Android使用surfaceView自定义抽奖大转盘

private SurfaceHolder mSurfaceHolder;private Canvas    mCanvas;

public SurfaceViewTemplate(Context context,AttributeSet attrs) {  super(context, attrs);  //初始化  mSurfaceHolder = getHolder();  mSurfaceHolder.addCallback(this);  //设置可获得焦点  setFocusable(true);  setFocusableInTouchMode(true);  //这是常亮  setKeepScreenOn(true);}

 @Overridepublic void surfaceCreated(SurfaceHolder surfaceHolder) {  //surface创建的时候  mThread = new Thread(this);  //创建的时候就开启线程  isRunning = true;  mThread.start();}@Overridepublic void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {  //变化的时候}@Overridepublic void surfaceDestroyed(SurfaceHolder surfaceHolder) {  //销毁的时候 关闭线程  isRunning = false;}

 @Overridepublic void run() {  //在子线程中不断的绘制  while (isRunning) {    draw();  }}private void draw() {  try {    mCanvas = mSurfaceHolder.lockCanvas();    if (null != mCanvas) {  //避免执行到这里的时候程序已经退出 surfaceView已经销毁那么获取到canvas为null    }  } catch (Exception e) {    //异常可以不必处理  } finally {    //一定要释放canvas避免泄露    mSurfaceHolder.unlockCanvasAndPost(mCanvas);  }}

@Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {    super.onMeasure(widthMeasureSpec, heightMeasureSpec);    //直接控制Span为正方形    int width = Math.min(getMeasuredWidth(), getMeasuredHeight());    mPadding = getPaddingLeft();    //直径    mRadius = width - mPadding * 2;    //设置中心点    mCenter = width / 2;    //设置成正方形    setMeasuredDimension(width, width);  }

public void surfaceCreated(SurfaceHolder surfaceHolder) {    //初始化绘制Span的画笔    mSpanPaint = new Paint();    mSpanPaint.setAntiAlias(true);    mSpanPaint.setDither(true);    //初始化绘制文本的画笔    mTextPaint = new Paint();    mTextPaint.setTextSize(mTextSize);    mTextPaint.setColor(0Xffa58453);    //绘制圆环的画笔    mCirclePaint = new Paint();    mCirclePaint.setAntiAlias(true);    mCirclePaint.setColor(0xffdfc89c);    //初始化Span的范围    mRectRange = new RectF(mPadding, mPadding, mPadding + mRadius, mPadding + mRadius);    mRectCircleRange = new RectF(mPadding * 3 / 2, mPadding * 3 / 2, getMeasuredWidth() - mPadding * 3 / 2, getMeasuredWidth() - mPadding * 3 / 2);    //初始化bitmap    mImgIconBitmap = new Bitmap[mSpanCount];    //将奖项的icon存储为Bitmap    for (int i = 0; i < mSpanCount; i++) {      mImgIconBitmap[i] = BitmapFactory.decodeResource(getResources(), mPrizeIcon[i]);    }    //surface创建的时候    mThread = new Thread(this);    //创建的时候就开启线程    isRunning = true;    mThread.start();  }

 @Override  public void run() {    //在子线程中不断的绘制    while (isRunning) {      //保证绘制不低于50毫秒 优化性能      long start = SystemClock.currentThreadTimeMillis();      draw();      long end = SystemClock.currentThreadTimeMillis();      if ((end - start) < 50) {        //休眠到50毫秒        SystemClock.sleep(50 - (end - start));      }    }  }

 try {    mCanvas = mSurfaceHolder.lockCanvas();    if (null != mCanvas) {      //避免执行到这里的时候程序已经退出 surfaceView已经销毁那么获取到canvas为null      //绘制背景      drawBg();      //绘制圆环      mCanvas.drawCircle(mCenter, mCenter, mRadius / 2 + mPadding / 20, mCirclePaint);      drawSpan();    }  } catch (Exception e) {    //异常可以不必处理  } finally {    //一定要释放canvas避免泄露    mSurfaceHolder.unlockCanvasAndPost(mCanvas);  }

//绘制背景  private void drawBg() {    //背景设置为白色    mCanvas.drawColor(0xffffffff);    mCanvas.drawBitmap(mSpanBackground, null, new RectF(mPadding / 2, mPadding / 2, getMeasuredWidth() - mPadding / 2, getMeasuredHeight() - mPadding / 2), mSpanPaint);  }

  mSpanBackground背景图片  new RectF(mPadding / 2, mPadding / 2, getMeasuredWidth() - mPadding / 2, getMeasuredHeight() - mPadding / 2)  //限制背景在一个矩形范围之类 

mCanvas.drawCircle(mCenter, mCenter, mRadius / 2 + mPadding / 20, mCirclePaint); 

//定义一个变量临时记录开始转动的角度float tempAngle = mStartSpanAngle;//每个盘块所占的角度 CIRCLE_ANGLE = 360float sweepAngle = CIRCLE_ANGLE / mSpanCount;//循环绘制八个板块  for (int i = 0; i < mSpanCount; i++) {    //设置每个盘块画笔的颜色    mSpanPaint.setColor(mSpanColor[i]);    //绘制扇形盘块，第四个参数为true就是扇形否则就是弧形    mCanvas.drawArc(mRectCircleRange, tempAngle, sweepAngle, true, mSpanPaint);    //绘制文字    drawText(tempAngle, sweepAngle, mPrizeName[i]);    //绘制奖项Icon    drawPrizeIcon(tempAngle, mImgIconBitmap[i]);      //改变角度      tempAngle += sweepAngle;    }

private void drawText(float tempAngle, float sweepAngle, String text) {  //绘制有弧度的文字 根据path绘制文字的路径  Path path = new Path();  path.addArc(mRectRange, tempAngle, sweepAngle);  //让文字水平居中 那绘制文字的起点位子就是 弧度的一半 - 文字的一半  float textWidth = mTextPaint.measureText(text);  float hOval = (float) ((mRadius * Math.PI / mSpanCount / 2) - (textWidth / 2));  float vOval = mRadius / 15;//竖直偏移量可以自定义  mCanvas.drawTextOnPath(text, path, hOval, vOval, mTextPaint); //第三个四个参数是竖直和水平偏移量}

private void drawPrizeIcon(float tempAngle, Bitmap bitmap) {  //图片的大小设置成直径的1/8  int iconWidth = mRadius / 20;  //根据角度计算icon中心点  //角度计算 1度 == Math.PI / 180  double angle = (tempAngle + CIRCLE_ANGLE / mSpanCount / 2) * Math.PI / 180;  //根据三角函数，计算中心点(x,y)  int x = (int) (mCenter + mRadius / 4 * Math.cos(angle));  int y = (int) (mCenter + mRadius / 4 * Math.sin(angle));  //定义一个矩形 限制icon位置  RectF rectF = new RectF(x - iconWidth, y - iconWidth, x + iconWidth, y + iconWidth);  mCanvas.drawBitmap(bitmap, null, rectF, null);}

 mStartSpanAngle += mSpeed;//mSpeed的数值控制转动的速度   //声明的一个结束标志  if (isSpanEnd) {    mSpeed -= 1;  }  if (mSpeed <= 0) {    //停止旋转了    mSpeed = 0;    isSpanEnd = false;    //定义一个回调，监控转盘停止转动   mSpanRollListener.onSpanRollListener(mSpeed);  }

//抽奖转盘重点就在这里，根据自己传入的index控制抽到的奖品public void luckyStart(int index) {  //根据index控制停留的位置 angle 是每个奖品所占的角度范围  float angle = CIRCLE_ANGLE / mSpanCount;  //计算指针停留在某个index下的角度范围HALF_CIRCLE_ANGLE=180度  float from = HALF_CIRCLE_ANGLE - (index - 1) * angle;  float end = from + angle;  //设置需要停下来的时候转动的距离 保证每次不停留的某个index下的同一个位置  float targetFrom = 4 * CIRCLE_ANGLE + from;  float targetEnd = 4 * CIRCLE_ANGLE + end;//最终停下来的位置在from-end之间，4 * CIRCLE_ANGLE 自定义要多转几圈  //计算要停留下来的时候速度的范围，这里注意：涉及到等差数列的公式，因为涉及到让转盘停止转动是使mSpeed-=1；所以它是从 vFrom--0等差递减的一个过程，所以可以算出来vFrom，同理计算出vEnd  float vFrom = (float) ((Math.sqrt(1 + 8 * targetFrom) - 1) / 2);  float vEnd = (float) ((Math.sqrt(1 + 8 * targetEnd) - 1) / 2);  //在点击开始转动的时候 传递进来的index值就已经决定停留在那一项上面了  mSpeed = vFrom + Math.random() * (vEnd - vFrom);  isSpanEnd = false;}

 public void luckStop() {  //在停止转盘的时候强制吧开始角度赋值为0 因为控制停留指定位置的角度计算是根据开始角度为0计算的  mStartSpanAngle = 0;  isSpanEnd = true;}