微信曾經推出了一個查找附近好友的功能,大致功能是這樣的:屏幕上有一個按鈕,長按按鈕的時候,會有一圈圈水波紋的動畫向外擴散,松手后,動畫結束。
現在簡單來實現這樣的一個動畫功能:
思路: 主要用到了下面的藍色的圖片,定義三個ImageView,background都設置為藍色的圖片,然后定義一個包括縮放和透明度變化的動畫集,然后每隔一段時間,讓3個ImageView依次啟動這個動畫集,看起來就像藍色的圓圈像水波紋向外擴散一樣。
	
    
相關實現邏輯如下:
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; //每個動畫的播放時間間隔  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);// 設置循環  AlphaAnimation aa = new AlphaAnimation(1, 0.1f);  aa.setDuration(OFFSET * 3);  aa.setRepeatCount(Animation.INFINITE);//設置循環  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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