Add prototype for colorwheel effect

Author: tekktrik

displayio_effects/colorwheel_effect.py

@@ -0,0 +1,83 @@
+# SPDX-FileCopyrightText: 2017 Scott Shawcroft, written for Adafruit Industries
+# SPDX-FileCopyrightText: Copyright (c) 2022 Alec Delaney for CircuitPython Organization
+#
+# SPDX-License-Identifier: MIT
+# pylint: disable=protected-access
+"""
+`displayio_effects.fluctuation_effect`
+================================================================================
+
+Add the colorwheel effect to your widgets
+
+
+* Author(s): Alec Delaney
+
+Implementation Notes
+--------------------
+
+**Software and Dependencies:**
+
+* Adafruit CircuitPython firmware for the supported boards:
+  https://circuitpython.org/downloads
+"""
+
+from rainbowio import colorwheel
+from adafruit_itertools.adafruit_itertools import cycle
+from displayio_effects import WidgetType, WIDGET_TYPE_ATTR
+
+__version__ = "0.0.0-auto.0"
+__repo__ = "https://github.com/tekktrik/CircuitPython_Org_DisplayIO_Effects.git"
+
+
+COLORWHEEL_WIDGET_VALUES = {
+    WidgetType.DIAL: {
+        "path": ("_needle", "_palette"),
+        "index" : 0,
+    },
+    WidgetType.GAUGE: {
+        "path": ("_palette"),
+        "index": 2,
+    },
+}
+
+COLORWHEEL_COLORS = cycle([colorwheel(color_value) for color_value in range(256)])
+
+
+def update_colorwheel(self):
+    """Updates the widget value and propagates the fluctuation effect refresh"""
+
+    palette_map = getattr(self, WIDGET_TYPE_ATTR)
+    palette_attr = self
+    for attr_path in palette_map["path"]:
+        palette_attr = getattr(palette_attr, attr_path)
+    palette_attr[palette_map["index"]] = next(COLORWHEEL_COLORS)
+
+
+def hook_colorwheel_effect(widget_class, widget_type):
+    """Adds the colorwheel effect for the given class
+
+    :param widget_class: The widget class that should have this effect hooked
+        into it
+    :param int widget_type: The enum value of this widget type, must be a
+        valid ~WidgetType
+
+    For example, to hook this into the ``Dial`` widget, you would use the
+    following code:
+
+    .. code-block:: python
+
+        from displayio_dial import Dial
+        from displayio_effects import WidgetType, colorwheel_effect
+
+        fluctuation_effect.hook_colorwheel_effect(Dial, WidgetType.DIAL)
+
+    """
+
+    if not COLORWHEEL_WIDGET_VALUES.get(widget_type):
+        raise ValueError(
+            "The given widget does not have the ability to use this effect"
+        )
+
+    setattr(widget_class, WIDGET_TYPE_ATTR, widget_type)
+
+    setattr(widget_class, "update_colorwheel", update_colorwheel)