Add extended tone demo to examples

Author: apendley

examples/macropad_tone_keypad_extended.py

@@ -0,0 +1,102 @@
+# SPDX-FileCopyrightText: Copyright (c) 2021 Aaron Pendley
+#
+# SPDX-License-Identifier: Unlicense
+"""
+MacroPad extended tone demo. Expands upon the basic tone demo by using
+a stack to track pressed keys, allowing multiple keys to be pressed at once,
+while preserving the order they were pressed. Also, improved responsiveness by 
+updating the Neopixels only when one of the key states has changed.
+"""
+
+from adafruit_macropad import MacroPad
+from rainbowio import colorwheel
+
+macropad = MacroPad()
+
+# We'll show the pixels manually
+macropad.pixels.auto_write = False
+
+# Notes for each key
+tones = [196, 220, 246, 262, 294, 330, 349, 392, 440, 494, 523, 587]
+
+# When a key is pressed we'll append it to the end, and when a key is
+# released we'll remove it. This results in a list of pressed keys in 
+# the order they were pressed.
+key_pressed_stack = []
+
+# When at least one key is pressed, this will 
+# be the index of the currently playing note.
+playing_index = None
+
+# Helper to convert an integer to an rgb value.
+def rgb_from_int(rgb):
+    b = rgb & 255
+    g = (rgb >> 8) & 255
+    r = (rgb >> 16) & 255
+    return r, g, b
+
+# Loop forever, until the heat death of the universe 
+# (or we lose power, whichever comes first).
+while True:
+    # To save time, we'll only update the pixels when a key event happens.
+    update_pixels = False
+
+    # Process all pending events.
+    while macropad.keys.events:
+        key_event = macropad.keys.events.get()
+
+        # We need to update the pixels again at the end of the main loop.
+        update_pixels = True
+
+        if key_event.pressed:
+            # Append pressed key to the end of the stack
+            key_pressed_stack.append(key_event.key_number)
+        else:
+            # Remove released key from the stack
+            key_pressed_stack.remove(key_event.key_number)
+
+            # Turn this pixel off since the key is no longer pressed.
+            macropad.pixels[key_event.key_number] = 0
+
+    # How many keys are currently pressed?
+    pressed_count = len(key_pressed_stack)
+
+    # There are some keys pressed.
+    if pressed_count > 0:
+        # Get the most recently pressed key
+        top_index = key_pressed_stack[pressed_count - 1]
+
+        # If the most recently pressed key's tone isn't already playing;
+        if top_index != playing_index:
+            # If a tone was playing, stop it, so we can play the next one.
+            if playing_index is not None:
+                macropad.stop_tone()
+
+            # Play this key's tone and remember which one it is.
+            macropad.start_tone(tones[top_index])
+            playing_index = top_index
+
+    # There are no keys pressed.
+    else:
+        # If a tone was playing, stop it.
+        if playing_index is not None:
+            macropad.stop_tone()            
+            playing_index = None
+
+    # If a key was pressed or released, update the pixels for the pressed keys.
+    if update_pixels:
+        for key_index in key_pressed_stack:
+            # Get the color for this key.
+            wheel_color = colorwheel(int(255 / 12) * key_index)
+
+            if key_index == playing_index:
+                # Show the currently playing key at full brightness.
+                macropad.pixels[key_index] = wheel_color
+            else:
+                # Dim the rest of the keys to 10% brightness.
+                (r, g, b) = rgb_from_int(wheel_color)
+                macropad.pixels[key_index] = (r * 0.1, g * 0.1, b * 0.1)
+
+        # Don't forget to show the pixels!
+        macropad.pixels.show()
+