Hybrid Wayland/X11 platform: improve control of chosen backend.

FL/Fl.H

@@ -61,6 +61,8 @@ extern FL_EXPORT const char* fl_local_ctrl;  ///< string pointer used in shortcu
 extern FL_EXPORT const char* fl_local_meta;  ///< string pointer used in shortcuts, you can change it to another language
 extern FL_EXPORT const char* fl_local_shift; ///< string pointer used in shortcuts, you can change it to another language
 
+extern FL_EXPORT void fl_disable_wayland();
+
 /** \defgroup  callback_functions  Callback Function Typedefs
 
   \brief Typedefs defined in <FL/Fl.H> for callback or handler functions passed as function parameters.

FL/platform.H

@@ -76,6 +76,5 @@ extern FL_EXPORT void fl_close_display();
 extern FL_EXPORT Window fl_window;
 extern FL_EXPORT int fl_parse_color(const char* p, uchar& r, uchar& g, uchar& b);
 extern FL_EXPORT void fl_open_callback(void (*)(const char *));
-extern FL_EXPORT void fl_disable_wayland();
 
 #endif // !FL_PLATFORM_H

src/Fl.cxx

@@ -2016,8 +2016,8 @@ void fl_close_display()
 }
 
 /** Prevent the FLTK library from using its wayland backend.
- Call this early in your main(), before fl_open_display() runs.
- This has no effect on non-Wayland platforms.
+ Call this early in your main(), before fl_open_display() runs, or any window is created, or the screen is accessed.
+ This function has no effect on non-Wayland platforms.
  */
 void fl_disable_wayland()
 {

src/drivers/Wayland/Fl_Wayland_Screen_Driver.H

@@ -66,8 +66,6 @@ public:
   static FL_EXPORT struct wl_display *wl_display;
   // use it to make sure the Wayland leg was selected and fl_open_display() has run
   static struct wl_registry *wl_registry;
-  // true when an app is forbidden to use its Wayland leg
-  static bool wld_disabled;
   static void insertion_point_location(int x, int y, int height);
   static bool insertion_point_location(int *px, int *py, int *pwidth, int *pheight);
   int get_mouse_unscaled(int &xx, int &yy);
@@ -176,6 +174,7 @@ public:
   static compositor_name compositor; // identifies the used Wayland compositor
   void set_spot(int font, int height, int x, int y, int w, int h, Fl_Window *win);
   void reset_spot();
+  static bool undo_wayland_backend_if_needed();
 };
 
 

src/drivers/Wayland/Fl_Wayland_Screen_Driver.cxx

@@ -230,8 +230,6 @@ struct wl_display *Fl_Wayland_Screen_Driver::wl_display = NULL;
 struct wl_registry *Fl_Wayland_Screen_Driver::wl_registry = NULL;
 
 
-bool Fl_Wayland_Screen_Driver::wld_disabled = false;
-
 Fl_Window *Fl_Wayland_Screen_Driver::surface_to_window(struct wl_surface *surface) {
   if (surface) {
     Fl_X *xp = Fl_X::first;
@@ -1089,12 +1087,31 @@ Fl_Wayland_Screen_Driver::Fl_Wayland_Screen_Driver() : Fl_Screen_Driver() {
   reset_cursor();
 }
 
+
+bool Fl_Wayland_Screen_Driver::undo_wayland_backend_if_needed() {
+  const char *backend = getenv("FLTK_BACKEND");
+  if (wl_display && backend && strcmp(backend, "x11") == 0) {
+    wl_display_disconnect(wl_display);
+    wl_display = NULL;
+    delete Fl_Screen_Driver::system_driver;
+    Fl_Screen_Driver::system_driver = NULL;
+    return true;
+  }
+  return false;
+}
+
+
 void Fl_Wayland_Screen_Driver::open_display_platform() {
   static bool beenHereDoneThat = false;
   if (beenHereDoneThat)
     return;
 
   beenHereDoneThat = true;
+  if (undo_wayland_backend_if_needed()) {
+    Fl::screen_driver()->open_display();
+    return;
+  }
+  
   if (!wl_display) {
     wl_display = wl_display_connect(NULL);
     if (!wl_display) {
@@ -1116,6 +1133,8 @@ void Fl_Wayland_Screen_Driver::open_display_platform() {
   }*/
   Fl::add_fd(wl_display_get_fd(wl_display), FL_READ, (Fl_FD_Handler)fd_callback, wl_display);
   fl_create_print_window();
+  Fl_Wayland_System_Driver::too_late_to_disable = true;
+puts("Using Wayland backend");
 }
 
 void Fl_Wayland_Screen_Driver::close_display() {

src/drivers/Wayland/Fl_Wayland_System_Driver.H

@@ -27,6 +27,7 @@ public:
   int get_key(int k);
   virtual void *control_maximize_button(void *data);
   virtual void disable_wayland();
+  static bool too_late_to_disable;
 };
 
 #endif /* FL_WAYLAND_SYSTEM_DRIVER_H */

src/drivers/Wayland/Fl_Wayland_System_Driver.cxx

@@ -21,6 +21,10 @@
 #include "Fl_Wayland_Screen_Driver.H"
 #include <FL/platform.H>
 #include "../../../libdecor/src/libdecor.h"
+#include <stdlib.h>
+
+
+bool Fl_Wayland_System_Driver::too_late_to_disable = false;
 
 
 int Fl_Wayland_System_Driver::event_key(int k) {
@@ -91,18 +95,12 @@ void *Fl_Wayland_System_Driver::control_maximize_button(void *data) {
 
 
 void Fl_Wayland_System_Driver::disable_wayland() {
-  if (fl_wl_display()) {
+  if (too_late_to_disable) {
     fprintf(stderr, "Error: fl_disable_wayland() cannot be called "
-            "after the Wayland display was opened\n");
+            "after the Wayland display was opened\n"
+            "or a Wayland window was created or the Wayland screen was accessed\n");
     exit(1);
   }
-
-  if (Fl_Wayland_Screen_Driver::wl_display) {
-    wl_display_disconnect(Fl_Wayland_Screen_Driver::wl_display);
-    Fl_Wayland_Screen_Driver::wl_display = NULL;
-    delete Fl_Screen_Driver::system_driver;
-    Fl_Screen_Driver::system_driver = NULL;
-  }
-  Fl_Wayland_Screen_Driver::wld_disabled = true;
-  Fl::system_driver();
+  setenv("FLTK_BACKEND", "x11", 1);
+  Fl_Wayland_Screen_Driver::undo_wayland_backend_if_needed();
 }

src/drivers/Wayland/fl_wayland_platform_init.cxx

@@ -41,8 +41,7 @@ Fl_System_Driver *Fl_System_Driver::newSystemDriver() {
   // fprintf(stderr, "FLTK_BACKEND='%s' XDG_RUNTIME_DIR='%s'\n",
   //         backend ? backend : "", xdgrt ? xdgrt : "");
 
-  if (Fl_Wayland_Screen_Driver::wld_disabled ||
-      (backend && strcmp(backend, "x11") == 0)) {
+  if (backend && strcmp(backend, "x11") == 0) {
     return new Fl_X11_System_Driver();
   }
 
@@ -100,12 +99,11 @@ FL_EXPORT Fl_Fontdesc *fl_fonts = built_in_table;
 
 
 Fl_Graphics_Driver *Fl_Graphics_Driver::newMainGraphicsDriver() {
+  Fl_Wayland_Screen_Driver::undo_wayland_backend_if_needed();
   if (Fl_Wayland_Screen_Driver::wl_display) {
     fl_graphics_driver = new Fl_Wayland_Graphics_Driver();
-puts("using Fl_Wayland_Graphics_Driver");
   } else {
     fl_graphics_driver = new Fl_Display_Cairo_Graphics_Driver();
-puts("using Fl_Display_Cairo_Graphics_Driver");
   }
   return fl_graphics_driver;
 }
@@ -118,7 +116,12 @@ Fl_Copy_Surface_Driver *Fl_Copy_Surface_Driver::newCopySurfaceDriver(int w, int
 
 
 Fl_Screen_Driver *Fl_Screen_Driver::newScreenDriver() {
-  if (Fl_Wayland_Screen_Driver::wl_display) return new Fl_Wayland_Screen_Driver();
+  if (!Fl_Screen_Driver::system_driver) Fl::system_driver();
+  Fl_Wayland_Screen_Driver::undo_wayland_backend_if_needed();
+  if (Fl_Wayland_Screen_Driver::wl_display) {
+    Fl_Wayland_System_Driver::too_late_to_disable = true;
+    return new Fl_Wayland_Screen_Driver();
+  }
 
   Fl_X11_Screen_Driver *d = new Fl_X11_Screen_Driver();
   for (int i = 0;  i < MAX_SCREENS; i++) d->screens[i].scale = 1;
@@ -129,6 +132,13 @@ Fl_Screen_Driver *Fl_Screen_Driver::newScreenDriver() {
 
 Fl_Window_Driver *Fl_Window_Driver::newWindowDriver(Fl_Window *w)
 {
+  if (!Fl_Screen_Driver::system_driver) Fl::system_driver();
+  static bool been_here = false;
+  if (!been_here) {
+    been_here = true;
+    Fl_Wayland_System_Driver::too_late_to_disable = true;
+    Fl_Wayland_Screen_Driver::undo_wayland_backend_if_needed();
+  }
   if (Fl_Wayland_Screen_Driver::wl_display) return new Fl_Wayland_Window_Driver(w);
   return new Fl_X11_Window_Driver(w);
 }