compositor: add weston_surface_set_label_func()

When printing out logs from Weston's actions, mainly for debugging, it
can be very difficult to identify the different surfaces.  Inspecting
the configure function pointer is not useful, as the configure functions
may live in modules.

Add vfunc get_label to weston_surface, which will produce a short,
human-readable description of the surface, which allows identifying it
better, rather than just looking at the surface size, for instance.

Set the label function from most parts of Weston, to identify cursors and
drag icons, and panels, backgrounds, screensavers and lock surfaces, and
the desktop shell's application surfaces.

v2: renamed 'description' to 'label', so we get
	weston_surface_set_label_func().

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

6 files changed, 153 insertions, 0 deletions

diff --git a/desktop-shell/input-panel.c b/desktop-shell/input-panel.c
index 0b42c2fe..ffa3ade1 100644
--- a/desktop-shell/input-panel.c
+++ b/desktop-shell/input-panel.c
@@ -150,6 +150,12 @@ update_input_panels(struct wl_listener *listener, void *data)
 	memcpy(&shell->text_input.cursor_rectangle, data, sizeof(pixman_box32_t));
 }
 
+static int
+input_panel_get_label(struct weston_surface *surface, char *buf, size_t len)
+{
+	return snprintf(buf, len, "input panel");
+}
+
 static void
 input_panel_configure(struct weston_surface *surface, int32_t sx, int32_t sy)
 {
@@ -187,6 +193,7 @@ destroy_input_panel_surface(struct input_panel_surface *input_panel_surface)
 	wl_list_remove(&input_panel_surface->link);
 
 	input_panel_surface->surface->configure = NULL;
+	weston_surface_set_label_func(input_panel_surface->surface, NULL);
 	weston_view_destroy(input_panel_surface->view);
 
 	free(input_panel_surface);
@@ -228,6 +235,7 @@ create_input_panel_surface(struct desktop_shell *shell,
 
 	surface->configure = input_panel_configure;
 	surface->configure_private = input_panel_surface;
+	weston_surface_set_label_func(surface, input_panel_get_label);
 
 	input_panel_surface->shell = shell;
 
diff --git a/desktop-shell/shell.c b/desktop-shell/shell.c
index 9e8d45a4..b6f5f783 100644
--- a/desktop-shell/shell.c
+++ b/desktop-shell/shell.c
@@ -274,6 +274,31 @@ static void
 shell_surface_set_parent(struct shell_surface *shsurf,
                          struct weston_surface *parent);
 
+static int
+shell_surface_get_label(struct weston_surface *surface, char *buf, size_t len)
+{
+	struct shell_surface *shsurf;
+	const char *typestr[] = {
+		[SHELL_SURFACE_NONE] = "unidentified",
+		[SHELL_SURFACE_TOPLEVEL] = "top-level",
+		[SHELL_SURFACE_POPUP] = "popup",
+		[SHELL_SURFACE_XWAYLAND] = "Xwayland",
+	};
+	const char *t, *c;
+
+	shsurf = get_shell_surface(surface);
+	if (!shsurf)
+		return snprintf(buf, len, "unidentified window");
+
+	t = shsurf->title;
+	c = shsurf->class;
+
+	return snprintf(buf, len, "%s window%s%s%s%s%s",
+		typestr[shsurf->type],
+		t ? " '" : "", t ?: "", t ? "'" : "",
+		c ? " of " : "", c ?: "");
+}
+
 static bool
 shell_surface_is_top_fullscreen(struct shell_surface *shsurf)
 {
@@ -634,6 +659,12 @@ get_default_output(struct weston_compositor *compositor)
 			    struct weston_output, link);
 }
 
+static int
+focus_surface_get_label(struct weston_surface *surface, char *buf, size_t len)
+{
+	return snprintf(buf, len, "focus highlight effect for output %s",
+			surface->output->name);
+}
 
 /* no-op func for checking focus surface */
 static void
@@ -683,6 +714,7 @@ create_focus_surface(struct weston_compositor *ec,
 	surface->configure = focus_surface_configure;
 	surface->output = output;
 	surface->configure_private = fsurf;
+	weston_surface_set_label_func(surface, focus_surface_get_label);
 
 	fsurf->view = weston_view_create(surface);
 	if (fsurf->view == NULL) {
@@ -2741,6 +2773,33 @@ shell_surface_get_shell(struct shell_surface *shsurf)
 	return shsurf->shell;
 }
 
+static int
+black_surface_get_label(struct weston_surface *surface, char *buf, size_t len)
+{
+	struct weston_surface *fs_surface = surface->configure_private;
+	int n;
+	int rem;
+	int ret;
+
+	n = snprintf(buf, len, "black background surface for ");
+	if (n < 0)
+		return n;
+
+	rem = (int)len - n;
+	if (rem < 0)
+		rem = 0;
+
+	if (fs_surface->get_label)
+		ret = fs_surface->get_label(fs_surface, buf + n, rem);
+	else
+		ret = snprintf(buf + n, rem, "<unknown>");
+
+	if (ret < 0)
+		return n;
+
+	return n + ret;
+}
+
 static void
 black_surface_configure(struct weston_surface *es, int32_t sx, int32_t sy);
 
@@ -2766,6 +2825,7 @@ create_black_surface(struct weston_compositor *ec,
 
 	surface->configure = black_surface_configure;
 	surface->configure_private = fs_surface;
+	weston_surface_set_label_func(surface, black_surface_get_label);
 	weston_surface_set_color(surface, 0.0, 0.0, 0.0, 1);
 	pixman_region32_fini(&surface->opaque);
 	pixman_region32_init_rect(&surface->opaque, 0, 0, w, h);
@@ -3373,6 +3433,7 @@ destroy_shell_surface(struct shell_surface *shsurf)
 	 */
 	wl_list_remove(&shsurf->surface_destroy_listener.link);
 	shsurf->surface->configure = NULL;
+	weston_surface_set_label_func(shsurf->surface, NULL);
 	free(shsurf->title);
 
 	weston_view_destroy(shsurf->view);
@@ -3476,6 +3537,7 @@ create_common_surface(struct shell_client *owner, void *shell,
 
 	surface->configure = shell_surface_configure;
 	surface->configure_private = shsurf;
+	weston_surface_set_label_func(surface, shell_surface_get_label);
 
 	shsurf->resource_destroy_listener.notify = handle_resource_destroy;
 	wl_resource_add_destroy_listener(surface->resource,
@@ -4143,6 +4205,7 @@ configure_static_view(struct weston_view *ev, struct weston_layer *layer)
 		if (v->output == ev->output && v != ev) {
 			weston_view_unmap(v);
 			v->surface->configure = NULL;
+			weston_surface_set_label_func(v->surface, NULL);
 		}
 	}
 
@@ -4154,6 +4217,13 @@ configure_static_view(struct weston_view *ev, struct weston_layer *layer)
 	}
 }
 
+static int
+background_get_label(struct weston_surface *surface, char *buf, size_t len)
+{
+	return snprintf(buf, len, "background for output %s",
+			surface->output->name);
+}
+
 static void
 background_configure(struct weston_surface *es, int32_t sx, int32_t sy)
 {
@@ -4189,6 +4259,7 @@ desktop_shell_set_background(struct wl_client *client,
 
 	surface->configure = background_configure;
 	surface->configure_private = shell;
+	weston_surface_set_label_func(surface, background_get_label);
 	surface->output = wl_resource_get_user_data(output_resource);
 	view->output = surface->output;
 	desktop_shell_send_configure(resource, 0,
@@ -4197,6 +4268,13 @@ desktop_shell_set_background(struct wl_client *client,
 				     surface->output->height);
 }
 
+static int
+panel_get_label(struct weston_surface *surface, char *buf, size_t len)
+{
+	return snprintf(buf, len, "panel for output %s",
+			surface->output->name);
+}
+
 static void
 panel_configure(struct weston_surface *es, int32_t sx, int32_t sy)
 {
@@ -4232,6 +4310,7 @@ desktop_shell_set_panel(struct wl_client *client,
 
 	surface->configure = panel_configure;
 	surface->configure_private = shell;
+	weston_surface_set_label_func(surface, panel_get_label);
 	surface->output = wl_resource_get_user_data(output_resource);
 	view->output = surface->output;
 	desktop_shell_send_configure(resource, 0,
@@ -4240,6 +4319,12 @@ desktop_shell_set_panel(struct wl_client *client,
 				     surface->output->height);
 }
 
+static int
+lock_surface_get_label(struct weston_surface *surface, char *buf, size_t len)
+{
+	return snprintf(buf, len, "lock window");
+}
+
 static void
 lock_surface_configure(struct weston_surface *surface, int32_t sx, int32_t sy)
 {
@@ -4294,6 +4379,7 @@ desktop_shell_set_lock_surface(struct wl_client *client,
 	weston_view_create(surface);
 	surface->configure = lock_surface_configure;
 	surface->configure_private = shell;
+	weston_surface_set_label_func(surface, lock_surface_get_label);
 }
 
 static void
@@ -5657,6 +5743,13 @@ bind_desktop_shell(struct wl_client *client,
 			       "permission to bind desktop_shell denied");
 }
 
+static int
+screensaver_get_label(struct weston_surface *surface, char *buf, size_t len)
+{
+	return snprintf(buf, len, "screensaver for output %s",
+			surface->output->name);
+}
+
 static void
 screensaver_configure(struct weston_surface *surface, int32_t sx, int32_t sy)
 {
@@ -5704,6 +5797,7 @@ screensaver_set_surface(struct wl_client *client,
 
 	surface->configure = screensaver_configure;
 	surface->configure_private = shell;
+	weston_surface_set_label_func(surface, screensaver_get_label);
 	surface->output = output;
 }
 
diff --git a/src/compositor.c b/src/compositor.c
index 53f6220e..af9022c5 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -2724,6 +2724,12 @@ weston_subsurface_parent_commit(struct weston_subsurface *sub,
 		weston_subsurface_synchronized_commit(sub);
 }
 
+static int
+subsurface_get_label(struct weston_surface *surface, char *buf, size_t len)
+{
+	return snprintf(buf, len, "sub-surface");
+}
+
 static void
 subsurface_configure(struct weston_surface *surface, int32_t dx, int32_t dy)
 {
@@ -2807,6 +2813,14 @@ weston_surface_set_role(struct weston_surface *surface,
 	return -1;
 }
 
+WL_EXPORT void
+weston_surface_set_label_func(struct weston_surface *surface,
+			      int (*desc)(struct weston_surface *,
+					  char *, size_t))
+{
+	surface->get_label = desc;
+}
+
 static void
 subsurface_set_position(struct wl_client *client,
 			struct wl_resource *resource, int32_t x, int32_t y)
@@ -3039,6 +3053,7 @@ weston_subsurface_destroy(struct weston_subsurface *sub)
 
 		sub->surface->configure = NULL;
 		sub->surface->configure_private = NULL;
+		weston_surface_set_label_func(sub->surface, NULL);
 	} else {
 		/* the dummy weston_subsurface for the parent itself */
 		assert(sub->parent_destroy_listener.notify == NULL);
@@ -3170,6 +3185,7 @@ subcompositor_get_subsurface(struct wl_client *client,
 
 	surface->configure = subsurface_configure;
 	surface->configure_private = sub;
+	weston_surface_set_label_func(surface, subsurface_get_label);
 }
 
 static void
diff --git a/src/compositor.h b/src/compositor.h
index 2bec183d..d2574afe 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -898,6 +898,7 @@ struct weston_surface {
 	 */
 	void (*configure)(struct weston_surface *es, int32_t sx, int32_t sy);
 	void *configure_private;
+	int (*get_label)(struct weston_surface *surface, char *buf, size_t len);
 
 	/* Parent's list of its sub-surfaces, weston_subsurface:parent_link.
 	 * Contains also the parent itself as a dummy weston_subsurface,
@@ -1243,6 +1244,11 @@ weston_surface_set_role(struct weston_surface *surface,
 			struct wl_resource *error_resource,
 			uint32_t error_code);
 
+void
+weston_surface_set_label_func(struct weston_surface *surface,
+			      int (*desc)(struct weston_surface *,
+					  char *, size_t));
+
 struct weston_buffer *
 weston_buffer_from_resource(struct wl_resource *resource);
 
diff --git a/src/data-device.c b/src/data-device.c
index d28325dc..a0913a24 100644
--- a/src/data-device.c
+++ b/src/data-device.c
@@ -214,6 +214,13 @@ drag_surface_configure(struct weston_drag *drag,
 	weston_view_set_position(drag->icon, fx, fy);
 }
 
+static int
+pointer_drag_surface_get_label(struct weston_surface *surface,
+			       char *buf, size_t len)
+{
+	return snprintf(buf, len, "pointer drag icon");
+}
+
 static void
 pointer_drag_surface_configure(struct weston_surface *es,
 			       int32_t sx, int32_t sy)
@@ -226,6 +233,13 @@ pointer_drag_surface_configure(struct weston_surface *es,
 	drag_surface_configure(&drag->base, pointer, NULL, es, sx, sy);
 }
 
+static int
+touch_drag_surface_get_label(struct weston_surface *surface,
+			     char *buf, size_t len)
+{
+	return snprintf(buf, len, "touch drag icon");
+}
+
 static void
 touch_drag_surface_configure(struct weston_surface *es, int32_t sx, int32_t sy)
 {
@@ -351,6 +365,7 @@ data_device_end_drag_grab(struct weston_drag *drag,
 			weston_view_unmap(drag->icon);
 
 		drag->icon->surface->configure = NULL;
+		weston_surface_set_label_func(drag->icon->surface, NULL);
 		pixman_region32_clear(&drag->icon->surface->pending.input);
 		wl_list_remove(&drag->icon_destroy_listener.link);
 		weston_view_destroy(drag->icon);
@@ -560,6 +575,8 @@ weston_pointer_start_drag(struct weston_pointer *pointer,
 
 		icon->configure = pointer_drag_surface_configure;
 		icon->configure_private = drag;
+		weston_surface_set_label_func(icon,
+					pointer_drag_surface_get_label);
 	} else {
 		drag->base.icon = NULL;
 	}
@@ -615,6 +632,8 @@ weston_touch_start_drag(struct weston_touch *touch,
 
 		icon->configure = touch_drag_surface_configure;
 		icon->configure_private = drag;
+		weston_surface_set_label_func(icon,
+					touch_drag_surface_get_label);
 	} else {
 		drag->base.icon = NULL;
 	}
diff --git a/src/input.c b/src/input.c
index 59943feb..d3bfa5ea 100644
--- a/src/input.c
+++ b/src/input.c
@@ -431,6 +431,7 @@ pointer_unmap_sprite(struct weston_pointer *pointer)
 	wl_list_remove(&pointer->sprite_destroy_listener.link);
 	surface->configure = NULL;
 	surface->configure_private = NULL;
+	weston_surface_set_label_func(surface, NULL);
 	weston_view_destroy(pointer->sprite);
 	pointer->sprite = NULL;
 }
@@ -1582,6 +1583,13 @@ notify_touch_frame(struct weston_seat *seat)
 	grab->interface->frame(grab);
 }
 
+static int
+pointer_cursor_surface_get_label(struct weston_surface *surface,
+				 char *buf, size_t len)
+{
+	return snprintf(buf, len, "cursor");
+}
+
 static void
 pointer_cursor_surface_configure(struct weston_surface *es,
 				 int32_t dx, int32_t dy)
@@ -1653,6 +1661,8 @@ pointer_set_cursor(struct wl_client *client, struct wl_resource *resource,
 
 	surface->configure = pointer_cursor_surface_configure;
 	surface->configure_private = pointer;
+	weston_surface_set_label_func(surface,
+				      pointer_cursor_surface_get_label);
 	pointer->sprite = weston_view_create(surface);
 	pointer->hotspot_x = x;
 	pointer->hotspot_y = y;