Android自定义UI之粒子效果

public class Ball {

  public int color;//颜色
  public float x;//圆心x坐标
  public float y;//圆心y坐标
  public float r;//粒子半径

  public float vX;//粒子水平方向速度
  public float vY;//粒子y方向速度
  public float aX;//粒子水平方向加速度
  public float ay;//粒子y方向加速度
}

import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.LinearInterpolator;

import androidx.annotation.Nullable;

import java.util.ArrayList;
import java.util.List;

public class SplitView extends View {

  private Paint mPaint;
  private Bitmap mBitmap;
  private float d=3;//粒子直径
  private ValueAnimator mAnimator;
  private List mBalls=new ArrayList<>();
  public SplitView(Context context) {
    super(context);
  }

  public SplitView(Context context, @Nullable AttributeSet attrs) {
    super(context, attrs);
  }

  public SplitView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init();
  }

  private void init() {
    mPaint=new Paint();
    mBitmap= BitmapFactory.decodeResource(getResources(),R.drawable.ic_launcher_background);
    for (int i=0;i