Android自定义View 实现水波纹动画引导效果

package com.czhappy.showintroduce.view;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.View;
import android.widget.RelativeLayout;
/**
 * Description: 水波纹动画引导view
 * User: chenzheng
 * Date: 2017/1/14 0014
 * Time: 18:01
 */
public class RippleIntroView extends RelativeLayout implements Runnable {
  private int mMaxRadius = 70;
  private int mInterval = 20;
  private int count = 0;
  private Bitmap mCacheBitmap;
  private Paint mRipplePaint;
  private Paint mCirclePaint;
  private Path mArcPath;
  public RippleIntroView(Context context) {
    this(context, null);
  }
  public RippleIntroView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }
  public RippleIntroView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init();
  }
  private void init() {
    mRipplePaint = new Paint();
    mRipplePaint.setAntiAlias(true);
    mRipplePaint.setStyle(Paint.Style.STROKE);
    mRipplePaint.setColor(Color.WHITE);
    mRipplePaint.setStrokeWidth(2.f);
    mCirclePaint = new Paint();
    mCirclePaint.setAntiAlias(true);
    mCirclePaint.setStyle(Paint.Style.FILL);
    mCirclePaint.setColor(Color.WHITE);
    mArcPath = new Path();
  }
  /**
   * view大小变化时系统调用
   * @param w
   * @param h
   * @param oldw
   * @param oldh
   */
  @Override
  protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    if (mCacheBitmap != null) {
      mCacheBitmap.recycle();
      mCacheBitmap = null;
    }
  }
  @Override
  protected void onDraw(Canvas canvas) {
    //获取加号图片view
    View mPlusChild = getChildAt(0);
    //获取提示图片view
    View mRefsChild = getChildAt(1);
    if (mPlusChild == null || mRefsChild == null) return;
    //获取加号图片大小
    final int pw = mPlusChild.getWidth();
    final int ph = mPlusChild.getHeight();
    //获取提示图片大小
    final int fw = mRefsChild.getWidth();
    final int fh = mRefsChild.getHeight();
    if (pw == 0 || ph == 0) return;
    //加号图片中心点坐标
    final float px = mPlusChild.getX() + pw / 2;
    final float py = mPlusChild.getY() + ph / 2;
    //提示图片左上角坐标
    final float fx = mRefsChild.getX();
    final float fy = mRefsChild.getY();
    final int rw = pw / 2;
    final int rh = ph / 2;
    if (mCacheBitmap == null) {
      mCacheBitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
      Canvas cv = new Canvas(mCacheBitmap);
      super.onDraw(cv);
      //清空所有已经画过的path至原始状态
      mArcPath.reset();
      //起始轮廓点移至x，y坐标点,即加号图片正下方再往下20位置
      mArcPath.moveTo(px, py + rh + mInterval);
      //设置二次贝塞尔，实现平滑曲线，前两个参数为操作点坐标，后两个参数为结束点坐标
      mArcPath.quadTo(px, fy - mInterval, fx + fw * 0.618f, fy - mInterval);
      //0~255，数值越小越透明
      mRipplePaint.setAlpha(255);
      cv.drawPath(mArcPath, mRipplePaint);
      //绘制半径为6的实心圆点
      cv.drawCircle(px, py + rh + mInterval, 6, mCirclePaint);
    }
    //绘制背景图片
    canvas.drawBitmap(mCacheBitmap, 0, 0, mCirclePaint);
    //保存画布当前的状态
    int save = canvas.save();
    for (int step = count; step <= mMaxRadius; step += mInterval) {
      //step越大越靠外就越透明
      mRipplePaint.setAlpha(255 * (mMaxRadius - step) / mMaxRadius);
      canvas.drawCircle(px, py, (float) (rw + step), mRipplePaint);
    }
    //恢复Canvas的状态
    canvas.restoreToCount(save);
    //延迟80毫秒后开始运行
    postDelayed(this, 80);
  }
  @Override
  public void run() {
    //把run对象的引用从队列里拿出来，这样，他就不会执行了，但 run 没有销毁
    removeCallbacks(this);
    count += 2;
    count %= mInterval;
    invalidate();//重绘
  }
  /**
   * 销毁view时调用，收尾工作
   */
  @Override
  protected void onDetachedFromWindow() {
    super.onDetachedFromWindow();
    if (mCacheBitmap != null) {
      mCacheBitmap.recycle();
      mCacheBitmap = null;
    }
  }
}

package com.czhappy.showintroduce.activity;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.ViewGroup;
import com.czhappy.showintroduce.R;
public class MainActivity extends AppCompatActivity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    View view = findViewById(R.id.layout_ripple);
    view.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        ((ViewGroup) v.getParent()).removeView(v);
      }
    });
  }
}

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent">
  <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Hello World!" />
  <com.czhappy.showintroduce.view.RippleIntroView
    android:id="@+id/layout_ripple"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:clickable="true"
    android:fitsSystemWindows="true"
    android:background="#AA000000">
    <ImageView
      android:id="@+id/iv_plus"
      android:layout_marginTop="36dp"
      android:src="@mipmap/ic_add"
      android:layout_alignParentRight="true"
      android:layout_marginRight="6dp"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"/>
    <ImageView
      android:src="@mipmap/tips_subscribe"
      android:id="@+id/tv_title"
      android:layout_below="@id/iv_plus"
      android:layout_marginTop="50dp"
      android:layout_alignParentRight="true"
      android:layout_marginRight="40dp"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"/>
  </com.czhappy.showintroduce.view.RippleIntroView>
</FrameLayout>