Move detection for defaultDepth to xcbutils

outline.cpp

@@ -96,17 +96,7 @@ void Outline::showWithX()
         m_initialized   = true;
     }
 
-    int screen = QX11Info::appScreen();
-    int defaultDepth = 0;
-    // TODO: move into xcbutils or maybe kwinglobals
-    for (xcb_screen_iterator_t it = xcb_setup_roots_iterator(xcb_get_setup(connection()));
-            it.rem;
-            --screen, xcb_screen_next(&it)) {
-        if (screen == 0) {
-            defaultDepth = it.data->root_depth;
-            break;
-        }
-    }
+    const int defaultDepth = Xcb::defaultDepth();
 
 // left/right parts are between top/bottom, they don't reach as far as the corners
     const uint16_t verticalWidth = 5;

xcbutils.h

@@ -512,6 +512,24 @@ static inline void restackWindowsWithRaise(const QVector<xcb_window_t> &windows)
     restackWindows(windows);
 }
 
+static inline int defaultDepth()
+{
+    static int depth = 0;
+    if (depth != 0) {
+        return depth;
+    }
+    int screen = QX11Info::appScreen();
+    for (xcb_screen_iterator_t it = xcb_setup_roots_iterator(xcb_get_setup(connection()));
+            it.rem;
+            --screen, xcb_screen_next(&it)) {
+        if (screen == 0) {
+            depth = it.data->root_depth;
+            break;
+        }
+    }
+    return depth;
+}
+
 } // namespace X11
 
 } // namespace KWin