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();
}

<?xml version="1.0" encoding="utf-8"? 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.bwie.test.guaguale.MainActivity" 
<com.bwie.test.guaguale.GuaTwo
android:layout_width="wrap_content"
android:layout_height="wrap_content" / 
</RelativeLayout