSet;
import android.view.animation.ScaleAnimation;
import android.widget.ImageView;
public class MainActivity extends Activity {
 private ImageView mNormal, mWave1, mWave2, mWave3;
 private AnimationSet mAnimationSet1, mAnimationSet2, mAnimationSet3;
 private static final int OFFSET = 600; //每个动画的播放时间间隔
 private static final int MSG_WAVE2_ANIMATION = 2;
 private static final int MSG_WAVE3_ANIMATION = 3;
 private Handler mHandler = new Handler() {
 @Override
 public void handleMessage(Message msg) {
 switch (msg.what) {
 case MSG_WAVE2_ANIMATION:
 mWave2.startAnimation(mAnimationSet2);
 break;
 case MSG_WAVE3_ANIMATION:
 mWave3.startAnimation(mAnimationSet3);
 break;
 }
 }
 };
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 mNormal = (ImageView) findViewById(R.id.normal);
 mWave1 = (ImageView) findViewById(R.id.wave1);
 mWave2 = (ImageView) findViewById(R.id.wave2);
 mWave3 = (ImageView) findViewById(R.id.wave3);
 mAnimationSet1 = initAnimationSet();
 mAnimationSet2 = initAnimationSet();
 mAnimationSet3 = initAnimationSet();
 mNormal.setOnTouchListener(new View.OnTouchListener() {
 @Override
 public boolean onTouch(View v, MotionEvent event) {
 switch (event.getAction()) {
 case MotionEvent.ACTION_DOWN:
 showWaveAnimation();
 break;
 case MotionEvent.ACTION_UP:
 clearWaveAnimation();
 break;
 case MotionEvent.ACTION_CANCEL:
 clearWaveAnimation();
 }
 return true;
 }
 });
 }
 private AnimationSet initAnimationSet() {
 AnimationSet as = new AnimationSet(true);
 ScaleAnimation sa = new ScaleAnimation(1f, 2.3f, 1f, 2.3f,
 ScaleAnimation.RELATIVE_TO_SELF, 0.5f,
 ScaleAnimation.RELATIVE_TO_SELF, 0.5f);
 sa.setDuration(OFFSET * 3);
 sa.setRepeatCount(Animation.INFINITE);// 设置循环
 AlphaAnimation aa = new AlphaAnimation(1, 0.1f);
 aa.setDuration(OFFSET * 3);
 aa.setRepeatCount(Animation.INFINITE);//设置循环
 as.addAnimation(sa);
 as.addAnimation(aa);
 return as;
 }
 private void showWaveAnimation() {
 mWave1.startAnimation(mAnimationSet1);
 mHandler.sendEmptyMessageDelayed(MSG_WAVE2_ANIMATION, OFFSET);
 mHandler.sendEmptyMessageDelayed(MSG_WAVE3_ANIMATION, OFFSET * 2);
 }
 private void clearWaveAnimation() {
 mWave1.clearAnimation();
 mWave2.clearAnimation();
 mWave3.clearAnimation();
 }
}

效果如下：

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