Have libdecor-gtk implement the "GTK Shell" protocol

libdecor/build/Makefile

@@ -18,7 +18,7 @@ include ../../makeinclude
 
 OBJECTS =  fl_libdecor.o libdecor-cairo-blur.o fl_libdecor-plugins.o \
   ../../src/xdg-decoration-protocol.o ../../src/xdg-shell-protocol.o \
-  ../../src/text-input-protocol.o cursor-settings.o os-compatibility.o
+  ../../src/text-input-protocol.o ../../src/gtk-shell-protocol.o cursor-settings.o os-compatibility.o
 
 PROTOCOLS = `pkg-config --variable=pkgdatadir wayland-protocols`
 
@@ -38,7 +38,7 @@ all : $(OBJECTS)
 depend:
 	: echo "libdecor/build: make depend..."
 
-fl_libdecor.o : fl_libdecor.c ../src/libdecor.c ../../src/xdg-shell-protocol.c ../../src/xdg-decoration-protocol.c ../../src/text-input-protocol.c
+fl_libdecor.o : fl_libdecor.c ../src/libdecor.c ../../src/xdg-shell-protocol.c ../../src/xdg-decoration-protocol.c ../../src/text-input-protocol.c ../../src/gtk-shell-protocol.c
 	$(CC) $(CFLAGS) $(CFLAGS_DECOR) -c  fl_libdecor.c -DLIBDECOR_PLUGIN_API_VERSION=1 -DLIBDECOR_PLUGIN_DIR=\"\"
 
 fl_libdecor-plugins.o : fl_libdecor-plugins.c ../src/plugins/cairo/libdecor-cairo.c
@@ -75,10 +75,16 @@ cursor-settings.o : ../src/cursor-settings.c
 	    $(PROTOCOLS)/unstable/text-input/text-input-unstable-v3.xml \
 	    ../../src/text-input-client-protocol.h
 
+../../src/gtk-shell-protocol.c :
+	wayland-scanner private-code \
+	    gtk-shell.xml ../../src/gtk-shell-protocol.c
+	wayland-scanner client-header \
+	    gtk-shell.xml ../../src/gtk-shell-client-protocol.h
+
 install:
 	echo "Nothing to install"
 
 uninstall:
 
 clean:
-	$(RM) *.o ../../src/xdg-*.c ../../src/xdg-*.h ../../src/xdg-*.o ../../src/text-input-*
+	$(RM) *.o ../../src/xdg-*.c ../../src/xdg-*.h ../../src/xdg-*.o ../../src/text-input-* ../../src/gtk-shell-*

libdecor/build/fl_libdecor-plugins.c

@@ -27,6 +27,10 @@
 #include "../src/libdecor.h"
 #include <pango/pangocairo.h>
 
+#ifndef HAVE_GTK
+#  define HAVE_GTK 0
+#endif
+
 #if USE_SYSTEM_LIBDECOR
 #include "../src/libdecor-plugin.h"
 enum zxdg_toplevel_decoration_v1_mode {
@@ -55,7 +59,7 @@ struct buffer { // identical in libdecor-cairo.c and libdecor-gtk.c
 
 const struct libdecor_plugin_description *fl_libdecor_plugin_description = NULL;
 
-#  ifdef HAVE_GTK
+#  if HAVE_GTK
 #    include <gtk/gtk.h>
 #    include "../src/plugins/gtk/libdecor-gtk.c"
 #  else
@@ -316,3 +320,112 @@ unsigned char *fl_libdecor_titlebar_buffer(struct libdecor_frame *frame,
   }
   return NULL;
 }
+
+
+/* === Beginning of code to add support of GTK Shell to libdecor-gtk === */
+#if HAVE_GTK && !USE_SYSTEM_LIBDECOR
+
+#  include "gtk-shell-client-protocol.h"
+
+static struct gtk_shell1 *gtk_shell = NULL;
+
+// libdecor's button member of wl_pointer_listener objects
+static void (*decor_pointer_button)(void*, struct wl_pointer *,
+                                    uint32_t ,
+                                    uint32_t ,
+                                    uint32_t ,
+                                    uint32_t);
+
+// FLTK's replacement for button member of wl_pointer_listener objects
+static void fltk_pointer_button(void *data,
+                                struct wl_pointer *wl_pointer,
+                                uint32_t serial,
+                                uint32_t time,
+                                uint32_t button,
+                                uint32_t state) {
+  struct seat *seat = data;
+  struct libdecor_frame_gtk *frame_gtk;
+  if (!seat->pointer_focus || !own_surface(seat->pointer_focus))
+    return;
+
+  frame_gtk = wl_surface_get_user_data(seat->pointer_focus);
+  if (!frame_gtk)
+    return;
+
+  if (button == BTN_MIDDLE && state == WL_POINTER_BUTTON_STATE_PRESSED) {
+    struct gtk_surface1 *gtk_surface = gtk_shell1_get_gtk_surface(gtk_shell,
+                                                  frame_gtk->headerbar.wl_surface);
+    gtk_surface1_titlebar_gesture(gtk_surface, serial,
+                                  seat->wl_seat, GTK_SURFACE1_GESTURE_MIDDLE_CLICK);
+    gtk_surface1_release(gtk_surface);
+    return;
+  } else if (button == BTN_RIGHT && state == WL_POINTER_BUTTON_STATE_PRESSED) {
+    struct gtk_surface1 *gtk_surface = gtk_shell1_get_gtk_surface(gtk_shell,
+                                                  frame_gtk->headerbar.wl_surface);
+    gtk_surface1_titlebar_gesture(gtk_surface, serial,
+                                  seat->wl_seat, GTK_SURFACE1_GESTURE_RIGHT_CLICK);
+    gtk_surface1_release(gtk_surface);
+    return;
+  } else if (button == BTN_LEFT && state == WL_POINTER_BUTTON_STATE_PRESSED) {
+    static uint32_t previous_click = 0;
+    if (previous_click && time - previous_click < 250) { // < 0.25 sec for dble clicks
+      previous_click = 0;
+      struct gtk_surface1 *gtk_surface = gtk_shell1_get_gtk_surface(gtk_shell,
+                                                    frame_gtk->headerbar.wl_surface);
+      gtk_surface1_titlebar_gesture(gtk_surface, serial,
+                                    seat->wl_seat, GTK_SURFACE1_GESTURE_DOUBLE_CLICK);
+      gtk_surface1_release(gtk_surface);
+      return;
+    }
+    previous_click = time;
+  }
+  decor_pointer_button(data, wl_pointer, serial, time, button, state);
+}
+
+
+struct wl_object { // copied from wayland-private.h
+  const struct wl_interface *interface;
+  const void *implementation;
+  uint32_t id;
+};
+
+#endif // HAVE_GTK && !USE_SYSTEM_LIBDECOR
+
+
+// replace libdecor's pointer_button by FLTK's
+void use_FLTK_pointer_button(struct libdecor_frame *frame) {
+#if HAVE_GTK && !USE_SYSTEM_LIBDECOR
+  static struct wl_pointer_listener *fltk_listener = NULL;
+  if (!gtk_shell || fltk_listener) return;
+  struct libdecor_frame_gtk *lfg = (struct libdecor_frame_gtk *)frame;
+  if (wl_list_empty(&lfg->plugin_gtk->seat_list)) return;
+  struct seat *seat;
+  wl_list_for_each(seat, &lfg->plugin_gtk->seat_list, link) {
+    break;
+  }
+  struct wl_object *object = (struct wl_object *)seat->wl_pointer;
+  if (!object) return;
+  struct wl_pointer_listener *decor_listener =
+      (struct wl_pointer_listener*)object->implementation;
+  fltk_listener =
+      (struct wl_pointer_listener*)malloc(sizeof(struct wl_pointer_listener));
+  // initialize FLTK's listener with libdecor's values
+  *fltk_listener = *decor_listener;
+  // memorize libdecor's button cb
+  decor_pointer_button = decor_listener->button;
+  // replace libdecor's button by FLTK's
+  fltk_listener->button = fltk_pointer_button;
+  // replace the pointer listener by a copy whose button member is FLTK's
+  object->implementation = fltk_listener;
+#endif // HAVE_GTK && !USE_SYSTEM_LIBDECOR
+}
+
+
+void bind_to_gtk_shell(struct wl_registry *wl_registry, uint32_t id) {
+#if HAVE_GTK && !USE_SYSTEM_LIBDECOR
+  gtk_shell = (struct gtk_shell1*)wl_registry_bind(wl_registry, id,
+                                              &gtk_shell1_interface, 5);
+#endif // HAVE_GTK && !USE_SYSTEM_LIBDECOR
+}
+
+/* === End of code to add support of GTK Shell to libdecor-gtk === */

libdecor/build/gtk-shell.xml

@@ -0,0 +1,109 @@
+<!-- found at: https://gitlab.gnome.org/GNOME/gtk/-/blob/main/gdk/wayland/protocol/gtk-shell.xml -->
+<protocol name="gtk">
+
+  <interface name="gtk_shell1" version="5">
+    <description summary="gtk specific extensions">
+      gtk_shell is a protocol extension providing additional features for
+      clients implementing it.
+    </description>
+
+    <enum name="capability">
+      <entry name="global_app_menu" value="1"/>
+      <entry name="global_menu_bar" value="2"/>
+      <entry name="desktop_icons" value="3"/>
+    </enum>
+
+    <event name="capabilities">
+      <arg name="capabilities" type="uint"/>
+    </event>
+
+    <request name="get_gtk_surface">
+      <arg name="gtk_surface" type="new_id" interface="gtk_surface1"/>
+      <arg name="surface" type="object" interface="wl_surface"/>
+    </request>
+
+    <request name="set_startup_id">
+      <arg name="startup_id" type="string" allow-null="true"/>
+    </request>
+
+    <request name="system_bell">
+      <arg name="surface" type="object" interface="gtk_surface1" allow-null="true"/>
+    </request>
+
+    <!-- Version 3 additions -->
+    <request name="notify_launch" since="3">
+      <arg name="startup_id" type="string"/>
+    </request>
+  </interface>
+
+  <interface name="gtk_surface1" version="5">
+    <request name="set_dbus_properties">
+      <arg name="application_id" type="string" allow-null="true"/>
+      <arg name="app_menu_path" type="string" allow-null="true"/>
+      <arg name="menubar_path" type="string" allow-null="true"/>
+      <arg name="window_object_path" type="string" allow-null="true"/>
+      <arg name="application_object_path" type="string" allow-null="true"/>
+      <arg name="unique_bus_name" type="string" allow-null="true"/>
+    </request>
+
+    <request name="set_modal"/>
+    <request name="unset_modal"/>
+
+    <request name="present">
+      <arg name="time" type="uint"/>
+    </request>
+
+    <!-- Version 2 additions -->
+
+    <enum name="state">
+      <entry name="tiled" value="1"/>
+
+      <entry name="tiled_top" value="2" since="2" />
+      <entry name="tiled_right" value="3" since="2" />
+      <entry name="tiled_bottom" value="4" since="2" />
+      <entry name="tiled_left" value="5"  since="2" />
+    </enum>
+
+    <enum name="edge_constraint" since="2">
+      <entry name="resizable_top" value="1"/>
+      <entry name="resizable_right" value="2"/>
+      <entry name="resizable_bottom" value="3"/>
+      <entry name="resizable_left" value="4"/>
+    </enum>
+
+    <event name="configure">
+      <arg name="states" type="array"/>
+    </event>
+
+    <event name="configure_edges" since="2">
+      <arg name="constraints" type="array"/>
+    </event>
+
+    <!-- Version 3 additions -->
+    <request name="request_focus" since="3">
+      <arg name="startup_id" type="string" allow-null="true"/>
+    </request>
+
+    <!-- Version 4 additions -->
+    <request name="release" type="destructor" since="4"/>
+
+    <!-- Version 5 additions -->
+    <enum name="gesture" since="5">
+      <entry name="double_click" value="1"/>
+      <entry name="right_click" value="2"/>
+      <entry name="middle_click" value="3"/>
+    </enum>
+
+    <enum name="error" since="5">
+      <entry name="invalid_gesture" value="0"/>
+    </enum>
+
+    <request name="titlebar_gesture" since="5">
+      <arg name="serial" type="uint"/>
+      <arg name="seat" type="object" interface="wl_seat"/>
+      <arg name="gesture" type="uint" enum="gesture"/>
+    </request>
+  </interface>
+
+</protocol>
+

src/CMakeLists.txt

@@ -688,6 +688,17 @@ if (UNIX AND OPTION_USE_WAYLAND)
     )
     list (APPEND STATIC_FILES "xdg-decoration-protocol.c")
     list (APPEND SHARED_FILES "xdg-decoration-protocol.c")
+    if (GTK_FOUND AND OPTION_ALLOW_GTK_PLUGIN)
+      add_custom_command(
+        OUTPUT gtk-shell-protocol.c gtk-shell-client-protocol.h
+        COMMAND wayland-scanner private-code ${CMAKE_CURRENT_SOURCE_DIR}/../libdecor/build/gtk-shell.xml gtk-shell-protocol.c
+        COMMAND wayland-scanner client-header ${CMAKE_CURRENT_SOURCE_DIR}/../libdecor/build/gtk-shell.xml gtk-shell-client-protocol.h
+        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/../libdecor/build/gtk-shell.xml
+        VERBATIM
+      )
+      list (APPEND STATIC_FILES "gtk-shell-protocol.c")
+      list (APPEND SHARED_FILES "gtk-shell-protocol.c")
+    endif (GTK_FOUND AND OPTION_ALLOW_GTK_PLUGIN)
   endif (NOT OPTION_USE_SYSTEM_LIBDECOR)
   add_custom_command(
     OUTPUT text-input-protocol.c text-input-client-protocol.h

src/Makefile

@@ -424,6 +424,7 @@ CFILES_WAYLANDX11 = $(WLCFILES)
 EXTRA_OBJECTS_WAYLAND =  ../libdecor/build/fl_libdecor.o ../libdecor/build/libdecor-cairo-blur.o \
   ../libdecor/build/fl_libdecor-plugins.o \
   xdg-decoration-protocol.o xdg-shell-protocol.o text-input-protocol.o \
+  gtk-shell-protocol.o \
   ../libdecor/build/cursor-settings.o ../libdecor/build/os-compatibility.o
 EXTRA_OBJECTS_WAYLANDX11 = $(EXTRA_OBJECTS_WAYLAND)
 EXTRA_CXXFLAGS_WAYLAND = -I.

src/drivers/Wayland/Fl_Wayland_Screen_Driver.cxx

@@ -46,6 +46,7 @@
 #include <string.h> // for strerror()
 extern "C" {
   bool libdecor_get_cursor_settings(char **theme, int *size);
+  void bind_to_gtk_shell(struct wl_registry *, uint32_t);
 }
 
 
@@ -1146,6 +1147,9 @@ static void registry_handle_global(void *user_data, struct wl_registry *wl_regis
   } else if (strcmp(interface, "gtk_shell1") == 0) {
     Fl_Wayland_Screen_Driver::compositor = Fl_Wayland_Screen_Driver::MUTTER;
     //fprintf(stderr, "Running the Mutter compositor\n");
+    if ( version >= 5) {
+      bind_to_gtk_shell(wl_registry, id);
+    }
   } else if (strcmp(interface, "weston_desktop_shell") == 0) {
     Fl_Wayland_Screen_Driver::compositor = Fl_Wayland_Screen_Driver::WESTON;
     //fprintf(stderr, "Running the Weston compositor\n");

src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx

@@ -45,6 +45,7 @@ struct cursor_image { // as in wayland-cursor.c of the Wayland project source co
 extern "C" {
 # include "../../../libdecor/src/libdecor-plugin.h"
   uchar *fl_libdecor_titlebar_buffer(struct libdecor_frame *frame, int *w, int *h, int *stride);
+  void use_FLTK_pointer_button(struct libdecor_frame *);
 }
 
 #define fl_max(a,b) ((a) > (b) ? (a) : (b))
@@ -853,7 +854,7 @@ static void handle_configure(struct libdecor_frame *frame,
 #ifdef LIBDECOR_MR131
   if (is_1st_run) use_FLTK_toplevel_configure_cb(frame);
 #endif
-
+  use_FLTK_pointer_button(frame);
   struct wl_output *wl_output = NULL;
   if (window->fl_win->fullscreen_active()) {
     if (!(window->state & LIBDECOR_WINDOW_STATE_FULLSCREEN)) {