gtk/gdk/gdk.c

/* GDK - The GIMP Drawing Kit
 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * 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 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, see <http://www.gnu.org/licenses/>.
 */

/*
 * Modified by the GTK+ Team and others 1997-2000.  See the AUTHORS
 * file for a list of people on the GTK+ Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GTK+ at ftp://ftp.gtk.org/pub/gtk/. 
 */

#include "config.h"

#include "gdkversionmacros.h"

#include "gdkinternals.h"
#include "gdkintl.h"

#include "gdkresources.h"

#include "gdk-private.h"

#ifndef HAVE_XCONVERTCASE
#include "gdkkeysyms.h"
#endif

#include <string.h>
#include <stdlib.h>


/**
 * SECTION:general
 * @Short_description: Library initialization and miscellaneous functions
 * @Title: General
 *
 * This section describes the GDK initialization functions and miscellaneous
 * utility functions, as well as deprecation facilities.
 *
 * The GDK and GTK+ headers annotate deprecated APIs in a way that produces
 * compiler warnings if these deprecated APIs are used. The warnings
 * can be turned off by defining the macro %GDK_DISABLE_DEPRECATION_WARNINGS
 * before including the glib.h header.
 *
 * GDK and GTK+ also provide support for building applications against
 * defined subsets of deprecated or new APIs. Define the macro
 * %GDK_VERSION_MIN_REQUIRED to specify up to what version
 * you want to receive warnings about deprecated APIs. Define the
 * macro %GDK_VERSION_MAX_ALLOWED to specify the newest version
 * whose API you want to use.
 */

/**
 * GDK_WINDOWING_X11:
 *
 * The #GDK_WINDOWING_X11 macro is defined if the X11 backend
 * is supported.
 *
 * Use this macro to guard code that is specific to the X11 backend.
 */

/**
 * GDK_WINDOWING_WIN32:
 *
 * The #GDK_WINDOWING_WIN32 macro is defined if the Win32 backend
 * is supported.
 *
 * Use this macro to guard code that is specific to the Win32 backend.
 */

/**
 * GDK_WINDOWING_QUARTZ:
 *
 * The #GDK_WINDOWING_QUARTZ macro is defined if the Quartz backend
 * is supported.
 *
 * Use this macro to guard code that is specific to the Quartz backend.
 */

/**
 * GDK_WINDOWING_WAYLAND:
 *
 * The #GDK_WINDOWING_WAYLAND macro is defined if the Wayland backend
 * is supported.
 *
 * Use this macro to guard code that is specific to the Wayland backend.
 */

/**
 * GDK_DISABLE_DEPRECATION_WARNINGS:
 *
 * A macro that should be defined before including the gdk.h header.
 * If it is defined, no compiler warnings will be produced for uses
 * of deprecated GDK APIs.
 */

typedef struct _GdkPredicate  GdkPredicate;

struct _GdkPredicate
{
  GdkEventFunc func;
  gpointer data;
};

typedef struct _GdkThreadsDispatch GdkThreadsDispatch;

struct _GdkThreadsDispatch
{
  GSourceFunc func;
  gpointer data;
  GDestroyNotify destroy;
};


/* Private variable declarations
 */
static int gdk_initialized = 0;                     /* 1 if the library is initialized,
                                                     * 0 otherwise.
                                                     */

static GMutex gdk_threads_mutex;

static GCallback gdk_threads_lock = NULL;
static GCallback gdk_threads_unlock = NULL;

#ifdef G_ENABLE_DEBUG
static const GDebugKey gdk_debug_keys[] = {
  { "misc",            GDK_DEBUG_MISC },
  { "events",          GDK_DEBUG_EVENTS },
  { "dnd",             GDK_DEBUG_DND },
  { "input",           GDK_DEBUG_INPUT },
  { "eventloop",       GDK_DEBUG_EVENTLOOP },
  { "frames",          GDK_DEBUG_FRAMES },
  { "settings",        GDK_DEBUG_SETTINGS },
  { "opengl",          GDK_DEBUG_OPENGL },
  { "vulkan",          GDK_DEBUG_VULKAN },
  { "selection",       GDK_DEBUG_SELECTION },
  { "clipboard",       GDK_DEBUG_CLIPBOARD },
  { "nograbs",         GDK_DEBUG_NOGRABS },
  { "gl-disable",      GDK_DEBUG_GL_DISABLE },
  { "gl-software",     GDK_DEBUG_GL_SOFTWARE },
  { "gl-texture-rect", GDK_DEBUG_GL_TEXTURE_RECT },
  { "gl-legacy",       GDK_DEBUG_GL_LEGACY },
  { "gl-gles",         GDK_DEBUG_GL_GLES },
  { "vulkan-disable",  GDK_DEBUG_VULKAN_DISABLE },
  { "vulkan-validate", GDK_DEBUG_VULKAN_VALIDATE },
  { "cairo-image",     GDK_DEBUG_CAIRO_IMAGE }
};
#endif

static gpointer
register_resources (gpointer dummy G_GNUC_UNUSED)
{
  _gdk_register_resource ();

  return NULL;
}

static void
gdk_ensure_resources (void)
{
  static GOnce register_resources_once = G_ONCE_INIT;

  g_once (&register_resources_once, register_resources, NULL);
}

void
gdk_pre_parse (void)
{
  gdk_initialized = TRUE;

  gdk_ensure_resources ();

#ifdef G_ENABLE_DEBUG
  {
    gchar *debug_string = getenv("GDK_DEBUG");
    if (debug_string != NULL)
      _gdk_debug_flags = g_parse_debug_string (debug_string,
                                              (GDebugKey *) gdk_debug_keys,
                                              G_N_ELEMENTS (gdk_debug_keys));
  }
#endif  /* G_ENABLE_DEBUG */
}

/*< private >
 * gdk_display_open_default:
 *
 * Opens the default display specified by command line arguments or
 * environment variables, sets it as the default display, and returns
 * it. gdk_parse_args() must have been called first. If the default
 * display has previously been set, simply returns that. An internal
 * function that should not be used by applications.
 *
 * Returns: (nullable) (transfer none): the default display, if it
 *   could be opened, otherwise %NULL.
 */
GdkDisplay *
gdk_display_open_default (void)
{
  GdkDisplay *display;

  g_return_val_if_fail (gdk_initialized, NULL);

  display = gdk_display_get_default ();
  if (display)
    return display;

  display = gdk_display_open (NULL);

  return display;
}

/**
 * SECTION:threads
 * @Short_description: Functions for using GDK in multi-threaded programs
 * @Title: Threads
 *
 * For thread safety, GDK relies on the thread primitives in GLib,
 * and on the thread-safe GLib main loop.
 *
 * GLib is completely thread safe (all global data is automatically
 * locked), but individual data structure instances are not automatically
 * locked for performance reasons. So e.g. you must coordinate
 * accesses to the same #GHashTable from multiple threads.
 *
 * GTK+, however, is not thread safe. You should only use GTK+ and GDK
 * from the thread gtk_init() and gtk_main() were called on.
 * This is usually referred to as the “main thread”.
 *
 * Signals on GTK+ and GDK types, as well as non-signal callbacks, are
 * emitted in the main thread.
 *
 * You can schedule work in the main thread safely from other threads
 * by using gdk_threads_add_idle() and gdk_threads_add_timeout():
 *
 * |[<!-- language="C" -->
 * static void
 * worker_thread (void)
 * {
 *   ExpensiveData *expensive_data = do_expensive_computation ();
 *
 *   gdk_threads_add_idle (got_value, expensive_data);
 * }
 *
 * static gboolean
 * got_value (gpointer user_data)
 * {
 *   ExpensiveData *expensive_data = user_data;
 *
 *   my_app->expensive_data = expensive_data;
 *   gtk_button_set_sensitive (my_app->button, TRUE);
 *   gtk_button_set_label (my_app->button, expensive_data->result_label);
 *
 *   return G_SOURCE_REMOVE;
 * }
 * ]|
 *
 * You should use gdk_threads_add_idle() and gdk_threads_add_timeout()
 * instead of g_idle_add() and g_timeout_add() since libraries not under
 * your control might be using the deprecated GDK locking mechanism.
 * If you are sure that none of the code in your application and libraries
 * use the deprecated gdk_threads_enter() or gdk_threads_leave() methods,
 * then you can safely use g_idle_add() and g_timeout_add().
 *
 * For more information on this "worker thread" pattern, you should
 * also look at #GTask, which gives you high-level tools to perform
 * expensive tasks from worker threads, and will handle thread
 * management for you.
 */


/**
 * gdk_threads_enter:
 *
 * This function marks the beginning of a critical section in which
 * GDK and GTK+ functions can be called safely and without causing race
 * conditions. Only one thread at a time can be in such a critial
 * section.
 *
 * Deprecated:3.6: All GDK and GTK+ calls should be made from the main
 *     thread
 */
void
gdk_threads_enter (void)
{
  if (gdk_threads_lock)
    (*gdk_threads_lock) ();
}

/**
 * gdk_threads_leave:
 *
 * Leaves a critical region begun with gdk_threads_enter().
 *
 * Deprecated:3.6: All GDK and GTK+ calls should be made from the main
 *     thread
 */
void
gdk_threads_leave (void)
{
  if (gdk_threads_unlock)
    (*gdk_threads_unlock) ();
}

static void
gdk_threads_impl_lock (void)
{
  g_mutex_lock (&gdk_threads_mutex);
}

static void
gdk_threads_impl_unlock (void)
{
  /* we need a trylock() here because trying to unlock a mutex
   * that hasn't been locked yet is:
   *
   *  a) not portable
   *  b) fail on GLib ≥ 2.41
   *
   * trylock() will either succeed because nothing is holding the
   * GDK mutex, and will be unlocked right afterwards; or it's
   * going to fail because the mutex is locked already, in which
   * case we unlock it as expected.
   *
   * this is needed in the case somebody called gdk_threads_init()
   * without calling gdk_threads_enter() before calling gtk_main().
   * in theory, we could just say that this is undefined behaviour,
   * but our documentation has always been *less* than explicit as
   * to what the behaviour should actually be.
   *
   * see bug: https://bugzilla.gnome.org/show_bug.cgi?id=735428
   */
  g_mutex_trylock (&gdk_threads_mutex);
  g_mutex_unlock (&gdk_threads_mutex);
}

/**
 * gdk_threads_init:
 *
 * Initializes GDK so that it can be used from multiple threads
 * in conjunction with gdk_threads_enter() and gdk_threads_leave().
 *
 * This call must be made before any use of the main loop from
 * GTK+; to be safe, call it before gtk_init().
 *
 * Deprecated:3.6: All GDK and GTK+ calls should be made from the main
 *     thread
 */
void
gdk_threads_init (void)
{
  if (!gdk_threads_lock)
    gdk_threads_lock = gdk_threads_impl_lock;
  if (!gdk_threads_unlock)
    gdk_threads_unlock = gdk_threads_impl_unlock;
}

static gboolean
gdk_threads_dispatch (gpointer data)
{
  GdkThreadsDispatch *dispatch = data;
  gboolean ret = FALSE;

  gdk_threads_enter ();

  if (!g_source_is_destroyed (g_main_current_source ()))
    ret = dispatch->func (dispatch->data);

  gdk_threads_leave ();

  return ret;
}

static void
gdk_threads_dispatch_free (gpointer data)
{
  GdkThreadsDispatch *dispatch = data;

  if (dispatch->destroy && dispatch->data)
    dispatch->destroy (dispatch->data);

  g_slice_free (GdkThreadsDispatch, data);
}


/**
 * gdk_threads_add_idle_full: (rename-to gdk_threads_add_idle)
 * @priority: the priority of the idle source. Typically this will be in the
 *            range between #G_PRIORITY_DEFAULT_IDLE and #G_PRIORITY_HIGH_IDLE
 * @function: function to call
 * @data:     data to pass to @function
 * @notify: (allow-none):   function to call when the idle is removed, or %NULL
 *
 * Adds a function to be called whenever there are no higher priority
 * events pending.  If the function returns %FALSE it is automatically
 * removed from the list of event sources and will not be called again.
 *
 * This variant of g_idle_add_full() calls @function with the GDK lock
 * held. It can be thought of a MT-safe version for GTK+ widgets for the
 * following use case, where you have to worry about idle_callback()
 * running in thread A and accessing @self after it has been finalized
 * in thread B:
 *
 * |[<!-- language="C" -->
 * static gboolean
 * idle_callback (gpointer data)
 * {
 *    // gdk_threads_enter(); would be needed for g_idle_add()
 *
 *    SomeWidget *self = data;
 *    // do stuff with self
 *
 *    self->idle_id = 0;
 *
 *    // gdk_threads_leave(); would be needed for g_idle_add()
 *    return FALSE;
 * }
 *
 * static void
 * some_widget_do_stuff_later (SomeWidget *self)
 * {
 *    self->idle_id = gdk_threads_add_idle (idle_callback, self)
 *    // using g_idle_add() here would require thread protection in the callback
 * }
 *
 * static void
 * some_widget_finalize (GObject *object)
 * {
 *    SomeWidget *self = SOME_WIDGET (object);
 *    if (self->idle_id)
 *      g_source_remove (self->idle_id);
 *    G_OBJECT_CLASS (parent_class)->finalize (object);
 * }
 * ]|
 *
 * Returns: the ID (greater than 0) of the event source.
 *
 * Since: 2.12
 */
guint
gdk_threads_add_idle_full (gint           priority,
                           GSourceFunc    function,
                           gpointer       data,
                           GDestroyNotify notify)
{
  GdkThreadsDispatch *dispatch;

  g_return_val_if_fail (function != NULL, 0);

  dispatch = g_slice_new (GdkThreadsDispatch);
  dispatch->func = function;
  dispatch->data = data;
  dispatch->destroy = notify;

  return g_idle_add_full (priority,
                          gdk_threads_dispatch,
                          dispatch,
                          gdk_threads_dispatch_free);
}

/**
 * gdk_threads_add_idle: (skip)
 * @function: function to call
 * @data:     data to pass to @function
 *
 * A wrapper for the common usage of gdk_threads_add_idle_full() 
 * assigning the default priority, #G_PRIORITY_DEFAULT_IDLE.
 *
 * See gdk_threads_add_idle_full().
 *
 * Returns: the ID (greater than 0) of the event source.
 * 
 * Since: 2.12
 */
guint
gdk_threads_add_idle (GSourceFunc    function,
                      gpointer       data)
{
  return gdk_threads_add_idle_full (G_PRIORITY_DEFAULT_IDLE,
                                    function, data, NULL);
}


/**
 * gdk_threads_add_timeout_full: (rename-to gdk_threads_add_timeout)
 * @priority: the priority of the timeout source. Typically this will be in the
 *            range between #G_PRIORITY_DEFAULT_IDLE and #G_PRIORITY_HIGH_IDLE.
 * @interval: the time between calls to the function, in milliseconds
 *             (1/1000ths of a second)
 * @function: function to call
 * @data:     data to pass to @function
 * @notify: (allow-none):   function to call when the timeout is removed, or %NULL
 *
 * Sets a function to be called at regular intervals holding the GDK lock,
 * with the given priority.  The function is called repeatedly until it 
 * returns %FALSE, at which point the timeout is automatically destroyed 
 * and the function will not be called again.  The @notify function is
 * called when the timeout is destroyed.  The first call to the
 * function will be at the end of the first @interval.
 *
 * Note that timeout functions may be delayed, due to the processing of other
 * event sources. Thus they should not be relied on for precise timing.
 * After each call to the timeout function, the time of the next
 * timeout is recalculated based on the current time and the given interval
 * (it does not try to “catch up” time lost in delays).
 *
 * This variant of g_timeout_add_full() can be thought of a MT-safe version 
 * for GTK+ widgets for the following use case:
 *
 * |[<!-- language="C" -->
 * static gboolean timeout_callback (gpointer data)
 * {
 *    SomeWidget *self = data;
 *    
 *    // do stuff with self
 *    
 *    self->timeout_id = 0;
 *    
 *    return G_SOURCE_REMOVE;
 * }
 *  
 * static void some_widget_do_stuff_later (SomeWidget *self)
 * {
 *    self->timeout_id = g_timeout_add (timeout_callback, self)
 * }
 *  
 * static void some_widget_finalize (GObject *object)
 * {
 *    SomeWidget *self = SOME_WIDGET (object);
 *    
 *    if (self->timeout_id)
 *      g_source_remove (self->timeout_id);
 *    
 *    G_OBJECT_CLASS (parent_class)->finalize (object);
 * }
 * ]|
 *
 * Returns: the ID (greater than 0) of the event source.
 * 
 * Since: 2.12
 */
guint
gdk_threads_add_timeout_full (gint           priority,
                              guint          interval,
                              GSourceFunc    function,
                              gpointer       data,
                              GDestroyNotify notify)
{
  GdkThreadsDispatch *dispatch;

  g_return_val_if_fail (function != NULL, 0);

  dispatch = g_slice_new (GdkThreadsDispatch);
  dispatch->func = function;
  dispatch->data = data;
  dispatch->destroy = notify;

  return g_timeout_add_full (priority, 
                             interval,
                             gdk_threads_dispatch, 
                             dispatch, 
                             gdk_threads_dispatch_free);
}

/**
 * gdk_threads_add_timeout: (skip)
 * @interval: the time between calls to the function, in milliseconds
 *             (1/1000ths of a second)
 * @function: function to call
 * @data:     data to pass to @function
 *
 * A wrapper for the common usage of gdk_threads_add_timeout_full() 
 * assigning the default priority, #G_PRIORITY_DEFAULT.
 *
 * See gdk_threads_add_timeout_full().
 * 
 * Returns: the ID (greater than 0) of the event source.
 *
 * Since: 2.12
 */
guint
gdk_threads_add_timeout (guint       interval,
                         GSourceFunc function,
                         gpointer    data)
{
  return gdk_threads_add_timeout_full (G_PRIORITY_DEFAULT,
                                       interval, function, data, NULL);
}


/**
 * gdk_threads_add_timeout_seconds_full: (rename-to gdk_threads_add_timeout_seconds)
 * @priority: the priority of the timeout source. Typically this will be in the
 *            range between #G_PRIORITY_DEFAULT_IDLE and #G_PRIORITY_HIGH_IDLE.
 * @interval: the time between calls to the function, in seconds
 * @function: function to call
 * @data:     data to pass to @function
 * @notify: (allow-none): function to call when the timeout is removed, or %NULL
 *
 * A variant of gdk_threads_add_timeout_full() with second-granularity.
 * See g_timeout_add_seconds_full() for a discussion of why it is
 * a good idea to use this function if you don’t need finer granularity.
 *
 * Returns: the ID (greater than 0) of the event source.
 * 
 * Since: 2.14
 */
guint
gdk_threads_add_timeout_seconds_full (gint           priority,
                                      guint          interval,
                                      GSourceFunc    function,
                                      gpointer       data,
                                      GDestroyNotify notify)
{
  GdkThreadsDispatch *dispatch;

  g_return_val_if_fail (function != NULL, 0);

  dispatch = g_slice_new (GdkThreadsDispatch);
  dispatch->func = function;
  dispatch->data = data;
  dispatch->destroy = notify;

  return g_timeout_add_seconds_full (priority, 
                                     interval,
                                     gdk_threads_dispatch, 
                                     dispatch, 
                                     gdk_threads_dispatch_free);
}

/**
 * gdk_threads_add_timeout_seconds: (skip)
 * @interval: the time between calls to the function, in seconds
 * @function: function to call
 * @data:     data to pass to @function
 *
 * A wrapper for the common usage of gdk_threads_add_timeout_seconds_full() 
 * assigning the default priority, #G_PRIORITY_DEFAULT.
 *
 * For details, see gdk_threads_add_timeout_full().
 * 
 * Returns: the ID (greater than 0) of the event source.
 *
 * Since: 2.14
 */
guint
gdk_threads_add_timeout_seconds (guint       interval,
                                 GSourceFunc function,
                                 gpointer    data)
{
  return gdk_threads_add_timeout_seconds_full (G_PRIORITY_DEFAULT,
                                               interval, function, data, NULL);
}