刮刮卡功能的具体实现

今天整理之前的代码，忽然看到之前自己写的一个刮刮卡，整理下以便以后使用，同时分享给需要的朋友，如有错误，还请多多指正。

实现的步骤，其实就是徒手画三个图层叠加在一起，最上层是绘制需要的问题，就是以上所述的“骚年，刮我吧”，第二层就是覆盖宽高的灰层，第三层是结果层，多的不啰嗦了，具体实现如下，附上详细注释。

/**
 * 
 * created by zero on 2016-9-9
 * 
 * 刮刮卡
 * 
 */
public class ScratchView extends View
{

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

    private Canvas mCanvas = null;
    private Path mPath = null;
    private Paint mPaint = null;

    // 定义画布的宽和高
    private int screenWidth = 720;
    private int screenHeight = 360;
    private Bitmap bitmap = null;

    private void init() {
        // TODO Auto-generated method stub
        mPath = new Path();
        bitmap = Bitmap.createBitmap(screenWidth, screenHeight,
                Config.ARGB_8888);

        // 对mPaint的设置
        mPaint = new Paint();
        mPaint.setFlags(Paint.ANTI_ALIAS_FLAG);
        mPaint.setAntiAlias(true);
        mCanvas = new Canvas();
        mPaint.setDither(true);
        // 设置画笔为空心
        mPaint.setStyle(Style.STROKE);
        // 设置线宽，即每次擦除的宽度
        mPaint.setStrokeWidth(10);
        mPaint.setStrokeCap(Cap.ROUND);
        mPaint.setStrokeJoin(Join.ROUND);
        // 设置图形重叠时的处理方式，一共有16种方式，有兴趣可自己查阅
        mPaint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
        mPaint.setAlpha(0);

        mCanvas = new Canvas(bitmap);
        mCanvas.drawColor(Color.parseColor("#c0c0c0"));
        setBitmapText();
    }

    private void setBitmapText() {
        Paint paint = new Paint();
        paint.setTextSize(40);
        paint.setColor(Color.parseColor("#9f9fa0"));
        paint.setFlags(Paint.ANTI_ALIAS_FLAG);
        paint.setAntiAlias(true);
        paint.setTextAlign(Paint.Align.CENTER);
        paint.setFakeBoldText(true);

        Canvas canvas = new Canvas(bitmap);
        canvas.drawColor(Color.alpha(0));
        canvas.rotate(-20);
        // 遍历绘制文字
        for (int i = 0; i < screenWidth + 200; i += 300)
        {
            for (int j = 0; j < screenHeight + 200; j += 60)
            {
                canvas.drawText("刮我吧，骚年！", i, j, paint);
            }
        }
        setScratchBackground("一等奖");
    }

    // 接收后台传来的文字，即中奖或者未中奖的文字
    public void setScratchBackground(String txt_win) {
        // TODO Auto-generated method stub
        Paint paint = new Paint();
        Bitmap bitmap = Bitmap.createBitmap(screenWidth, screenHeight,
                Config.ARGB_8888);
        paint.setTextSize(40);
        paint.setColor(Color.BLACK);
        paint.setFlags(Paint.ANTI_ALIAS_FLAG);
        paint.setAntiAlias(true);
        paint.setTextAlign(Paint.Align.CENTER);

        Canvas canvas = new Canvas(bitmap);
        canvas.drawColor(Color.alpha(0));
        canvas.drawText(txt_win, screenWidth / 2, 60, paint);
        setBackgroundDrawable(new BitmapDrawable(getResources(), bitmap));
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        super.onDraw(canvas);
        mCanvas.drawPath(mPath, mPaint);
        canvas.drawBitmap(bitmap, 0, 0, null);
    }

    int x = 0;
    int y = 0;

    @SuppressLint("ClickableViewAccessibility")
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // TODO Auto-generated method stub
        int action = event.getAction();
        int currX = (int) event.getX();
        int currY = (int) event.getY();
        switch (action)
        {
        case MotionEvent.ACTION_DOWN:
        {
            mPath.reset();
            x = currX;
            y = currY;
            mPath.moveTo(x, y);
        }
            break;
        case MotionEvent.ACTION_MOVE:
        {
            mPath.quadTo(x, y, currX, currY);
            x = currX;
            y = currY;
            postInvalidate();
        }
            break;
        case MotionEvent.ACTION_UP:
        {
            new Thread(mRunnable).start();
        }
        case MotionEvent.ACTION_CANCEL:
        {
            mPath.reset();
        }
            break;
        }
        return true;
    }

    private Runnable mRunnable = new Runnable()
    {
        private int[] mPixels;

        @Override
        public void run() {
            float wipeArea = 0;
            float totalArea = screenWidth * screenHeight;
            Bitmap mBitmap = bitmap;
            mPixels = new int[screenWidth * screenHeight];
            /**
             * 拿到所有的像素信息
             */
            mBitmap.getPixels(mPixels, 0, screenWidth, 0, 0, screenWidth,
                    screenHeight);
            /**
             * 遍历统计擦除的区域
             */
            for (int i = 0; i < screenWidth; i++)
            {
                for (int j = 0; j < screenHeight; j++)
                {
                    int index = i + j * screenWidth;
                    if (mPixels[index] == 0)
                    {
                        wipeArea++;
                    }
                }
            }

            /**
             * 根据所占百分比，进行一些操作
             */
            if (wipeArea > 0 && totalArea > 0)
            {
                int percent = (int) (wipeArea * 100 / totalArea);
                /**
                 * 设置达到多少百分比的时候，弹窗提醒是否中奖此处设置为20
                 */
                if (percent > 20)
                {
                    /**
                     * 刮开奖以后的操作，此处在子线程toast，可能会发生线程阻塞，只为测试使用
                     */
                    Looper.prepare();
                    Toast.makeText(getContext(), "已刮开" + percent + "%",
                            Toast.LENGTH_LONG).show();
                    Looper.loop();
                }
            }
        }
    };
}

发的是公司需要的效果，以上代码只是一个实现，各种样式还需要自己去实现。