From 0de0f494bd75786ff361da2ac05c85d8aeac3b37 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Sat, 5 Apr 2014 00:51:43 +0200
Subject: [PATCH] QPageLayout: use QExplicitlySharedDataPointer

Many setters check for an actual change before making changes to
data members, but because of QSharedDataPointer, the detach had
already happened by the time the comparison returned false.

Change-Id: I320806e74de4a64fa3a340831621c1f5120ebb0f
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: John Layt <jlayt@kde.org>
---
 src/gui/painting/qpagelayout.cpp | 11 +++++++++++
 src/gui/painting/qpagelayout.h   |  2 +-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/gui/painting/qpagelayout.cpp b/src/gui/painting/qpagelayout.cpp
index 3da550a411..5589a4364c 100644
--- a/src/gui/painting/qpagelayout.cpp
+++ b/src/gui/painting/qpagelayout.cpp
@@ -466,6 +466,7 @@ bool QPageLayout::isValid() const
 
 void QPageLayout::setMode(Mode mode)
 {
+    d.detach();
     d->m_mode = mode;
 }
 
@@ -494,6 +495,7 @@ void QPageLayout::setPageSize(const QPageSize &pageSize, const QMarginsF &minMar
 {
     if (!pageSize.isValid())
         return;
+    d.detach();
     d->m_pageSize = pageSize;
     d->m_fullSize = d->fullSizeUnits(d->m_units);
     d->setDefaultMargins(minMargins);
@@ -522,6 +524,7 @@ QPageSize QPageLayout::pageSize() const
 void QPageLayout::setOrientation(Orientation orientation)
 {
     if (orientation != d->m_orientation) {
+        d.detach();
         d->m_orientation = orientation;
         d->m_fullSize = d->fullSizeUnits(d->m_units);
         // Adust the max margins to reflect change in max page size
@@ -549,6 +552,7 @@ QPageLayout::Orientation QPageLayout::orientation() const
 void QPageLayout::setUnits(Unit units)
 {
     if (units != d->m_units) {
+        d.detach();
         d->m_margins = qt_convertMargins(d->m_margins, d->m_units, units);
         d->m_minMargins = qt_convertMargins(d->m_minMargins, d->m_units, units);
         d->m_maxMargins = qt_convertMargins(d->m_maxMargins, d->m_units, units);
@@ -585,6 +589,7 @@ QPageLayout::Unit QPageLayout::units() const
 bool QPageLayout::setMargins(const QMarginsF &margins)
 {
     if (d->m_mode == FullPageMode) {
+        d.detach();
         d->m_margins = margins;
         return true;
     } else if (margins.left() >= d->m_minMargins.left()
@@ -595,6 +600,7 @@ bool QPageLayout::setMargins(const QMarginsF &margins)
                && margins.right() <= d->m_maxMargins.right()
                && margins.top() <= d->m_maxMargins.top()
                && margins.bottom() <= d->m_maxMargins.bottom()) {
+        d.detach();
         d->m_margins = margins;
         return true;
     }
@@ -621,6 +627,7 @@ bool QPageLayout::setLeftMargin(qreal leftMargin)
 {
     if (d->m_mode == FullPageMode
         || (leftMargin >= d->m_minMargins.left() && leftMargin <= d->m_maxMargins.left())) {
+        d.detach();
         d->m_margins.setLeft(leftMargin);
         return true;
     }
@@ -647,6 +654,7 @@ bool QPageLayout::setRightMargin(qreal rightMargin)
 {
     if (d->m_mode == FullPageMode
         || (rightMargin >= d->m_minMargins.right() && rightMargin <= d->m_maxMargins.right())) {
+        d.detach();
         d->m_margins.setRight(rightMargin);
         return true;
     }
@@ -673,6 +681,7 @@ bool QPageLayout::setTopMargin(qreal topMargin)
 {
     if (d->m_mode == FullPageMode
         || (topMargin >= d->m_minMargins.top() && topMargin <= d->m_maxMargins.top())) {
+        d.detach();
         d->m_margins.setTop(topMargin);
         return true;
     }
@@ -699,6 +708,7 @@ bool QPageLayout::setBottomMargin(qreal bottomMargin)
 {
     if (d->m_mode == FullPageMode
         || (bottomMargin >= d->m_minMargins.bottom() && bottomMargin <= d->m_maxMargins.bottom())) {
+        d.detach();
         d->m_margins.setBottom(bottomMargin);
         return true;
     }
@@ -764,6 +774,7 @@ QMargins QPageLayout::marginsPixels(int resolution) const
 
 void QPageLayout::setMinimumMargins(const QMarginsF &minMargins)
 {
+    d.detach();
     d->setDefaultMargins(minMargins);
 }
 
diff --git a/src/gui/painting/qpagelayout.h b/src/gui/painting/qpagelayout.h
index 6e2752c3a1..c636ca7476 100644
--- a/src/gui/painting/qpagelayout.h
+++ b/src/gui/painting/qpagelayout.h
@@ -137,7 +137,7 @@ public:
 
 private:
     friend class QPageLayoutPrivate;
-    QSharedDataPointer<QPageLayoutPrivate> d;
+    QExplicitlySharedDataPointer<QPageLayoutPrivate> d;
 };
 
 Q_DECLARE_SHARED(QPageLayout)