// 设备
@property (strong, nonatomic) AVCaptureDevice      *device;
// 结合输入输出
@property (strong, nonatomic) AVCaptureSession     *session;
// 输入设备
@property (strong, nonatomic) AVCaptureDeviceInput   *input;
// 输出设备
@property (strong, nonatomic) AVCaptureVideoDataOutput *output;
// 输出的所有点
@property (strong, nonatomic) NSMutableArray      *points;

// 记录浮点变化的前一次的值
static float lastH = 0;
// 用于判断是否是第一个福点值
static int  count = 0;

// 初始化
self.device   = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
self.session  = [[AVCaptureSession alloc]init];
self.input   = [[AVCaptureDeviceInput alloc]initWithDevice:self.device error:nil];
self.output   = [[AVCaptureVideoDataOutput alloc]init];
self.points   = [[NSMutableArray alloc]init];

// 开启闪光灯
 if ([self.device isTorchModeSupported:AVCaptureTorchModeOn]) {
   [self.device lockForConfiguration:nil];
    // 开启闪光灯
    self.device.torchMode=AVCaptureTorchModeOn;
    // 调低闪光灯亮度（为了减少内存占用和避免时间长手机发烫）
    [self.device setTorchModeOnWithLevel:0.01 error:nil];
    [self.device unlockForConfiguration];
  }

  // 开始配置input output
  [self.session beginConfiguration];

  // 设置像素输出格式
  NSNumber *BGRA32Format = [NSNumber numberWithInt:kCVPixelFormatType_32BGRA];
  NSDictionary *setting =@{(id)kCVPixelBufferPixelFormatTypeKey:BGRA32Format};
  [self.output setVideoSettings:setting];

  // 抛弃延迟的帧
  [self.output setAlwaysDiscardsLateVideoFrames:YES];
  //开启摄像头采集图像输出的子线程
  dispatch_queue_t outputQueue = dispatch_queue_create("VideoDataOutputQueue", DISPATCH_QUEUE_SERIAL);
  // 设置子线程执行代理方法
  [self.output setSampleBufferDelegate:self queue:outputQueue];

  // 向session添加
  if ([self.session canAddInput:self.input])  [self.session addInput:self.input];
  if ([self.session canAddOutput:self.output]) [self.session addOutput:self.output];

  // 降低分辨率，减少采样率（为了减少内存占用）
  self.session.sessionPreset = AVCaptureSessionPreset1280x720;
  // 设置最小的视频帧输出间隔
  self.device.activeVideoMinFrameDuration = CMTimeMake(1, 10);

  // 用当前的output 初始化connection
  AVCaptureConnection *connection =[self.output connectionWithMediaType:AVMediaTypeVideo];
  [connection setVideoOrientation:AVCaptureVideoOrientationPortrait];

  // 完成编辑
  [self.session commitConfiguration];
  // 开始运行
  [self.session startRunning];

// captureOutput->当前output  sampleBuffer->样本缓冲  connection->捕获连接
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {

  //获取图层缓冲
  CVPixelBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
  CVPixelBufferLockBaseAddress(imageBuffer, 0);
  uint8_t*buf = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);
  size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
  size_t width = CVPixelBufferGetWidth(imageBuffer);
  size_t height = CVPixelBufferGetHeight(imageBuffer);

  float r = 0, g = 0,b = 0;
  float h,s,v;
  // 计算RGB
  TORGB(buf, width, height, bytesPerRow, &r, &g, &b);
  // RGB转HSV
  RGBtoHSV(r, g, b, &h, &s, &v);
  // 获取当前时间戳（精确到毫秒）
  double t = [[NSDate date] timeIntervalSince1970]*1000;
  // 返回处理后的浮点值
  float p = HeartRate(h);
  // 绑定浮点和时间戳
  NSDictionary *point = @{[NSNumber numberWithDouble:t]:[NSNumber numberWithFloat:p]};
  //下面按个人情况可以进行计算心率或者画心率图
}

void TORGB (uint8_t *buf, float ww, float hh, size_t pr, float *r, float *g, float *b) {
  float wh = (float)(ww * hh );
  for(int y = 0; y < hh; y++) {
    for(int x = 0; x < ww * 4; x += 4) {
      *b += buf[x];
      *g += buf[x+1];
      *r += buf[x+2];
    }
    buf += pr;
  }
  *r /= 255 * wh;
  *g /= 255 * wh;
  *b /= 255 * wh;
}

void RGBtoHSV( float r, float g, float b, float *h, float *s, float *v ) {
  float min, max, delta;
  min = MIN( r, MIN(g, b ));
  max = MAX( r, MAX(g, b ));
  *v = max;
  delta = max - min;
  if( max != 0 )
    *s = delta / max;
  else {
    *s = 0;
    *h = -1;
    return;
  }
  if( r == max )
    *h = ( g - b ) / delta;
  else if( g == max )
    *h = 2 + (b - r) / delta;
  else
    *h = 4 + (r - g) / delta;
  *h *= 60;
  if( *h < 0 )
    *h += 360;
}

float HeartRate (float h) {
  float low = 0;
  count++;
  lastH = (count==1)?h:lastH;
  low = (h-lastH);
  lastH = h;
  return low;
}

- (void)analysisPointsWith:(NSDictionary *)point {

  [self.points addObject:point];
  if (self.points.count<=30) return;
  int count = (int)self.points.count;

  if (self.points.count == 0) {

    int d_i_c = 0;     //最低峰值的位置 姑且算在中间位置 c->center
    int d_i_l = 0;     //最低峰值左面的最低峰值位置 l->left
    int d_i_r = 0;     //最低峰值右面的最低峰值位置 r->right


    float trough_c = 0;   //最低峰值的浮点值
    float trough_l = 0;   //最低峰值左面的最低峰值浮点值
    float trough_r = 0;   //最低峰值右面的最低峰值浮点值

    // 1.先确定数据中的最低峰值
    for (int i = 0; i < count; i++) {
      float trough = [[[self.points[i] allObjects] firstObject] floatValue];
      if (trough < trough_c) {
        trough_c = trough;
        d_i_c = i;
      }
    }

    // 2.找到最低峰值以后 以最低峰值为中心 找到前0.5-1.5周期中的最低峰值 和后0.5-1.5周期的最低峰值

    if (d_i_c >= 1.5*T) {

      // a.如果最低峰值处在中心位置， 即距离前后都至少有1.5个周期
      if (d_i_c <= count-1.5*T) {
        // 左面最低峰值
        for (int j = d_i_c - 0.5*T; j > d_i_c - 1.5*T; j--) {
          float trough = [[[self.points[j] allObjects] firstObject] floatValue];
          if (trough < trough_l) {
            trough_l = trough;
            d_i_l = j;
          }
        }
        // 右面最低峰值
        for (int k = d_i_c + 0.5*T; k < d_i_c + 1.5*T; k++) {
          float trough = [[[self.points[k] allObjects] firstObject] floatValue];
          if (trough < trough_r) {
            trough_r = trough;
            d_i_r = k;
          }
        }

      }
      // b.如果最低峰值右面不够1.5个周期 分两种情况 不够0.5个周期和够0.5个周期
      else {
        // b.1 够0.5个周期
        if (d_i_c <count-0.5*T) {
          // 左面最低峰值
          for (int j = d_i_c - 0.5*T; j > d_i_c - 1.5*T; j--) {
            float trough = [[[self.points[j] allObjects] firstObject] floatValue];
            if (trough < trough_l) {
              trough_l = trough;
              d_i_l = j;
            }
          }
          // 右面最低峰值
          for (int k = d_i_c + 0.5*T; k < count; k++) {
            float trough = [[[self.points[k] allObjects] firstObject] floatValue];
            if (trough < trough_r) {
              trough_r = trough;
              d_i_r = k;
            }
          }
        }
        // b.2 不够0.5个周期
        else {
          // 左面最低峰值
          for (int j = d_i_c - 0.5*T; j > d_i_c - 1.5*T; j--) {
            float trough = [[[self.points[j] allObjects] firstObject] floatValue];
            if (trough < trough_l) {
              trough_l = trough;
              d_i_l = j;
            }
          }
        }
      }

    }
    // c. 如果左面不够1.5个周期 一样分两种情况 够0.5个周期 不够0.5个周期
    else {
      // c.1 够0.5个周期
      if (d_i_c>0.5*T) {
        // 左面最低峰值
        for (int j = d_i_c - 0.5*T; j > 0; j--) {
          float trough = [[[self.points[j] allObjects] firstObject] floatValue];
          if (trough < trough_l) {
            trough_l = trough;
            d_i_l = j;
          }
        }
        // 右面最低峰值
        for (int k = d_i_c + 0.5*T; k < d_i_c + 1.5*T; k++) {
          float trough = [[[self.points[k] allObjects] firstObject] floatValue];
          if (trough < trough_r) {
            trough_r = trough;
            d_i_r = k;
          }
        }

      }
      // c.2 不够0.5个周期
      else {
        // 右面最低峰值
        for (int k = d_i_c + 0.5*T; k < d_i_c + 1.5*T; k++) {
          float trough = [[[self.points[k] allObjects] firstObject] floatValue];
          if (trough < trough_r) {
            trough_r = trough;
            d_i_r = k;
          }
        }
      }

    }

    // 3. 确定哪一个与最低峰值更接近 用最接近的一个最低峰值测出瞬时心率 60*1000两个峰值的时间差
    if (trough_l-trough_c < trough_r-trough_c) {

      NSDictionary *point_c = self.points[d_i_c];
      NSDictionary *point_l = self.points[d_i_l];
      double t_c = [[[point_c allKeys] firstObject] doubleValue];
      double t_l = [[[point_l allKeys] firstObject] doubleValue];
      NSInteger fre = (NSInteger)(60*1000)/(t_c - t_l);
      if (self.frequency)
        self.frequency(fre);
      if ([self.delegate respondsToSelector:@selector(startHeartDelegateRateFrequency:)])
        [self.delegate startHeartDelegateRateFrequency:fre];
    } else {
      NSDictionary *point_c = self.points[d_i_c];
      NSDictionary *point_r = self.points[d_i_r];
      double t_c = [[[point_c allKeys] firstObject] doubleValue];
      double t_r = [[[point_r allKeys] firstObject] doubleValue];
      NSInteger fre = (NSInteger)(60*1000)/(t_r - t_c);
      if (self.frequency)
        self.frequency(fre);
      if ([self.delegate respondsToSelector:@selector(startHeartDelegateRateFrequency:)])
        [self.delegate startHeartDelegateRateFrequency:fre];
    }
    // 4.删除过期数据
    for (int i = 0; i< 10; i++) {
      [self.points removeObjectAtIndex:0];
    }
  }
}

@property (strong, nonatomic) NSMutableArray *points;
// 在init中初始化数组
self.points = [[NSMutableArray alloc]init];
// 这个可以翻译过来，也是在init中
self.clearsContextBeforeDrawing = YES;

// 外部调用方法
- (void)drawRateWithPoint:(NSNumber *)point {
  // 倒叙插入数组
  [self.points insertObject:point atIndex:0];

  // 删除溢出屏幕数据
  if (self.points.count > self.frame.size.width/6) {
    [self.points removeLastObject];
  }

  dispatch_async(dispatch_get_main_queue(), ^{
    // 这个方法自动调取 drawRect:方法
    [self setNeedsDisplay];
  });
}

CGFloat ww = self.frame.size.width;
  CGFloat hh = self.frame.size.height;
  CGFloat pos_x = ww;
  CGFloat pos_y = hh/2;
  // 获取当前画布
  CGContextRef context = UIGraphicsGetCurrentContext();
  // 折线宽度
  CGContextSetLineWidth(context, 1.0);
  //消除锯齿
  //CGContextSetAllowsAntialiasing(context,false);
  // 折线颜色
  CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
  CGContextMoveToPoint(context, pos_x, pos_y);
  for (int i = 0; i < self.points.count; i++) {
    float h = [self.points[i] floatValue];
    pos_y = hh/2 + (h * hh/2) ;
    CGContextAddLineToPoint(context, pos_x, pos_y);
    pos_x -=6;
  }
  CGContextStrokePath(context);

static CGFloat grid_w = 30.0f;
- (void)buildGrid {

  CGFloat wight = self.frame.size.width;
  CGFloat height = self.frame.size.height;

  // 获取当前画布
  CGContextRef context = UIGraphicsGetCurrentContext();

  CGFloat pos_x = 0.0f;
  CGFloat pos_y = 0.0f;

  // 在wight范围内画竖线
  while (pos_x < wight) {
    // 设置网格线宽度
    CGContextSetLineWidth(context, 0.2);
    // 设置网格线颜色
    CGContextSetStrokeColorWithColor(context, [UIColor greenColor].CGColor);
    // 起点
    CGContextMoveToPoint(context, pos_x, 1.0f);
    // 终点
    CGContextAddLineToPoint(context, pos_x, height);
    pos_x +=grid_w;
    //开始划线
    CGContextStrokePath(context);
  }

  // 在height范围内画横线
  while (pos_y < height) {

    CGContextSetLineWidth(context, 0.2);
    CGContextSetStrokeColorWithColor(context, [UIColor greenColor].CGColor);
    CGContextMoveToPoint(context, 1.0f, pos_y);
    CGContextAddLineToPoint(context, wight, pos_y);
    pos_y +=grid_w;
    CGContextStrokePath(context);
  }
  pos_x = 0.0f; pos_y = 0.0f;

  // 在wight范围内画竖线
  while (pos_x < wight) {
    CGContextSetLineWidth(context, 0.1);
    CGContextSetStrokeColorWithColor(context, [UIColor greenColor].CGColor);
    CGContextMoveToPoint(context, pos_x, 1.0f);
    CGContextAddLineToPoint(context, pos_x, height);
    pos_x +=grid_w/5;
    CGContextStrokePath(context);
  }

  // 在height范围内画横线
  while (pos_y < height) {
    CGContextSetLineWidth(context, 0.1);
    CGContextSetStrokeColorWithColor(context, [UIColor greenColor].CGColor);
    CGContextMoveToPoint(context, 1.0f, pos_y);
    CGContextAddLineToPoint(context, wight, pos_y);
    pos_y +=grid_w/5;
    CGContextStrokePath(context);
  }

}