Create value strategy for twos compliement delta encoders

Author: MaddyGuthridge

coverage.sh

@@ -0,0 +1,2 @@
+
+coverage run -m pytest && coverage report && coverage html && python -m webbrowser htmlcov/index.html > /dev/null 2>&1

src/common/states/devicedetect.py

@@ -164,7 +164,6 @@ def processEvent(self, event: EventData) -> None:
                     verbosity.INFO,
                     eventToString(event)
                 )
-                event.handled = True
                 common.getContext().setState(self._to.create(dev))
             except DeviceRecogniseError:
                 log(

src/common/util/misc.py

@@ -78,3 +78,18 @@ def formatLongTime(t: float) -> str:
     t_obj = time.localtime(t)
     ms = f"{t - math.floor(t):.3}".lstrip("0.")
     return f"{t_obj.tm_hour:02}:{t_obj.tm_min:02}:{t_obj.tm_sec:02}.{ms}"
+
+
+def clamp(value: float, lower: float, upper: float) -> float:
+    """
+    Clamp value between lower and upper
+
+    ### Args:
+    * `value` (`float`): value to clamp
+    * `lower` (`float`): lowest allowed value
+    * `upper` (`float`): greatest allowed value
+
+    ### Returns:
+    * `float`: clamped value
+    """
+    return min(max(value, lower), upper)

src/controlsurfaces/valuestrategies/__init__.py

@@ -13,16 +13,18 @@
     'NoteStrategy',
     'Data2Strategy',
     'Data1Strategy',
+    'TwosComplimentDeltaStrategy',
     'ButtonData2Strategy',
     'ButtonSinglePressStrategy',
     'ForwardedStrategy',
     'ForwardedUnionStrategy',
-    'NullEventStrategy'
+    'NullEventStrategy',
 ]
 
 from .ivaluestrategy import IValueStrategy
 from .notestrategy import NoteStrategy
 from .datastrategy import Data2Strategy, Data1Strategy
+from .twoscomplimentdelta import TwosComplimentDeltaStrategy
 from .buttondata2strategy import ButtonData2Strategy
 from .buttonsinglepressstrategy import ButtonSinglePressStrategy
 from .forwardedstrategy import ForwardedStrategy, ForwardedUnionStrategy

src/controlsurfaces/valuestrategies/twoscomplimentdelta.py

@@ -0,0 +1,41 @@
+"""
+controlsurfaces > valuestrategies > twoscomplimentdelta
+
+Contains the definitions for a two's compliment delta value strategy
+
+Authors:
+* Miguel Guthridge [hdsq@outlook.com.au, HDSQ#2154]
+"""
+from common.types.eventdata import EventData, isEventStandard
+from common.util.misc import clamp
+from . import IValueStrategy
+
+
+class TwosComplimentDeltaStrategy(IValueStrategy):
+    """
+    Defines a value strategy that gets its values relative to the current
+    value, using the data2 property of events to calculate an offset using
+    two's compliment. This is used by many endless encoders.
+    """
+    def __init__(self, scaling: float = 1.0) -> None:
+        """
+        Create a TwosComplimentDeltaStrategy
+
+        ### Args:
+        * `scaling` (`float`, optional): amount to scale deltas by. Defaults to
+          `1.0`.
+        """
+        self.__scaling = scaling
+
+    def getValueFromEvent(self, event: EventData, value: float) -> float:
+        assert isEventStandard(event)
+        if event.data2 < 64:
+            # Positive
+            delta = event.data2
+        else:
+            delta = event.data2 - 128
+        return clamp((delta / 64) * self.__scaling + value, 0.0, 1.0)
+
+    def getChannelFromEvent(self, event: EventData) -> int:
+        assert isEventStandard(event)
+        return event.status & 0xF

tests/valuestrategy/twoscomplimentdelta_test.py

@@ -0,0 +1,49 @@
+
+import pytest
+from common.types import EventData
+from controlsurfaces.valuestrategies import TwosComplimentDeltaStrategy
+
+
+def test_zero():
+    s = TwosComplimentDeltaStrategy()
+    e = EventData(0, 0, 0)
+    assert s.getValueFromEvent(e, 0.5) == 0.5
+
+
+def test_positive():
+    s = TwosComplimentDeltaStrategy()
+    e = EventData(0, 0, 1)
+    assert s.getValueFromEvent(e, 0.5) == 0.5 + 1/64
+    e = EventData(0, 0, 5)
+    assert s.getValueFromEvent(e, 0.5) == 0.5 + 5/64
+
+
+def test_negative():
+    s = TwosComplimentDeltaStrategy()
+    e = EventData(0, 0, 127)
+    assert s.getValueFromEvent(e, 0.5) == 0.5 - 1/64
+    e = EventData(0, 0, 123)
+    assert s.getValueFromEvent(e, 0.5) == 0.5 - 5/64
+
+
+@pytest.mark.parametrize(
+    'e', [
+        EventData(0, 0, 1),
+        EventData(0, 0, 127),
+        EventData(0, 0, 0),
+        EventData(0, 0, 5),
+    ]
+)
+def test_scaling(e):
+    s1 = TwosComplimentDeltaStrategy()
+    s2 = TwosComplimentDeltaStrategy(2.0)
+    delta = s1.getValueFromEvent(e, 0.5) - 0.5
+    assert s2.getValueFromEvent(e, 0.5) - 0.5 == delta * 2
+
+
+def test_clamp():
+    s = TwosComplimentDeltaStrategy()
+    e = EventData(0, 0, 127)
+    assert s.getValueFromEvent(e, 0.0) == 0.0
+    e = EventData(0, 0, 1)
+    assert s.getValueFromEvent(e, 1.0) == 1.0