Android 實現九宮格抽獎功能

其中每個矩形的寬高相同，長度為整個控件寬度的1/3。

代碼展示

public class NineLuckPan extends View { private Paint mPaint; private ArrayList<RectF> mRects;//存儲矩形的集合 private float mStrokWidth = 5;//矩形的描邊寬度 private int mRectSize;//矩形的寬和高（矩形為正方形） private int[] mItemColor = {Color.GREEN, Color.YELLOW};//矩形的顏色 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(); } /** * 初始化數據 */ 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;//獲取矩形的寬和高 mRects.clear();//當控件大小改變的時候清空數據 initRect();//重新加載矩形數據 } /** * 加載矩形數據 */ private void initRect() { //加載前三個矩形 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); } //加載第四個 mRects.add(new RectF(getWidth() - mRectSize, mRectSize, getWidth(), mRectSize * 2)); //加載第五~七個 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); } //加載第八個 mRects.add(new RectF(0, mRectSize, mRectSize, mRectSize * 2)); //加載第九個 mRects.add(new RectF(mRectSize, mRectSize, mRectSize * 2, mRectSize * 2)); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); drawRects(canvas); } /** * 畫矩形 * * @param canvas */ private void drawRects(Canvas canvas) { for (int x = 0; x < mRects.size(); x++) { RectF rectF = mRects.get(x); if (x == 8) {//中心的矩形背景為白色 mPaint.setColor(Color.WHITE); canvas.drawRect(rectF, mPaint); } else { mPaint.setColor(mItemColor[x % 2]); canvas.drawRect(rectF, mPaint); } } }}

效果展示

我們在矩形的中心點畫出圖片，圖片的寬高都為矩形寬高的1/2，其中矩形的中心點通過rectF.centerX()和rectF.centerY()獲取。

代碼展示（為了方便只展示部分代碼）

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);//畫矩形 drawImages(canvas);//畫圖片 } /** * 畫圖片 * * @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

這里我們使用ValueAnimator使數字從0遞增到我們的中獎位置比如3，然后改變遞增所在的位置的矩形的背景以實現抽獎的效果，另外為了讓用戶感到逼真我們需要讓抽獎色塊多轉幾圈，同時我們需要將下一次的開始位置設為上一次的結束位置。

代碼展示（為了方便只展示部分代碼）

NineLuckPan:

public class NineLuckPan extends View { private int mRepeatCount = 3;//轉的圈數 private int mLuckNum = 3;//最終中獎位置 private int mPosition = -1;//抽獎塊的位置 private int mStartLuckPosition = 0;//開始抽獎的位置 /** * 畫矩形 * @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(); } /** * 開始動畫 */ 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

雖然效果實現了但是我們發現好像點哪里都能啟動動畫，因此我們需要調整一下代碼使只有點擊中心的矩形才開始動畫。

//（為了方便只展示部分代碼）public class NineLuckPan extends View { private boolean mClickStartFlag = false;//是否點擊中間矩形的標記 //這樣需要我們將Activity里的啟動動畫的邏輯刪掉 @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();//判斷只有手指落下和抬起都在中間的矩形內才開始抽獎 } mClickStartFlag = false; } } return super.onTouchEvent(event); }}4.實現動態設置參數：

效果基本實現了，接下來就需要實現動態設置數據了。

代碼展示（這里為了方便只展示部分代碼）

public class NineLuckPan extends View { private int mLuckNum = 3;//最終中獎位置 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','雞腿','米飯','卷心菜','南瓜','糖葫蘆','大蝦','香腸'};//這是抽獎的提示信息 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();//要注意設置完后要進行重繪 } public String[] getmLuckStr() { return mLuckStr; } public void setmLuckStr(String[] mLuckStr) { this.mLuckStr = mLuckStr; invalidate();;//要注意設置完后要進行重繪 }}5.添加抽獎結果回調

這里需要在動畫結束的回調里加入我們自定義的回調函數。

代碼展示（這里為了方便只展示部分代碼）

public class NineLuckPan extends View { private OnLuckPanAnimEndListener onLuckPanAnimEndListener; public OnLuckPanAnimEndListener getOnLuckPanAnimEndListener() { return onLuckPanAnimEndListener; } public void setOnLuckPanAnimEndListener(OnLuckPanAnimEndListener onLuckPanAnimEndListener) { this.onLuckPanAnimEndListener = onLuckPanAnimEndListener; } /** * 開始動畫 */ 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; //在動畫結束的回調函數里加入我們自定義的回調函數 if(onLuckPanAnimEndListener!=null){ onLuckPanAnimEndListener.onAnimEnd(mPosition,mLuckStr[mPosition]); } } }); valueAnimator.start(); } public interface OnLuckPanAnimEndListener{ void onAnimEnd(int position,String msg); }}

Activity代碼：

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

源碼地址：

https://github.com/myml666/NineLuckPan

到這里就結束啦！

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