mouse baterry

include/services/hidppBattery.hpp

@@ -0,0 +1,64 @@
+#pragma once
+
+#include <cstdint>
+#include <optional>
+#include <string>
+
+namespace hidpp {
+
+/// Battery state of a wireless Logitech device.
+struct BatteryStatus {
+    enum class Level : uint8_t { UNKNOWN,
+                                 CRITICAL,
+                                 LOW,
+                                 GOOD,
+                                 FULL };
+
+    bool connected     = false;
+    int percentage     = -1; // 0..100, or -1 when the device only reports a level
+    Level level        = Level::UNKNOWN;
+    bool charging      = false;
+    bool externalPower = false;
+};
+
+/// Reads the battery level of a Logitech HID++ 2.0 device.
+///
+/// Prefers the power_supply entry that hid-logitech-hidpp exports, and falls
+/// back to speaking HID++ 2.0 over /dev/hidraw* when that driver is not bound
+/// (the receiver then sits on hid-generic and exports no battery at all).
+///
+/// read() blocks on wireless round-trips that can take seconds when the device
+/// is asleep, so it must be called off the GTK main thread.
+class BatteryReader {
+  public:
+    explicit BatteryReader(std::string deviceName);
+    ~BatteryReader();
+
+    BatteryReader(const BatteryReader &)            = delete;
+    BatteryReader &operator=(const BatteryReader &) = delete;
+
+    BatteryStatus read();
+
+  private:
+    /// A resolved HID++ endpoint: which hidraw node, which device slot on it,
+    /// and the feature index the battery lives behind.
+    struct Endpoint {
+        int fd              = -1;
+        uint8_t deviceIndex = 0;
+        uint8_t featureIdx  = 0;
+        uint16_t featureId  = 0; // kFeatureUnifiedBattery or kFeatureBatteryStatus
+    };
+
+    std::string deviceName;
+    Endpoint endpoint{};
+
+    std::optional<BatteryStatus> readFromSysfs() const;
+    std::optional<BatteryStatus> readFromHidpp();
+
+    /// Finds the hidraw node and device slot our device answers on. Expensive:
+    /// only called on first use and after the cached endpoint stops replying.
+    bool resolveEndpoint();
+    void closeEndpoint();
+};
+
+} // namespace hidpp