wayland: fix resizing and fullscreen toggling

For starters, we need to correctly respond to 0,0 configure after unsetting
fullscreen. Also, turns out that there should be no drawing calls at all
in between eglSwapBuffers and wl_egl_window_resize, as otherwise EGL can
already allocate a wrongly sized buffer for a next frame, so handle those
together.

src/video/wayland/SDL_waylandopengles.c

@@ -22,12 +22,17 @@
 
 #if SDL_VIDEO_DRIVER_WAYLAND && SDL_VIDEO_OPENGL_EGL
 
+#include "../SDL_sysvideo.h"
+#include "../../events/SDL_windowevents_c.h"
 #include "SDL_waylandvideo.h"
 #include "SDL_waylandopengles.h"
 #include "SDL_waylandwindow.h"
 #include "SDL_waylandevents_c.h"
 #include "SDL_waylanddyn.h"
 
+#include "xdg-shell-client-protocol.h"
+#include "xdg-shell-unstable-v6-client-protocol.h"
+
 /* EGL implementation of SDL OpenGL ES support */
 
 int
@@ -57,10 +62,37 @@ Wayland_GLES_CreateContext(_THIS, SDL_Window * window)
 int
 Wayland_GLES_SwapWindow(_THIS, SDL_Window *window)
 {
-    if (SDL_EGL_SwapBuffers(_this, ((SDL_WindowData *) window->driverdata)->egl_surface) < 0) {
+    SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
+    struct wl_region *region;
+
+    if (SDL_EGL_SwapBuffers(_this, data->egl_surface) < 0) {
         return -1;
     }
-    WAYLAND_wl_display_flush( ((SDL_VideoData*)_this->driverdata)->display );
+
+    // Wayland-EGL forbids drawing calls in-between SwapBuffers and wl_egl_window_resize
+    if (data->resize.pending) {
+        SDL_SendWindowEvent(window, SDL_WINDOWEVENT_RESIZED, data->resize.width, data->resize.height);
+        window->w = data->resize.width;
+        window->h = data->resize.height;
+
+        WAYLAND_wl_egl_window_resize(data->egl_window, window->w, window->h, 0, 0);
+
+        if (data->waylandData->shell.xdg) {
+           xdg_surface_ack_configure(data->shell_surface.xdg.surface, data->resize.serial);
+        } else if (data->waylandData->shell.zxdg) {
+           zxdg_surface_v6_ack_configure(data->shell_surface.zxdg.surface, data->resize.serial);
+        }
+
+        region = wl_compositor_create_region(data->waylandData->compositor);
+        wl_region_add(region, 0, 0, window->w, window->h);
+        wl_surface_set_opaque_region(data->surface, region);
+        wl_region_destroy(region);
+
+        data->resize.pending = SDL_FALSE;
+    }
+
+    WAYLAND_wl_display_flush( data->waylandData->display );
+
     return 0;
 }
 

src/video/wayland/SDL_waylandwindow.c

@@ -55,7 +55,6 @@ handle_configure_wl_shell_surface(void *data, struct wl_shell_surface *shell_sur
 {
     SDL_WindowData *wind = (SDL_WindowData *)data;
     SDL_Window *window = wind->sdlwindow;
-    struct wl_region *region;
 
     /* wl_shell_surface spec states that this is a suggestion.
        Ignore if less than or greater than max/min size. */
@@ -80,15 +79,9 @@ handle_configure_wl_shell_surface(void *data, struct wl_shell_surface *shell_sur
         }
     }
 
-    WAYLAND_wl_egl_window_resize(wind->egl_window, width, height, 0, 0);
-    region = wl_compositor_create_region(wind->waylandData->compositor);
-    wl_region_add(region, 0, 0, width, height);
-    wl_surface_set_opaque_region(wind->surface, region);
-    wl_region_destroy(region);
-
-    SDL_SendWindowEvent(window, SDL_WINDOWEVENT_RESIZED, width, height);
-    window->w = width;
-    window->h = height;
+    wind->resize.width = width;
+    wind->resize.height = height;
+    wind->resize.pending = SDL_TRUE;
 }
 
 static void
@@ -112,15 +105,25 @@ handle_configure_zxdg_shell_surface(void *data, struct zxdg_surface_v6 *zxdg, ui
     SDL_Window *window = wind->sdlwindow;
     struct wl_region *region;
 
-    wind->shell_surface.zxdg.initial_configure_seen = SDL_TRUE;
+    if (!wind->shell_surface.zxdg.initial_configure_seen) {
+        SDL_SendWindowEvent(window, SDL_WINDOWEVENT_RESIZED, wind->resize.width, wind->resize.height);
+        window->w = wind->resize.width;
+        window->h = wind->resize.height;
 
         WAYLAND_wl_egl_window_resize(wind->egl_window, window->w, window->h, 0, 0);
 
+        zxdg_surface_v6_ack_configure(zxdg, serial);
+
         region = wl_compositor_create_region(wind->waylandData->compositor);
         wl_region_add(region, 0, 0, window->w, window->h);
         wl_surface_set_opaque_region(wind->surface, region);
         wl_region_destroy(region);
-    zxdg_surface_v6_ack_configure(zxdg, serial);
+
+        wind->shell_surface.zxdg.initial_configure_seen = SDL_TRUE;
+    } else {
+        wind->resize.pending = SDL_TRUE;
+        wind->resize.serial = serial;
+    }
 }
 
 static const struct zxdg_surface_v6_listener shell_surface_listener_zxdg = {
@@ -138,14 +141,23 @@ handle_configure_zxdg_toplevel(void *data,
     SDL_WindowData *wind = (SDL_WindowData *)data;
     SDL_Window *window = wind->sdlwindow;
 
-    /* wl_shell_surface spec states that this is a suggestion.
-       Ignore if less than or greater than max/min size. */
-
-    if (width == 0 || height == 0) {
-        return;
+    enum zxdg_toplevel_v6_state *state;
+    SDL_bool fullscreen = SDL_FALSE;
+    wl_array_for_each(state, states) {
+        if (*state == ZXDG_TOPLEVEL_V6_STATE_FULLSCREEN) {
+            fullscreen = SDL_TRUE;
+        }
     }
 
-    if (!(window->flags & SDL_WINDOW_FULLSCREEN)) {
+    if (!fullscreen) {
+        if (width == 0 || height == 0) {
+            width = window->windowed.w;
+            height = window->windowed.h;
+        }
+
+        /* zxdg_toplevel spec states that this is a suggestion.
+           Ignore if less than or greater than max/min size. */
+
         if ((window->flags & SDL_WINDOW_RESIZABLE)) {
             if (window->max_w > 0) {
                 width = SDL_min(width, window->max_w);
@@ -157,13 +169,20 @@ handle_configure_zxdg_toplevel(void *data,
             }
             height = SDL_max(height, window->min_h);
         } else {
+            wind->resize.width = window->w;
+            wind->resize.height = window->h;
             return;
         }
     }
 
-    SDL_SendWindowEvent(window, SDL_WINDOWEVENT_RESIZED, width, height);
-    window->w = width;
-    window->h = height;
+    if (width == 0 || height == 0) {
+        wind->resize.width = window->w;
+        wind->resize.height = window->h;
+        return;
+    }
+
+    wind->resize.width = width;
+    wind->resize.height = height;
 }
 
 static void
@@ -187,15 +206,25 @@ handle_configure_xdg_shell_surface(void *data, struct xdg_surface *xdg, uint32_t
     SDL_Window *window = wind->sdlwindow;
     struct wl_region *region;
 
-    wind->shell_surface.xdg.initial_configure_seen = SDL_TRUE;
+    if (!wind->shell_surface.xdg.initial_configure_seen) {
+        SDL_SendWindowEvent(window, SDL_WINDOWEVENT_RESIZED, wind->resize.width, wind->resize.height);
+        window->w = wind->resize.width;
+        window->h = wind->resize.height;
 
         WAYLAND_wl_egl_window_resize(wind->egl_window, window->w, window->h, 0, 0);
 
+        xdg_surface_ack_configure(xdg, serial);
+
         region = wl_compositor_create_region(wind->waylandData->compositor);
         wl_region_add(region, 0, 0, window->w, window->h);
         wl_surface_set_opaque_region(wind->surface, region);
         wl_region_destroy(region);
-    xdg_surface_ack_configure(xdg, serial);
+
+        wind->shell_surface.xdg.initial_configure_seen = SDL_TRUE;
+    } else {
+        wind->resize.pending = SDL_TRUE;
+        wind->resize.serial = serial;
+    }
 }
 
 static const struct xdg_surface_listener shell_surface_listener_xdg = {
@@ -213,14 +242,23 @@ handle_configure_xdg_toplevel(void *data,
     SDL_WindowData *wind = (SDL_WindowData *)data;
     SDL_Window *window = wind->sdlwindow;
 
-    /* wl_shell_surface spec states that this is a suggestion.
-       Ignore if less than or greater than max/min size. */
-
-    if (width == 0 || height == 0) {
-        return;
+    enum xdg_toplevel_state *state;
+    SDL_bool fullscreen = SDL_FALSE;
+    wl_array_for_each(state, states) {
+        if (*state == XDG_TOPLEVEL_STATE_FULLSCREEN) {
+            fullscreen = SDL_TRUE;
+        }
      }
 
-    if (!(window->flags & SDL_WINDOW_FULLSCREEN)) {
+    if (!fullscreen) {
+        if (width == 0 || height == 0) {
+            width = window->windowed.w;
+            height = window->windowed.h;
+        }
+
+        /* xdg_toplevel spec states that this is a suggestion.
+           Ignore if less than or greater than max/min size. */
+
         if ((window->flags & SDL_WINDOW_RESIZABLE)) {
             if (window->max_w > 0) {
                 width = SDL_min(width, window->max_w);
@@ -232,17 +270,20 @@ handle_configure_xdg_toplevel(void *data,
             }
             height = SDL_max(height, window->min_h);
         } else {
+            wind->resize.width = window->w;
+            wind->resize.height = window->h;
             return;
         }
     }
 
-    if (width == window->w && height == window->h) {
+    if (width == 0 || height == 0) {
+        wind->resize.width = window->w;
+        wind->resize.height = window->h;
         return;
     }
 
-    SDL_SendWindowEvent(window, SDL_WINDOWEVENT_RESIZED, width, height);
-    window->w = width;
-    window->h = height;
+    wind->resize.width = width;
+    wind->resize.height = height;
 }
 
 static void
@@ -508,6 +549,8 @@ int Wayland_CreateWindow(_THIS, SDL_Window *window)
     data->waylandData = c;
     data->sdlwindow = window;
 
+    data->resize.pending = SDL_FALSE;
+
     data->surface =
         wl_compositor_create_surface(c->compositor);
     wl_surface_set_user_data(data->surface, data);

src/video/wayland/SDL_waylandwindow.h

@@ -67,6 +67,12 @@ typedef struct {
 #ifdef SDL_VIDEO_DRIVER_WAYLAND_QT_TOUCH
     struct qt_extended_surface *extended_surface;
 #endif /* SDL_VIDEO_DRIVER_WAYLAND_QT_TOUCH */
+
+    struct {
+        SDL_bool pending;
+        uint32_t serial;
+        int width, height;
+    } resize;
 } SDL_WindowData;
 
 extern void Wayland_ShowWindow(_THIS, SDL_Window *window);