Loading and saving GazePositionCalibrator instance from JSON file.

2 files changed, 58 insertions, 6 deletions

diff --git a/src/argaze/ArFeatures.py b/src/argaze/ArFeatures.py
index cb1b2f6..2e278ea 100644
--- a/src/argaze/ArFeatures.py
+++ b/src/argaze/ArFeatures.py
@@ -607,14 +607,21 @@ class ArFrame():
 
 			gaze_position_calibrator_value = frame_data.pop('gaze_position_calibrator')
 
-			gaze_position_calibrator_module_path, gaze_position_calibrator_parameters = gaze_position_calibrator_value.popitem()
+			# str: relative path to file
+			if type(gaze_position_calibrator_value) == str:
 
-			# Prepend argaze.GazeAnalysis path when a single name is provided
-			if len(gaze_position_calibrator_module_path.split('.')) == 1:
-				gaze_position_calibrator_module_path = f'argaze.GazeAnalysis.{gaze_position_calibrator_module_path}'
+				filepath = os.path.join(working_directory, gaze_position_calibrator_value)
+				file_format = filepath.split('.')[-1]
+
+				# JSON file format
+				if file_format == 'json':
+
+					new_gaze_position_calibrator = GazeFeatures.GazePositionCalibrator.from_json(filepath)
+
+			# dict:
+			else:
 
-			gaze_position_calibrator_module = importlib.import_module(gaze_position_calibrator_module_path)
-			new_gaze_position_calibrator = gaze_position_calibrator_module.GazePositionCalibrator(**gaze_position_calibrator_parameters)
+				new_gaze_position_calibrator = GazePositionCalibrator.from_dict(gaze_position_calibrator_value)
 
 		except KeyError:
 
diff --git a/src/argaze/GazeFeatures.py b/src/argaze/GazeFeatures.py
index eddd01d..46e9f17 100644
--- a/src/argaze/GazeFeatures.py
+++ b/src/argaze/GazeFeatures.py
@@ -12,6 +12,7 @@ from dataclasses import dataclass, field
 import math
 import ast
 import json
+import importlib
 from inspect import getmembers
 
 from argaze import DataStructures
@@ -208,10 +209,54 @@ class GazePositionCalibrationFailed(Exception):
 
         super().__init__(message)
 
+GazePositionCalibratorType = TypeVar('GazePositionCalibrator', bound="GazePositionCalibrator")
+# Type definition for type annotation convenience
+
 @dataclass
 class GazePositionCalibrator():
     """Abstract class to define what should provide a gaze position calibrator algorithm."""
 
+    @classmethod
+    def from_dict(self, calibrator_data: dict) -> GazePositionCalibratorType:
+        """Load gaze position calibrator from dictionary.
+
+        Parameters:
+            calibrator_data: dictionary with class name and attributes to load
+        """
+        gaze_position_calibrator_module_path, gaze_position_calibrator_parameters = calibrator_data.popitem()
+
+        # Prepend argaze.GazeAnalysis path when a single name is provided
+        if len(gaze_position_calibrator_module_path.split('.')) == 1:
+            gaze_position_calibrator_module_path = f'argaze.GazeAnalysis.{gaze_position_calibrator_module_path}'
+
+        gaze_position_calibrator_module = importlib.import_module(gaze_position_calibrator_module_path)
+        return gaze_position_calibrator_module.GazePositionCalibrator(**gaze_position_calibrator_parameters)
+
+    @classmethod
+    def from_json(self, json_filepath: str) -> GazePositionCalibratorType:
+        """Load calibrator from .json file."""
+
+        # Remember file path to ease rewriting
+        self.__json_filepath = json_filepath
+
+        # Open file
+        with open(self.__json_filepath) as calibration_file:
+
+            return GazePositionCalibrator.from_dict(json.load(calibration_file))
+
+    def to_json(self, json_filepath: str = None):
+        """Save calibrator into .json file."""
+
+        # Remember file path to ease rewriting
+        if json_filepath is not None:
+
+            self.__json_filepath = json_filepath
+
+        # Open file
+        with open(self.__json_filepath, 'w', encoding='utf-8') as calibration_file:
+
+            json.dump({DataStructures.module_path(self):DataStructures.JsonEncoder().default(self)}, calibration_file, ensure_ascii=False, indent=4)
+
     def store(self, timestamp: int|float, observed_gaze_position: GazePosition, expected_gaze_position: GazePosition):
         """Store observed and expected gaze positions.