Android实现水波纹外扩效果

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

[html] view
plaincopy

<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

[java] view
plaincopy

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：