Added: 7 ## **PROTOCOLS** ## DeviceListenerRegistry *Defined in [fuchsia.ui.policy/device_listener.fidl](https://cs.opensource.google/fuchsia/fuchsia/+/main:sdk/fidl/fuchsia.ui.policy/device_listener.fidl;l=10)* Service for exposing state and events of devices, such as media buttons.
### RegisterListener Registers a listener to receive media button related events, such as changes from volume buttons and mute switches. On registration, the `listener` receives the last media button event that occurred, if one exists, and all media button events going forward. #### Request | Name | Type | |---|---| | `listener` | `client_end:https://fuchsia.dev/reference/fidl/fuchsia.ui.policy#MediaButtonsListener` | #### Response \ ### RegisterMediaButtonsListener Registers a listener to receive media button related events, such as changes from volume buttons and mute switches. **DEPRECATED**- Use RegisterListener() #### Request | Name | Type | |---|---| | `listener` | `client_end:https://fuchsia.dev/reference/fidl/fuchsia.ui.policy#MediaButtonsListener` | ### RegisterTouchButtonsListener Registers a listener to receive touch button related events. On registration, the `listener` receives the last touch button event that occurred, if one exists, and all touch button events going forward. Added: 28 #### Request | Name | Type | |---|---| | `listener` | `client_end:https://fuchsia.dev/reference/fidl/fuchsia.ui.policy#TouchButtonsListener` | #### Response \ ## DisplayBacklight *Defined in [fuchsia.ui.policy/display_backlight.fidl](https://cs.opensource.google/fuchsia/fuchsia/+/main:sdk/fidl/fuchsia.ui.policy/display_backlight.fidl;l=21)* Manipulates global policy for display backlight. Serves as the main "front end" interface for usage by UX components; other protocols (such as fuchsia.ui.scenic.Session and fuchsia.hardware.display.Controller) act as implementation. Global Scope. All displays, in all display controllers, are affected uniformly. Effect Timing. This protocol does not guarantee a deadline by which the minimum value is applied to a display; it is best effort. Multiple clients. This protocol does not guarantee unique access to manipulate display backlight functionality. Reference. Related to fuchsia.hardware.display.Controller.
### SetMinimumRgb Submits a new minimum color channel value for display backlight. The valid range for a minimum value is \[0, 255\] (inclusive). For a new minimum value M, each color channel's range will be limited to \[M, 255\]. Flow control: The caller is allowed at most one in-flight \|SetMinimumRgb\| at at time. Subsequent calls must wait until the acknowledgment returns. Non-compliance results in channel closure. #### Request | Name | Type | |---|---| | `minimum_rgb` | `uint8` | #### Response \ ## MediaButtonsListener *Defined in [fuchsia.ui.policy/device_listener.fidl](https://cs.opensource.google/fuchsia/fuchsia/+/main:sdk/fidl/fuchsia.ui.policy/device_listener.fidl;l=54)* Added: HEAD
### OnEvent #### Request | Name | Type | |---|---| | `event` | `https://fuchsia.dev/reference/fuchsia.ui.input//https://fuchsia.dev/reference/fuchsia.ui.input#MediaButtonsEvent` | #### Response \ ### OnMediaButtonsEvent **DEPRECATED**- Use OnEvent() #### Request | Name | Type | |---|---| | `event` | `https://fuchsia.dev/reference/fuchsia.ui.input//https://fuchsia.dev/reference/fuchsia.ui.input#MediaButtonsEvent` | ## TouchButtonsListener *Defined in [fuchsia.ui.policy/device_listener.fidl](https://cs.opensource.google/fuchsia/fuchsia/+/main:sdk/fidl/fuchsia.ui.policy/device_listener.fidl;l=78)* Added: HEAD
### OnEvent #### Request | Name | Type | |---|---| | `event` | `https://fuchsia.dev/reference/fuchsia.ui.input//https://fuchsia.dev/reference/fuchsia.ui.input#TouchButtonsEvent` | #### Response \