Have FLTK use libdecor at version > 0.2.2

- it's no longer necessary to take care of the change in the layout of "struct libdecor"
between versions ≤ 0.2.2 and > 0.2.2 of libdecor
- version > 0.2.2 contains MR131, that is, it defines LIBDECOR_WINDOW_STATE_RESIZING
so the hack to emulate it is no longer  necessary
- CMake option FLTK_USE_SYSTEM_LIBDECOR now requires libdecor version > 0.2.2
to be activated, otherwise the bundled libdecor is used
- what will be the libdecor version after 0.2.2 (0.2.3? 0.3.0?) is not known as of today

CMake/options.cmake

@@ -297,7 +297,7 @@ if(UNIX)
     endif()
     unset(FLTK_GRAPHICS_CAIRO CACHE)
     set(FLTK_GRAPHICS_CAIRO TRUE CACHE BOOL "all drawing to X11 windows uses Cairo")
-    option(FLTK_USE_SYSTEM_LIBDECOR "use libdecor from the system" ON)
+    option(FLTK_USE_SYSTEM_LIBDECOR "use libdecor from the system" OFF)
     set(USE_SYSTEM_LIBDECOR 1)
     unset(FLTK_USE_XRENDER CACHE)
     unset(FLTK_USE_XINERAMA CACHE)
@@ -333,9 +333,9 @@ if(UNIX)
     unset(FLTK_USE_PANGO CACHE)
     set(FLTK_USE_PANGO TRUE CACHE BOOL "use lib Pango")
     if(FLTK_USE_SYSTEM_LIBDECOR)
-      pkg_check_modules(SYSTEM_LIBDECOR libdecor-0>=0.2.0 QUIET)
+      pkg_check_modules(SYSTEM_LIBDECOR libdecor-0>0.2.2 QUIET)
       if(NOT SYSTEM_LIBDECOR_FOUND)
-        message(STATUS "Warning: system libdecor doesn't satisfy version >= 0.2.0,")
+        message(STATUS "Warning: system libdecor doesn't satisfy version > 0.2.2,")
         message(STATUS "         using bundled libdecor library instead.")
         set(USE_SYSTEM_LIBDECOR 0)
       else()
@@ -355,10 +355,6 @@ if(UNIX)
       set(FLTK_USE_LIBDECOR_GTK ON)
     else()
       option(FLTK_USE_LIBDECOR_GTK "Allow to use libdecor's GTK plugin" ON)
-      # Temporarily, while built-in and system struct libdecor differ.
-      # Later, the version of the system libdecor will be required to have same
-      # struct libdecor as the built-in libdecor.
-      set(CMAKE_ENABLE_EXPORTS 1)
     endif(USE_SYSTEM_LIBDECOR)
 
     if(${CMAKE_HOST_SYSTEM_NAME} STREQUAL "FreeBSD")

README.CMake.txt

@@ -282,12 +282,12 @@ FLTK_USE_PTHREADS - default ON except on Windows.
     This option is ignored (switched OFF internally) on Windows except
     when using Cygwin.
 
-FLTK_USE_SYSTEM_LIBDECOR - default ON (Wayland only)
+FLTK_USE_SYSTEM_LIBDECOR - default OFF (Wayland only)
     This option makes FLTK use package libdecor-0-dev to draw window titlebars
-    under Wayland. When OFF or when this package has a version < 0.2.0, FLTK
+    under Wayland. When OFF or when this package has a version ≤ 0.2.2, FLTK
     uses its bundled copy of libdecor to draw window titlebars.
-    As of november 2023, version 0.2.0 of package libdecor-0-dev is available
-    only in testing distributions.
+    As of early 2024, no version > 0.2.2 of package libdecor-0-dev is available
+    yet.
 
 FLTK_USE_SYSTEM_LIBJPEG - default ON (macOS and Windows: OFF)
 FLTK_USE_SYSTEM_LIBPNG  - default ON (macOS and Windows: OFF)

README.Wayland.txt

@@ -126,8 +126,8 @@ cross-compiling for systems that lack X11 headers and libraries.
 The FLTK Wayland platform uses a library called libdecor which handles window decorations
 (i.e., titlebars, shade). On very recent Linux distributions (e.g., Debian trixie)
 libdecor is available as Linux packages (libdecor-0-dev and libdecor-0-plugin-1-gtk).
-FLTK requires version 0.2.0 of these packages or more.
-In other situations, FLTK uses a copy of libdecor bundled in the FLTK source code.
+FLTK requires a version > 0.2.2 of these packages that's not yet available.
+Therefore, FLTK uses a copy of libdecor bundled in the FLTK source code.
 FLTK equipped with libdecor supports both the client-side decoration mode (CSD) and the
 server-side decoration mode (SSD) as determined by the active Wayland compositor.
 Mutter (gnome's Wayland compositor) and Weston use CSD mode, KWin and Sway use SSD mode.
@@ -194,9 +194,6 @@ in section 2.1 of file README.Unix.txt :
 These packages allow to run FLTK apps under the Gnome-Wayland desktop:
 - gnome-core
 - libgtk-3-dev   <== highly recommended, gives windows a Gnome-style titlebar
-- libdecor-0-dev and libdecor-0-plugin-1-gtk in versions ≥ 0.2.0
-                 <== Recommended if available for the Linux version in use,
-                 <== FLTK uses a bundled copy of these packages otherwise.
 
 These packages allow to run FLTK apps under the KDE/Plasma-Wayland desktop:
 - kde-plasma-desktop
@@ -221,7 +218,6 @@ package groups listed in section 2.2 of file README.Unix.txt :
 - mesa-libGLU-devel
 - dbus-devel   <== recommended to query current cursor theme
 - gtk3-devel   <== highly recommended, gives windows a GTK-style titlebar
-- libdecor-0.2.0 <== recommended, present in Fedora Rawhide, not in Fedora 39
 - glew-devel   <== necessary to use OpenGL version 3 or above
 - cmake        <== if you plan to build with CMake
 - cmake-gui    <== if you plan to use the GUI of CMake

configure.ac

@@ -1074,7 +1074,7 @@ AS_CASE([$host_os_gui], [cygwin* | mingw*], [
        BUILD="WAYLANDX11"
        graphics="Wayland or X11 with cairo"
        ])
-      AS_IF([$PKGCONFIG --exists 'libdecor-0 >= 0.2.0'],
+      AS_IF([$PKGCONFIG --exists 'libdecor-0 > 0.2.2'],
       [
         plugin_dir="$($PKGCONFIG --variable=libdir libdecor-0)/libdecor/plugins-1"
         CFLAGS="$CFLAGS -DUSE_SYSTEM_LIBDECOR"

documentation/src/wayland.dox

@@ -1104,8 +1104,7 @@ and also to draw window titlebars when in CSD mode (see \ref bundled-libdecor).
 \c Libdecor is conceived to be present in a shared library linked to the Wayland
 client application which itself, and if the running Wayland compositor uses CSD mode,
 loads another shared library intended to draw titlebars in a way that best matches the
-Desktop. As of late 2023, libdecor is at version 0.2.0 and contains two titlebar-drawing
-plugins:
+Desktop. As of late 2023, libdecor contains two titlebar-drawing plugins:
 - \c libdecor-gtk intended for the Gnome desktop;
 - \c libdecor-cairo for other situations.
 
@@ -1114,15 +1113,10 @@ FLTK bundles the most recent source code of \c libdecor and its plugins. This co
 is included in libfltk. FLTK uses \c libdecor-gtk when software package \c libgtk-3-dev
 is present in the build system, and \c libdecor-cairo otherwise.
 
-As of late 2023, libdecor version 0.2.0 is available in very recent Linux distributions
-in packages \c libdecor-0-dev and \c libdecor-0-plugin-1-gtk. If they are installed on the
-build system, preprocessor variable \c USE_SYSTEM_LIBDECOR is 1,
-and both \c libdecor and its plugin are loaded at run-time from shared libraries.
-When these packages are not available or are at an earlier version, FLTK uses the bundled
-copy of \c libdecor.
-When CMake \c FLTK_USE_SYSTEM_LIBDECOR is OFF, FLTK uses the bundled \c libdecor copy
-even if shared libraries \c libdecor.so and \c libdecor-gtk.so are installed.
-This option is ON by default.
+As of early 2024, libdecor version 0.2.2 is available in very recent Linux distributions.
+This version is not binary compatible with the libdecor version bundled by FLTK.
+For this reason, CMake option \c FLTK_USE_SYSTEM_LIBDECOR is OFF by default, and
+FLTK uses the bundled \c libdecor copy to draw titlebars.
 
 \c Libdecor uses the Wayland protocol
 <a href=https://wayland.app/protocols/xdg-decoration-unstable-v1>XDG decoration</a>

libdecor/build/fl_libdecor-plugins.c

@@ -301,23 +301,6 @@ unsigned char *fl_libdecor_titlebar_buffer(struct libdecor_frame *frame,
 }
 
 
-// When the libdecor version after 0.2.2 will be released, support of older versions
-// will be removed from FLTK. LIBDECOR_MR131 stuff also will be removed.
-struct libdecor_022 { // for libdecor versions ≤ 0.2.2
-  int ref_count;
-  const struct libdecor_interface *iface;
-  struct libdecor_plugin *plugin;
-  bool plugin_ready;
-  struct wl_display *wl_display;
-  struct wl_registry *wl_registry;
-  struct xdg_wm_base *xdg_wm_base;
-  struct zxdg_decoration_manager_v1 *decoration_manager;
-  struct wl_callback *init_callback;
-  bool init_done;
-  bool has_error;
-  struct wl_list frames;
-};
-
 struct libdecor { // copied from libdecor.c, for libdecor versions > 0.2.2
   int ref_count;
   const struct libdecor_interface *iface;
@@ -338,18 +321,9 @@ struct libdecor { // copied from libdecor.c, for libdecor versions > 0.2.2
 /* Returns whether surface is a GTK-titlebar created by libdecor-gtk */
 bool fl_is_surface_gtk_titlebar(struct wl_surface *surface, struct libdecor *context) {
   if (!context || get_plugin_kind(NULL) != GTK3) return false;
-  static void *new_symbol = NULL;
-  static bool first = true;
-  if (first) {
-    first = false;
-    // new_symbol is NULL for libdecor versions ≤ 0.2.2
-    new_symbol = dlsym(RTLD_DEFAULT, "libdecor_frame_get_user_data");
-  }
-  struct wl_list *frames_addr = (new_symbol ? &context->frames :
-                                 &(((struct libdecor_022*)context)->frames) );
   // loop over all decorations created by libdecor-gtk
   struct libdecor_frame *frame;
-  wl_list_for_each(frame, frames_addr, link) {
+  wl_list_for_each(frame, &context->frames, link) {
     struct libdecor_frame_gtk *frame_gtk = (struct libdecor_frame_gtk*)frame;
     if (frame_gtk->headerbar.wl_surface == surface) return true;
   }

src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx

@@ -769,69 +769,6 @@ static struct Fl_Wayland_Screen_Driver::output *screen_num_to_output(int num_scr
 }
 
 
-#define LIBDECOR_MR131 1 // this means libdecor does not include MR!131 yet
-
-#ifdef LIBDECOR_MR131
-/* === Beginning of hack that would become un-needed if libdecor accepted MR!131 === */
-
-// true while the GUI is interactively resizing a decorated window
-static bool in_decorated_window_resizing = false;
-
-
-// libdecor's configure cb function for xdg_toplevel objects
-static void (*decor_xdg_toplevel_configure)(void*, struct xdg_toplevel *, int32_t,
-                                            int32_t, struct wl_array *);
-
-
-static void fltk_xdg_toplevel_configure(void *user_data, struct xdg_toplevel *xdg_toplevel,
-                                        int32_t width, int32_t height,
-                                        struct wl_array *states) {
-  uint32_t *p;
-  in_decorated_window_resizing = false;
-  // Replace wl_array_for_each(p, states) rejected by C++
-  for (p = (uint32_t *)(states)->data;
-      (const char *) p < ((const char *) (states)->data + (states)->size);
-      (p)++) {
-    if (*p == XDG_TOPLEVEL_STATE_RESIZING) {
-      in_decorated_window_resizing = true;
-      break;
-    }
-  }
-  decor_xdg_toplevel_configure(user_data, xdg_toplevel, width, height, states);
-}
-
-
-struct wl_object { // copied from wayland-private.h
-  const struct wl_interface *interface;
-  const void *implementation;
-  uint32_t id;
-};
-
-
-// replace libdecor's toplevel configure cb by FLTK's
-static void use_FLTK_toplevel_configure_cb(struct libdecor_frame *frame) {
-  struct wl_object *object = (struct wl_object *)libdecor_frame_get_xdg_toplevel(frame);
-  static struct xdg_toplevel_listener *fltk_listener = NULL;
-  if (!fltk_listener) {
-    struct xdg_toplevel_listener *decor_listener = (struct xdg_toplevel_listener*)
-        object->implementation;
-    fltk_listener = (struct xdg_toplevel_listener*)
-        malloc(sizeof(struct xdg_toplevel_listener));
-    // initialize FLTK's listener with libdecor's values
-    *fltk_listener = *decor_listener;
-    // memorize libdecor's toplevel configure cb
-    decor_xdg_toplevel_configure = decor_listener->configure;
-    // replace libdecor's toplevel configure cb by FLTK's
-    fltk_listener->configure = fltk_xdg_toplevel_configure;
-  }
-  // replace the toplevel listener by a copy whose configure member is FLTK's
-  object->implementation = fltk_listener;
-}
-
-/* === End of hack that would become un-needed if libdecor accepted MR!131 === */
-#endif // LIBDECOR_MR131
-
-
 static void handle_configure(struct libdecor_frame *frame,
      struct libdecor_configuration *configuration, void *user_data)
 {
@@ -849,9 +786,6 @@ static void handle_configure(struct libdecor_frame *frame,
 
   if (!window->xdg_surface) window->xdg_surface = libdecor_frame_get_xdg_surface(frame);
 
-#ifdef LIBDECOR_MR131
-  if (is_1st_run) use_FLTK_toplevel_configure_cb(frame);
-#endif
   struct wl_output *wl_output = NULL;
   if (window->fl_win->fullscreen_active()) {
     if (!(window->state & LIBDECOR_WINDOW_STATE_FULLSCREEN)) {
@@ -905,16 +839,13 @@ static void handle_configure(struct libdecor_frame *frame,
     //fprintf(stderr,"handle_configure: using floating %dx%d\n",width,height);
   }
 
-#ifndef LIBDECOR_MR131
-  bool in_decorated_window_resizing = (window->state & LIBDECOR_WINDOW_STATE_RESIZING);
-#endif
-  bool condition = in_decorated_window_resizing;
+  bool condition = (window->state & LIBDECOR_WINDOW_STATE_RESIZING);
   if (condition) { // see issue #878
     condition = (window->covered ? (window->buffer && window->buffer->in_use) : (window->frame_cb != NULL));
   }
   if (condition) {
     // Skip resizing & redrawing. The last resize request won't be skipped because
-    // in_decorated_window_resizing will be false or cb will be NULL then.
+    // LIBDECOR_WINDOW_STATE_RESIZING will be off or cb will be NULL then.
     return;
   }