Android自定义控件实现水波纹效果

package com.example.mhy.shuibowen; import android.support.v7.app.AppCompatActivity;import android.os.Bundle; public class MainActivity extends AppCompatActivity {   @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);  }}

<?xml version="1.0" encoding="utf-8"?><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="com.example.mhy.shuibowen.MainActivity">   <com.example.mhy.shuibowen.MyRingWave    android:layout_width="match_parent"    android:layout_height="match_parent"    /></RelativeLayout>

package com.example.mhy.shuibowen; import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.os.Handler;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.View; import java.util.ArrayList; /** * 水波纹效果 * Created by mhy on 2016/6/16. */public class MyRingWave extends View {  /**   * 二个相临波浪中心点的最小距离   */  private static final int DIS_SOLP = 13;  protected boolean isRunning = false;   private ArrayList<Wave> wList;   public MyRingWave(Context context,AttributeSet attrs) {    super(context, attrs);    wList = new ArrayList<MyRingWave.Wave>();  }   @Override  protected void onDraw(Canvas canvas) {    for(int i=0; i<wList.size(); i++) {      Wave wave = wList.get(i);      canvas.drawCircle(wave.cx, wave.cy, wave.r, wave.p);    }  }   @Override  public boolean onTouchEvent(MotionEvent event) {    super.onTouchEvent(event);     switch(event.getAction()) {      case MotionEvent.ACTION_DOWN:      case MotionEvent.ACTION_MOVE:         int x = (int) event.getX();        int y = (int) event.getY();         addPoint(x, y);         break;      default:        break;    }    return true;  }   private Handler handler = new Handler(){    public void handleMessage(android.os.Message msg) {       //刷新数据      flushData();      //刷新页面      invalidate();      //循环动画      if (isRunning) {        handler.sendEmptyMessageDelayed(0, 50);      }     }  };   /**   * 刷新数据   */  private void flushData() {     for (int i = 0; i < wList.size(); i++) {       Wave w = wList.get(i);       //如果透明度为 0 从集合中删除      int alpha = w.p.getAlpha();      if(alpha == 0){        wList.remove(i); //删除i 以后，i的值应该再减1 否则会漏掉一个对象，不过，在此处影响不大，效果上看不出来。        continue;      }       alpha-=5;      if(alpha<5){        alpha =0;      }      //降低透明度      w.p.setAlpha(alpha);       //扩大半径      w.r = w.r+3;      //设置半径厚度      w.p.setStrokeWidth(w.r/3);    }  /*  * 如果集合被清空，就停止刷新动画  */    if(wList.size() == 0){      isRunning = false;    }  }   /**   * 添加新的波浪中心点   * @param x   * @param y   */  private void addPoint(int x, int y) {     if(wList.size() == 0) {      addPoint2List(x, y);      isRunning = true;      handler.sendEmptyMessage(0);    }else{      Wave w = wList.get(wList.size()-1);       if(Math.abs(w.cx - x)>DIS_SOLP || Math.abs(w.cy-y)>DIS_SOLP){        addPoint2List(x,y);      }     };  }   /**   * 添加新的波浪   * @param x   * @param y   */  private void addPoint2List(int x, int y) {    Wave w = new Wave();    w.cx = x;    w.cy=y;    Paint pa=new Paint();    pa.setColor(colors[(int)(Math.random()*4)]);    pa.setAntiAlias(true);    pa.setStyle(Paint.Style.STROKE);     w.p = pa;     wList.add(w);  }   private int [] colors = new int[]{Color.BLUE,Color.RED,Color.YELLOW,Color.GREEN};  private class Wave {    //圆心    int cx;    int cy;     //画笔    Paint p;    //半径    int r;  }}

package com.example.mhy.shuibowen; import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.os.Handler;import android.os.Message;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.View; /** * Created by mhy on 2016/6/16. */public class MyRing extends View {   /**   * 圆心的X坐标   */  private float cx;   /**   * 圆心的Y坐标   */  private float cy;  /**   * 圆环半径   */  private float radius = 0;  /**   * 默认画笔   */  private Paint paint;  private boolean isRuning = false;   public MyRing(Context context, AttributeSet attrs) {    super(context, attrs);    initView();  }   private void initView() {    radius = 0;    paint = new Paint();    paint.setAntiAlias(true);    paint.setStyle(Paint.Style.STROKE); // 空心圆    paint.setStrokeWidth(radius / 4); // 画笔宽度 半径4分之一    paint.setColor(Color.GREEN); // 画笔颜色    paint.setAlpha(255); //不透明  }   @Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {    super.onMeasure(widthMeasureSpec, heightMeasureSpec);  }   @Override  protected void onLayout(boolean changed, int l, int t, int r, int b) {    if(changed) {      cx = getWidth() / 2;      cy = getHeight() / 2;    }  }   @Override  protected void onDraw(Canvas canvas) {    canvas.drawCircle(cx, cy, radius, paint);  }   @Override  protected void onAttachedToWindow() {    super.onAttachedToWindow();  }   @Override  protected void onDetachedFromWindow() {    super.onDetachedFromWindow();    isRuning = false;  }   @Override  public boolean onTouchEvent(MotionEvent event) {    super.onTouchEvent(event);     if(event.getAction() == MotionEvent.ACTION_DOWN) {      cx = event.getX();      cy = event.getY();      initView();      startAnim();    }    return true;  }   private Handler handler = new Handler(){    @Override    public void handleMessage(Message msg) {       // 设置透明度      int alpha = paint.getAlpha();      if(alpha == 0) {        isRuning = false;      }       // 透明度 慢慢变透明      alpha = Math.max(0, alpha-10);       paint.setAlpha(alpha);       System.out.println(alpha);       // 设置半径      radius += 5;      paint.setStrokeWidth(radius / 3);      invalidate();       if(isRuning) {        handler.sendEmptyMessageDelayed(0, 50);      }    }  };  private void startAnim() {    isRuning = true;    handler.sendEmptyMessageDelayed(0, 50);  } }