Android studio实现刮刮乐的方法

 public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } } 

 public class GuaTwo extends View { /*第一种方法*/ private Path mPath;//手刮动的path，过程 private Paint mOutterPaint;//绘制mPath的画笔 private Canvas mCanvas;//临时画布 private Bitmap mBitmap;//临时图片 //记录用户path每次的开始坐标值 private int mLastX; private int mLastY; private Bitmap mOutterBitmap;//图片遮罩，就是手刮动，要擦掉的那张图 public GuaTwo(Context context) { this(context, null); } public GuaTwo(Context context, AttributeSet attrs) { this(context, attrs, 0); } public GuaTwo(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); //获得控件的宽高 int width = getMeasuredWidth(); int height = getMeasuredHeight(); //初始化bitmap mBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888); mCanvas = new Canvas(mBitmap); //设置画笔属性 setupOutPaint(); mCanvas.drawColor(Color.parseColor("#c0c0c0")); } @Override protected void onDraw(Canvas canvas) { mOutterPaint.setStyle(Paint.Style.STROKE); mOutterPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));//Mode.DST_OUT改模式就类似橡皮檫，这个属性设置是关键 canvas.drawBitmap(mOutterBitmap, 0, 0, null); canvas.drawBitmap(mBitmap, 0, 0, null); mCanvas.drawPath(mPath, mOutterPaint); } @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://按下 //记录按下的时候的X和Y值，以便于之后移动的时候绘制 mLastX = x; mLastY = y; mPath.moveTo(mLastX, mLastY); break; case MotionEvent.ACTION_MOVE://移动 //拿到用户移动的X绝对值，Y轴绝对值 int dx = Math.abs(x - mLastX); int dy = Math.abs(y - mLastY); //用户滑动超过3像素才会改变，这个可以不做，做只是为了避免很频繁的响应而已。 if (dx > 3 || dy > 3) { mPath.lineTo(x, y); } mLastX = x; mLastY = y; break; } invalidate();//刷新UI return true; } /** * 绘制path（也就是手刮动的path来绘制） 的画笔属性 * 类似橡皮擦 */ private void setupOutPaint() { mOutterPaint.setColor(Color.RED); mOutterPaint.setAntiAlias(true); mOutterPaint.setDither(true); mOutterPaint.setStrokeJoin(Paint.Join.ROUND);//设置圆角 mOutterPaint.setStrokeCap(Paint.Cap.ROUND); mOutterPaint.setStyle(Paint.Style.FILL); mOutterPaint.setStrokeWidth(60);//设置画笔宽度 } /** * 初始化信息 */ private void init() { mOutterPaint = new Paint(); mPath = new Path(); mOutterBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.mein); } 

 private Path mPath;//手刮动的path，过程 private Paint mOutterPaint;//绘制mPath的画笔 private Canvas mCanvas; private Bitmap mBitmap; //记录用户path每次的开始坐标值 private int mLastX; private int mLastY; private Bitmap mOutterBitmap;//图片遮罩，就是手刮动，要擦掉的那张图 private String mText;//刮奖文本信息 private Rect mTextBound; private Paint mBackPaint;//刮奖信息的画笔 public GuaTwo(Context context) { this(context, null); } public GuaTwo(Context context, AttributeSet attrs) { this(context, attrs, 0); } public GuaTwo(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); //获得控件的宽高 int width = getMeasuredWidth(); int height = getMeasuredHeight(); //初始化bitmap mBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888); mCanvas = new Canvas(mBitmap);//用指定的位图构造一个画布来绘制。 //设置画笔属性 setupOutPaint(); setUpBackPaint(); //    mCanvas.drawColor(Color.parseColor("#c0c0c0")); mCanvas.drawRoundRect(new RectF(0, 0, width, height), 30, 30, mOutterPaint);//用mOutterPaint画圆角矩形 mCanvas.drawBitmap(mOutterBitmap, null, new Rect(0, 0, width, height), null);//在刚刚画的圆角矩形上面再画一个bitmap图片，让图片大小和圆角矩形大小相关联 } @Override protected void onDraw(Canvas canvas) { mOutterPaint.setStyle(Paint.Style.STROKE); mOutterPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));//Mode.DST_OUT改模式就类似橡皮檫，这个属性设置是关键 canvas.drawText(mText, (getWidth() - mTextBound.width()) / 2, getHeight() / 2 - mTextBound.height() / 2, mBackPaint);//把获奖信息放在正中间 mCanvas.drawPath(mPath, mOutterPaint); canvas.drawBitmap(mBitmap, 0, 0, null); } @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://按下 //记录按下的时候的X和Y值，以便于之后移动的时候绘制 mLastX = x; mLastY = y; mPath.moveTo(mLastX, mLastY); break; case MotionEvent.ACTION_MOVE://移动 //拿到用户移动的X绝对值，Y轴绝对值 int dx = Math.abs(x - mLastX); int dy = Math.abs(y - mLastY); //用户滑动超过3像素才会改变，这个可以不做，做只是为了避免很频繁的相应而已。 if (dx > 3 || dy > 3) { mPath.lineTo(x, y); } mLastX = x; mLastY = y; break; } invalidate();//刷新UI return true; } private void setUpBackPaint() { mBackPaint.setColor(Color.RED); mBackPaint.setStyle(Paint.Style.FILL); mBackPaint.setTextSize(60); //获得当前画笔绘制文本的宽和高 mBackPaint.getTextBounds(mText, 0, mText.length(), mTextBound); } *//** * 绘制path（也就是手刮动的path来绘制） 的画笔属性 * 类似橡皮擦 *//* private void setupOutPaint() { mOutterPaint.setColor(Color.RED); mOutterPaint.setAntiAlias(true); mOutterPaint.setDither(true); mOutterPaint.setStrokeJoin(Paint.Join.ROUND);//设置圆角 mOutterPaint.setStrokeCap(Paint.Cap.ROUND); mOutterPaint.setStyle(Paint.Style.FILL); mOutterPaint.setStrokeWidth(60);//设置画笔宽度 } *//** * 初始化信息 *//* private void init() { mOutterPaint = new Paint(); mPath = new Path(); mOutterBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.huahua); mText = "您中奖了！"; mTextBound = new Rect(); mBackPaint = new Paint(); }