src/events/SDL_events.c

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2011 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

/* General event handling code for SDL */

#include "SDL.h"
#include "SDL_events.h"
#include "SDL_syswm.h"
#include "SDL_thread.h"
#include "SDL_events_c.h"
#include "../timer/SDL_timer_c.h"
#if !SDL_JOYSTICK_DISABLED
#include "../joystick/SDL_joystick_c.h"
#endif
#include "../video/SDL_sysvideo.h"

/* Public data -- the event filter */
SDL_EventFilter SDL_EventOK = NULL;
void *SDL_EventOKParam;

typedef struct SDL_EventWatcher {
    SDL_EventFilter callback;
    void *userdata;
    struct SDL_EventWatcher *next;
} SDL_EventWatcher;

static SDL_EventWatcher *SDL_event_watchers = NULL;

typedef struct {
    Uint32 bits[8];
} SDL_DisabledEventBlock;

static SDL_DisabledEventBlock *SDL_disabled_events[256];
static Uint32 SDL_userevents = SDL_USEREVENT;

/* Private data -- event queue */
#define MAXEVENTS	128
static struct
{
    SDL_mutex *lock;
    int active;
    int head;
    int tail;
    SDL_Event event[MAXEVENTS];
    int wmmsg_next;
    struct SDL_SysWMmsg wmmsg[MAXEVENTS];
} SDL_EventQ;


static __inline__ SDL_bool
SDL_ShouldPollJoystick()
{
#if !SDL_JOYSTICK_DISABLED
    if (SDL_numjoysticks &&
        (!SDL_disabled_events[SDL_JOYAXISMOTION >> 8] ||
         SDL_JoystickEventState(SDL_QUERY))) {
        return SDL_TRUE;
    }
#endif
    return SDL_FALSE;
}

/* Public functions */

void
SDL_StopEventLoop(void)
{
    int i;

    if (SDL_EventQ.lock) {
        SDL_DestroyMutex(SDL_EventQ.lock);
        SDL_EventQ.lock = NULL;
    }

    /* Clean out EventQ */
    SDL_EventQ.head = 0;
    SDL_EventQ.tail = 0;
    SDL_EventQ.wmmsg_next = 0;

    /* Clear disabled event state */
    for (i = 0; i < SDL_arraysize(SDL_disabled_events); ++i) {
        if (SDL_disabled_events[i]) {
            SDL_free(SDL_disabled_events[i]);
            SDL_disabled_events[i] = NULL;
        }
    }

    while (SDL_event_watchers) {
        SDL_EventWatcher *tmp = SDL_event_watchers;
        SDL_event_watchers = tmp->next;
        SDL_free(tmp);
    }
}

/* This function (and associated calls) may be called more than once */
int
SDL_StartEventLoop(void)
{
    /* Clean out the event queue */
    SDL_EventQ.lock = NULL;
    SDL_StopEventLoop();

    /* No filter to start with, process most event types */
    SDL_EventOK = NULL;
    SDL_EventState(SDL_SYSWMEVENT, SDL_DISABLE);

    /* Create the lock and set ourselves active */
#if !SDL_THREADS_DISABLED
    SDL_EventQ.lock = SDL_CreateMutex();
    if (SDL_EventQ.lock == NULL) {
        return (-1);
    }
#endif /* !SDL_THREADS_DISABLED */
    SDL_EventQ.active = 1;

    return (0);
}


/* Add an event to the event queue -- called with the queue locked */
static int
SDL_AddEvent(SDL_Event * event)
{
    int tail, added;

    tail = (SDL_EventQ.tail + 1) % MAXEVENTS;
    if (tail == SDL_EventQ.head) {
        /* Overflow, drop event */
        added = 0;
    } else {
        SDL_EventQ.event[SDL_EventQ.tail] = *event;
        if (event->type == SDL_SYSWMEVENT) {
            /* Note that it's possible to lose an event */
            int next = SDL_EventQ.wmmsg_next;
            SDL_EventQ.wmmsg[next] = *event->syswm.msg;
            SDL_EventQ.event[SDL_EventQ.tail].syswm.msg =
                &SDL_EventQ.wmmsg[next];
            SDL_EventQ.wmmsg_next = (next + 1) % MAXEVENTS;
        }
        SDL_EventQ.tail = tail;
        added = 1;
    }
    return (added);
}

/* Cut an event, and return the next valid spot, or the tail */
/*                           -- called with the queue locked */
static int
SDL_CutEvent(int spot)
{
    if (spot == SDL_EventQ.head) {
        SDL_EventQ.head = (SDL_EventQ.head + 1) % MAXEVENTS;
        return (SDL_EventQ.head);
    } else if ((spot + 1) % MAXEVENTS == SDL_EventQ.tail) {
        SDL_EventQ.tail = spot;
        return (SDL_EventQ.tail);
    } else
        /* We cut the middle -- shift everything over */
    {
        int here, next;

        /* This can probably be optimized with SDL_memcpy() -- careful! */
        if (--SDL_EventQ.tail < 0) {
            SDL_EventQ.tail = MAXEVENTS - 1;
        }
        for (here = spot; here != SDL_EventQ.tail; here = next) {
            next = (here + 1) % MAXEVENTS;
            SDL_EventQ.event[here] = SDL_EventQ.event[next];
        }
        return (spot);
    }
    /* NOTREACHED */
}

/* Lock the event queue, take a peep at it, and unlock it */
int
SDL_PeepEvents(SDL_Event * events, int numevents, SDL_eventaction action,
               Uint32 minType, Uint32 maxType)
{
    int i, used;

    /* Don't look after we've quit */
    if (!SDL_EventQ.active) {
        return (-1);
    }
    /* Lock the event queue */
    used = 0;
    if (SDL_mutexP(SDL_EventQ.lock) == 0) {
        if (action == SDL_ADDEVENT) {
            for (i = 0; i < numevents; ++i) {
                used += SDL_AddEvent(&events[i]);
            }
        } else {
            SDL_Event tmpevent;
            int spot;

            /* If 'events' is NULL, just see if they exist */
            if (events == NULL) {
                action = SDL_PEEKEVENT;
                numevents = 1;
                events = &tmpevent;
            }
            spot = SDL_EventQ.head;
            while ((used < numevents) && (spot != SDL_EventQ.tail)) {
                Uint32 type = SDL_EventQ.event[spot].type;
                if (minType <= type && type <= maxType) {
                    events[used++] = SDL_EventQ.event[spot];
                    if (action == SDL_GETEVENT) {
                        spot = SDL_CutEvent(spot);
                    } else {
                        spot = (spot + 1) % MAXEVENTS;
                    }
                } else {
                    spot = (spot + 1) % MAXEVENTS;
                }
            }
        }
        SDL_mutexV(SDL_EventQ.lock);
    } else {
        SDL_SetError("Couldn't lock event queue");
        used = -1;
    }
    return (used);
}

SDL_bool
SDL_HasEvent(Uint32 type)
{
    return (SDL_PeepEvents(NULL, 0, SDL_PEEKEVENT, type, type) > 0);
}

SDL_bool
SDL_HasEvents(Uint32 minType, Uint32 maxType)
{
    return (SDL_PeepEvents(NULL, 0, SDL_PEEKEVENT, minType, maxType) > 0);
}

void
SDL_FlushEvent(Uint32 type)
{
    SDL_FlushEvents(type, type);
}

void
SDL_FlushEvents(Uint32 minType, Uint32 maxType)
{
    /* Don't look after we've quit */
    if (!SDL_EventQ.active) {
        return;
    }

    /* Make sure the events are current */
#if 0
    /* Actually, we can't do this since we might be flushing while processing
       a resize event, and calling this might trigger further resize events.
    */
    SDL_PumpEvents();
#endif

    /* Lock the event queue */
    if (SDL_mutexP(SDL_EventQ.lock) == 0) {
        int spot = SDL_EventQ.head;
        while (spot != SDL_EventQ.tail) {
            Uint32 type = SDL_EventQ.event[spot].type;
            if (minType <= type && type <= maxType) {
                spot = SDL_CutEvent(spot);
            } else {
                spot = (spot + 1) % MAXEVENTS;
            }
        }
        SDL_mutexV(SDL_EventQ.lock);
    }
}

/* Run the system dependent event loops */
void
SDL_PumpEvents(void)
{
    SDL_VideoDevice *_this = SDL_GetVideoDevice();

    /* Get events from the video subsystem */
    if (_this) {
        _this->PumpEvents(_this);
    }
#if !SDL_JOYSTICK_DISABLED
    /* Check for joystick state change */
    if (SDL_ShouldPollJoystick()) {
        SDL_JoystickUpdate();
    }
#endif
}

/* Public functions */

int
SDL_PollEvent(SDL_Event * event)
{
    return SDL_WaitEventTimeout(event, 0);
}

int
SDL_WaitEvent(SDL_Event * event)
{
    return SDL_WaitEventTimeout(event, -1);
}

int
SDL_WaitEventTimeout(SDL_Event * event, int timeout)
{
    Uint32 expiration = 0;

    if (timeout > 0)
        expiration = SDL_GetTicks() + timeout;

    for (;;) {
        SDL_PumpEvents();
        switch (SDL_PeepEvents(event, 1, SDL_GETEVENT, SDL_FIRSTEVENT, SDL_LASTEVENT)) {
        case -1:
            return 0;
        case 1:
            return 1;
        case 0:
            if (timeout == 0) {
                /* Polling and no events, just return */
                return 0;
            }
            if (timeout > 0 && ((int) (SDL_GetTicks() - expiration) >= 0)) {
                /* Timeout expired and no events */
                return 0;
            }
            SDL_Delay(10);
            break;
        }
    }
}

int
SDL_PushEvent(SDL_Event * event)
{
    SDL_EventWatcher *curr;

    if (SDL_EventOK && !SDL_EventOK(SDL_EventOKParam, event)) {
        return 0;
    }

    for (curr = SDL_event_watchers; curr; curr = curr->next) {
        curr->callback(curr->userdata, event);
    }

    if (SDL_PeepEvents(event, 1, SDL_ADDEVENT, 0, 0) <= 0) {
        return -1;
    }

    SDL_GestureProcessEvent(event);
    

    return 1;
}

void
SDL_SetEventFilter(SDL_EventFilter filter, void *userdata)
{
    SDL_Event bitbucket;

    /* Set filter and discard pending events */
    SDL_EventOK = filter;
    SDL_EventOKParam = userdata;
    while (SDL_PollEvent(&bitbucket) > 0);
}

SDL_bool
SDL_GetEventFilter(SDL_EventFilter * filter, void **userdata)
{
    if (filter) {
        *filter = SDL_EventOK;
    }
    if (userdata) {
        *userdata = SDL_EventOKParam;
    }
    return SDL_EventOK ? SDL_TRUE : SDL_FALSE;
}

/* FIXME: This is not thread-safe yet */
void
SDL_AddEventWatch(SDL_EventFilter filter, void *userdata)
{
    SDL_EventWatcher *watcher;

    watcher = (SDL_EventWatcher *)SDL_malloc(sizeof(*watcher));
    if (!watcher) {
        /* Uh oh... */
        return;
    }
    watcher->callback = filter;
    watcher->userdata = userdata;
    watcher->next = SDL_event_watchers;
    SDL_event_watchers = watcher;
}

/* FIXME: This is not thread-safe yet */
void
SDL_DelEventWatch(SDL_EventFilter filter, void *userdata)
{
    SDL_EventWatcher *prev = NULL;
    SDL_EventWatcher *curr;

    for (curr = SDL_event_watchers; curr; prev = curr, curr = curr->next) {
        if (curr->callback == filter && curr->userdata == userdata) {
            if (prev) {
                prev->next = curr->next;
            } else {
                SDL_event_watchers = curr->next;
            }
            SDL_free(curr);
            break;
        }
    }
}

void
SDL_FilterEvents(SDL_EventFilter filter, void *userdata)
{
    if (SDL_mutexP(SDL_EventQ.lock) == 0) {
        int spot;

        spot = SDL_EventQ.head;
        while (spot != SDL_EventQ.tail) {
            if (filter(userdata, &SDL_EventQ.event[spot])) {
                spot = (spot + 1) % MAXEVENTS;
            } else {
                spot = SDL_CutEvent(spot);
            }
        }
    }
    SDL_mutexV(SDL_EventQ.lock);
}

Uint8
SDL_EventState(Uint32 type, int state)
{
    Uint8 current_state;
    Uint8 hi = ((type >> 8) & 0xff);
    Uint8 lo = (type & 0xff);

    if (SDL_disabled_events[hi] &&
        (SDL_disabled_events[hi]->bits[lo/32] & (1 << (lo&31)))) {
        current_state = SDL_DISABLE;
    } else {
        current_state = SDL_ENABLE;
    }

    if (state != current_state)
    {
        switch (state) {
        case SDL_DISABLE:
            /* Disable this event type and discard pending events */
            if (!SDL_disabled_events[hi]) {
                SDL_disabled_events[hi] = (SDL_DisabledEventBlock*) SDL_calloc(1, sizeof(SDL_DisabledEventBlock));
                if (!SDL_disabled_events[hi]) {
                    /* Out of memory, nothing we can do... */
                    break;
                }
            }
            SDL_disabled_events[hi]->bits[lo/32] |= (1 << (lo&31));
            SDL_FlushEvent(type);
            break;
        case SDL_ENABLE:
            SDL_disabled_events[hi]->bits[lo/32] &= ~(1 << (lo&31));
            break;
        default:
            /* Querying state... */
            break;
        }
    }

    return current_state;
}

Uint32
SDL_RegisterEvents(int numevents)
{
    Uint32 event_base;

    if (SDL_userevents+numevents <= SDL_LASTEVENT) {
        event_base = SDL_userevents;
        SDL_userevents += numevents;
    } else {
        event_base = (Uint32)-1;
    }
    return event_base;
}

/* This is a generic event handler.
 */
int
SDL_SendSysWMEvent(SDL_SysWMmsg * message)
{
    int posted;

    posted = 0;
    if (SDL_GetEventState(SDL_SYSWMEVENT) == SDL_ENABLE) {
        SDL_Event event;
        SDL_memset(&event, 0, sizeof(event));
        event.type = SDL_SYSWMEVENT;
        event.syswm.msg = message;
        posted = (SDL_PushEvent(&event) > 0);
    }
    /* Update internal event state */
    return (posted);
}

/* vi: set ts=4 sw=4 expandtab: */