类似刮奖

转载：http://blog.csdn.net/lmj623565791/article/details/40162163

其中Sa全称为Source alpha表示源图的Alpha通道；Sc全称为Source color表示源图的颜色；Da全称为Destination alpha表示目标图的Alpha通道；Dc全称为Destination color表示目标图的颜色，[…,..]前半部分计算的是结果图像的Alpha通道值，“,”后半部分计算的是结果图像的颜色值。图像混排后是依靠这两个值来重新计算ARGB值的

布局

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    tools:context="com.example.administrator.testapplication.Main2Activity"    >  <!--    android:background="@mipmap/a" -->  <com.example.administrator.testapplication.HappyCard      android:layout_height="100dp"      android:layout_width="300dp"      ></com.example.administrator.testapplication.HappyCard></LinearLayout>

2

public class HappyCard extends View {    /*绘制线条的Pain，用户手指绘制path*/    private Paint mOutterPaint = new Paint();    /*记录用户绘制的Path*/    private Path mPath ;    /*内存中创建的Canvas*/    private Canvas mCanvas;    /*mCanvas绘制内容在其上*/    private Bitmap mBitmap;    private int mLastX,mLastY;    private Paint mBackPin = new Paint();    private Rect mTextBound = new Rect();    private String mText = "￥500,000,000";    public HappyCard(Context context) {        this(context,null,0);    }    public HappyCard(Context context, AttributeSet attrs) {        this(context, attrs,0);    }    public HappyCard(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        init();    }    private void init() {        mPath = new Path();        setUpOuterPaint();        setUpBackPaint();    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        super.onMeasure(widthMeasureSpec, heightMeasureSpec);        int width = getMeasuredWidth();        int height = getMeasuredHeight();        //初始化bitmap        mBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);        mCanvas = new Canvas(mBitmap);        //设置画笔//    mOutterPaint.setColor(Color.RED);        mOutterPaint.setStyle(Paint.Style.FILL);        mCanvas.drawRoundRect(new RectF(0, 0, width, height), 30, 30, mOutterPaint);//灰色层      ;        mCanvas.drawBitmap(BitmapFactory.decodeResource(getResources(),                R.mipmap.s_title), null, new RectF(0, 0, width, height), null);//图片层    }    @Override    protected void onDraw(Canvas canvas) {  //     canvas.drawBitmap(mBitmap, 0, 0, null);        //绘制奖金        canvas.drawText(mText, getWidth() / 2 - mTextBound.width() / 2, getHeight() / 2 + mTextBound.height() / 2, mBackPin);       if(!isComplete) {           drawPath();           canvas.drawBitmap(mBitmap, 0, 0, null);       }    }    /*绘制细线*/    private void drawPath() {        mOutterPaint.setStyle(Paint.Style.STROKE);        mOutterPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));        mCanvas.drawPath(mPath,mOutterPaint);    }    private void setUpBackPaint(){        mBackPin.setStyle(Paint.Style.FILL);        mBackPin.setTextScaleX(2f);        mBackPin.setColor(Color.DKGRAY);        mBackPin.setTextSize(32);        mBackPin.getTextBounds(mText, 0, mText.length(), mTextBound);    }    private void setUpOuterPaint(){        mOutterPaint.setAntiAlias(true);        mOutterPaint.setColor(Color.parseColor("#c0c0c0"));        mOutterPaint.setDither(true);        mOutterPaint.setStyle(Paint.Style.STROKE);        mOutterPaint.setStrokeJoin(Paint.Join.ROUND);        mOutterPaint.setStrokeCap(Paint.Cap.ROUND);        mOutterPaint.setStrokeWidth(20); //设置画笔宽度    }    @Override    public boolean onTouchEvent(MotionEvent event) {        int action = event.getAction();        int x = (int) event.getX();        int y = (int) event.getY();        switch (action){            case MotionEvent.ACTION_DOWN:                mLastX = x;                mLastY = y;                mPath.moveTo(mLastX, mLastY);                break;            case MotionEvent.ACTION_MOVE:                int dx = Math.abs(x - mLastX);                int dy = Math.abs(y - mLastY);                if(dx > 3 || dy >3)                    mPath.lineTo(x, y);                    mLastX = x;                    mLastY = y;                break;            case MotionEvent.ACTION_UP:                new Thread((mRunnable)).start();                break;        }        invalidate();        return true;    }    //统计擦除区域任务    private  Runnable mRunnable = new Runnable() {        private int[] mPixels;        @Override        public void run() {            int w = getWidth();            int h = getHeight();            float wipeArea = 0;            float totalArea = w*h;            Bitmap bitmap = mBitmap;            mPixels = new int[w*h];            //拿到所有像素信息            bitmap.getPixels(mPixels, 0, w, 0, 0, w, h);            //遍历统计擦除的区域            for (int i = 0; i < w; i++) {                for (int j = 0; j < h; j++) {                    int index = i+j*w;                    if(mPixels[index] == 0){                        wipeArea++;                    }                }            }        //根据所占比例，进行一些操作            if(wipeArea>0&&totalArea>0){                int percent   =(int)(wipeArea*100/totalArea);                if(percent >70){                    isComplete = true;                    postInvalidate();                }            }        }    };            boolean isComplete;}