evince －程序流程

evince 的程序入口在shell/Main.c中；

int main (int argc, char *argv[])
{
    GOptionContext *context;
    GError         *error = NULL;

GOptionContext用于处理命令行传递的参数。

命令行参数处理完成后进入 

if (!ev_init ())
                return 1;

ev_init()函数用于backend相关的处理，evince 支持pdf,xps,odf等等backend;

#if defined(WITH_SMCLIENT) && defined(GDK_WINDOWING_X11)
    egg_set_desktop_file (GNOMEDATADIR "/applications/evince.desktop");
#else
    /* Manually set name and icon */
    g_set_application_name (_("Document Viewer"));
    gtk_window_set_default_icon_name ("evince");
#endif /* WITH_SMCLIENT && GDK_WINDOWING_X11 */

    ev_application_load_session (EV_APP);
    load_files (file_arguments);

然后调用ev_application_load_session，此函数完成了创建窗体，并且显示文档。EV_APP是一个函数宏，些函数完成了application的创建。

#define EV_APP                    (ev_application_get_instance ())

/**
* ev_application_get_instance:
*
* Checks for #EvApplication instance, if it doesn't exist it does create it.
*
* Returns: an instance of the #EvApplication data.
*/
EvApplication *
ev_application_get_instance (void)
{
    if (!instance) {
        instance = EV_APPLICATION (g_object_new (EV_TYPE_APPLICATION, NULL));
    }

    return instance;
}

 直接创建了一个Application对象的instance。

ev_application_load_session，顾名，猜测其主要用于加载会话（session）.

/* Session */
gboolean ev_application_load_session (EvApplication *application)
{
    GKeyFile *state_file;
    gchar    *uri;

#ifdef WITH_SMCLIENT
    if (egg_sm_client_is_resumed (application->smclient)) {
        state_file = egg_sm_client_get_state_file (application->smclient);
        if (!state_file)
            return FALSE;
    } else
#endif /* WITH_SMCLIENT */
        return FALSE;

    uri = g_key_file_get_string (state_file, "Evince", "uri", NULL);
    if (!uri)
        return FALSE;

    ev_application_open_uri_at_dest (application, uri,
                     gdk_screen_get_default (),
                     NULL, 0, NULL,
                     GDK_CURRENT_TIME);
    g_free (uri);
    g_key_file_free (state_file);

    return TRUE;
}

如果没有#define WITH_SMCLIENT，即证明没有会话可加载，则函数直接返回为FALSE;如果定义，则检测保存在application中的smclient所 指向的state_file是否存在，不存在，也直接返回；然后根据stat_file获取Evince组的session 的uri.

然后调用

ev_application_open_uri_at_dest

此函数是真正完成工作的函数。它根据给定的application, uri,绘制窗体，加载文件。在load_file函数中也会对它进行调用。

void  ev_application_open_uri_at_dest (EvApplication  *application,
                 const char     *uri,
                 GdkScreen      *screen,
                 EvLinkDest     *dest,
                 EvWindowRunMode mode,
                 const gchar    *search_string,
                 guint           timestamp)
{
    g_return_if_fail (uri != NULL);

    if (application->uri && strcmp (application->uri, uri) != 0) {
        /* spawn a new evince process */
        ev_spawn (uri, screen, dest, mode, search_string, timestamp);
        return;
    } else if (!application->uri) {
        application->uri = g_strdup (uri);
    }

#ifdef ENABLE_DBUS
    /* Register the uri or send Reload to
     * remote instance if already registered
     */
    ev_application_register_uri (application, uri, screen, dest, mode, search_string, timestamp);
#else
    _ev_application_open_uri_at_dest (application, uri, screen, dest, mode, search_string, timestamp);
#endif /* ENABLE_DBUS */
}

如果application有一个uri，并且跟现在的uri不同则创建一个新的evince进程。如果没有，则把当前的uri赋值给application->uri。

假如未启用dbus，程序则进入：

_ev_application_open_uri_at_dest (application, uri, screen, dest, mode, search_string, timestamp);

 原型如下：

static void
_ev_application_open_uri_at_dest (EvApplication  *application,
                  const gchar    *uri,
                  GdkScreen      *screen,
                  EvLinkDest     *dest,
                  EvWindowRunMode mode,
                  const gchar    *search_string,
                  guint           timestamp)
{
    EvWindow *ev_window;

    ev_window = ev_application_get_empty_window (application, screen);
    if (!ev_window)
        ev_window = EV_WINDOW (ev_window_new ());

    ev_application_open_uri_in_window (application, uri, ev_window,
                       screen, dest, mode,
                       search_string,
                       timestamp);
}

此函数先找到一个空的窗体，分为两种情况，

1.直接在application结构体中的windows list 中寻找空的窗体。

2.查找不成功，调用ev_window_new 创建一个新的窗体。

窗体创建成功后进入

ev_application_open_uri_in_window

static void
ev_application_open_uri_in_window (EvApplication  *application,
                   const char     *uri,
                   EvWindow       *ev_window,
                   GdkScreen      *screen,
                   EvLinkDest     *dest,
                   EvWindowRunMode mode,
                   const gchar    *search_string,
                   guint           timestamp)
{
#ifdef GDK_WINDOWING_X11
    GdkWindow *gdk_window;
#endif

    if (screen) {
        ev_stock_icons_set_screen (screen);
        gtk_window_set_screen (GTK_WINDOW (ev_window), screen);
    }

    /* We need to load uri before showing the window, so
       we can restore window size without flickering */
    ev_window_open_uri (ev_window, uri, dest, mode, search_string);

    if (!gtk_widget_get_realized (GTK_WIDGET (ev_window)))
        gtk_widget_realize (GTK_WIDGET (ev_window));

#ifdef GDK_WINDOWING_X11
    gdk_window = gtk_widget_get_window (GTK_WIDGET (ev_window));

    if (timestamp <= 0)
        timestamp = gdk_x11_get_server_time (gdk_window);
    gdk_x11_window_set_user_time (gdk_window, timestamp);

    gtk_window_present (GTK_WINDOW (ev_window));
#else
    gtk_window_present_with_time (GTK_WINDOW (ev_window), timestamp);
#endif /* GDK_WINDOWING_X11 */
}

函数主要做2件事情 ：
1、调用ev_window_open_uri (ev_window, uri, dest, mode, search_string)打开文档；
2、调用gtk_window_present(GTK_WINDOW(ev_window))显示。