pydartsnut 1.2.1

dartsnut python package

pydartsnut

Python module for interfacing with Dartsnut hardware. Provides dart position tracking, button state monitoring, display control, and event-based input handling.

Installation

pip install pydartsnut

Requirements

• Python >= 3.1
• PIL/Pillow (for image handling, optional)

Usage

Initialize the module

from pydartsnut import Dartsnut

dartsnut = Dartsnut()

The Dartsnut class accepts command-line arguments:

• --params: JSON string for widget parameters (default: "{}")
• --shm: Shared memory name for display (default: "pdishm")
• --data-store: Path to data store directory (defaults to script directory)

Example:

# When running from command line:
# python your_script.py --params '{"city": "New York"}' --shm pdishm --data-store /path/to/data

Retrieve user input parameters

params = dartsnut.widget_params
# Returns a dictionary of current widget parameters.
print(params)

# Safely get the city name from params
city_name = ""
if params is not None:
    city_name = params.get("city", "")
if city_name == "":
    # TODO: assign default value or show a warning image
    pass

Update the frame buffer for display

from PIL import Image

# Using a PIL Image
image = Image.open("your_image.png")
dartsnut.update_frame_buffer(image)

# Or using a bytearray (RGB888 format)
dartsnut.update_frame_buffer(bytearray_data)

The update_frame_buffer() method returns True if the frame was successfully updated, False if the display buffer is busy or in an invalid state.

Get dart positions (polling)

darts = dartsnut.get_darts()
# Returns a list of 12 [x, y] coordinates.
# [-1, -1] means the dart is not present.
# Coordinates are in range 0-127 for both x and y.

Get dart hits (event-based)

dart_hits = dartsnut.get_dart_hits()
# Returns a list of tuples (dart_index, x, y) for new dart hits.
# Only registers hits when a dart transitions from invalid to valid position.
# Each dart index is blocked after detection to prevent duplicate events.
# Darts are automatically unblocked after 0.5 seconds of invalid state.

for dart_index, x, y in dart_hits:
    print(f"Dart {dart_index} hit at ({x}, {y})")

Get active darts (all current darts)

active_darts = dartsnut.get_active_darts()
# Returns a list of tuples (dart_index, x, y) for ALL active darts.
# Useful for continuous tracking regardless of blocking state.

for dart_index, x, y in active_darts:
    print(f"Dart {dart_index} is at ({x}, {y})")

Reset dart blocking state

dartsnut.reset_blocking_state()
# Clears all blocked dart indices, allowing all darts to be eligible for event detection again.

Get button states (polling)

buttons = dartsnut.get_buttons()
# Returns a dictionary with current button states (with 30ms debouncing):
# {
#     "btn_a": False,
#     "btn_b": False,
#     "btn_up": False,
#     "btn_right": False,
#     "btn_left": False,
#     "btn_down": False,
#     "btn_home": False,
#     "btn_reserved": False,
# }

Get button events (event-based)

button_events = dartsnut.get_button_events()
# Returns a dictionary where buttons are True only on press (transition from False to True).
# This provides event-based button detection rather than continuous state polling.

if button_events["btn_a"]:
    print("Button A was just pressed!")

Set display brightness

dartsnut.set_brightness(50)  # Brightness level between 10 and 100

Data persistence

The module provides methods to store and retrieve data in a JSON file:

# Store a value
dartsnut.set_value("player_name", "John Doe")
dartsnut.set_value("high_score", 180)
dartsnut.set_value("settings", {"theme": "dark", "sound": True})

# Retrieve a value
player_name = dartsnut.get_value("player_name", "Unknown")
high_score = dartsnut.get_value("high_score", 0)
settings = dartsnut.get_value("settings", {})

Data is stored atomically to prevent corruption during writes. The default storage location is the script directory, but can be customized with the --data-store argument.

Running state management

# Check if the application should continue running
while dartsnut.running:
    # Your main loop
    dart_hits = dartsnut.get_dart_hits()
    # ... process events ...
    
# The running flag is automatically set to False on SIGINT (Ctrl+C)

Complete Example

from pydartsnut import Dartsnut
from PIL import Image, ImageDraw

dartsnut = Dartsnut()

# Create a simple image
img = Image.new('RGB', (128, 128), color='black')
draw = ImageDraw.Draw(img)

while dartsnut.running:
    # Check for dart hits
    dart_hits = dartsnut.get_dart_hits()
    for dart_index, x, y in dart_hits:
        print(f"Dart {dart_index} hit at ({x}, {y})")
        # Draw a circle at the hit position
        draw.ellipse([x-2, y-2, x+2, y+2], fill='red')
    
    # Check for button presses
    button_events = dartsnut.get_button_events()
    if button_events["btn_a"]:
        print("Button A pressed!")
        # Clear the image
        img = Image.new('RGB', (128, 128), color='black')
        draw = ImageDraw.Draw(img)
    
    # Update display
    dartsnut.update_frame_buffer(img)
    
    # Small delay to prevent excessive CPU usage
    import time
    time.sleep(0.01)

API Reference

Dartsnut Class

Attributes

• running: Boolean flag indicating if the application should continue running
• widget_params: Dictionary of widget parameters parsed from command line

Methods

• update_frame_buffer(frame): Update display frame buffer (returns bool)
• get_darts(): Get current dart positions (returns list of 12 [x, y] coordinates)
• get_dart_hits(): Get new dart hits as events (returns list of (dart_index, x, y) tuples)
• get_active_darts(): Get all currently active darts (returns list of (dart_index, x, y) tuples)
• reset_blocking_state(): Reset dart blocking state
• get_buttons(): Get current button states with debouncing (returns dict)
• get_button_events(): Get button press events (returns dict)
• set_brightness(brightness): Set display brightness (10-100)
• set_value(key, value): Store a value in the data store
• get_value(key, default=None): Retrieve a value from the data store

License

See the project repository for license information.

Links

• Homepage
• Bug Tracker