From ea6a5146397b668bf535ee7249bd4262d6185234 Mon Sep 17 00:00:00 2001
From: Andreas Aardal Hanssen <andreas.hanssen@tandberg.com>
Date: Wed, 14 Jul 2010 12:02:08 +0200
Subject: Work around memory leak issue in grid and linear layouts.
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These classes create a new QWidget and assign it to a static pointer
which is never cleaned up. Using Q_GLOBAL_STATIC ensures that they are
deleted on library unload. This is really just a cosmetic change that
removes a leak warning - the real fix should be to find a way to not
use a new QWidget like this. It seems odd that QGraphicsLayouts, which
don't use QWidget in any other way, should depend on QWidget like this.

Task-number: QTBUG-10768

Merge-request: 741
Reviewed-by: Jan-Arve Sæther <jan-arve.saether@nokia.com>
---
 src/gui/graphicsview/qgraphicsgridlayout.cpp                   | 7 +++----
 src/gui/graphicsview/qgraphicslinearlayout.cpp                 | 7 +++----
 tests/auto/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp     | 7 +++++++
 tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp | 7 +++++++
 4 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/src/gui/graphicsview/qgraphicsgridlayout.cpp b/src/gui/graphicsview/qgraphicsgridlayout.cpp
index 83db3ec..062b5ac 100644
--- a/src/gui/graphicsview/qgraphicsgridlayout.cpp
+++ b/src/gui/graphicsview/qgraphicsgridlayout.cpp
@@ -94,14 +94,13 @@ public:
 #endif
 };
 
+Q_GLOBAL_STATIC(QWidget, globalStyleInfoWidget);
+
 QLayoutStyleInfo QGraphicsGridLayoutPrivate::styleInfo() const
 {
-    static QWidget *wid = 0;
-    if (!wid)
-        wid = new QWidget;
     QGraphicsItem *item = parentItem();
     QStyle *style = (item && item->isWidget()) ? static_cast<QGraphicsWidget*>(item)->style() : QApplication::style();
-    return QLayoutStyleInfo(style, wid);
+    return QLayoutStyleInfo(style, globalStyleInfoWidget());
 }
 
 /*!
diff --git a/src/gui/graphicsview/qgraphicslinearlayout.cpp b/src/gui/graphicsview/qgraphicslinearlayout.cpp
index b828722..37408ef 100644
--- a/src/gui/graphicsview/qgraphicslinearlayout.cpp
+++ b/src/gui/graphicsview/qgraphicslinearlayout.cpp
@@ -171,14 +171,13 @@ int QGraphicsLinearLayoutPrivate::gridColumn(int index) const
     return int(qMin(uint(index), uint(engine.columnCount())));
 }
 
+Q_GLOBAL_STATIC(QWidget, globalStyleInfoWidget)
+
 QLayoutStyleInfo QGraphicsLinearLayoutPrivate::styleInfo() const
 {
-    static QWidget *wid = 0;
-    if (!wid)
-        wid = new QWidget;
     QGraphicsItem *item = parentItem();
     QStyle *style = (item && item->isWidget()) ? static_cast<QGraphicsWidget*>(item)->style() : QApplication::style();
-    return QLayoutStyleInfo(style, wid);
+    return QLayoutStyleInfo(style, globalStyleInfoWidget());
 }
 
 /*!
diff --git a/tests/auto/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp b/tests/auto/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp
index b9a5c66..d1d6860 100644
--- a/tests/auto/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp
+++ b/tests/auto/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp
@@ -105,6 +105,7 @@ private slots:
     void geometries_data();
     void geometries();
     void avoidRecursionInInsertItem();
+    void styleInfoLeak();
     void task236367_maxSizeHint();
 };
 
@@ -2196,6 +2197,12 @@ void tst_QGraphicsGridLayout::avoidRecursionInInsertItem()
     QCOMPARE(layout->count(), 0);
 }
 
+void tst_QGraphicsGridLayout::styleInfoLeak()
+{
+    QGraphicsGridLayout grid;
+    grid.horizontalSpacing();
+}
+
 void tst_QGraphicsGridLayout::task236367_maxSizeHint()
 {
     QGraphicsWidget *widget = new QGraphicsWidget;
diff --git a/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp b/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp
index c26e5d4..6107fa1 100644
--- a/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp
+++ b/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp
@@ -102,6 +102,7 @@ private slots:
     void layoutDirection();
     void removeLayout();
     void avoidRecursionInInsertItem();
+    void styleInfoLeak();
 
     // Task specific tests
     void task218400_insertStretchCrash();
@@ -1443,6 +1444,12 @@ void tst_QGraphicsLinearLayout::avoidRecursionInInsertItem()
     QCOMPARE(layout->count(), 0);
 }
 
+void tst_QGraphicsLinearLayout::styleInfoLeak()
+{
+    QGraphicsLinearLayout layout;
+    layout.spacing();
+}
+
 void tst_QGraphicsLinearLayout::task218400_insertStretchCrash()
 {
     QGraphicsScene *scene = new QGraphicsScene;
-- 
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