fn install_system_changed_callback()

in src/backend/mod.rs [4413:4479]

• 56 lines of code
• 7 McCabe index (conditional complexity)

    fn install_system_changed_callback(&mut self) -> Result<()> {
        self.debug_assert_is_on_stream_queue();
        assert!(!self.stm_ptr.is_null());
        let stm = unsafe { &(*self.stm_ptr) };

        if !self.output_unit.is_null()
            && self
                .output_device
                .flags
                .contains(device_flags::DEV_SELECTED_DEFAULT)
        {
            assert!(
                self.default_output_listener.is_none(),
                "register default_output_listener without unregistering the one in use"
            );

            // Get the notification when the default output audio changes, e.g.,
            // when the user plugs in a USB headset and the system chooses it automatically as the default,
            // or when another device is chosen in the dropdown list.
            self.default_output_listener = Some(device_property_listener::new(
                kAudioObjectSystemObject,
                get_property_address(
                    Property::HardwareDefaultOutputDevice,
                    DeviceType::INPUT | DeviceType::OUTPUT,
                ),
                audiounit_property_listener_callback,
            ));
            let r = stm.add_device_listener(self.default_output_listener.as_ref().unwrap());
            if r != NO_ERR {
                self.default_output_listener = None;
                cubeb_log!("AudioObjectAddPropertyListener/output/kAudioHardwarePropertyDefaultOutputDevice rv={}", r);
                return Err(Error::error());
            }
        }

        if !self.input_unit.is_null()
            && self
                .input_device
                .flags
                .contains(device_flags::DEV_SELECTED_DEFAULT)
        {
            assert!(
                self.default_input_listener.is_none(),
                "register default_input_listener without unregistering the one in use"
            );

            // Get the notification when the default intput audio changes, e.g.,
            // when the user plugs in a USB mic and the system chooses it automatically as the default,
            // or when another device is chosen in the system preference.
            self.default_input_listener = Some(device_property_listener::new(
                kAudioObjectSystemObject,
                get_property_address(
                    Property::HardwareDefaultInputDevice,
                    DeviceType::INPUT | DeviceType::OUTPUT,
                ),
                audiounit_property_listener_callback,
            ));
            let r = stm.add_device_listener(self.default_input_listener.as_ref().unwrap());
            if r != NO_ERR {
                self.default_input_listener = None;
                cubeb_log!("AudioObjectAddPropertyListener/input/kAudioHardwarePropertyDefaultInputDevice rv={}", r);
                return Err(Error::error());
            }
        }

        Ok(())
    }