Widgets focus abstraction: Skip isFocusChainConsistent w/o logging cat

QWidgetPrivate::isFocusChainConsistent() iterates over
QApplication::allWidgets() to identify and log inconsistencies.
In applications with many widgets, this has a major performance
impact.

Disable the check and return true, unless the logging category
qt.widgets.focus is enabled.

Adapt tst_QWidget::focusAbstraction() to enable the logging category.

This amends 58d5d4b7c2faaeaa2c2ccdabb3da6d37f9db880a.

Fixes: QTBUG-124666
Change-Id: Ia487b381ab45b052638b189bf56acaf4353b1a37
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index b302b32b88..e8342a4788 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -13614,7 +13614,8 @@ bool QWidgetPrivate::isInFocusChain() const
     when the focus chain has been initialized. A newly constructed widget is considered to have
     a consistent focus chain, while not being part of a focus chain.
 
-    This method returns \c true early, if a widget is pointing to itself.
+    The method always returns \c true, when the logging category "qt.widgets.focus" is disabled.
+    When it is enabled, the method returns \c true early, if a widget is pointing to itself.
     It returns \c false, if one of the following is detected:
     \list
     \li nullptr found in a previous/next pointer.
@@ -13631,6 +13632,10 @@ bool QWidgetPrivate::isInFocusChain() const
 bool QWidgetPrivate::isFocusChainConsistent() const
 {
     Q_Q(const QWidget);
+    const bool skip = !QLoggingCategory("qt.widgets.focus").isDebugEnabled();
+    if (skip)
+        return true;
+
     if (!isInFocusChain())
         return true;