From 705f53e985104dcd52d684228cc923e9dbd9938b Mon Sep 17 00:00:00 2001
From: Pierre Lamot <pierre@videolabs.io>
Date: Mon, 27 Feb 2023 11:18:24 +0100
Subject: [PATCH] qml: fix race condition while initializing
 FlickableScrollHandler

fix: #27890
---
 modules/gui/qt/util/flickable_scroll_handler.cpp |  8 +++++---
 modules/gui/qt/util/flickable_scroll_handler.hpp | 10 +++++++---
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/modules/gui/qt/util/flickable_scroll_handler.cpp b/modules/gui/qt/util/flickable_scroll_handler.cpp
index 451e9d9ad2..f39061bbb6 100644
--- a/modules/gui/qt/util/flickable_scroll_handler.cpp
+++ b/modules/gui/qt/util/flickable_scroll_handler.cpp
@@ -34,8 +34,6 @@ FlickableScrollHandler::FlickableScrollHandler(QObject *parent)
     });
 
     setScaleFactor(1.0);
-
-    QMetaObject::invokeMethod(this, &FlickableScrollHandler::init, Qt::QueuedConnection);
 }
 
 FlickableScrollHandler::~FlickableScrollHandler()
@@ -43,7 +41,11 @@ FlickableScrollHandler::~FlickableScrollHandler()
     detach();
 }
 
-void FlickableScrollHandler::init()
+void FlickableScrollHandler::classBegin()
+{
+}
+
+void FlickableScrollHandler::componentComplete()
 {
     assert(parent());
 
diff --git a/modules/gui/qt/util/flickable_scroll_handler.hpp b/modules/gui/qt/util/flickable_scroll_handler.hpp
index b5a82887ff..8b68bb99b2 100644
--- a/modules/gui/qt/util/flickable_scroll_handler.hpp
+++ b/modules/gui/qt/util/flickable_scroll_handler.hpp
@@ -22,8 +22,9 @@
 #include <QQmlProperty>
 #include <QPointer>
 #include <QQuickItem>
+#include <QQmlParserStatus>
 
-class FlickableScrollHandler : public QObject
+class FlickableScrollHandler : public QObject, public QQmlParserStatus
 {
     Q_OBJECT
 
@@ -35,6 +36,8 @@ class FlickableScrollHandler : public QObject
     Q_PROPERTY(bool fallbackScroll MEMBER m_fallbackScroll NOTIFY fallbackScrollChanged FINAL)
     Q_PROPERTY(bool handleOnlyPixelDelta MEMBER m_handleOnlyPixelDelta NOTIFY handleOnlyPixelDeltaChanged FINAL)
 
+    Q_INTERFACES(QQmlParserStatus)
+
 public:
     explicit FlickableScrollHandler(QObject *parent = nullptr);
     ~FlickableScrollHandler();
@@ -46,6 +49,9 @@ public:
     void setScaleFactor(qreal newScaleFactor);
     void setEnabled(bool newEnabled);
 
+    void classBegin() override;
+    void componentComplete() override;
+
 signals:
     void initialized();
 
@@ -57,8 +63,6 @@ signals:
     void handleOnlyPixelDeltaChanged();
 
 private slots:
-    void init();
-
     void adjustScrollBarV();
     void adjustScrollBarH();