battery: Interpolate battery level in percent

Estimate remaining battery based on measured battery voltage. Use linear
interpolation to achieve a smooth line instead of 10 percent jumps.

Fixes #2744

lib/logitech_receiver/hidpp20.py

@@ -1503,25 +1503,6 @@ def feature_request(device, feature, function=0x00, *params, no_reply=False):
             return device.request((feature_index << 8) + (function & 0xFF), *params, no_reply=no_reply)
 
 
-# voltage to remaining charge from Logitech
-battery_voltage_remaining = (
-    (4186, 100),
-    (4067, 90),
-    (3989, 80),
-    (3922, 70),
-    (3859, 60),
-    (3811, 50),
-    (3778, 40),
-    (3751, 30),
-    (3717, 20),
-    (3671, 10),
-    (3646, 5),
-    (3579, 2),
-    (3500, 0),
-    (-1000, 0),
-)
-
-
 class Hidpp20:
     def get_firmware(self, device) -> tuple[common.FirmwareInfo] | None:
         """Reads a device's firmware info.
@@ -1962,9 +1943,41 @@ def decipher_adc_measurement(report) -> tuple[SupportedFeature, Battery]:
 
 
 def estimate_battery_level_percentage(value_millivolt: int) -> int | None:
-    charge_level = None
-    for level in battery_voltage_remaining:
-        if level[0] < value_millivolt:
-            charge_level = level[1]
-            break
-    return charge_level
+    """Estimate battery level percentage based on battery voltage.
+
+    Uses linear approximation to estimate the battery level in percent.
+
+    Parameters
+    ----------
+    value_millivolt
+        Measured battery voltage in millivolt.
+    """
+    battery_voltage_to_percentage = [
+        (4186, 100),
+        (4067, 90),
+        (3989, 80),
+        (3922, 70),
+        (3859, 60),
+        (3811, 50),
+        (3778, 40),
+        (3751, 30),
+        (3717, 20),
+        (3671, 10),
+        (3646, 5),
+        (3579, 2),
+        (3500, 0),
+    ]
+
+    if value_millivolt >= battery_voltage_to_percentage[0][0]:
+        return battery_voltage_to_percentage[0][1]
+    if value_millivolt <= battery_voltage_to_percentage[-1][0]:
+        return battery_voltage_to_percentage[-1][1]
+
+    for i in range(len(battery_voltage_to_percentage) - 1):
+        v_high, p_high = battery_voltage_to_percentage[i]
+        v_low, p_low = battery_voltage_to_percentage[i + 1]
+        if v_low <= value_millivolt <= v_high:
+            # Linear interpolation
+            percent = p_low + (p_high - p_low) * (value_millivolt - v_low) / (v_high - v_low)
+            return round(percent)
+    return 0

tests/logitech_receiver/test_hidpp20_simple.py

@@ -107,7 +107,7 @@ def test_get_battery_voltage():
     feature, battery = _hidpp20.get_battery_voltage(device)
 
     assert feature == SupportedFeature.BATTERY_VOLTAGE
-    assert battery.level == 90
+    assert battery.level == 92
     assert common.BatteryStatus.RECHARGING in battery.status
     assert battery.voltage == 0x1000
 
@@ -130,7 +130,7 @@ def test_get_adc_measurement():
     feature, battery = _hidpp20.get_adc_measurement(device)
 
     assert feature == SupportedFeature.ADC_MEASUREMENT
-    assert battery.level == 90
+    assert battery.level == 92
     assert battery.status == common.BatteryStatus.RECHARGING
     assert battery.voltage == 0x1000
 
@@ -389,7 +389,7 @@ def test_decipher_battery_voltage():
     feature, battery = hidpp20.decipher_battery_voltage(report)
 
     assert feature == SupportedFeature.BATTERY_VOLTAGE
-    assert battery.level == 90
+    assert battery.level == 92
     assert common.BatteryStatus.RECHARGING in battery.status
     assert battery.voltage == 0x1000
 
@@ -410,7 +410,7 @@ def test_decipher_adc_measurement():
     feature, battery = hidpp20.decipher_adc_measurement(report)
 
     assert feature == SupportedFeature.ADC_MEASUREMENT
-    assert battery.level == 90
+    assert battery.level == 92
     assert battery.status == common.BatteryStatus.RECHARGING
     assert battery.voltage == 0x1000
 
@@ -454,36 +454,27 @@ def test_led_zone_locations(code, expected_name):
 @pytest.mark.parametrize(
     "millivolt, expected_percentage",
     [
-        (-1234, None),
+        (-1234, 0),
         (500, 0),
         (2000, 0),
         (3500, 0),
-        (3501, 0),
         (3519, 0),
-        (3520, 0),
-        (3579, 0),
-        (3646, 2),
-        (3580, 2),
-        (3671, 5),
-        (3672, 10),
-        (3717, 10),
-        (3718, 20),
-        (3751, 20),
-        (3752, 30),
-        (3778, 30),
-        (3779, 40),
-        (3811, 40),
-        (3812, 50),
-        (3859, 50),
-        (3860, 60),
-        (3922, 60),
-        (3923, 70),
-        (3989, 70),
-        (3990, 80),
-        (4067, 80),
-        (4068, 90),
-        (4186, 90),
-        (4187, 100),
+        (3520, 1),
+        (3559, 1),
+        (3579, 2),
+        (3646, 5),
+        (3671, 10),
+        (3717, 20),
+        (3751, 30),
+        (3778, 40),
+        (3811, 50),
+        (3859, 60),
+        (3922, 70),
+        (3989, 80),
+        (4067, 90),
+        (4180, 99),
+        (4181, 100),
+        (4186, 100),
         (4500, 100),
     ],
 )