utils.py 文件源码

def _drawSpeed(image, speed, frameHeight=480, frameWidth=640):
    maxBars = 8
    numBars = min(int(speed/6)+1, maxBars)  # 6 m/s per speed bar
    for i in xrange(maxBars):
      overlay = image.copy()
      color = (10, 42*i, 42*(maxBars-1-i))  # BGR
      cv2.rectangle(
          overlay, (i*20, frameHeight-i*10),
          (frameWidth-i*20, frameHeight-(i+1)*10), color, thickness=-1)
      opacity = 0.08
      cv2.addWeighted(overlay, opacity, image, 1-opacity, 0, image)
      if i <= numBars:
        # Shade bars to represent the speed
        opacity = 0.4
        cv2.addWeighted(overlay, opacity, image, 1-opacity, 0, image)