Android刮刮乐效果

Android刮刮乐效果

刮刮乐中奖效果，纯属好玩，效果不错。

一、思路：

自定义组件ScratchCardView

二、效果图：

三、关键代码：

public class ScratchCardView extends View {

    //处理文字
    private String mText = "欧王中奖了";
    private Paint mTextPaint;
    private Rect mRect;

    //处理图层
    private Paint mForePaint;
    private Path mPath;

    private Bitmap mBitmap;//加载资源文件
    private Canvas mForeCanvas;//前景图Canvas
    private Bitmap mForeBitmap;//前景图Bitmap

    //记录位置
    private int mLastX;
    private int mLastY;

    private volatile boolean isClear;//标志是否被清除


    public ScratchCardView(Context context) {
        this(context, null);

    }

    public ScratchCardView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public ScratchCardView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }


    private void init() {

        mRect = new Rect();
        mPath = new Path();

        //文字画笔
        mTextPaint = new Paint();
        mTextPaint.setAntiAlias(true);
        mTextPaint.setColor(Color.GREEN);
        mTextPaint.setStyle(Paint.Style.FILL);
        mTextPaint.setTextSize(30);
        mTextPaint.getTextBounds(mText, 0, mText.length(), mRect);

        //擦除画笔
        mForePaint = new Paint();
        mForePaint.setAntiAlias(true);
        mForePaint.setAlpha(0);
        mForePaint.setStrokeCap(Paint.Cap.ROUND);
        mForePaint.setStrokeJoin(Paint.Join.ROUND);
        mForePaint.setStyle(Paint.Style.STROKE);
        mForePaint.setStrokeWidth(30);
        mForePaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));


        //通过资源文件创建Bitmap对象
        mBitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.bg1);
        mForeBitmap = Bitmap.createBitmap(mBitmap.getWidth(), mBitmap.getHeight(), Bitmap.Config.ARGB_8888);
        //双缓冲,装载画布
        mForeCanvas = new Canvas(mForeBitmap);
        mForeCanvas.drawBitmap(mBitmap, 0, 0, null);

    }


    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawText(mText, mForeBitmap.getWidth() / 2 - mRect.width() / 2, mForeBitmap.getHeight() / 2 + mRect.height() / 2, mTextPaint);
        if (!isClear) {
            canvas.drawBitmap(mForeBitmap, 0, 0, null);
        }
    }


    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mLastX = (int) event.getX();
                mLastY = (int) event.getY();
                mPath.moveTo(mLastX, mLastY);
                break;
            case MotionEvent.ACTION_MOVE:
                mLastX = (int) event.getX();
                mLastY = (int) event.getY();
                mPath.lineTo(mLastX, mLastY);
                break;
            case MotionEvent.ACTION_UP:
                new Thread(mRunnable).start();
                break;
            default:
                break;
        }

        mForeCanvas.drawPath(mPath, mForePaint);
        invalidate();
        return true;
    }

四、项目demo源码结构图：

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