From b4d8bed97612dc57cd9f4df97133bad193f43e7b Mon Sep 17 00:00:00 2001
From: Théo de la Hogue
Date: Tue, 9 May 2023 17:50:51 +0200
Subject: Defining VisualScan interface.

---
 src/argaze/GazeFeatures.py | 103 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 102 insertions(+), 1 deletion(-)

diff --git a/src/argaze/GazeFeatures.py b/src/argaze/GazeFeatures.py
index a65f55b..bfe19fb 100644
--- a/src/argaze/GazeFeatures.py
+++ b/src/argaze/GazeFeatures.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 
-from typing import TypeVar, Tuple
+from typing import TypeVar, Tuple, Any
 from dataclasses import dataclass, field
 import math
 import ast
@@ -285,3 +285,104 @@ class GazeMovementIdentifier():
                 continue
 
         return ts_fixations, ts_saccades, ts_status
+
+VisualScanNodeType = TypeVar('VisualScanNode', bound="VisualScanNode")
+# Type definition for type annotation convenience
+
+@dataclass(frozen=True)
+class VisualScanNode():
+    """Define a visual scan node as a set of successive gaze movements onto a same AOI."""
+
+    movements: TimeStampedGazeMovements
+    """ """
+
+    aoi: str = field(default='')
+    """Name of the looked AOI"""
+
+VisualScanArcType = TypeVar('VisualScanArc', bound="VisualScanArc")
+# Type definition for type annotation convenience
+
+@dataclass(frozen=True)
+class VisualScanArc():
+    """Define a visual scan arc as a saccade to a next visual scan node."""
+
+    saccade: Saccade
+    """Saccade to the next scan node"""
+
+    to: VisualScanNode
+    """Node where the saccade ends"""
+
+class VisualScan(list):
+    """Build a linear path made of nodes relied by arcs from successive timestamped gaze movements over aoi."""
+
+    def __init__(self):
+
+        super().__init__()
+        
+        self.__movements = TimeStampedGazeMovements()
+        self.__last_aoi = ''
+
+    def __repr__(self):
+        """String representation"""
+
+        return str(super())
+
+    def __str__(self) -> str:
+        """String display"""
+
+        output = ''
+
+        for arc in self:
+
+            output += f'> {arc.to.aoi} '
+
+        return output
+
+    def append_saccade(self, ts, saccade):
+        """Append a new saccade to visual scan."""
+        
+        self.__movements[ts] = saccade
+
+    def append_fixation(self, ts, fixation, looked_aoi: str) -> bool:
+        """Append a new fixation to visual scan and return True if a new arc have been created."""
+
+        # Is the fixation onto a new aoi?
+        if looked_aoi != self.__last_aoi and len(self.__movements) > 0:
+
+            # Last movement should be a saccade
+            last_ts, last_movement = self.__movements.pop_last()
+            assert(type(last_movement).__bases__[0] == Saccade)
+
+            # Edit new node and arc
+            new_node = VisualScanNode(self.__movements, looked_aoi)
+            new_arc = VisualScanArc(last_movement, new_node)
+
+            # Append new arc
+            super().append(new_arc)
+
+            # Clear movements
+            self.__movements = TimeStampedGazeMovements()
+
+            # Append new fixation
+            self.__movements[ts] = fixation
+
+            # Remember new aoi
+            self.__last_aoi = looked_aoi
+
+            # Notify that a new arc have been created
+            return True
+
+        else:
+
+            # Append new fixation
+            self.__movements[ts] = fixation
+
+            return False
+
+class VisualScanAnalyzer():
+    """Abstract class to define what should provide a visual scan analyser."""
+
+    def analyze(self, visual_scan: list[VisualScanArcType]) -> Any:
+        """Analyze visual scan."""
+
+        raise NotImplementedError('analyze() method not implemented')
-- 
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