tests/wayland-client-utils: Add simple toplevel helper

Add a helper to create a toplevel painted with a given color, size and
title. It's meant to be "dumb" and have a default size, but respect any
configured size.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2770>

src/tests/wayland-test-clients/wayland-test-client-utils.c

@@ -381,6 +381,94 @@ draw_surface (WaylandDisplay    *display,
   wl_surface_attach (surface, buffer, 0, 0);
 }
 
+static void
+handle_xdg_toplevel_configure (void                *data,
+                               struct xdg_toplevel *xdg_toplevel,
+                               int32_t              width,
+                               int32_t              height,
+                               struct wl_array     *state)
+{
+  WaylandSurface *surface = data;
+
+  if (width == 0)
+    surface->width = surface->default_width;
+  else
+    surface->width = width;
+
+  if (height == 0)
+    surface->height = surface->default_height;
+  else
+    surface->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
+handle_xdg_surface_configure (void               *data,
+                              struct xdg_surface *xdg_surface,
+                              uint32_t            serial)
+{
+  WaylandSurface *surface = data;
+
+  draw_surface (surface->display,
+                surface->wl_surface,
+                surface->width, surface->height,
+                surface->color);
+
+  xdg_surface_ack_configure (xdg_surface, serial);
+  wl_surface_commit (surface->wl_surface);
+}
+
+static const struct xdg_surface_listener xdg_surface_listener = {
+  handle_xdg_surface_configure,
+};
+
+WaylandSurface *
+wayland_surface_new (WaylandDisplay *display,
+                     const char     *title,
+                     int             default_width,
+                     int             default_height,
+                     uint32_t        color)
+{
+  WaylandSurface *surface;
+
+  surface = g_new0 (WaylandSurface, 1);
+  surface->display = display;
+  surface->default_width = default_width;
+  surface->default_height = default_height;
+  surface->color = color;
+  surface->wl_surface = wl_compositor_create_surface (display->compositor);
+  surface->xdg_surface = xdg_wm_base_get_xdg_surface (display->xdg_wm_base,
+                                                      surface->wl_surface);
+  xdg_surface_add_listener (surface->xdg_surface, &xdg_surface_listener,
+                            surface);
+  surface->xdg_toplevel = xdg_surface_get_toplevel (surface->xdg_surface);
+  xdg_toplevel_add_listener (surface->xdg_toplevel, &xdg_toplevel_listener,
+                             surface);
+  xdg_toplevel_set_title (surface->xdg_toplevel, title);
+
+  return surface;
+}
+
+void
+wayland_surface_free (WaylandSurface *surface)
+{
+  g_clear_pointer (&surface->xdg_toplevel, xdg_toplevel_destroy);
+  g_clear_pointer (&surface->xdg_surface, xdg_surface_destroy);
+  g_clear_pointer (&surface->wl_surface, wl_surface_destroy);
+  g_free (surface);
+}
+
 const char *
 lookup_property_value (WaylandDisplay *display,
                        const char     *name)

src/tests/wayland-test-clients/wayland-test-client-utils.h

@@ -36,6 +36,22 @@ typedef struct _WaylandDisplay
   GHashTable *properties;
 } WaylandDisplay;
 
+typedef struct _WaylandSurface
+{
+  WaylandDisplay *display;
+
+  struct wl_surface *wl_surface;
+  struct xdg_surface *xdg_surface;
+  struct xdg_toplevel *xdg_toplevel;
+
+  int default_width;
+  int default_height;
+  int width;
+  int height;
+
+  uint32_t color;
+} WaylandSurface;
+
 G_DECLARE_FINAL_TYPE (WaylandDisplay, wayland_display,
                       WAYLAND, DISPLAY,
                       GObject)
@@ -44,6 +60,14 @@ int create_anonymous_file (off_t size);
 
 WaylandDisplay * wayland_display_new (WaylandDisplayCapabilities capabilities);
 
+WaylandSurface * wayland_surface_new (WaylandDisplay *display,
+                                      const char     *title,
+                                      int             default_width,
+                                      int             default_height,
+                                      uint32_t        color);
+
+void wayland_surface_free (WaylandSurface *surface);
+
 gboolean create_shm_buffer (WaylandDisplay    *display,
                             int                width,
                             int                height,