From ff6156204d2cc33771540ef71500605817dc4911 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Fri, 9 Jul 2021 15:51:40 +0200
Subject: QColorTrcLut: hold in shared_ptr

... instead of raw pointers or QSharedPointer.

Raw pointers are, of course, a no-no in modern code. In particular,
when the result is then held in shared_ptr or QSharedPointer,
make_shared or QSharedPointer::create() should be used to reduce
number of memory allocations.

Since this is private API, we're free to use std::shared_ptr, which
does only half the atomic operations on copies, compared to
QSharedPointer, so is more efficient.

For either make_shared or QSharedPointer::create(), we need to work
around the private ctor, which we do by inheriting a member-function
local class from QColorTrcLut and make_shared'ing that. As a
member-function-local class, it has access to the otherwise private
parts of QColorTrcLut, including its default constructor. As a public
subclass, shared_ptr has no problem performing the derived-to-base
pointer adjustment in the return statement. This way, we can use
make_shared even though our target's class' ctor is private.

Change-Id: Icb11249b54cd5e544e692f6a0bf1f9dda1710454
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
---
 src/gui/kernel/qguiapplication_p.h | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

(limited to 'src/gui/kernel/qguiapplication_p.h')

diff --git a/src/gui/kernel/qguiapplication_p.h b/src/gui/kernel/qguiapplication_p.h
index ca4ed3f12e..b98a1b9ecf 100644
--- a/src/gui/kernel/qguiapplication_p.h
+++ b/src/gui/kernel/qguiapplication_p.h
@@ -56,7 +56,6 @@
 #include <QtGui/qicon.h>
 
 #include <QtCore/QPointF>
-#include <QtCore/QSharedPointer>
 #include <QtCore/private/qcoreapplication_p.h>
 
 #include <QtCore/qnativeinterface.h>
@@ -68,6 +67,8 @@
 #  include "private/qshortcutmap_p.h"
 #endif
 
+#include <memory>
+
 QT_BEGIN_NAMESPACE
 
 class QColorTrcLut;
@@ -332,9 +333,9 @@ private:
     static QGuiApplicationPrivate *self;
     static int m_fakeMouseSourcePointId;
 #ifdef Q_OS_WIN
-    QSharedPointer<QColorTrcLut> m_a8ColorProfile;
+    std::shared_ptr<QColorTrcLut> m_a8ColorProfile;
 #endif
-    QSharedPointer<QColorTrcLut> m_a32ColorProfile;
+    std::shared_ptr<QColorTrcLut> m_a32ColorProfile;
 
     bool ownGlobalShareContext;
 
-- 
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