test/wayland: Add subsurface-corner-cases unit test

It tests various sub-surface corner cases. It would fail without the
previous fixes.

v2:
* Fix draw_descendant parameter formatting
* Make toplevel window fullscreen (Robert Mader)

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3364>

src/tests/wayland-test-clients/meson.build

@@ -24,6 +24,9 @@ wayland_test_clients = [
   {
     'name': 'single-pixel-buffer',
   },
+  {
+    'name': 'subsurface-corner-cases',
+  },
   {
     'name': 'subsurface-remap-toplevel',
   },

src/tests/wayland-test-clients/subsurface-corner-cases.c

@@ -0,0 +1,275 @@
+/*
+ * Copyright (C) 2023 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib.h>
+#include <wayland-client.h>
+
+#include "wayland-test-client-utils.h"
+
+static WaylandDisplay *display;
+static struct wl_surface *toplevel_surface, *child_surface, *grandchild_surface;
+static struct wl_subsurface *child, *grandchild;
+static struct xdg_surface *xdg_surface;
+static struct xdg_toplevel *xdg_toplevel;
+
+static gboolean waiting_for_configure = FALSE;
+static gboolean fullscreen = 0;
+static uint32_t window_width = 0;
+static uint32_t window_height = 0;
+
+static void
+handle_xdg_toplevel_configure (void                *data,
+                               struct xdg_toplevel *xdg_toplevel,
+                               int32_t              width,
+                               int32_t              height,
+                               struct wl_array     *states)
+{
+  uint32_t *p;
+
+  fullscreen = 0;
+  wl_array_for_each(p, states)
+    {
+      uint32_t state = *p;
+
+      switch (state)
+        {
+        case XDG_TOPLEVEL_STATE_FULLSCREEN:
+          fullscreen = 1;
+          break;
+        }
+    }
+
+  if (width > 0 && height > 0)
+    {
+      window_width = width;
+      window_height = height;
+    }
+}
+
+static void
+handle_xdg_toplevel_close(void                *data,
+                          struct xdg_toplevel *xdg_toplevel)
+{
+  g_assert_not_reached ();
+}
+
+static const struct xdg_toplevel_listener xdg_toplevel_listener = {
+  handle_xdg_toplevel_configure,
+  handle_xdg_toplevel_close,
+};
+
+static void
+draw_toplevel (void)
+{
+  struct wl_buffer *buffer;
+  void *buffer_data;
+  int size;
+  uint32_t *pixels;
+
+  if (!create_shm_buffer (display, window_width, window_height,
+                          &buffer, &buffer_data, &size))
+    g_error ("Failed to create shm buffer");
+
+  for (pixels = buffer_data; size > 0; size -= 4)
+    *pixels++ = 0xffffffffu;
+
+  wl_surface_attach (toplevel_surface, buffer, 0, 0);
+}
+
+static void
+handle_xdg_surface_configure (void               *data,
+                              struct xdg_surface *xdg_surface,
+                              uint32_t            serial)
+{
+  xdg_surface_ack_configure (xdg_surface, serial);
+
+  waiting_for_configure = FALSE;
+}
+
+static const struct xdg_surface_listener xdg_surface_listener = {
+  handle_xdg_surface_configure,
+};
+
+static void
+draw_descendant (struct wl_surface *descendant,
+                 uint32_t           color)
+{
+  struct wl_buffer *buffer;
+  void *buffer_data;
+  int size;
+  uint32_t *pixels;
+
+  if (!create_shm_buffer (display, window_width / 2, window_height / 2,
+                          &buffer, &buffer_data, &size))
+    g_error ("Failed to create shm buffer");
+
+  for (pixels = buffer_data; size > 0; size -= 4)
+    *pixels++ = color;
+
+  wl_surface_attach (descendant, buffer, 0, 0);
+}
+
+static void
+draw_child (void)
+{
+  draw_descendant (child_surface, 0xff000000u);
+}
+
+static void
+draw_grandchild (void)
+{
+  draw_descendant (grandchild_surface, 0xffff0000u);
+}
+
+static void
+wait_for_configure (void)
+{
+  waiting_for_configure = TRUE;
+  while (waiting_for_configure || window_width == 0)
+    {
+      if (wl_display_dispatch (display->display) == -1)
+        exit (EXIT_FAILURE);
+    }
+}
+
+int
+main (int    argc,
+      char **argv)
+{
+  display = wayland_display_new (WAYLAND_DISPLAY_CAPABILITY_TEST_DRIVER);
+
+  toplevel_surface = wl_compositor_create_surface (display->compositor);
+  xdg_surface = xdg_wm_base_get_xdg_surface (display->xdg_wm_base, toplevel_surface);
+  xdg_surface_add_listener (xdg_surface, &xdg_surface_listener, NULL);
+  xdg_toplevel = xdg_surface_get_toplevel (xdg_surface);
+  xdg_toplevel_add_listener (xdg_toplevel, &xdg_toplevel_listener, NULL);
+  xdg_toplevel_set_title (xdg_toplevel, "subsurface-corner-cases");
+
+  xdg_toplevel_set_fullscreen (xdg_toplevel, NULL);
+  wl_surface_commit (toplevel_surface);
+  wait_for_configure ();
+
+  draw_toplevel ();
+  wl_surface_commit (toplevel_surface);
+  wait_for_effects_completed (display, toplevel_surface);
+
+  child_surface = wl_compositor_create_surface (display->compositor);
+  child = wl_subcompositor_get_subsurface (display->subcompositor,
+                                           child_surface,
+                                           toplevel_surface);
+  draw_child ();
+  wl_surface_commit (child_surface);
+  /* No toplevel commit → sub-surface must not be mapped yet */
+  wait_for_view_verified (display, 0);
+
+  wl_surface_commit (toplevel_surface);
+  /* Toplevel commit → sub-surface must be mapped */
+  wait_for_view_verified (display, 1);
+
+  wl_subsurface_set_position (child, window_width / 2, window_height / 2);
+  /* No toplevel commit → sub-surface must not have moved yet */
+  wait_for_view_verified (display, 2);
+
+  wl_surface_commit (toplevel_surface);
+  /* Toplevel commit → sub-surface must have moved */
+  wait_for_view_verified (display, 3);
+
+  wl_surface_attach (child_surface, NULL, 0, 0);
+  wl_surface_commit (child_surface);
+  /* No toplevel commit → sub-surface must not be unmapped yet */
+  wait_for_view_verified (display, 4);
+
+  wl_surface_commit (toplevel_surface);
+  /* Toplevel commit → sub-surface must be unmapped */
+  wait_for_view_verified (display, 5);
+
+  draw_child ();
+  wl_surface_commit (child_surface);
+  wl_subsurface_set_desync (child);
+  wl_surface_attach (child_surface, NULL, 0, 0);
+  wl_surface_commit (child_surface);
+  /* Desync sub-surface must have been unmapped */
+  wait_for_view_verified (display, 6);
+
+  draw_child ();
+  wl_surface_commit (child_surface);
+  wl_subsurface_set_sync (child);
+  wl_subsurface_destroy (child);
+  /* Sub-surface destroyed → must be unmapped */
+  wait_for_view_verified (display, 7);
+
+  child = wl_subcompositor_get_subsurface (display->subcompositor,
+                                           child_surface,
+                                           toplevel_surface);
+  draw_child ();
+  wl_surface_commit (child_surface);
+  /* No toplevel commit → sub-surface must not be mapped yet */
+  wait_for_view_verified (display, 8);
+
+  wl_surface_commit (toplevel_surface);
+  /* Sub-surface position must have reset to (0, 0) */
+  wait_for_view_verified (display, 9);
+
+  wl_subsurface_place_below (child, toplevel_surface);
+  /* No toplevel commit → sub-surface must still be above toplevel */
+  wait_for_view_verified (display, 10);
+
+  wl_subsurface_destroy (child);
+  child = wl_subcompositor_get_subsurface (display->subcompositor,
+                                           child_surface,
+                                           toplevel_surface);
+  draw_child ();
+  wl_surface_commit (child_surface);
+  wl_surface_commit (toplevel_surface);
+  /* New sub-surface → placement below toplevel must not have taken effect */
+  wait_for_view_verified (display, 11);
+
+  grandchild_surface = wl_compositor_create_surface (display->compositor);
+  grandchild = wl_subcompositor_get_subsurface (display->subcompositor,
+                                                grandchild_surface,
+                                                child_surface);
+  draw_grandchild ();
+  wl_subsurface_set_position (grandchild, window_width / 4, window_height / 4);
+  wl_surface_commit (grandchild_surface);
+  wl_surface_commit (child_surface);
+  /* No toplevel commit → grand-child surface must not be mapped yet */
+  wait_for_view_verified (display, 12);
+
+  wl_surface_commit (toplevel_surface);
+  /* Toplevel commit → grand-child surface must be mapped */
+  wait_for_view_verified (display, 13);
+
+  wl_subsurface_place_below (grandchild, child_surface);
+  wl_surface_commit (child_surface);
+  wl_subsurface_destroy (grandchild);
+  grandchild = wl_subcompositor_get_subsurface (display->subcompositor,
+                                                grandchild_surface,
+                                                child_surface);
+  draw_grandchild ();
+  wl_subsurface_set_position (grandchild, window_width / 4, window_height / 4);
+  wl_surface_commit (grandchild_surface);
+  wl_surface_commit (child_surface);
+  wl_surface_commit (toplevel_surface);
+  /* New grandchild must be placed above its parent */
+  wait_for_view_verified (display, 14);
+
+  g_clear_object (&display);
+
+  return EXIT_SUCCESS;
+}

src/tests/wayland-unit-tests.c

@@ -77,6 +77,16 @@ single_pixel_buffer (void)
   meta_wayland_test_client_finish (wayland_test_client);
 }
 
+static void
+subsurface_corner_cases (void)
+{
+  MetaWaylandTestClient *wayland_test_client;
+
+  wayland_test_client =
+    meta_wayland_test_client_new (test_context, "subsurface-corner-cases");
+  meta_wayland_test_client_finish (wayland_test_client);
+}
+
 static void
 subsurface_reparenting (void)
 {
@@ -853,6 +863,8 @@ init_tests (void)
                    subsurface_invalid_subsurfaces);
   g_test_add_func ("/wayland/subsurface/invalid-xdg-shell-actions",
                    subsurface_invalid_xdg_shell_actions);
+  g_test_add_func ("/wayland/subsurface/corner-cases",
+                   subsurface_corner_cases);
   g_test_add_func ("/wayland/subsurface/parent-unmapped",
                    subsurface_parent_unmapped);
   g_test_add_func ("/wayland/toplevel/apply-limits",