SDL2/src/core/linux/SDL_fcitx.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "../../SDL_internal.h"

#include <unistd.h>

#include "SDL_fcitx.h"
#include "../../events/SDL_keyboard_c.h"
#include "SDL_dbus.h"

#ifdef SDL_VIDEO_DRIVER_X11
#include "../../video/x11/SDL_x11video.h"
#define SDL_ENABLE_SYSWM_X11
#endif
#include <SDL3/SDL_syswm.h>


#define FCITX_DBUS_SERVICE "org.freedesktop.portal.Fcitx"

#define FCITX_IM_DBUS_PATH "/org/freedesktop/portal/inputmethod"

#define FCITX_IM_DBUS_INTERFACE "org.fcitx.Fcitx.InputMethod1"
#define FCITX_IC_DBUS_INTERFACE "org.fcitx.Fcitx.InputContext1"

#define DBUS_TIMEOUT 500

typedef struct _FcitxClient
{
    SDL_DBusContext *dbus;

    char *ic_path;

    int id;

    SDL_Rect cursor_rect;
} FcitxClient;

static FcitxClient fcitx_client;

static char*
GetAppName()
{
#if defined(__LINUX__) || defined(__FREEBSD__)
    char *spot;
    char procfile[1024];
    char linkfile[1024];
    int linksize;

#if defined(__LINUX__)
    SDL_snprintf(procfile, sizeof(procfile), "/proc/%d/exe", getpid());
#elif defined(__FREEBSD__)
    SDL_snprintf(procfile, sizeof(procfile), "/proc/%d/file", getpid());
#endif
    linksize = readlink(procfile, linkfile, sizeof(linkfile) - 1);
    if (linksize > 0) {
        linkfile[linksize] = '\0';
        spot = SDL_strrchr(linkfile, '/');
        if (spot) {
            return SDL_strdup(spot + 1);
        } else {
            return SDL_strdup(linkfile);
        }
    }
#endif /* __LINUX__ || __FREEBSD__ */

    return SDL_strdup("SDL_App");
}

static size_t
Fcitx_GetPreeditString(SDL_DBusContext *dbus,
        DBusMessage *msg,
        char **ret,
        Sint32 *start_pos,
        Sint32 *end_pos)
{
    char *text = NULL, *subtext;
    size_t text_bytes = 0;
    DBusMessageIter iter, array, sub;
    Sint32 p_start_pos = -1;
    Sint32 p_end_pos = -1;

    dbus->message_iter_init(msg, &iter);
    /* Message type is a(si)i, we only need string part */
    if (dbus->message_iter_get_arg_type(&iter) == DBUS_TYPE_ARRAY) {
        size_t pos = 0;
        /* First pass: calculate string length */
        dbus->message_iter_recurse(&iter, &array);
        while (dbus->message_iter_get_arg_type(&array) == DBUS_TYPE_STRUCT) {
            dbus->message_iter_recurse(&array, &sub);
            subtext = NULL;
            if (dbus->message_iter_get_arg_type(&sub) == DBUS_TYPE_STRING) {
                dbus->message_iter_get_basic(&sub, &subtext);
                if (subtext && *subtext) {
                    text_bytes += SDL_strlen(subtext);
                }
            }
            dbus->message_iter_next(&sub);
            if (dbus->message_iter_get_arg_type(&sub) == DBUS_TYPE_INT32 && p_end_pos == -1) {
                /* Type is a bit field defined as follows:                */
                /* bit 3: Underline, bit 4: HighLight, bit 5: DontCommit, */
                /* bit 6: Bold,      bit 7: Strike,    bit 8: Italic      */
                Sint32 type;
                dbus->message_iter_get_basic(&sub, &type);
                /* We only consider highlight */
                if (type & (1 << 4)) {
                    if (p_start_pos == -1) {
                        p_start_pos = pos;
                    }
                } else if (p_start_pos != -1 && p_end_pos == -1) {
                    p_end_pos = pos;
                }
            }
            dbus->message_iter_next(&array);
            if (subtext && *subtext) {
                pos += SDL_utf8strlen(subtext);
            }
        }
        if (p_start_pos != -1 && p_end_pos == -1) {
            p_end_pos = pos;
        }
        if (text_bytes) {
            text = SDL_malloc(text_bytes + 1);
        }

        if (text) {
            char* pivot = text;
            /* Second pass: join all the sub string */
            dbus->message_iter_recurse(&iter, &array);
            while (dbus->message_iter_get_arg_type(&array) == DBUS_TYPE_STRUCT) {
                dbus->message_iter_recurse(&array, &sub);
                if (dbus->message_iter_get_arg_type(&sub) == DBUS_TYPE_STRING) {
                    dbus->message_iter_get_basic(&sub, &subtext);
                    if (subtext && *subtext) {
                        size_t length = SDL_strlen(subtext);
                        SDL_strlcpy(pivot, subtext, length + 1);
                        pivot += length;
                    }
                }
                dbus->message_iter_next(&array);
            }
        } else {
            text_bytes = 0;
        }
    }

    *ret = text;
    *start_pos = p_start_pos;
    *end_pos = p_end_pos;
    return text_bytes;
}

static Sint32
Fcitx_GetPreeditCursorByte(SDL_DBusContext *dbus, DBusMessage *msg)
{
    Sint32 byte = -1;
    DBusMessageIter iter;

    dbus->message_iter_init(msg, &iter);

    dbus->message_iter_next(&iter);

    if (dbus->message_iter_get_arg_type(&iter) != DBUS_TYPE_INT32) {
        return -1;
    }

    dbus->message_iter_get_basic(&iter, &byte);

    return byte;
}

static DBusHandlerResult
DBus_MessageFilter(DBusConnection *conn, DBusMessage *msg, void *data)
{
    SDL_DBusContext *dbus = (SDL_DBusContext *)data;

    if (dbus->message_is_signal(msg, FCITX_IC_DBUS_INTERFACE, "CommitString")) {
        DBusMessageIter iter;
        const char *text = NULL;

        dbus->message_iter_init(msg, &iter);
        dbus->message_iter_get_basic(&iter, &text);

        if (text && *text) {
            char buf[SDL_TEXTINPUTEVENT_TEXT_SIZE];
            size_t text_bytes = SDL_strlen(text), i = 0;

            while (i < text_bytes) {
                size_t sz = SDL_utf8strlcpy(buf, text+i, sizeof(buf));
                SDL_SendKeyboardText(buf);

                i += sz;
            }
        }

        return DBUS_HANDLER_RESULT_HANDLED;
    }

    if (dbus->message_is_signal(msg, FCITX_IC_DBUS_INTERFACE, "UpdateFormattedPreedit")) {
        char *text = NULL;
        Sint32 start_pos, end_pos;
        size_t text_bytes = Fcitx_GetPreeditString(dbus, msg, &text, &start_pos, &end_pos);
        if (text_bytes) {
            if (SDL_GetHintBoolean(SDL_HINT_IME_SUPPORT_EXTENDED_TEXT, SDL_FALSE)) {
                if (start_pos == -1) {
                    Sint32 byte_pos = Fcitx_GetPreeditCursorByte(dbus, msg);
                    start_pos = byte_pos >= 0 ? SDL_utf8strnlen(text, byte_pos) : -1;
                }
                SDL_SendEditingText(text, start_pos, end_pos >= 0 ? end_pos - start_pos : -1);
            } else {
                char buf[SDL_TEXTEDITINGEVENT_TEXT_SIZE];
                size_t i = 0;
                size_t cursor = 0;
                while (i < text_bytes) {
                    const size_t sz = SDL_utf8strlcpy(buf, text + i, sizeof(buf));
                    const size_t chars = SDL_utf8strlen(buf);

                    SDL_SendEditingText(buf, cursor, chars);

                    i += sz;
                    cursor += chars;
                }
            }
            SDL_free(text);
        } else {
            SDL_SendEditingText("", 0, 0);
        }

        SDL_Fcitx_UpdateTextRect(NULL);
        return DBUS_HANDLER_RESULT_HANDLED;
    }

    return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
}

static void
FcitxClientICCallMethod(FcitxClient *client, const char *method)
{
    if (!client->ic_path) {
        return;
    }
    SDL_DBus_CallVoidMethod(FCITX_DBUS_SERVICE, client->ic_path, FCITX_IC_DBUS_INTERFACE, method, DBUS_TYPE_INVALID);
}

static void SDLCALL
Fcitx_SetCapabilities(void *data,
        const char *name,
        const char *old_val,
        const char *internal_editing)
{
    FcitxClient *client = (FcitxClient *)data;
    Uint64 caps = 0;
    if (!client->ic_path) {
        return;
    }

    if (!(internal_editing && *internal_editing == '1')) {
        caps |= (1 << 1); /* Preedit Flag */
        caps |= (1 << 4); /* Formatted Preedit Flag */
    }

    SDL_DBus_CallVoidMethod(FCITX_DBUS_SERVICE, client->ic_path, FCITX_IC_DBUS_INTERFACE, "SetCapability", DBUS_TYPE_UINT64, &caps, DBUS_TYPE_INVALID);
}

static SDL_bool
FcitxCreateInputContext(SDL_DBusContext* dbus, const char *appname, char **ic_path) {
    const char *program = "program";
    SDL_bool retval = SDL_FALSE;
    if (dbus->session_conn) {
        DBusMessage *msg = dbus->message_new_method_call(FCITX_DBUS_SERVICE, FCITX_IM_DBUS_PATH, FCITX_IM_DBUS_INTERFACE, "CreateInputContext");
        if (msg) {
            DBusMessage *reply = NULL;
            DBusMessageIter args, array, sub;
            dbus->message_iter_init_append(msg, &args);
            dbus->message_iter_open_container(&args, DBUS_TYPE_ARRAY, "(ss)", &array);
            dbus->message_iter_open_container(&array, DBUS_TYPE_STRUCT, 0, &sub);
            dbus->message_iter_append_basic(&sub, DBUS_TYPE_STRING, &program);
            dbus->message_iter_append_basic(&sub, DBUS_TYPE_STRING, &appname);
            dbus->message_iter_close_container(&array, &sub);
            dbus->message_iter_close_container(&args, &array);
            reply = dbus->connection_send_with_reply_and_block(dbus->session_conn, msg, 300, NULL);
            if (reply) {
                if (dbus->message_get_args(reply, NULL, DBUS_TYPE_OBJECT_PATH, ic_path, DBUS_TYPE_INVALID)) {
                    retval = SDL_TRUE;
                }
                dbus->message_unref(reply);
            }
            dbus->message_unref(msg);
        }
    }
    return retval;
}

static SDL_bool
FcitxClientCreateIC(FcitxClient *client)
{
    char *appname = GetAppName();
    char *ic_path = NULL;
    SDL_DBusContext *dbus = client->dbus;

    /* SDL_DBus_CallMethod cannot handle a(ss) type, call dbus function directly */
    if (!FcitxCreateInputContext(dbus, appname, &ic_path)) {
        ic_path = NULL;  /* just in case. */
    }

    SDL_free(appname);

    if (ic_path) {
        SDL_free(client->ic_path);
        client->ic_path = SDL_strdup(ic_path);

        dbus->bus_add_match(dbus->session_conn,
                "type='signal', interface='org.fcitx.Fcitx.InputContext1'",
                NULL);
        dbus->connection_add_filter(dbus->session_conn,
                &DBus_MessageFilter, dbus,
                NULL);
        dbus->connection_flush(dbus->session_conn);

        SDL_AddHintCallback(SDL_HINT_IME_INTERNAL_EDITING, Fcitx_SetCapabilities, client);
        return SDL_TRUE;
    }

    return SDL_FALSE;
}

static Uint32
Fcitx_ModState(void)
{
    Uint32 fcitx_mods = 0;
    SDL_Keymod sdl_mods = SDL_GetModState();

    if (sdl_mods & KMOD_SHIFT) {
        fcitx_mods |= (1 << 0);
    }
    if (sdl_mods & KMOD_CAPS) {
        fcitx_mods |= (1 << 1);
    }
    if (sdl_mods & KMOD_CTRL) {
        fcitx_mods |= (1 << 2);
    }
    if (sdl_mods & KMOD_ALT) {
        fcitx_mods |= (1 << 3);
    }
    if (sdl_mods & KMOD_NUM) {
        fcitx_mods |= (1 << 4);
    }
    if (sdl_mods & KMOD_MODE) {
        fcitx_mods |= (1 << 7);
    }
    if (sdl_mods & KMOD_LGUI) {
        fcitx_mods |= (1 << 6);
    }
    if (sdl_mods & KMOD_RGUI) {
        fcitx_mods |= (1 << 28);
    }

    return fcitx_mods;
}

SDL_bool
SDL_Fcitx_Init()
{
    fcitx_client.dbus = SDL_DBus_GetContext();

    fcitx_client.cursor_rect.x = -1;
    fcitx_client.cursor_rect.y = -1;
    fcitx_client.cursor_rect.w = 0;
    fcitx_client.cursor_rect.h = 0;

    return FcitxClientCreateIC(&fcitx_client);
}

void
SDL_Fcitx_Quit()
{
    FcitxClientICCallMethod(&fcitx_client, "DestroyIC");
    if (fcitx_client.ic_path) {
        SDL_free(fcitx_client.ic_path);
        fcitx_client.ic_path = NULL;
    }
}

void
SDL_Fcitx_SetFocus(SDL_bool focused)
{
    if (focused) {
        FcitxClientICCallMethod(&fcitx_client, "FocusIn");
    } else {
        FcitxClientICCallMethod(&fcitx_client, "FocusOut");
    }
}

void
SDL_Fcitx_Reset(void)
{
    FcitxClientICCallMethod(&fcitx_client, "Reset");
    FcitxClientICCallMethod(&fcitx_client, "CloseIC");
}

SDL_bool
SDL_Fcitx_ProcessKeyEvent(Uint32 keysym, Uint32 keycode, Uint8 state)
{
    Uint32 mod_state = Fcitx_ModState();
    Uint32 handled = SDL_FALSE;
    Uint32 is_release = (state == SDL_RELEASED);
    Uint32 event_time = 0;

    if (!fcitx_client.ic_path) {
        return SDL_FALSE;
    }

    if (SDL_DBus_CallMethod(FCITX_DBUS_SERVICE, fcitx_client.ic_path, FCITX_IC_DBUS_INTERFACE, "ProcessKeyEvent",
            DBUS_TYPE_UINT32, &keysym, DBUS_TYPE_UINT32, &keycode, DBUS_TYPE_UINT32, &mod_state, DBUS_TYPE_BOOLEAN, &is_release, DBUS_TYPE_UINT32, &event_time, DBUS_TYPE_INVALID,
            DBUS_TYPE_BOOLEAN, &handled, DBUS_TYPE_INVALID)) {
        if (handled) {
            SDL_Fcitx_UpdateTextRect(NULL);
            return SDL_TRUE;
        }
    }

    return SDL_FALSE;
}

void
SDL_Fcitx_UpdateTextRect(const SDL_Rect *rect)
{
    SDL_Window *focused_win = NULL;
    SDL_SysWMinfo info;
    int x = 0, y = 0;
    SDL_Rect *cursor = &fcitx_client.cursor_rect;

    if (rect) {
        SDL_copyp(cursor, rect);
    }

    focused_win = SDL_GetKeyboardFocus();
    if (focused_win == NULL) {
        return ;
    }

    SDL_GetWindowPosition(focused_win, &x, &y);

    if (SDL_GetWindowWMInfo(focused_win, &info, SDL_SYSWM_CURRENT_VERSION) == 0) {
#ifdef SDL_ENABLE_SYSWM_X11
        if (info.subsystem == SDL_SYSWM_X11) {
            Display *x_disp = info.info.x11.display;
            int x_screen = info.info.x11.screen;
            Window x_win = info.info.x11.window;
            Window unused;
            X11_XTranslateCoordinates(x_disp, x_win, RootWindow(x_disp, x_screen), 0, 0, &x, &y, &unused);
        }
#endif
    }

    if (cursor->x == -1 && cursor->y == -1 && cursor->w == 0 && cursor->h == 0) {
        /* move to bottom left */
        int w = 0, h = 0;
        SDL_GetWindowSize(focused_win, &w, &h);
        cursor->x = 0;
        cursor->y = h;
    }

    x += cursor->x;
    y += cursor->y;

    SDL_DBus_CallVoidMethod(FCITX_DBUS_SERVICE, fcitx_client.ic_path, FCITX_IC_DBUS_INTERFACE, "SetCursorRect",
        DBUS_TYPE_INT32, &x, DBUS_TYPE_INT32, &y, DBUS_TYPE_INT32, &cursor->w, DBUS_TYPE_INT32, &cursor->h, DBUS_TYPE_INVALID);
}

void
SDL_Fcitx_PumpEvents(void)
{
    SDL_DBusContext *dbus = fcitx_client.dbus;
    DBusConnection *conn = dbus->session_conn;

    dbus->connection_read_write(conn, 0);

    while (dbus->connection_dispatch(conn) == DBUS_DISPATCH_DATA_REMAINS) {
        /* Do nothing, actual work happens in DBus_MessageFilter */
        usleep(10);
    }
}

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