Wayland: use "XDG activation" protocol to support a window activating another window.

See
https://stackoverflow.com/questions/75861687/how-to-request-a-window-be-activated-with-the-wayland-protocol
explaining the "XDG activation" protocol is necessary and able to programmatically
activate a window.
The effect of the new code is visible with FLTK test program windowfocus.

CMake/options.cmake

@@ -318,6 +318,12 @@ if(UNIX)
     else()
       set(HAVE_XDG_DIALOG 0)
     endif()
+    if(EXISTS ${PROTOCOLS}/staging/xdg-activation/xdg-activation-v1.xml)
+      set(HAVE_XDG_ACTIVATION 1)
+      message(STATUS "Found dev files for Wayland protocol 'XDG activation'")
+    else()
+      set(HAVE_XDG_ACTIVATION 0)
+    endif()
     if(EXISTS ${PROTOCOLS}/staging/cursor-shape/cursor-shape-v1.xml AND
         EXISTS ${PROTOCOLS}/stable/tablet/tablet-v2.xml)
       set(HAVE_CURSOR_SHAPE 1)

config.h.in

@@ -356,3 +356,10 @@
  */
 
 #cmakedefine01 HAVE_CURSOR_SHAPE
+
+
+/*
+ * Can we use the "XDG activation" Wayland protocol?
+ */
+
+#cmakedefine01 HAVE_XDG_ACTIVATION

documentation/src/wayland.dox

@@ -101,7 +101,8 @@ beginning with \c wl_, \c xkb_ or \c libdecor_ and belong to the \c libwayland-c
 \c libwayland-cursor.so, \c libxkbcommon.so and \c libdecor.so shared libraries.
 FLTK calls also several other functions which operate other used Wayland protocols.
 These have names beginning with \c xdg_, \c zwp_text_input_v3, \c zxdg_toplevel_decoration_,
-\c gtk_shell1_, \c gtk_surface1_, \c wp_cursor_shape_ and \c zwp_tablet_v2.
+\c gtk_shell1_, \c gtk_surface1_, \c wp_cursor_shape_, \c xdg_activation_ and
+\c zwp_tablet_v2.
 FLTK never writes itself to the socket; this is done inside the functions just mentioned.
 - Compositor to client: the callback function \c wld_socket_callback() runs when there are
 data to read in the socket; it calls \c libdecor_dispatch() which reads available data from
@@ -161,6 +162,7 @@ wayland-scanner client-header $PROTOCOLS/stable/xdg-shell/xdg-shell.xml xdg-shel
 \endcode
 Similar operations are performed for FLTK to use protocols
 <a href=https://wayland.app/protocols/xdg-dialog-v1>XDG dialog windows</a>,
+<a href=https://wayland.app/protocols/xdg-activation-v1>XDG activation</a>,
 <a href=https://wayland.app/protocols/xdg-decoration-unstable-v1>XDG decoration</a>,
 <a href=https://wayland.app/protocols/cursor-shape-v1>Cursor shape</a>,
 <a href=https://wayland.app/protocols/text-input-unstable-v3>Text input</a>,
@@ -332,6 +334,7 @@ Here is the list of the \c interface value for all protocols and system features
   wl_data_device                     | support of copy/paste/drag-n-drop
   wl_output                          | received once for each display
   xdg_wm_base                        | create mapped windows
+  xdg_activation_v1                  | programmatically activate a window
   xdg_wm_dialog_v1                   | create dialogs related to other windows
   wp_cursor_shape_manager_v1         | set cursor images using enumerated cursors
   gtk_shell1                         | indicates Mutter is in use + titlebar gestures

src/CMakeLists.txt

@@ -817,6 +817,19 @@ if(UNIX AND FLTK_USE_WAYLAND)
   list(APPEND STATIC_FILES "xdg-shell-protocol.c")
   list(APPEND SHARED_FILES "xdg-shell-protocol.c")
 
+  if(HAVE_XDG_ACTIVATION)
+    set(INFILE ${PROTOCOLS}/staging/xdg-activation/xdg-activation-v1.xml)
+    add_custom_command(
+      OUTPUT xdg-activation-protocol.c xdg-activation-client-protocol.h
+      COMMAND wayland-scanner private-code  ${INFILE} xdg-activation-protocol.c
+      COMMAND wayland-scanner client-header ${INFILE} xdg-activation-client-protocol.h
+      DEPENDS ${INFILE}
+      VERBATIM
+    )
+    list(APPEND STATIC_FILES "xdg-activation-protocol.c")
+    list(APPEND SHARED_FILES "xdg-activation-protocol.c")
+  endif()
+
   if(NOT USE_SYSTEM_LIBDECOR)
     set(INFILE ${PROTOCOLS}/unstable/xdg-decoration/xdg-decoration-unstable-v1.xml)
     fl_check_required_file(STOP_REQUIRED ${INFILE})

src/drivers/Wayland/Fl_Wayland_Screen_Driver.H

@@ -110,6 +110,9 @@ public:
 #if HAVE_XDG_DIALOG
   struct xdg_wm_dialog_v1 *xdg_wm_dialog;
 #endif
+#if HAVE_XDG_ACTIVATION
+  struct xdg_activation_v1 *xdg_activation;
+#endif
 #if HAVE_CURSOR_SHAPE
   struct wp_cursor_shape_manager_v1 *wp_cursor_shape_manager;
   struct wp_cursor_shape_device_v1 *wp_cursor_shape_device;

src/drivers/Wayland/Fl_Wayland_Screen_Driver.cxx

@@ -39,6 +39,9 @@
 #if HAVE_XDG_DIALOG
 #  include "xdg-dialog-client-protocol.h"
 #endif
+#if HAVE_XDG_ACTIVATION
+#  include "xdg-activation-client-protocol.h"
+#endif
 #if HAVE_CURSOR_SHAPE
 #  include "cursor-shape-client-protocol.h"
 #  include "tablet-client-protocol.h"
@@ -1393,6 +1396,11 @@ static void registry_handle_global(void *user_data, struct wl_registry *wl_regis
     scr_driver->xdg_wm_dialog = (struct xdg_wm_dialog_v1 *)
       wl_registry_bind(wl_registry, id, &xdg_wm_dialog_v1_interface, 1);
 #endif // HAVE_XDG_DIALOG
+#if HAVE_XDG_ACTIVATION
+  } else if (strcmp(interface, xdg_activation_v1_interface.name) == 0) {
+    scr_driver->xdg_activation = (struct xdg_activation_v1 *)
+      wl_registry_bind(wl_registry, id, &xdg_activation_v1_interface, 1);
+#endif // HAVE_XDG_ACTIVATION
 #if HAVE_CURSOR_SHAPE
   } else if (strcmp(interface, wp_cursor_shape_manager_v1_interface.name) == 0) {
     scr_driver->wp_cursor_shape_manager = (struct wp_cursor_shape_manager_v1 *)
@@ -1460,6 +1468,9 @@ Fl_Wayland_Screen_Driver::Fl_Wayland_Screen_Driver() : Fl_Unix_Screen_Driver() {
 #if HAVE_XDG_DIALOG
   xdg_wm_dialog = NULL;
 #endif
+#if HAVE_XDG_ACTIVATION
+  xdg_activation = NULL;
+#endif
 #if HAVE_CURSOR_SHAPE
   wp_cursor_shape_manager = NULL;
   wp_cursor_shape_device = NULL;
@@ -1636,6 +1647,12 @@ void Fl_Wayland_Screen_Driver::close_display() {
     xdg_wm_dialog = NULL;
   }
 #endif // HAVE_XDG_DIALOG
+#if HAVE_XDG_ACTIVATION
+  if (xdg_activation) {
+    xdg_activation_v1_destroy(xdg_activation);
+    xdg_activation = NULL;
+  }
+#endif // HAVE_XDG_ACTIVATION
 #if HAVE_CURSOR_SHAPE
   if (wp_cursor_shape_device ) {
     wp_cursor_shape_device_v1_destroy(wp_cursor_shape_device);

src/drivers/Wayland/Fl_Wayland_Window_Driver.H

@@ -64,6 +64,7 @@ private:
   struct gl_start_support *gl_start_support_; // for support of gl_start/gl_finish
   bool is_popup_window_;
   bool previous_border_; // records whether window before being turned fullscreen had a border
+  void activate_(Fl_Window *);
 public:
   inline Fl_Cursor standard_cursor() { return standard_cursor_; }
   bool in_handle_configure; // distinguish OS and user window resize

src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx

@@ -23,6 +23,9 @@
 #include <wayland-cursor.h>
 #include "../../../libdecor/build/fl_libdecor.h"
 #include "xdg-shell-client-protocol.h"
+#if HAVE_XDG_ACTIVATION
+#  include "xdg-activation-client-protocol.h"
+#endif
 #include "gtk-shell-client-protocol.h"
 #if HAVE_XDG_DIALOG
 #  include "xdg-dialog-client-protocol.h"
@@ -164,15 +167,12 @@ void Fl_Wayland_Window_Driver::take_focus()
   struct wld_window *w = fl_wl_xid(pWindow);
   if (w) {
     Fl_Window *old_first = Fl::first_window();
-    struct wld_window *first_xid = (old_first ? fl_wl_xid(old_first->top_window()) : NULL);
-    if (first_xid && first_xid != w && xdg_toplevel()) {
-      // this will move the target window to the front
-      Fl_Wayland_Window_Driver *top_dr =
-        Fl_Wayland_Window_Driver::driver(old_first->top_window());
-      xdg_toplevel_set_parent(xdg_toplevel(), top_dr->xdg_toplevel());
-      // this will remove the parent-child relationship
-      xdg_toplevel_set_parent(xdg_toplevel(), NULL);
-      wl_surface_commit(w->wl_surface);
+    if (old_first) {
+      if (old_first->parent()) old_first = old_first->top_window();
+      if (old_first != pWindow && xdg_toplevel()) {
+        // let the current active window activate this window
+        Fl_Wayland_Window_Driver::driver(old_first)->activate_(pWindow);
+      }
     }
     // this sets the first window
     fl_wl_find(w);
@@ -2203,3 +2203,53 @@ void Fl_Wayland_Window_Driver::un_maximize() {
   if (xid->kind == DECORATED) libdecor_frame_unset_maximized(xid->frame);
   else Fl_Window_Driver::un_maximize();
 }
+
+
+#if HAVE_XDG_ACTIVATION
+
+static void xdg_activation_done(void *data,
+                         struct xdg_activation_token_v1 *xdg_activation_token_v1,
+                         const char *token) {
+  Fl_Wayland_Screen_Driver *screen_driver = (Fl_Wayland_Screen_Driver*)Fl::screen_driver();
+  xdg_activation_v1_activate(screen_driver->xdg_activation, token, (struct wl_surface*)data);
+  xdg_activation_token_v1_destroy(xdg_activation_token_v1);
+}
+
+
+static struct xdg_activation_token_v1_listener xdg_activation_token_listener = {
+  .done = xdg_activation_done
+};
+
+#endif // HAVE_XDG_ACTIVATION
+
+
+/* This function lets one toplevel window, currently active, activate
+ another toplevel window given in its target parameter.
+ Wayland requires the "XDG activation" protocol for that.
+ This function also implements a fallback method used in absence of this protocol
+ which brings the target to front but doesn't activate it.
+ */
+void Fl_Wayland_Window_Driver::activate_(Fl_Window *target) {
+  struct wl_surface *target_surface = fl_wl_xid(target)->wl_surface;
+#if HAVE_XDG_ACTIVATION
+  Fl_Wayland_Screen_Driver *screen_driver = (Fl_Wayland_Screen_Driver*)Fl::screen_driver();
+  if (screen_driver->xdg_activation) {
+    struct xdg_activation_token_v1 *token = xdg_activation_v1_get_activation_token(screen_driver->xdg_activation);
+    const char *appid = pWindow->xclass() ? pWindow->xclass() : get_prog_name();
+    xdg_activation_token_v1_set_app_id(token, appid);
+    xdg_activation_token_v1_set_surface(token, fl_wl_xid(pWindow)->wl_surface);
+    xdg_activation_token_v1_set_serial(token, screen_driver->seat->serial,
+                                       screen_driver->seat->wl_seat);
+    xdg_activation_token_v1_add_listener(token, &xdg_activation_token_listener, target_surface);
+    xdg_activation_token_v1_commit(token);
+  } else
+#endif // HAVE_XDG_ACTIVATION
+  { // Fallback in absence of support of the adequate Wayland protocol.
+    // this will move the target window to the front
+    Fl_Wayland_Window_Driver *top_dr = Fl_Wayland_Window_Driver::driver(target);
+    xdg_toplevel_set_parent(top_dr->xdg_toplevel(), xdg_toplevel());
+    // this will remove the parent-child relationship
+    xdg_toplevel_set_parent(top_dr->xdg_toplevel(), NULL);
+    wl_surface_commit(target_surface);
+  }
+}