From 6c6156932f95c6e4b31cc8f1fed77f4d098f773f Mon Sep 17 00:00:00 2001
From: Uli Schlachter <psychon@znc.in>
Date: Wed, 3 Oct 2018 14:59:27 +0200
Subject: [PATCH] Convert find_client_win() to XCB

This function was the only caller of wid_get_children() which called
XQueryTree().

Signed-off-by: Uli Schlachter <psychon@znc.in>
---
 src/compton.c | 22 ++++++++++++----------
 src/compton.h | 26 ++------------------------
 2 files changed, 14 insertions(+), 34 deletions(-)

diff --git a/src/compton.c b/src/compton.c
index 96db232..75f437a 100644
--- a/src/compton.c
+++ b/src/compton.c
@@ -985,27 +985,29 @@ paint_root(session_t *ps, const region_t *reg_paint) {
 /**
  * Look for the client window of a particular window.
  */
-Window
-find_client_win(session_t *ps, Window w) {
+xcb_window_t
+find_client_win(session_t *ps, xcb_window_t w) {
   if (wid_has_prop(ps, w, ps->atom_client)) {
     return w;
   }
 
-  Window *children;
-  unsigned int nchildren;
-  unsigned int i;
-  Window ret = 0;
-
-  if (!wid_get_children(ps, w, &children, &nchildren)) {
+  xcb_connection_t *c = XGetXCBConnection(ps->dpy);
+  xcb_query_tree_reply_t *reply = xcb_query_tree_reply(c,
+      xcb_query_tree(c, w), NULL);
+  if (!reply)
     return 0;
-  }
+
+  xcb_window_t *children = xcb_query_tree_children(reply);
+  int nchildren = xcb_query_tree_children_length(reply);
+  int i;
+  xcb_window_t ret = 0;
 
   for (i = 0; i < nchildren; ++i) {
     if ((ret = find_client_win(ps, children[i])))
       break;
   }
 
-  cxfree(children);
+  free(reply);
 
   return ret;
 }
diff --git a/src/compton.h b/src/compton.h
index bae513d..5dea260 100644
--- a/src/compton.h
+++ b/src/compton.h
@@ -43,8 +43,8 @@ void add_damage(session_t *ps, const region_t *damage);
 
 long determine_evmask(session_t *ps, Window wid, win_evmode_t mode);
 
-Window
-find_client_win(session_t *ps, Window w);
+xcb_window_t
+find_client_win(session_t *ps, xcb_window_t w);
 
 win *find_toplevel2(session_t *ps, Window wid);
 
@@ -326,28 +326,6 @@ win_ev_stop(session_t *ps, win *w) {
   }
 }
 
-/**
- * Get the children of a window.
- *
- * @param ps current session
- * @param w window to check
- * @param children [out] an array of child window IDs
- * @param nchildren [out] number of children
- * @return 1 if successful, 0 otherwise
- */
-static inline bool
-wid_get_children(session_t *ps, Window w,
-    Window **children, unsigned *nchildren) {
-  Window troot, tparent;
-
-  if (!XQueryTree(ps->dpy, w, &troot, &tparent, children, nchildren)) {
-    *nchildren = 0;
-    return false;
-  }
-
-  return true;
-}
-
 /**
  * Check whether a window has WM frames.
  */