Avoid using QPainter::brushOrigin() to save and restore the origin

Avoid QPainter::brushOrigin() since it returns a QPoint instead QPointF
so it might loose precision. Use QPainterStateGuard instead to make
sure the correct QPainter state is restored later on.

Pick-to: 6.10
Task-number: QTBUG-137885
Change-Id: I3f49c72c0425e22ffb1246b42d926e704dc9d8dd
Reviewed-by: Eirik Aavitsland <[email protected]>

5 files changed, 13 insertions, 12 deletions

diff --git a/src/plugins/styles/modernwindows/qwindowsvistastyle.cpp b/src/plugins/styles/modernwindows/qwindowsvistastyle.cpp
index 7bda5e91b6e..0301b770a1e 100644
--- a/src/plugins/styles/modernwindows/qwindowsvistastyle.cpp
+++ b/src/plugins/styles/modernwindows/qwindowsvistastyle.cpp
@@ -5,6 +5,7 @@
 #include "qwindowsvistastyle_p_p.h"
 #include "qwindowsvistaanimation_p.h"
 #include <qoperatingsystemversion.h>
+#include <qpainterstateguard.h>
 #include <qscreen.h>
 #include <qstylehints.h>
 #include <qwindow.h>
@@ -2114,10 +2115,9 @@ void QWindowsVistaStyle::drawPrimitive(PrimitiveElement element, const QStyleOpt
             QPixmap pixmap;
 
             if (vopt->backgroundBrush.style() != Qt::NoBrush) {
-                const QPointF oldBrushOrigin = painter->brushOrigin();
+                QPainterStateGuard psg(painter);
                 painter->setBrushOrigin(vopt->rect.topLeft());
                 painter->fillRect(vopt->rect, vopt->backgroundBrush);
-                painter->setBrushOrigin(oldBrushOrigin);
             }
 
             if (hover || selected) {
diff --git a/src/widgets/itemviews/qheaderview.cpp b/src/widgets/itemviews/qheaderview.cpp
index 8a926b73002..b2fa08e406f 100644
--- a/src/widgets/itemviews/qheaderview.cpp
+++ b/src/widgets/itemviews/qheaderview.cpp
@@ -10,6 +10,7 @@
 #include <qdebug.h>
 #include <qevent.h>
 #include <qpainter.h>
+#include <qpainterstateguard.h>
 #include <qscrollbar.h>
 #include <qstyle.h>
 #include <qstyleoption.h>
@@ -3091,8 +3092,6 @@ void QHeaderView::paintSection(QPainter *painter, const QRect &rect, int logical
         return;
 
     QStyleOptionHeaderV2 opt;
-    QPointF oldBO = painter->brushOrigin();
-
     initStyleOption(&opt);
 
     QBrush oBrushButton = opt.palette.brush(QPalette::Button);
@@ -3106,13 +3105,14 @@ void QHeaderView::paintSection(QPainter *painter, const QRect &rect, int logical
     QBrush nBrushWindow = opt.palette.brush(QPalette::Window);
 
     // If relevant brushes are not the same as from the regular widgets we set the brush origin
+    QPainterStateGuard psg(painter, QPainterStateGuard::InitialState::NoSave);
     if (oBrushButton != nBrushButton || oBrushWindow != nBrushWindow) {
+        psg.save();
         painter->setBrushOrigin(opt.rect.topLeft());
     }
 
     // draw the section.
     style()->drawControl(QStyle::CE_Header, &opt, painter, this);
-    painter->setBrushOrigin(oldBO);
 }
 
 /*!
diff --git a/src/widgets/itemviews/qitemdelegate.cpp b/src/widgets/itemviews/qitemdelegate.cpp
index ccc35fd807b..1816853db70 100644
--- a/src/widgets/itemviews/qitemdelegate.cpp
+++ b/src/widgets/itemviews/qitemdelegate.cpp
@@ -7,6 +7,7 @@
 #include <qapplication.h>
 #include <qbrush.h>
 #include <qpainter.h>
+#include <qpainterstateguard.h>
 #include <qpalette.h>
 #include <qpoint.h>
 #include <qrect.h>
@@ -775,10 +776,9 @@ void QItemDelegate::drawBackground(QPainter *painter,
     } else {
         QVariant value = index.data(Qt::BackgroundRole);
         if (value.canConvert<QBrush>()) {
-            QPointF oldBO = painter->brushOrigin();
+            QPainterStateGuard psg(painter);
             painter->setBrushOrigin(option.rect.topLeft());
             painter->fillRect(option.rect, qvariant_cast<QBrush>(value));
-            painter->setBrushOrigin(oldBO);
         }
     }
 }
diff --git a/src/widgets/itemviews/qtreeview.cpp b/src/widgets/itemviews/qtreeview.cpp
index 23588d4917c..b141d8c5b59 100644
--- a/src/widgets/itemviews/qtreeview.cpp
+++ b/src/widgets/itemviews/qtreeview.cpp
@@ -7,6 +7,7 @@
 #include <qapplication.h>
 #include <qscrollbar.h>
 #include <qpainter.h>
+#include <qpainterstateguard.h>
 #include <qstack.h>
 #include <qstyle.h>
 #include <qstyleoption.h>
@@ -1897,9 +1898,11 @@ void QTreeView::drawBranches(QPainter *painter, const QRect &rect,
         extraFlags |= QStyle::State_Enabled;
     if (hasFocus())
         extraFlags |= QStyle::State_Active;
-    QPoint oldBO = painter->brushOrigin();
-    if (verticalScrollMode() == QAbstractItemView::ScrollPerPixel)
+    QPainterStateGuard psg(painter, QPainterStateGuard::InitialState::NoSave);
+    if (verticalScrollMode() == QAbstractItemView::ScrollPerPixel) {
+        psg.save();
         painter->setBrushOrigin(QPoint(0, verticalOffset()));
+    }
 
     if (d->alternatingColors) {
         opt.features.setFlag(QStyleOptionViewItem::Alternate, d->current & 1);
@@ -1960,7 +1963,6 @@ void QTreeView::drawBranches(QPainter *painter, const QRect &rect,
         current = ancestor;
         ancestor = current.parent();
     }
-    painter->setBrushOrigin(oldBO);
 }
 
 /*!
diff --git a/src/widgets/styles/qcommonstyle.cpp b/src/widgets/styles/qcommonstyle.cpp
index 7a95e590211..b5972411534 100644
--- a/src/widgets/styles/qcommonstyle.cpp
+++ b/src/widgets/styles/qcommonstyle.cpp
@@ -698,10 +698,9 @@ void QCommonStyle::drawPrimitive(PrimitiveElement pe, const QStyleOption *opt, Q
                 p->fillRect(vopt->rect, vopt->palette.brush(cg, QPalette::Highlight));
             } else {
                 if (vopt->backgroundBrush.style() != Qt::NoBrush) {
-                    QPointF oldBO = p->brushOrigin();
+                    QPainterStateGuard psg(p);
                     p->setBrushOrigin(vopt->rect.topLeft());
                     p->fillRect(vopt->rect, vopt->backgroundBrush);
-                    p->setBrushOrigin(oldBO);
                 }
 
                 if (vopt->state & QStyle::State_Selected) {