Android实现刮刮乐效果

    /**        * FileName: RubblerAct.java        * @Desc    该类通过调用Text_Rubbler这个类将在Activity上显示一片刮一刮的区域，可以出发触摸事件        * @author  HTP        * @Date    20140312        * @version 1.00         */                        public class RubblerAct extends Activity {            // 刮开后文字显示            private TextView tv_rubbler;            // 得到刮一刮的内容            private Sentence mSentence;            // 下一张            private TextView tv_next;                    @Override            public void onCreate(Bundle savedInstanceState) {                super.onCreate(savedInstanceState);                        // setContentView(new Rubble(this,"谢谢惠顾",new Rect(100, 200,                // 300,250),2,1f,14));                        // /////////////////////////////////////////                setContentView(R.layout.rubbler);                // 设置的颜色必须要有透明度。                ((Text_Rubbler) findViewById(R.id.rubbler)).beginRubbler(0xFFFFFFFF, 20,                        1f);// 设置橡皮擦的宽度等                mSentence = new Sentence();                // 随机初始化文字                tv_rubbler = (TextView) findViewById(R.id.rubbler);                String str = mSentence.getSentence();                tv_rubbler.setText(str);                        tv_next = (TextView) findViewById(R.id.tv_next);                        // 点击下一步                tv_next.setOnClickListener(new OnClickListener() {                            @Override                    public void onClick(View v) {                        // TODO Auto-generated method stub                        String str = mSentence.getSentence();                        tv_rubbler.setText(str);                        ((Text_Rubbler) findViewById(R.id.rubbler))// 初始化状态                                .beginRubbler(0xFFFFFFFF, 20, 1f);                            }                });                    }                    class Rubble extends View {                        private final int PAINT_STROKE_WIDTH;                private final float TOUCH_TOLERANCE; // 填充距离，使线条更自然，柔和,值越小，越柔和。                private final int TEXT_SIZE;                        private Bitmap mBitmap;                // 画布                private Canvas mCanvas;                // 画笔                private Paint mPaint;                private Path mPath;                private float mX, mY;                private final int X, Y, W, H;                        private final Rect touchRect;                        public Rubble(Context context, String bgText, Rect rect,                        int paintStrokeWidth, float touchTolerance, int textSize) {                    super(context);                    setFocusable(true);                    touchRect = rect;                    W = rect.right - rect.left;                    H = rect.bottom - rect.top;                    X = rect.left;                    Y = rect.top;                    TEXT_SIZE = textSize;                    PAINT_STROKE_WIDTH = paintStrokeWidth;                    TOUCH_TOLERANCE = touchTolerance;                    setBackground(touchRect, bgText);                    initDrowTools();                        }                        private void setBackground(Rect rect, String bgText) {                    DisplayMetrics dm = new DisplayMetrics();                    dm = this.getResources().getDisplayMetrics();                            Bitmap bitmap = Bitmap.createBitmap(dm.widthPixels,                            dm.heightPixels, Config.ARGB_8888);                    Canvas canvas = new Canvas(bitmap);                            Paint paint = new Paint();                    paint.setColor(0x88000000);                    // paint.setStyle(Style.STROKE);                    // paint.setTextAlign(Align.CENTER);                    paint.setTextSize(TEXT_SIZE);                            // paint.setTextScaleX(1.5f);                    canvas.drawColor(Color.WHITE);                    // 画字的坐标不好控制                    int x = rect.left                            + (rect.right - rect.left - bgText.length() * TEXT_SIZE)                            / 2;                    int y = rect.top + (rect.bottom - rect.top - TEXT_SIZE) / 2;                    // int y = 218+25;                    canvas.drawText(bgText, x, y, paint);                    Drawable drawable = new BitmapDrawable(bitmap);                    setBackgroundDrawable(drawable);                }                        private void initDrowTools() {                    // 设置画笔                    mPaint = new Paint();                    // mPaint.setAlpha(0);                    // 画笔划过的痕迹就变成透明色了                    mPaint.setColor(Color.BLACK); // 此处不能为透明色                    mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));                    // 或者                    // mPaint.setAlpha(0);                    // mPaint.setXfermode(new                    // PorterDuffXfermode(PorterDuff.Mode.DST_IN));                            mPaint.setAntiAlias(true);                    mPaint.setDither(true);                    mPaint.setStyle(Paint.Style.STROKE);                    mPaint.setStrokeJoin(Paint.Join.ROUND); // 前圆角                    mPaint.setStrokeCap(Paint.Cap.ROUND); // 后圆角                    mPaint.setStrokeWidth(PAINT_STROKE_WIDTH); // 笔宽                            // 痕迹                    mPath = new Path();                    ;                            // 覆盖                    mBitmap = Bitmap.createBitmap(W, H, Config.ARGB_8888);                    mCanvas = new Canvas(mBitmap);                    mCanvas.drawColor(0x88000000);                        }                        @Override                protected void onDraw(Canvas canvas) {                    super.onDraw(canvas);                    mCanvas.drawPath(mPath, mPaint);                    // mCanvas.drawPoint(mX, mY, mPaint);                    canvas.drawBitmap(mBitmap, X, Y, null);                }                        @Override                public boolean onTouchEvent(MotionEvent event) {                    System.out.print("X--" + event.getX());                    System.out.println("Y--" + event.getY());                    if (!touchRect.contains((int) event.getX(), (int) event.getY())) {                        return false;                    }                            switch (event.getAction()) {                    // 触点按下                    case MotionEvent.ACTION_DOWN: {                        touchDown(event.getRawX(), event.getRawY());                        touchDown(event.getX() - touchRect.left, event.getY()                                - touchRect.top);                        invalidate();                        break;                    }                                            case MotionEvent.ACTION_MOVE: // 触点移动                        touchMove(event.getX() - touchRect.left, event.getY()                                - touchRect.top);                                invalidate();                        break;                    case MotionEvent.ACTION_UP: // 触点弹起                        touchUp(event.getX() - touchRect.left, event.getY()                                - touchRect.top);                        invalidate();                        break;                    default:                        break;                    }                    return true;                }                        private void touchDown(float x, float y) {                    mPath.reset();                    mPath.moveTo(x, y);                    mX = x;                    mY = y;                }                        private void touchMove(float x, float y) {                    float dx = Math.abs(x - mX);                    float dy = Math.abs(y - mY);                    if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {                        mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);                        mX = x;                        mY = y;                    }                        }                        private void touchUp(float x, float y) {                    mPath.lineTo(x, y);                    mCanvas.drawPath(mPath, mPaint);                    mPath.reset();                }                    }                    /**            * 键盘事件，当按下back键的时候询问是否再按一次退出程序            */            // 退出时间            private long exitTime = 0;            @Override            public boolean onKeyDown(int keyCode, KeyEvent event) {                if (keyCode == KeyEvent.KEYCODE_BACK                        && event.getAction() == KeyEvent.ACTION_DOWN) {                    if ((System.currentTimeMillis() - exitTime) > 2000) {                        Toast.makeText(getApplicationContext(), "再按一次退出程序",                                Toast.LENGTH_SHORT).show();                        exitTime = System.currentTimeMillis();                    } else {                        finish();                        System.exit(0);                            }                    return true;                }                return super.onKeyDown(keyCode, event);            }                }