Starboard Module Reference: event.h

Defines the event system that wraps the Starboard main loop and entry point.

The Starboard Application Lifecycle

    ---------- *
   |           |
   |        Preload
   |           |
   |           V
 Start   [ PRELOADING ] ------------
   |           |                    |
   |         Start                  |
   |           |                    |
   |           V                    |
    ----> [ STARTED ] <----         |
               |           |        |
             Pause       Unpause    |
               |           |     Suspend
               V           |        |
    -----> [ PAUSED ] -----         |
   |           |                    |
Resume      Suspend                 |
   |           |                    |
   |           V                    |
    ---- [ SUSPENDED ] <------------
               |
              Stop
               |
               V
          [ STOPPED ]

The first event that a Starboard application receives is either Start (kSbEventTypeStart) or Preload (kSbEventTypePreload). Start puts the application in the STARTED state, whereas Preload puts the application in the PRELOADING state.

PRELOADING can only happen as the first application state. In this state, the application should start and run as normal, but will not receive any input, and should not try to initialize graphics resources (via GL or SbBlitter). In PRELOADING, the application can receive Start or Suspend events. Start will receive the same data that was passed into Preload.

In the STARTED state, the application is in the foreground and can expect to do all of the normal things it might want to do. Once in the STARTED state, it may receive a Pause event, putting the application into the PAUSED state.

In the PAUSED state, the application is still visible, but has lost focus, or it is partially obscured by a modal dialog, or it is on its way to being shut down. The application should pause activity in this state. In this state, it can receive Unpause to be brought back to the foreground state (STARTED), or Suspend to be pushed further in the background to the SUSPENDED state.

In the SUSPENDED state, the application is generally not visible. It should immediately release all graphics and video resources, and shut down all background activity (timers, rendering, etc). Additionally, the application should flush storage to ensure that if the application is killed, the storage will be up-to-date. The application may be killed at this point, but will ideally receive a Stop event for a more graceful shutdown.

Note that the application is always expected to transition through PAUSED to SUSPENDED before receiving Stop or being killed.

Enums

SbEventType

An enumeration of all possible event types dispatched directly by the system. Each event is accompanied by a void* data argument, and each event must define the type of the value pointed to by that data argument, if any.

Values

  • kSbEventTypePreload

    Applications should perform initialization and prepare to react to subsequent events, but must not initialize any graphics resources (through GL or SbBlitter). The intent of this event is to allow the application to do as much work as possible ahead of time, so that when the application is first brought to the foreground, it's as fast as a resume.

    The kSbEventTypeStart event may be sent at any time, regardless of initialization state. Input events will not be sent in the PRELOADING state. This event will only be sent once for a given process launch. SbEventStartData is passed as the data argument.

    The system may send kSbEventTypeSuspend in PRELOADING if it wants to push the app into a lower resource consumption state. Applications can alo call SbSystemRequestSuspend() when they are done preloading to request this.

  • kSbEventTypeStart

    The first event that an application receives on startup when starting normally (i.e. not being preloaded). Applications should perform initialization, start running, and prepare to react to subsequent events. Applications that wish to run and then exit must call SbSystemRequestStop() to terminate. This event will only be sent once for a given process launch. SbEventStartData is passed as the data argument. In case of preload, the SbEventStartData will be the same as what was passed to kSbEventTypePreload.

  • kSbEventTypePause

    A dialog will be raised or the application will otherwise be put into a background-but-visible or partially-obscured state (PAUSED). Graphics and video resources will still be available, but the application should pause foreground activity like animations and video playback. Can only be received after a Start event. The only events that should be dispatched after a Pause event are Unpause or Suspend. No data argument.

  • kSbEventTypeUnpause

    The application is returning to the foreground (STARTED) after having been put in the PAUSED (e.g. partially-obscured) state. The application should unpause foreground activity like animations and video playback. Can only be received after a Pause or Resume event. No data argument.

  • kSbEventTypeSuspend

    The operating system will put the application into a Suspended state after this event is handled. The application is expected to stop periodic background work, release ALL graphics and video resources, and flush any pending SbStorage writes. Some platforms will terminate the application if work is done or resources are retained after suspension. Can only be received after a Pause event. The only events that should be dispatched after a Suspend event are Resume or Stop. On some platforms, the process may also be killed after Suspend without a Stop event. No data argument.

  • kSbEventTypeResume

    The operating system has restored the application to the PAUSED state from the SUSPENDED state. This is the first event the application will receive coming out of SUSPENDED, and it will only be received after a Suspend event. The application will now be in the PAUSED state. No data argument.

  • kSbEventTypeStop

    The operating system will shut the application down entirely after this event is handled. Can only be recieved after a Suspend event, in the SUSPENDED state. No data argument.

  • kSbEventTypeInput

    A user input event, including keyboard, mouse, gesture, or something else. SbInputData (from input.h) is passed as the data argument.

  • kSbEventTypeUser

    A user change event, which means a new user signed-in or signed-out, or the current user changed. No data argument, call SbUserGetSignedIn() and SbUserGetCurrent() to get the latest changes.

  • kSbEventTypeLink

    A navigational link has come from the system, and the application should consider handling it by navigating to the corresponding application location. The data argument is an application-specific, null-terminated string.

  • kSbEventTypeVerticalSync

    The beginning of a vertical sync has been detected. This event is very timing-sensitive, so as little work as possible should be done on the main thread if the application wants to receive this event in a timely manner. No data argument.

  • kSbEventTypeScheduled

    An event type reserved for scheduled callbacks. It will only be sent in response to an application call to SbEventSchedule(), and it will call the callback directly, so SbEventHandle should never receive this event directly. The data type is an internally-defined structure.

  • kSbEventTypeAccessiblitySettingsChanged

    The platform's accessibility settings have changed. The application should query the accessibility settings using the appropriate APIs to get the new settings. Note this excludes captions settings changes, which causes kSbEventTypeAccessibilityCaptionSettingsChanged to fire.

  • kSbEventTypeLowMemory

    An optional event that platforms may send to indicate that the application may soon be terminated (or crash) due to low memory availability. The application may respond by reducing memory consumption by running a Garbage Collection, flushing caches, or something similar. There is no requirement to respond to or handle this event, it is only advisory.

  • kSbEventTypeWindowSizeChanged

    The size or position of a SbWindow has changed. The data is SbEventWindowSizeChangedData .

  • kSbEventTypeOnScreenKeyboardShown

    The platform has shown the on screen keyboard. This event is triggered by the system or by the application's OnScreenKeyboard show method. The event has int data representing a ticket. The ticket is used by the application to mark individual calls to the show method as successfully completed. Events triggered by the application have tickets passed in via SbWindowShowOnScreenKeyboard. System-triggered events have ticket value kSbEventOnScreenKeyboardInvalidTicket.

  • kSbEventTypeOnScreenKeyboardHidden

    The platform has hidden the on screen keyboard. This event is triggered by the system or by the application's OnScreenKeyboard hide method. The event has int data representing a ticket. The ticket is used by the application to mark individual calls to the hide method as successfully completed. Events triggered by the application have tickets passed in via SbWindowHideOnScreenKeyboard. System-triggered events have ticket value kSbEventOnScreenKeyboardInvalidTicket.

  • kSbEventTypeOnScreenKeyboardFocused

    The platform has focused the on screen keyboard. This event is triggered by the system or by the application's OnScreenKeyboard focus method. The event has int data representing a ticket. The ticket is used by the application to mark individual calls to the focus method as successfully completed. Events triggered by the application have tickets passed in via SbWindowFocusOnScreenKeyboard. System-triggered events have ticket value kSbEventOnScreenKeyboardInvalidTicket.

  • kSbEventTypeOnScreenKeyboardBlurred

    The platform has blurred the on screen keyboard. This event is triggered by the system or by the application's OnScreenKeyboard blur method. The event has int data representing a ticket. The ticket is used by the application to mark individual calls to the blur method as successfully completed. Events triggered by the application have tickets passed in via SbWindowBlurOnScreenKeyboard. System-triggered events have ticket value kSbEventOnScreenKeyboardInvalidTicket.

  • kSbEventTypeOnScreenKeyboardSuggestionsUpdated

    The platform has updated the on screen keyboard suggestions. This event is triggered by the system or by the application's OnScreenKeyboard update suggestions method. The event has int data representing a ticket. The ticket is used by the application to mark individual calls to the update suggestions method as successfully completed. Events triggered by the application have tickets passed in via SbWindowUpdateOnScreenKeyboardSuggestions. System-triggered events have ticket value kSbEventOnScreenKeyboardInvalidTicket.

  • kSbEventTypeAccessibilityCaptionSettingsChanged

    One or more of the fields returned by SbAccessibilityGetCaptionSettings has changed.

Typedefs

SbEventCallback

A function that can be called back from the main Starboard event pump.

Definition

typedef void(* SbEventCallback) (void *context)

SbEventDataDestructor

A function that will cleanly destroy an event data instance of a specific type.

Definition

typedef void(* SbEventDataDestructor) (void *data)

SbEventId

An ID that can be used to refer to a scheduled event.

Definition

typedef uint32_t SbEventId

Structs

SbEvent

Structure representing a Starboard event and its data.

Members

  • SbEventType type
  • void * data

SbEventStartData

Event data for kSbEventTypeStart events.

Members

  • char ** argument_values

    The command-line argument values (argv).

  • int argument_count

    The command-line argument count (argc).

  • const char * link

    The startup link, if any.

SbEventWindowSizeChangedData

Event data for kSbEventTypeWindowSizeChanged events.

Members

  • SbWindow window
  • SbWindowSize size

Functions

SbEventCancel

Cancels the specified event_id. Note that this function is a no-op if the event already fired. This function can be safely called from any thread, but the only way to guarantee that the event does not run anyway is to call it from the main Starboard event loop thread.

Declaration

void SbEventCancel(SbEventId event_id)

SbEventHandle

The entry point that Starboard applications MUST implement. Any memory pointed at by event or the data field inside event is owned by the system, and that memory is reclaimed after this function returns, so the implementation must copy this data to extend its life. This behavior should also be assumed of all fields within the data object, unless otherwise explicitly specified.

This function is only called from the main Starboard thread. There is no specification about what other work might happen on this thread, so the application should generally do as little work as possible on this thread, and just dispatch it over to another thread.

Declaration

SB_IMPORT void SbEventHandle(const SbEvent *event)

SbEventIsIdValid

Returns whether the given event handle is valid.

Declaration

static bool SbEventIsIdValid(SbEventId handle)

SbEventSchedule

Schedules an event callback into the main Starboard event loop. This function may be called from any thread, but callback is always called from the main Starboard thread, queued with other pending events.

callback: The callback function to be called. context: The context that is passed to the callback function. delay: The minimum number of microseconds to wait before calling the callback function. Set delay to 0 to call the callback as soon as possible.

Declaration

SbEventId SbEventSchedule(SbEventCallback callback, void *context, SbTime delay)