Shared Library Changes for Release 2.1.0

Shared library libddcutil is backwardly compatible with the one in ddcutil 2.0.0. The SONAME is unchanged as The released library file is

Library Initialization

Changed Comments
enum DDCA_Init_Options   added value DDCA_INIT_OPTIONS_ENABLE_INIT_MSGS

New Functions  Comments
ddca_init2  Replaces ddca_init

API function ddca_init2() replaces ddca_init(). It has an an additiona parameter, infomsg_loc, for collecting informational msgs

This change givea the client control over what is done with informational messages issued by libddcutil at startup. Previously, such messages were always written to the terminal. Flag DDCA_INIT_OPTIONS_ENABLE_INIT_MSGS controls whether such messages are emitted.

With this change, DDCA_INIT_OPTIONS_ENABLE_INIT_MSGS still controls whether libddcutil writes messages to the terminal. If infomsg_loc is non-null, it specifies the addess at which to return a null-terminated array of messages.

Thus, to give the client complete control over what to do with the messages, do not set DDCA_INIT_OPTIONS_ENABLE_INIT_MSGS, so the server does not write informational msgs, and use infomsg_loc to return the informational msgs for display by the client.

For API functions that require libddcutil initialization, if ddca_init2() has not already been called, the function prolog automatically calls ddca_init2() with options such that it can never fail. If an explicit call to ddca_init2() has failed, then any subsequent call to a function requiring initialization fails with status DDCRC_UNINITIALIZED

Changed Functions Comments
ddca_init  Deprecated. Use ddca_init2()


  • segfault on freeing Parsed_Edid when command parsing failed

Sleep multiplier control

New typedefs  Comments
DDCS_Sleep_Multiplier  standardizes the type for sleep-multiplier values

Deprecated Functions Comments

New Functions Comments

New Status Codes Comments

Display Hotplug Detection

libddcutil watches for display connection and disconnection, and for changes to DPMS state, and reports them to the client using callback functions.

Events can be connection or disconnection of a display, or change in DPMS sleep state. The effect of turning a monitor on or off is monitor dependant and cannot reliably be detected. It is therefore not an event that is reported.

Callback functions must be of type DDCA_Display_Status_Callback_Func. The function delives a DDCA_Display_Status_Event to the client. The type of event being reported is specified by enum DDCA_Event_Type.

New typedefs Comments

New enums Comments
DDCA_Display_Event_Type  type of display status event

New structs Comments
DDCA_Display_Status_Event  delived by callback function

New Functions Comments

Key points: - When a event of type DDCA_EVENT_DISPLAY_DISCONNECTED is reported, the DDCA_Display_Reference specified in struct DDCA_Display_Status_Event is no longer valid. - When an event of type DDCA_EVENT_DISPLAY_CONNECTED occurs, the client must call ddca_redetect_displays() to reinitialize libddcutil and the call ddca_get_display_refs() to get a new set of valid display references. - Requires DRM video drivers (e.g. amdgpu, i915) - A future release may provide a new valid display reference when a monitor is connected, making che call to ddca_redetect_displays() unnecessary.

- new status codes possible for many current API functions: 
  • ddca_dref_state(): reports whether monitor asleep, disconnected, etc.
  • Sleep multiplier control:

Can report display connection/disconnection and dpms sleep status


Changed   Comments
struct DDCA_Feature_Metadata  rename latest_sl_values -> unused