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"""
╔══════════════════════════════════════════════════════════════════════════════╗
║ Models: gesture.py ║
║ Core classes for representing hand gestures ║
╚══════════════════════════════════════════════════════════════════════════════╝
This module contains:
• GestureRanking - The ranking system for gestures
• GestureImage - Represents a captured gesture with its data
📚 WHY SEPARATE FILES?
In the procedural style, you might put everything in one big file.
In OOP, we organize related classes into modules (files).
Benefits:
• Easier to find code (gesture stuff is in gesture.py)
• Easier to test (can test gesture.py independently)
• Easier to reuse (import just what you need)
• Easier to collaborate (different people work on different files)
"""
from dataclasses import dataclass
from typing import List, Optional
from PIL import Image
# ==============================================================================
# CLASS: GestureRanking
# ==============================================================================
# This class holds the RANKING SYSTEM for gestures.
# It's like a rulebook that says "fist comes before one, one comes before peace..."
#
# 💡 WHY A CLASS?
# In procedural code, this would be a dictionary floating around globally.
# As a class, we can:
# 1. Add METHODS to work with the data (get_rank, get_emoji, compare)
# 2. PROTECT the data from accidental changes
# 3. Keep related functions TOGETHER with the data they use
# ==============================================================================
class GestureRanking:
"""
Defines the ordering of hand gestures for sorting purposes.
This class encapsulates (bundles together):
- The ranking of each gesture (which comes first in sorted order)
- The emoji representation of each gesture
- Methods to compare gestures
┌─────────────────────────────────────────────────────────────────────────┐
│ 📚 CONCEPT: Class Attributes vs Instance Attributes │
│ │
│ CLASS ATTRIBUTES: Shared by ALL instances (objects) of the class │
│ - Defined directly in the class body │
│ - Like a shared resource everyone can read │
│ - Here: RANKINGS and EMOJIS are class attributes │
│ │
│ INSTANCE ATTRIBUTES: Unique to EACH instance │
│ - Defined in __init__ using self.attribute_name │
│ - Like personal belongings each person carries │
│ - Here: GestureRanking doesn't have instance attributes │
│ (it's a utility class with shared data) │
└─────────────────────────────────────────────────────────────────────────┘
"""
# -------------------------------------------------------------------------
# Class Attribute: RANKINGS
# -------------------------------------------------------------------------
# This dictionary maps gesture names to their rank (sorting order).
# Lower rank = comes first when sorted in ascending order.
#
# 💭 Design Decision: We ordered gestures roughly by "finger count"
# fist (0 fingers) → one → peace (2) → three → four → palm (5) → special signs
# -------------------------------------------------------------------------
RANKINGS = {
"fist": 1, # ✊ Closed fist (0 fingers showing)
"one": 2, # ☝️ One finger up
"two_up": 3, # ✌️ Two fingers (peace sign)
"peace": 3, # ✌️ Alias for two_up (same gesture, different name)
"three": 4, # 🤟 Three fingers
"four": 5, # 🖖 Four fingers
"palm": 6, # 🖐️ Open palm (5 fingers)
"stop": 6, # 🖐️ Alias for palm
"ok": 7, # 👌 OK sign
"like": 8, # 👍 Thumbs up
"dislike": 9, # 👎 Thumbs down
"rock": 10, # 🤘 Rock sign
"call": 11, # 🤙 Call me sign
"mute": 12, # 🤫 Shush/mute gesture
"no_gesture": 99, # Unknown or no gesture detected
}
# -------------------------------------------------------------------------
# Class Attribute: EMOJIS
# -------------------------------------------------------------------------
# Visual representation of each gesture.
# Makes the UI more engaging and helps identify gestures quickly.
# -------------------------------------------------------------------------
EMOJIS = {
"fist": "✊",
"one": "☝️",
"two_up": "✌️",
"peace": "✌️",
"three": "🤟",
"four": "🖖",
"palm": "🖐️",
"stop": "🖐️",
"ok": "👌",
"like": "👍",
"dislike": "👎",
"rock": "🤘",
"call": "🤙",
"mute": "🤫",
"no_gesture": "❓",
}
# -------------------------------------------------------------------------
# Class Method: get_rank
# -------------------------------------------------------------------------
# 📚 CONCEPT: @classmethod
#
# A classmethod belongs to the CLASS, not to an instance.
# - Regular method: needs an object to be called (object.method())
# - Class method: can be called on the class itself (ClassName.method())
#
# Use @classmethod when the method needs CLASS data but not INSTANCE data.
# -------------------------------------------------------------------------
@classmethod
def get_rank(cls, gesture_name: str) -> int:
"""
Get the sorting rank of a gesture.
Args:
gesture_name: The name of the gesture (e.g., "peace", "fist")
Returns:
The rank (1-99) of the gesture. Lower = earlier in sorted order.
Returns 99 if gesture is unknown.
Example:
>>> GestureRanking.get_rank("peace")
3
>>> GestureRanking.get_rank("fist")
1
"""
# .get() returns the value if key exists, otherwise the default (99)
# This prevents crashes if someone passes an unknown gesture name
return cls.RANKINGS.get(gesture_name.lower(), 99)
@classmethod
def get_emoji(cls, gesture_name: str) -> str:
"""
Get the emoji representation of a gesture.
Args:
gesture_name: The name of the gesture
Returns:
The emoji string for this gesture, or ❓ if unknown.
"""
return cls.EMOJIS.get(gesture_name.lower(), "❓")
@classmethod
def compare(cls, gesture_a: str, gesture_b: str) -> int:
"""
Compare two gestures for sorting order.
This follows the standard comparison convention:
- Returns NEGATIVE if a < b (a comes before b)
- Returns ZERO if a == b (same rank)
- Returns POSITIVE if a > b (a comes after b)
Args:
gesture_a: First gesture name
gesture_b: Second gesture name
Returns:
Negative, zero, or positive integer.
Example:
>>> GestureRanking.compare("fist", "peace")
-2 # Negative: fist comes before peace
>>> GestureRanking.compare("peace", "fist")
2 # Positive: peace comes after fist
"""
return cls.get_rank(gesture_a) - cls.get_rank(gesture_b)
@classmethod
def get_all_gestures(cls) -> List[str]:
"""
Get a list of all known gestures, sorted by rank.
Returns:
List of gesture names in sorted order.
"""
# Sort the gesture names by their rank value
# This uses a lambda function as the sorting key
sorted_gestures = sorted(
cls.RANKINGS.keys(),
key=lambda name: cls.RANKINGS[name]
)
# Remove duplicates while preserving order
seen = set()
unique = []
for gesture in sorted_gestures:
if gesture not in seen:
seen.add(gesture)
unique.append(gesture)
return unique
# ==============================================================================
# CLASS: GestureImage (using @dataclass)
# ==============================================================================
"""
╔══════════════════════════════════════════════════════════════════════════════╗
║ 📚 CONCEPT: What is a @dataclass? ║
╠══════════════════════════════════════════════════════════════════════════════╣
║ ║
║ A @dataclass is a shortcut for creating classes that mainly hold DATA. ║
║ ║
║ WITHOUT @dataclass (the long way): ║
║ ───────────────────────────────── ║
║ class GestureImage: ║
║ def __init__(self, gesture, rank, emoji, image, capture_id): ║
║ self.gesture = gesture ║
║ self.rank = rank ║
║ self.emoji = emoji ║
║ self.image = image ║
║ self.capture_id = capture_id ║
║ ║
║ def __repr__(self): ║
║ return f"GestureImage(gesture={self.gesture}, ...)" ║
║ ║
║ def __eq__(self, other): ║
║ return self.gesture == other.gesture and ... ║
║ ║
║ WITH @dataclass (the shortcut): ║
║ ─────────────────────────────── ║
║ @dataclass ║
║ class GestureImage: ║
║ gesture: str ║
║ rank: int ║
║ emoji: str ║
║ image: Image ║
║ capture_id: int ║
║ ║
║ The @dataclass automatically generates __init__, __repr__, __eq__, etc! ║
║ ║
╚══════════════════════════════════════════════════════════════════════════════╝
"""
@dataclass
class GestureImage:
"""
Represents a captured hand gesture image with its classification.
This is the CORE DATA STRUCTURE of our application.
Each GestureImage bundles together:
- The actual image (pixels)
- The AI's prediction of what gesture it shows
- A unique ID for tracking (important for stability testing)
- Visual representations (emoji, rank)
┌─────────────────────────────────────────────────────────────────────────┐
│ 💡 WHY THIS MATTERS: Encapsulation │
│ │
│ In procedural code, you'd pass around separate variables: │
│ process_gesture(image, name, rank, emoji, id) # 5 parameters! │
│ │
│ With OOP, you pass ONE object that contains everything: │
│ process_gesture(gesture_image) # 1 parameter! │
│ │
│ Benefits: │
│ ✓ Less room for errors (can't mix up parameter order) │
│ ✓ Easier to add new attributes later │
│ ✓ Methods travel WITH the data they operate on │
└─────────────────────────────────────────────────────────────────────────┘
Attributes:
gesture: The name of the detected gesture (e.g., "peace", "fist")
rank: Numeric rank for sorting (lower = comes first)
emoji: Visual emoji representation
image: The actual PIL Image (can be None if not needed)
capture_id: Unique ID from capture order (for stability testing)
thumbnail: Smaller version for display (generated automatically)
"""
# -------------------------------------------------------------------------
# Dataclass Fields (Attributes)
# -------------------------------------------------------------------------
# These define what data each GestureImage object will hold.
# The type hints (: str, : int, etc.) help document and catch errors.
# -------------------------------------------------------------------------
gesture: str # Name of the gesture
rank: int # Sorting rank (from GestureRanking)
emoji: str # Emoji representation
capture_id: int # Unique ID (for stability tracking)
image: Optional[Image.Image] = None # The actual image (optional)
thumbnail: Optional[Image.Image] = None # Small version for display
confidence: float = 0.0 # AI's confidence in the prediction
# -------------------------------------------------------------------------
# Special Method: __post_init__
# -------------------------------------------------------------------------
# This runs AFTER the automatic __init__ created by @dataclass.
# We use it to create the thumbnail from the full image.
# -------------------------------------------------------------------------
def __post_init__(self):
"""
Called automatically after the object is created.
Generates a thumbnail if an image is provided.
"""
if self.image is not None and self.thumbnail is None:
self._create_thumbnail()
def _create_thumbnail(self, max_size: int = 80):
"""
Create a smaller version of the image for display.
The underscore prefix (_create_thumbnail) is a Python convention
meaning "this is an internal method, not meant to be called from outside".
Args:
max_size: Maximum width/height of the thumbnail
"""
if self.image is not None:
# Create a copy so we don't modify the original
thumb = self.image.copy()
# Resize while maintaining aspect ratio
thumb.thumbnail((max_size, max_size), Image.Resampling.LANCZOS)
self.thumbnail = thumb
# -------------------------------------------------------------------------
# Comparison Methods: Making objects sortable
# -------------------------------------------------------------------------
"""
╔═════════════════════════════════════════════════════════════════════════╗
║ 📚 CONCEPT: Magic Methods (Dunder Methods) ║
╠═════════════════════════════════════════════════════════════════════════╣
║ ║
║ Python has special method names surrounded by double underscores. ║
║ These are called "magic methods" or "dunder methods" (double under). ║
║ ║
║ They let your objects work with Python's built-in operations: ║
║ ║
║ __lt__(self, other) → enables: object1 < object2 ║
║ __le__(self, other) → enables: object1 <= object2 ║
║ __eq__(self, other) → enables: object1 == object2 ║
║ __gt__(self, other) → enables: object1 > object2 ║
║ __ge__(self, other) → enables: object1 >= object2 ║
║ __str__(self) → enables: str(object) or print(object) ║
║ __repr__(self) → enables: repr(object) (for debugging) ║
║ ║
║ 💡 WHY THIS MATTERS: ║
║ With these methods, Python's built-in sorted() function ║
║ automatically works with our GestureImage objects! ║
║ ║
║ gestures = [gesture1, gesture2, gesture3] ║
║ sorted_gestures = sorted(gestures) # Just works! ✨ ║
║ ║
╚═════════════════════════════════════════════════════════════════════════╝
"""
def __lt__(self, other: 'GestureImage') -> bool:
"""
Less than comparison. Enables: gesture1 < gesture2
Compares by rank. If ranks are equal, maintains stability
by comparing capture_id (earlier captured = smaller).
"""
if self.rank != other.rank:
return self.rank < other.rank
# If same rank, compare by capture_id for stable sorting
return self.capture_id < other.capture_id
def __le__(self, other: 'GestureImage') -> bool:
"""Less than or equal. Enables: gesture1 <= gesture2"""
return self.rank <= other.rank
def __gt__(self, other: 'GestureImage') -> bool:
"""Greater than. Enables: gesture1 > gesture2"""
if self.rank != other.rank:
return self.rank > other.rank
return self.capture_id > other.capture_id
def __ge__(self, other: 'GestureImage') -> bool:
"""Greater than or equal. Enables: gesture1 >= gesture2"""
return self.rank >= other.rank
def __eq__(self, other: object) -> bool:
"""
Equality comparison. Enables: gesture1 == gesture2
Two gestures are equal if they have the same rank.
Note: We compare RANKS, not capture_ids, for sorting purposes.
"""
if not isinstance(other, GestureImage):
return False
return self.rank == other.rank
def __hash__(self) -> int:
"""
Hash function. Required for using objects in sets or as dict keys.
We hash by capture_id since it's unique.
"""
return hash(self.capture_id)
# -------------------------------------------------------------------------
# Display Methods
# -------------------------------------------------------------------------
def __str__(self) -> str:
"""
Human-readable string representation.
Called by print() and str().
Example: "✌️₁" (peace sign, capture #1)
"""
# Subscript numbers for capture_id
subscripts = "₀₁₂₃₄₅₆₇₈₉"
sub_id = ''.join(subscripts[int(d)] for d in str(self.capture_id))
return f"{self.emoji}{sub_id}"
def __repr__(self) -> str:
"""
Developer-friendly representation (for debugging).
Called by repr() and shown in interactive Python.
"""
return f"GestureImage(gesture='{self.gesture}', rank={self.rank}, id={self.capture_id})"
def display_label(self) -> str:
"""
Get a label for UI display.
Shows emoji, gesture name, and capture ID.
"""
return f"{self.emoji} {self.gesture} (#{self.capture_id})"
# -------------------------------------------------------------------------
# Factory Methods
# -------------------------------------------------------------------------
"""
╔═════════════════════════════════════════════════════════════════════════╗
║ 📚 CONCEPT: Factory Methods ║
╠═════════════════════════════════════════════════════════════════════════╣
║ ║
║ A Factory Method is a class method that CREATES instances. ║
║ ║
║ Instead of: ║
║ gesture = GestureImage( ║
║ gesture="peace", ║
║ rank=GestureRanking.get_rank("peace"), ║
║ emoji=GestureRanking.get_emoji("peace"), ║
║ capture_id=1, ║
║ image=my_image, ║
║ confidence=0.95 ║
║ ) ║
║ ║
║ You can use: ║
║ gesture = GestureImage.create_from_prediction( ║
║ gesture_name="peace", ║
║ capture_id=1, ║
║ image=my_image, ║
║ confidence=0.95 ║
║ ) ║
║ ║
║ The factory method handles the details of looking up rank/emoji! ║
║ ║
╚═════════════════════════════════════════════════════════════════════════╝
"""
@classmethod
def create_from_prediction(
cls,
gesture_name: str,
capture_id: int,
image: Optional[Image.Image] = None,
confidence: float = 0.0
) -> 'GestureImage':
"""
Factory method to create a GestureImage from an AI prediction.
This is a convenient way to create GestureImage objects without
needing to manually look up ranks and emojis.
Args:
gesture_name: The predicted gesture name
capture_id: Unique identifier for this capture
image: The original image (optional)
confidence: AI confidence score (0.0 to 1.0)
Returns:
A new GestureImage instance
"""
return cls(
gesture=gesture_name.lower(),
rank=GestureRanking.get_rank(gesture_name),
emoji=GestureRanking.get_emoji(gesture_name),
capture_id=capture_id,
image=image,
confidence=confidence
)
@classmethod
def create_manual(
cls,
gesture_name: str,
capture_id: int,
image: Optional[Image.Image] = None
) -> 'GestureImage':
"""
Create a GestureImage with manual gesture assignment (no AI).
Same as create_from_prediction but with 100% confidence.
"""
return cls.create_from_prediction(
gesture_name=gesture_name,
capture_id=capture_id,
image=image,
confidence=1.0 # Manual assignment = 100% confident
)
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