Android 实现九宫格抽奖功能

效果展示

实现步骤

1.生成抽奖矩形：

其中每个矩形的宽高相同，长度为整个控件宽度的1/3。

代码展示

public class NineLuckPan extends View {
 private Paint mPaint;
 private ArrayList<RectF> mRects;//存储矩形的集合
 private float mStrokWidth = 5;//矩形的描边宽度
 private int mRectSize;//矩形的宽和高（矩形为正方形）
 private int[] mItemColor = {Color.GREEN, Color.YELLOW};//矩形的颜色

 public NineLuckPan(Context context) {
  this(context, null);
 }

 public NineLuckPan(Context context, @Nullable AttributeSet attrs) {
  this(context, attrs, 0);
 }

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

 /**
  * 初始化数据
  */
 private void init() {
  mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
  mPaint.setStyle(Paint.Style.FILL);
  mPaint.setStrokeWidth(mStrokWidth);
  mRects = new ArrayList<>();
 }

 @Override
 protected void onSizeChanged(int w, int h, int oldw, int oldh) {
  super.onSizeChanged(w, h, oldw, oldh);
  mRectSize = Math.min(w, h) / 3;//获取矩形的宽和高
  mRects.clear();//当控件大小改变的时候清空数据
  initRect();//重新加载矩形数据
 }

 /**
  * 加载矩形数据
  */
 private void initRect() {
  //加载前三个矩形
  for (int x = 0; x < 3; x++) {
   float left = x * mRectSize;
   float top = 0;
   float right = (x + 1) * mRectSize;
   float bottom = mRectSize;
   RectF rectF = new RectF(left, top, right, bottom);
   mRects.add(rectF);
  }
  //加载第四个
  mRects.add(new RectF(getWidth() - mRectSize, mRectSize, getWidth(), mRectSize * 2));
  //加载第五~七个
  for (int y = 3; y > 0; y--) {
   float left = getWidth() - (4 - y) * mRectSize;
   float top = mRectSize * 2;
   float right = (y - 3) * mRectSize + getWidth();
   float bottom = mRectSize * 3;
   RectF rectF = new RectF(left, top, right, bottom);
   mRects.add(rectF);
  }
  //加载第八个
  mRects.add(new RectF(0, mRectSize, mRectSize, mRectSize * 2));
  //加载第九个
  mRects.add(new RectF(mRectSize, mRectSize, mRectSize * 2, mRectSize * 2));
 }

 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  drawRects(canvas);
 }

 /**
  * 画矩形
  *
  * @param canvas
  */
 private void drawRects(Canvas canvas) {
  for (int x = 0; x < mRects.size(); x++) {
   RectF rectF = mRects.get(x);
   if (x == 8) {//中心的矩形背景为白色
    mPaint.setColor(Color.WHITE);
    canvas.drawRect(rectF, mPaint);
   } else {
    mPaint.setColor(mItemColor[x % 2]);
    canvas.drawRect(rectF, mPaint);
   }
  }
 }
}

效果展示

2.添加奖品图片：

我们在矩形的中心点画出图片，图片的宽高都为矩形宽高的1/2，其中矩形的中心点通过rectF.centerX()和rectF.centerY()获取。

代码展示（为了方便只展示部分代码）

public class NineLuckPan extends View {
 private int[] mImgs = {R.drawable.ic_df, R.drawable.ic_jt, R.drawable.ic_mf, R.drawable.ic_scjx, R.drawable.ic_scng, R.drawable.ic_thl, R.drawable.ic_x, R.drawable.ic_xc, R.drawable.ic_j};

 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  drawRects(canvas);//画矩形
  drawImages(canvas);//画图片
 }

 /**
  * 画图片
  *
  * @param canvas
  */
 private void drawImages(Canvas canvas) {
  for (int x = 0; x < mRects.size(); x++) {
   RectF rectF = mRects.get(x);
   float left = rectF.centerX() - mRectSize / 4;
   float top = rectF.centerY() - mRectSize / 4;
   canvas.drawBitmap(Bitmap.createScaledBitmap(BitmapFactory.decodeResource(getResources(), mImgs[x]), mRectSize / 2, mRectSize / 2, false), left, top, null);
  }
 }
}

效果展示

3.实现抽奖动画：

这里我们使用ValueAnimator使数字从0递增到我们的中奖位置比如3，然后改变递增所在的位置的矩形的背景以实现抽奖的效果，另外为了让用户感到逼真我们需要让抽奖色块多转几圈，同时我们需要将下一次的开始位置设为上一次的结束位置。

代码展示（为了方便只展示部分代码）

NineLuckPan:

public class NineLuckPan extends View {
 private int mRepeatCount = 3;//转的圈数
 private int mLuckNum = 3;//最终中奖位置
 private int mPosition = -1;//抽奖块的位置
 private int mStartLuckPosition = 0;//开始抽奖的位置
 /**
  * 画矩形
  * @param canvas
  */
 private void drawRects(Canvas canvas) {
  for (int x = 0;x<mRects.size();x++){
   RectF rectF = mRects.get(x);
   if(x == 8){
    mPaint.setColor(Color.WHITE);
    canvas.drawRect(rectF, mPaint);
   }else {
    mPaint.setColor(mItemColor[x%2]);
    if(mPosition == x){
     mPaint.setColor(Color.BLUE);
    }
    canvas.drawRect(rectF, mPaint);
   }
  }
 }
 public void setPosition(int position){
  mPosition = position;
  invalidate();
 }
 /**
  * 开始动画
  */
 public void startAnim(){
  ValueAnimator valueAnimator = ValueAnimator.ofInt(mStartLuckPosition, mRepeatCount * 8 + mLuckNum).setDuration(5000);
  valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
   @Override
   public void onAnimationUpdate(ValueAnimator animation) {
    int position = (int) animation.getAnimatedValue();
    setPosition(position%8);
   }
  });
  valueAnimator.addListener(new AnimatorListenerAdapter() {
   @Override
   public void onAnimationEnd(Animator animation) {
    mStartLuckPosition = mLuckNum;
   }
  });
  valueAnimator.start();
 }
}

Activity:

public class MainActivity extends AppCompatActivity {
 private NineLuckPan luckpan;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  luckpan = (NineLuckPan) findViewById(R.id.luckpan);
  luckpan.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    luckpan.startAnim();
   }
  });
 }
}

效果展示

虽然效果实现了但是我们发现好像点哪里都能启动动画，因此我们需要调整一下代码使只有点击中心的矩形才开始动画。

//（为了方便只展示部分代码）
public class NineLuckPan extends View {
 private boolean mClickStartFlag = false;//是否点击中间矩形的标记

 //这样需要我们将Activity里的启动动画的逻辑删掉
 @Override
 public boolean onTouchEvent(MotionEvent event) {
  if(event.getAction() == MotionEvent.ACTION_DOWN){
   if(mRects.get(8).contains(event.getX(),event.getY())){
    mClickStartFlag = true;
   }else {
    mClickStartFlag = false;
   }
   return true;
  }
  if(event.getAction() == MotionEvent.ACTION_UP){
   if(mClickStartFlag){
    if(mRects.get(8).contains(event.getX(),event.getY())){
     startAnim();//判断只有手指落下和抬起都在中间的矩形内才开始抽奖
    }
    mClickStartFlag = false;
   }
  }
  return super.onTouchEvent(event);
 }
}

4.实现动态设置参数：

效果基本实现了，接下来就需要实现动态设置数据了。

代码展示（这里为了方便只展示部分代码）

public class NineLuckPan extends View {
 private int mLuckNum = 3;//最终中奖位置
 private int [] mImgs = {R.drawable.ic_df,R.drawable.ic_jt,R.drawable.ic_mf,R.drawable.ic_scjx,R.drawable.ic_scng,R.drawable.ic_thl,R.drawable.ic_x,R.drawable.ic_xc,R.drawable.ic_j};
 private String[] mLuckStr = {"豆腐","鸡腿","米饭","卷心菜","南瓜","糖葫芦","大虾","香肠"};//这是抽奖的提示信息

 public int getmLuckNum() {
  return mLuckNum;
 }

 public void setmLuckNum(int mLuckNum) {
  this.mLuckNum = mLuckNum;
 }

 public int[] getmImgs() {
  return mImgs;
 }

 public void setmImgs(int[] mImgs) {
  this.mImgs = mImgs;
  invalidate();//要注意设置完后要进行重绘
 }

 public String[] getmLuckStr() {
  return mLuckStr;
 }

 public void setmLuckStr(String[] mLuckStr) {
  this.mLuckStr = mLuckStr;
  invalidate();;//要注意设置完后要进行重绘
 }
}

5.添加抽奖结果回调

这里需要在动画结束的回调里加入我们自定义的回调函数。

代码展示（这里为了方便只展示部分代码）

public class NineLuckPan extends View {
 private OnLuckPanAnimEndListener onLuckPanAnimEndListener;

 public OnLuckPanAnimEndListener getOnLuckPanAnimEndListener() {
  return onLuckPanAnimEndListener;
 }

 public void setOnLuckPanAnimEndListener(OnLuckPanAnimEndListener onLuckPanAnimEndListener) {
  this.onLuckPanAnimEndListener = onLuckPanAnimEndListener;
 }

 /**
  * 开始动画
  */
 private void startAnim(){
  ValueAnimator valueAnimator = ValueAnimator.ofInt(mStartLuckPosition, mRepeatCount * 8 + mLuckNum).setDuration(5000);
  valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
   @Override
   public void onAnimationUpdate(ValueAnimator animation) {
    int position = (int) animation.getAnimatedValue();
    setPosition(position%8);
   }
  });
  valueAnimator.addListener(new AnimatorListenerAdapter() {
   @Override
   public void onAnimationEnd(Animator animation) {
    mStartLuckPosition = mLuckNum;
    //在动画结束的回调函数里加入我们自定义的回调函数
    if(onLuckPanAnimEndListener!=null){
     onLuckPanAnimEndListener.onAnimEnd(mPosition,mLuckStr[mPosition]);
    }
   }
  });
  valueAnimator.start();
 }
 public interface OnLuckPanAnimEndListener{
  void onAnimEnd(int position,String msg);
 }
}

Activity代码：

public class MainActivity extends AppCompatActivity {
 private NineLuckPan luckpan;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  luckpan = (NineLuckPan) findViewById(R.id.luckpan);
  luckpan.setOnLuckPanAnimEndListener(new NineLuckPan.OnLuckPanAnimEndListener() {
   @Override
   public void onAnimEnd(int position, String msg) {
    Toast.makeText(MainActivity.this, "位置："+position+"提示信息："+msg, Toast.LENGTH_SHORT).show();
   }
  });
 }
}

效果展示

源码地址：

https://github.com/myml666/NineLuckPan

到这里就结束啦！

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