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// Copyright 2015 Google Inc. All Rights Reserved.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
// Module Overview: Starboard Event module
// Defines the event system that wraps the Starboard main loop and entry point.
// ## The Starboard Application life cycle
// | ---------- *
// | | |
// | | 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.
#include "starboard/configuration.h"
#include "starboard/export.h"
#include "starboard/time.h"
#include "starboard/types.h"
#include "starboard/window.h"
#ifdef __cplusplus
extern "C" {
// 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.
typedef enum SbEventType {
// 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.
#endif // SB_API_VERSION >= 6
// 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|.
// 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.
// 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.
// 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.
// 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.
// 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.
// A user input event, including keyboard, mouse, gesture, or something else.
// SbInputData (from input.h) is passed as the data argument.
// 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.
// 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.
// 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.
// The platform has detected a network disconnection. The platform should make
// a best effort to send an event of this type when the network disconnects,
// but there are likely to be cases where the platform cannot detect the
// disconnection (e.g. if the connection is via a powered hub which becomes
// disconnected), so the current network state cannot always be inferred from
// the sequence of Connect/Disconnect events.
// The platform has detected a network connection. This event may be sent at
// application start-up, and should always be sent if the network reconnects
// since a disconnection event was sent.
// 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.
// The platform's accessibility settings have changed. The application should
// query the accessibility settings using the appropriate APIs to get the
// new settings.
// 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.
#endif // SB_API_VERSION >= 6
// The size or position of a SbWindow has changed. The data is
// SbEventWindowSizeChangedData.
} SbEventType;
// Structure representing a Starboard event and its data.
typedef struct SbEvent {
SbEventType type;
void* data;
} SbEvent;
// A function that can be called back from the main Starboard event pump.
typedef void (*SbEventCallback)(void* context);
// A function that will cleanly destroy an event data instance of a specific
// type.
typedef void (*SbEventDataDestructor)(void* data);
// An ID that can be used to refer to a scheduled event.
typedef uint32_t SbEventId;
// Event data for kSbEventTypeStart events.
typedef struct SbEventStartData {
// The command-line argument values (argv).
char** argument_values;
// The command-line argument count (argc).
int argument_count;
// The startup link, if any.
const char* link;
} SbEventStartData;
// Event data for kSbEventTypeWindowSizeChanged events.
typedef struct SbEventWindowSizeChangedData {
SbWindow window;
SbWindowSize size;
} SbEventWindowSizeChangedData;
#define kSbEventIdInvalid (SbEventId)0
// Returns whether the given event handle is valid.
static SB_C_FORCE_INLINE bool SbEventIsIdValid(SbEventId handle) {
return handle != kSbEventIdInvalid;
// 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.
SB_IMPORT void SbEventHandle(const SbEvent* event);
// 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.
SB_EXPORT SbEventId SbEventSchedule(SbEventCallback callback,
void* context,
SbTime delay);
// 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.
SB_EXPORT void SbEventCancel(SbEventId event_id);
#ifdef __cplusplus
} // extern "C"