Android刮刮樂實現代碼

public class ActionersView extends View {
    private Paint mPaint = new Paint();
    private Paint txtPaint = new Paint();//文字畫筆
    private Path mPath = new Path();//手指滑動路徑
    private Canvas mCanvas;//緩存畫布
    private Bitmap mBitmap;//緩存圖片
    private float pointX, pointY;//觸點坐標
    private String txtStr = "￥5,000,000";


public ActionersView(Context context, AttributeSet attrs) {
    super(context, attrs);
}


@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    int width = getMeasuredWidth();
    int height = getMeasuredHeight();

    mBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888); // 初始化bitmap
    mCanvas = new Canvas(mBitmap);

    initPaint();//初始化畫筆

//        mCanvas.drawRoundRect(new RectF(100, 500, width - 100, height - 500), 30, 30, mPaint);//效果一：背景為灰色的矩形
        mCanvas.drawBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.bg1), null, new RectF(100, 500, width - 100, height - 500), null);//效果二：背景為圖片

}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    txtPaint.setTextSize(60);
    canvas.drawText(txtStr, getWidth() / 2 - 150, getHeight() / 2, txtPaint);

    mCanvas.drawPath(mPath, mPaint);
    canvas.drawBitmap(mBitmap, 0, 0, null);
}


@Override
public boolean onTouchEvent(MotionEvent event) {
    pointX = event.getX();
    pointY = event.getY();
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            mPath.moveTo(pointX, pointY);//將路徑移動到點(pointX, pointY)，不繪制
            break;
        case MotionEvent.ACTION_MOVE:
            mPath.lineTo(pointX, pointY);//繪制一條從上個觸點到點(pointX, pointY)的線條
            break;
    }
    invalidate();//重新繪圖
    return true;
}


private void initPaint() {//初始化畫筆
    mPaint.setDither(true);
    mPaint.setAntiAlias(true);
    mPaint.setStrokeWidth(30);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setColor(Color.parseColor("#c0c0c0"));
    mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
}


}</pre>