Android自定义View实现直播点赞特效的方法

import android.animation.Animator;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.animation.TypeEvaluator;
import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.PointF;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.DecelerateInterpolator;
import android.view.animation.Interpolator;
import android.view.animation.LinearInterpolator;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import com.xinrui.ndkapp.R;
import java.util.Random;

/**
 * Created by liuyong
 * Data: 2017/8/8
 * Github:https://github.com/MrAllRight
 * 直播点赞view
 */

public class GivePraiseView extends RelativeLayout {
  private RelativeLayout.LayoutParams layoutParams;//图片布局参数
  private PointF mPointF0, mPointF1, mPointF2, mPointF3;//通过3阶贝塞尔曲线控制图片的移动轨迹
  private int mScreenWidth, mScreenHeight;//屏幕宽高
  private Drawable[] mImageDrawables;//加载点赞红心图片，红黄蓝
  private int mDrawableWidth, mDrawableHeight;//图片的宽高
  private Random mRandom = new Random();
  private int count = 0;
  private Interpolator[] interpolators = new Interpolator[4];

  public GivePraiseView(Context context) {
    super(context);
    init();
  }

  public GivePraiseView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init();
  }

  public GivePraiseView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init();
  }

  @Override
  protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    mScreenHeight = h;
    mScreenWidth = w;
  }

  //初始化drawable，layoutParams
  private void init() {
    mImageDrawables = new Drawable[4];
    mImageDrawables[0] = getResources().getDrawable(R.drawable.pl_blue);
    mImageDrawables[1] = getResources().getDrawable(R.drawable.pl_red);
    mImageDrawables[2] = getResources().getDrawable(R.drawable.pl_yellow);
    mImageDrawables[3] = getResources().getDrawable(R.drawable.pl_red);
    // 插值器
    interpolators[0] = new AccelerateDecelerateInterpolator(); // 在动画开始与结束的地方速率改变比较慢，在中间的时候加速
    interpolators[1] = new AccelerateInterpolator(); // 在动画开始的地方速率改变比较慢，然后开始加速
    interpolators[2] = new DecelerateInterpolator(); // 在动画开始的地方快然后慢
    interpolators[3] = new LinearInterpolator(); // 以常量速率改变
    mDrawableWidth = mImageDrawables[0].getIntrinsicWidth();
    mDrawableHeight = mImageDrawables[0].getIntrinsicHeight();
    layoutParams = new LayoutParams(50, 50);
    layoutParams.addRule(ALIGN_PARENT_BOTTOM, TRUE);
    layoutParams.addRule(ALIGN_PARENT_RIGHT, TRUE);
    layoutParams.setMargins(0, 0, 60, 60);//放置在屏幕的右下角
    //这里为了演示我们现在布局初始化的时候，放置一个imageview，颜色随机，设置点击屏幕出现点赞效果
    ImageView iv = new ImageView(getContext());
    iv.setLayoutParams(layoutParams);
    iv.setImageDrawable(mImageDrawables[0]);
    addView(iv);
    this.setOnClickListener(new OnClickListener() {
      @Override
      public void onClick(View v) {
        for(int i=0;i<10;i++) {
          addGivePraiseImg(count);
          count++;
          if (count == 4) count = 0;
        }
      }
    });
  }

  //点击图片是添加imageview到布局中，并添加动画
  private void addGivePraiseImg(int count) {
    final ImageView givepraiseImg = new ImageView(getContext());
    givepraiseImg.setLayoutParams(layoutParams);
    givepraiseImg.setImageDrawable(mImageDrawables[count]);
    addView(givepraiseImg);
    addAnimator(givepraiseImg);//添加动画效果，动画分两部分，第一部分是产生图片时缩放和透明度，第二部是移动图片再进行透明度变化
  }

  private void addAnimator(final ImageView imageView) {
    //点击的时候，让图片经过放大，缩放效果，之后再开始沿着贝塞尔曲线的轨迹移动
    ObjectAnimator alpha = ObjectAnimator.ofFloat(imageView, "alpha", 0.3f, 1f);
    ObjectAnimator scaleX = ObjectAnimator.ofFloat(imageView, "scaleX", 0.2f, 1f);
    ObjectAnimator scaleY = ObjectAnimator.ofFloat(imageView, "scaleY", 0.2f, 1f);
    AnimatorSet set = new AnimatorSet();
    set.setDuration(100);
    set.playTogether(alpha, scaleX, scaleY);
    set.setTarget(imageView);
    set.addListener(new Animator.AnimatorListener() {
      @Override
      public void onAnimationStart(Animator animation) {

      }

      @Override
      public void onAnimationEnd(Animator animation) {
        //设置贝塞尔曲线移动效果
        ValueAnimator va = getBzierAnimator(imageView);//第二部分动画
        va.start();
      }

      @Override
      public void onAnimationCancel(Animator animation) {

      }

      @Override
      public void onAnimationRepeat(Animator animation) {

      }
    });
    set.start();
  }

  //初始化贝塞尔曲线的4个点
  private void initPointF() {
    mPointF0 = new PointF(mScreenWidth - 60 - 50, mScreenHeight - 60 - 50);//起点是初始化时的点
    mPointF1 = new PointF(mRandom.nextInt(mScreenWidth), mRandom.nextInt((int) mPointF0.y));//第一个控制点必须要在起始点的上方
    mPointF2 = new PointF(mRandom.nextInt(mScreenWidth), mRandom.nextInt((int) mPointF1.y));//第二个控制点必须在第一个点的上方
    mPointF3 = new PointF(mRandom.nextInt(mScreenWidth), -50);//终点在屏幕的最顶部0-图片的高度
  }


  /**
   *  自定义估值器计算图片移动的轨迹
   *  计算公式参考贝塞尔曲线3阶计算公式
   *  自定义估值器的方法可百度搜索
   *  其中估值器定义返回的结果为PointF
   */
  public class BezierEvaluator implements TypeEvaluator<PointF> {
    private PointF pointF1, pointF2;

    public BezierEvaluator(PointF p1, PointF p2) {
      this.pointF1 = p1;
      this.pointF2 = p2;
    }

    @Override
    public PointF evaluate(float t, PointF p0, PointF p3) {
      PointF point = new PointF();
      point.x = p0.x * (1 - t) * (1 - t) * (1 - t) //
          + 3 * pointF1.x * t * (1 - t) * (1 - t)//
          + 3 * pointF2.x * t * t * (1 - t)//
          + p3.x * t * t * t;//

      point.y = p0.y * (1 - t) * (1 - t) * (1 - t) //
          + 3 * pointF1.y * t * (1 - t) * (1 - t)//
          + 3 * pointF2.y * t * t * (1 - t)//
          + p3.y * t * t * t;//
      return point;
    }
  }

  private ValueAnimator getValueAnimator(final ImageView imageView) {
    initPointF();
    BezierEvaluator bezierEvaluator = new BezierEvaluator(mPointF1, mPointF2);
    ValueAnimator valueAnimator = ValueAnimator.ofObject(bezierEvaluator, mPointF0, mPointF3);
    valueAnimator.setDuration(3000);
    valueAnimator.setTarget(imageView);
    valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override
      public void onAnimationUpdate(ValueAnimator animation) {
        //改变imageview位置实现移动效果
        PointF point = (PointF) animation.getAnimatedValue();
        imageView.setX(point.x);
        imageView.setY(point.y);
        imageView.setAlpha(1 - animation.getAnimatedFraction());
        //动画结束移除imageview
        if (animation.getAnimatedFraction() >= 1) {
          removeView(imageView);
        }
      }
    });
    return valueAnimator;
  }

  /**
   * 贝塞尔动画
   * */
  private ValueAnimator getBzierAnimator(final ImageView iv) {
    // TODO Auto-generated method stub
    PointF[] PointFs = getPointFs(iv); // 4个点的坐标
    BezierEvaluator evaluator = new BezierEvaluator(PointFs[1], PointFs[2]);
    ValueAnimator valueAnim = ValueAnimator.ofObject(evaluator, PointFs[0], PointFs[3]);
    valueAnim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {

      @Override
      public void onAnimationUpdate(ValueAnimator animation) {
        // TODO Auto-generated method stub
        PointF p = (PointF) animation.getAnimatedValue();
        iv.setX(p.x);
        iv.setY(p.y);
        iv.setAlpha(1- animation.getAnimatedFraction()); // 透明度
        //动画结束移除imageview
        if (animation.getAnimatedFraction() >= 1) {
          removeView(iv);
        }
      }
    });
    valueAnim.setTarget(iv);
    valueAnim.setDuration(3000);
    valueAnim.setInterpolator(interpolators[new Random().nextInt(4)]);
    return valueAnim;
  }

  private PointF[] getPointFs(ImageView iv) {
    // TODO Auto-generated method stub
    PointF[] PointFs = new PointF[4];
    PointFs[0] = new PointF(); // p0
    PointFs[0].x = (mScreenWidth- layoutParams.width)/ 2;
    PointFs[0].y = mScreenHeight - layoutParams.height;

    PointFs[1] = new PointF(); // p1
    PointFs[1].x = new Random().nextInt(mScreenWidth);
    PointFs[1].y = new Random().nextInt(mScreenHeight /2) + mScreenHeight / 2 + layoutParams.height;

    PointFs[2] = new PointF(); // p2
    PointFs[2].x = new Random().nextInt(mScreenWidth);
    PointFs[2].y = new Random().nextInt(mScreenHeight /2);

    PointFs[3] = new PointF(); // p3
    PointFs[3].x = new Random().nextInt(mScreenWidth);
    PointFs[3].y = 0;
    return PointFs;
  }
}

<&#63;xml version="1.0" encoding="utf-8"&#63;>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@android:color/darker_gray">
  <com.xinrui.ndkapp.view.GivePraiseView
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>
  <!--<com.xinrui.ndkapp.view.LoveLayout-->
    <!--android:layout_width="match_parent"-->
    <!--android:layout_height="match_parent"/>-->
</RelativeLayout>

import android.app.Activity;
import android.os.Bundle;

public class GivePraiseActivity extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.givepraise_layout);
  }
}