add GPIO input detection

Playzing.py

@@ -6,8 +6,18 @@ import argparse, os, pathlib, pygame, sys
 import lib.pgfw.pgfw as pgfw
 from games.ibitfit.electric_sieve.ElectricSieve import ElectricSieve
 
+# Import GPIO library if available 
+try:
+    import RPi.GPIO as GPIO
+except ImportError:
+    pass
+
 class Playzing(pgfw.Game):
 
+    # The GPIO pins corresponding to the buttons
+    PIN_BUTTON_LEFT = 17
+    PIN_BUTTON_RIGHT = 27
+
     def __init__(self, config_overrides=None):
         """
         Create logo sprite, clear screen, and subscribe to events.
@@ -35,6 +45,10 @@ class Playzing(pgfw.Game):
         # Clear screen to black
         self.get_display_surface().fill(self.configuration.get("display", "clear"))
 
+        # Initialize GPIO input and callbacks if GPIO library is loaded
+        if "RPi.GPIO" in sys.modules:
+            self.initialize_gpio()
+
         # Subscribe to PGFW command events
         self.subscribe(self.respond)
 
@@ -53,6 +67,45 @@ class Playzing(pgfw.Game):
         self.register(self.reveal_text, interval=40)
         self.play(self.animate_logo, play_once=True)
 
+    def initialize_gpio(self):
+        """
+        Set pin numbering mode to GPIO, initialize all buttons to input pullup.
+        """
+        # Use GPIO numbering
+        GPIO.setmode(GPIO.BCM)
+    
+        # Set button pins to pullup and attach to each a callback that runs on press or release
+        for pin in self.PIN_BUTTON_LEFT, self.PIN_BUTTON_RIGHT:
+            GPIO.setup(pin, GPIO.IN, pull_up_down=GPIO.PUD_UP)
+            GPIO.add_event_detect(pin, GPIO.BOTH, self.gpio_input)
+
+    def gpio_input(self, pin):
+        """
+        Translate GPIO input into PGFW commands, so Raspberry Pi wired controllers be used for input. 
+
+        Compare the pin state to what is stored in memory. Only fire an event if there has been a change in state. A change
+        from high to low triggers a press event. A change from low to high triggers a press cancel event.
+
+        @param pin   Raspberry Pi pin number as read by the RPi.GPIO library
+        """
+        # Print the input state of each pin if debug is requested on the command line
+        if "--debug" in sys.argv:
+            pin_name = "left" if pin == self.PIN_BUTTON_LEFT else "right"
+            left_pin_state = GPIO.input(self.PIN_BUTTON_LEFT)
+            right_pin_state = GPIO.input(self.PIN_BUTTON_RIGHT)
+            print(f"Received {pin} ({pin_name}) input. Left state is {left_pin_state}. Right state is {right_pin_state}")
+
+        # If the saved state of the pin is the same, there hasn't been a real button press or release, so don't continue
+        if self.pin_states[pin] != GPIO.input(pin):
+            self.pin_states[pin] = GPIO.input(pin)
+            # A high signal means the button is released, and a low signal means it is pressed
+            cancel = not (GPIO.input(pin) == GPIO.LOW)
+            if pin == self.PIN_BUTTON_LEFT:
+                self.input.post_command("left", cancel=cancel)
+            elif pin == self.PIN_BUTTON_RIGHT:
+                self.input.post_command("right", cancel=cancel)
+            self.input.post_any_command(id=pin, cancel=cancel)
+
     @property
     def rotated(self):
         return self.configuration.get("display", "rotated")