win: remove find_managed_window_or_parent

It has only one caller left, inline it. The only legitimate use of
ancestral search - looking for the focused window.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/picom.c

@@ -533,24 +533,53 @@ static void recheck_focus(session_t *ps) {
 
 	// Determine the currently focused window so we can apply appropriate
 	// opacity on it
-	xcb_window_t wid = XCB_NONE;
-	xcb_get_input_focus_reply_t *reply =
-	    xcb_get_input_focus_reply(ps->c.c, xcb_get_input_focus(ps->c.c), NULL);
+	xcb_generic_error_t *e = NULL;
+	auto reply = xcb_get_input_focus_reply(ps->c.c, xcb_get_input_focus(ps->c.c), &e);
+	if (reply == NULL) {
+		// Not able to get input focus means very not good things...
+		log_error_x_error(e, "Failed to get focused window.");
+		free(e);
+		return;
+	}
+	xcb_window_t wid = reply->focus;
+	free(reply);
 
-	if (reply) {
-		wid = reply->focus;
-		free(reply);
+	if (wid == XCB_NONE || wid == XCB_INPUT_FOCUS_POINTER_ROOT ||
+	    wid == ps->c.screen_info->root) {
+		// Focus is not on a toplevel.
+		return;
 	}
 
-	auto w = find_managed_window_or_parent(ps, wid);
+	// Trace upwards until we reach the toplevel containing the focus window.
+	while (true) {
+		auto tree = xcb_query_tree_reply(ps->c.c, xcb_query_tree(ps->c.c, wid), &e);
+		if (tree == NULL) {
+			// xcb_query_tree probably fails if you run picom when X is
+			// somehow initializing (like add it in .xinitrc). In this case
+			// just leave it alone.
+			log_error_x_error(e, "Failed to query window tree.");
+			free(e);
+			return;
+		}
 
-	log_trace("%#010" PRIx32 " (%#010lx \"%s\") focused.", wid,
-	          (w ? w->base.id : XCB_NONE), (w ? w->name : NULL));
+		auto parent = tree->parent;
+		free(tree);
+
+		if (parent == ps->c.screen_info->root) {
+			break;
+		}
+		wid = parent;
+	}
+
+	auto w = find_managed_win(ps, wid);
 
 	// And we set the focus state here
 	if (w) {
+		log_debug("%#010" PRIx32 " (%#010" PRIx32 " \"%s\") focused.", wid,
+		          w->base.id, w->name);
 		win_set_focused(ps, w);
-		return;
+	} else {
+		log_warn("Focus window %#010" PRIx32 " not found.", wid);
 	}
 }
 
@@ -1697,14 +1726,7 @@ static void handle_pending_updates(EV_P_ struct session *ps) {
 		// Process window flags
 		refresh_windows(ps);
 
-		{
-			auto r = xcb_get_input_focus_reply(
-			    ps->c.c, xcb_get_input_focus(ps->c.c), NULL);
-			if (!ps->active_win || (r && r->focus != ps->active_win->base.id)) {
-				recheck_focus(ps);
-			}
-			free(r);
-		}
+		recheck_focus(ps);
 
 		// Process window flags (stale images)
 		refresh_images(ps);

src/win.c

@@ -2640,43 +2640,6 @@ struct managed_win *find_toplevel(session_t *ps, xcb_window_t id) {
 	return NULL;
 }
 
-/**
- * Find a managed window that is, or is a parent of `wid`.
- *
- * @param ps current session
- * @param wid window ID
- * @return struct _win object of the found window, NULL if not found
- */
-struct managed_win *find_managed_window_or_parent(session_t *ps, xcb_window_t wid) {
-	// TODO(yshui) this should probably be an "update tree", then
-	// find_toplevel. current approach is a bit more "racy", as the server
-	// state might be ahead of our state
-	struct win *w = NULL;
-
-	// We traverse through its ancestors to find out the frame
-	// Using find_win here because if we found a unmanaged window we know
-	// about, we can stop early.
-	while (wid && wid != ps->c.screen_info->root && !(w = find_win(ps, wid))) {
-		// xcb_query_tree probably fails if you run picom when X is
-		// somehow initializing (like add it in .xinitrc). In this case
-		// just leave it alone.
-		auto reply =
-		    xcb_query_tree_reply(ps->c.c, xcb_query_tree(ps->c.c, wid), NULL);
-		if (reply == NULL) {
-			break;
-		}
-
-		wid = reply->parent;
-		free(reply);
-	}
-
-	if (w == NULL || !w->managed) {
-		return NULL;
-	}
-
-	return (struct managed_win *)w;
-}
-
 /// Set flags on a window. Some sanity checks are performed
 void win_set_flags(struct managed_win *w, uint64_t flags) {
 	log_debug("Set flags %" PRIu64 " to window %#010x (%s)", flags, w->base.id, w->name);

src/win.h

@@ -421,14 +421,6 @@ void win_skip_fading(struct managed_win *w);
 struct managed_win *find_managed_win(session_t *ps, xcb_window_t id);
 struct win *find_win(session_t *ps, xcb_window_t id);
 struct managed_win *find_toplevel(session_t *ps, xcb_window_t id);
-/**
- * Find a managed window that is, or is a parent of `wid`.
- *
- * @param ps current session
- * @param wid window ID
- * @return struct _win object of the found window, NULL if not found
- */
-struct managed_win *find_managed_window_or_parent(session_t *ps, xcb_window_t wid);
 
 /**
  * Check if a window is focused, without using any focus rules or forced focus settings