Add prototype code for dynamically setting effects

Author: tekktrik

displayio_effects.py

@@ -31,7 +31,73 @@
 # * Adafruit's Register library: https://github.com/adafruit/Adafruit_CircuitPython_Register
 """
 
-# imports
+import random
 
 __version__ = "0.0.0-auto.0"
 __repo__ = "https://github.com/tekktrik/CircuitPython_Org_DisplayIO_Effects.git"
+
+
+@property
+def throttle_effect(self):
+    """The furtherest the throttle effect can randomly set the dial value relative
+    to its true position, in either direction.
+    """
+    return self._throttle_setting
+
+@throttle_effect.setter
+def throttle_effect(self, setting):
+    if setting < 0:
+        raise ValueError("Throttle effect setting must be larger than 0")
+    if setting:
+        self._throttle_hold_value = self.value
+    self._throttle_setting = setting
+
+@property
+def throttle_effect_move_rate(self):
+    """The speed at which the throttle effect moves the dial per update"""
+    return self._throttle_move_rate
+
+@throttle_effect_move_rate.setter
+def throttle_effect_move_rate(self, rate):
+    self._throttle_move_rate = rate
+
+def throttle_update(self):
+    """Updates the gauge and propagates the throttle effect refresh"""
+
+    if self._throttle_setting == 0:
+        self._throttle_destination = None
+        return
+
+    if self._throttle_destination in (None, self._throttle_hold_value):
+        limit_bound = self._throttle_setting * 10
+        self._throttle_destination = (
+            random.uniform(-limit_bound, limit_bound) / 10
+            + self._throttle_hold_value
+        )
+
+    self.value = (
+        self.value + self._throttle_move_rate
+        if self._throttle_destination > self.value
+        else self.value - self._throttle_move_rate
+    )
+
+    threshold_check = (
+        self.value >= self._throttle_destination
+        if self._throttle_destination >= self._throttle_hold_value
+        else self.value <= self._throttle_destination
+    )
+    if threshold_check:
+        self._throttle_destination = self._throttle_hold_value
+
+def hook_throttle_effect(*widget_classes):
+    for widget_class in widget_classes:
+
+        setattr(widget_class, "_throttle_destination", None)
+        setattr(widget_class, "_throttle_value", 0)
+
+        setattr(widget_class, "throttle_effect", throttle_effect)
+        setattr(widget_class, "_throttle_effect", 0)
+        setattr(widget_class, "throttle_effect_move_rate", throttle_effect_move_rate)
+        setattr(widget_class, "_throttle_move_rate", 0.1)
+
+        setattr(widget_class, "throttle_update", throttle_update)