# MediaPipe graph to calculate hand region of interest (ROI) from landmarks
# detected by "HandLandmarkCpu" or "HandLandmarkGpu".

type: "HandLandmarkLandmarksToRoi"

# Normalized landmarks. (NormalizedLandmarkList)
input_stream: "LANDMARKS:landmarks"
# Image size (width & height). (std::pair<int, int>)
input_stream: "IMAGE_SIZE:image_size"

# ROI according to landmarks. (NormalizedRect)
output_stream: "ROI:roi"

# Extracts a subset of the hand landmarks that are relatively more stable across
# frames (e.g. comparing to finger tips) for computing the bounding box. The box
# will later be expanded to contain the entire hand. In this approach, it is
# more robust to drastically changing hand size.
# The landmarks extracted are: wrist, MCP/PIP of five fingers.
node {
  calculator: "SplitNormalizedLandmarkListCalculator"
  input_stream: "landmarks"
  output_stream: "partial_landmarks"
  options: {
    [mediapipe.SplitVectorCalculatorOptions.ext] {
      ranges: { begin: 0 end: 4 }
      ranges: { begin: 5 end: 7 }
      ranges: { begin: 9 end: 11 }
      ranges: { begin: 13 end: 15 }
      ranges: { begin: 17 end: 19 }
      combine_outputs: true
    }
  }
}

# Converts the hand landmarks into a rectangle (normalized by image size)
# that encloses the hand. The calculator uses a subset of all hand landmarks
# extracted from SplitNormalizedLandmarkListCalculator above to
# calculate the bounding box and the rotation of the output rectangle. Please
# see the comments in the calculator for more detail.
node {
  calculator: "HandLandmarksToRectCalculator"
  input_stream: "NORM_LANDMARKS:partial_landmarks"
  input_stream: "IMAGE_SIZE:image_size"
  output_stream: "NORM_RECT:hand_rect_from_landmarks"
}

# Expands the hand rectangle so that the box contains the entire hand and it's
# big enough so that it's likely to still contain the hand even with some motion
# in the next video frame .
node {
  calculator: "RectTransformationCalculator"
  input_stream: "NORM_RECT:hand_rect_from_landmarks"
  input_stream: "IMAGE_SIZE:image_size"
  output_stream: "roi"
  options: {
    [mediapipe.RectTransformationCalculatorOptions.ext] {
      scale_x: 2.0
      scale_y: 2.0
      shift_y: -0.1
      square_long: true
    }
  }
}