Windows style: Scale more native metrics per monitor

Fix a few places that were overlooked in
change 29c6e39086831f6811e94364273c1f4bff119bef.

Most notably, fixes MDI subwindow titles disappearing
when moving windows between monitors.

Task-number: QTBUG-49374
Change-Id: Ie6ffabc4909064e649a3820d9aa952f3991ef06b
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

2 files changed, 18 insertions, 15 deletions

diff --git a/src/widgets/styles/qwindowsvistastyle.cpp b/src/widgets/styles/qwindowsvistastyle.cpp
index fe9684a25f..52006815ed 100644
--- a/src/widgets/styles/qwindowsvistastyle.cpp
+++ b/src/widgets/styles/qwindowsvistastyle.cpp
@@ -1175,9 +1175,9 @@ void QWindowsVistaStyle::drawControl(ControlElement element, const QStyleOption
     case CE_MenuItem:
         if (const QStyleOptionMenuItem *menuitem = qstyleoption_cast<const QStyleOptionMenuItem *>(option)) {
             // windows always has a check column, regardless whether we have an icon or not
-            const qreal devicePixelRatio = QWindowsXPStylePrivate::devicePixelRatio(widget);
-            int checkcol = qRound(qreal(25) / devicePixelRatio);
-            const int gutterWidth = qRound(qreal(3) / devicePixelRatio);
+            const qreal factor = QWindowsXPStylePrivate::nativeMetricScaleFactor(widget);
+            int checkcol = qRound(qreal(25) * factor);
+            const int gutterWidth = qRound(qreal(3) * factor);
             {
                 XPThemeData theme(widget, 0, QWindowsXPStylePrivate::MenuTheme,
                                   MENU_POPUPCHECKBACKGROUND, MBI_HOT);
@@ -2166,8 +2166,9 @@ QRect QWindowsVistaStyle::subControlRect(ComplexControl control, const QStyleOpt
             const bool isToolTitle = false;
             const int height = tb->rect.height();
             const int width = tb->rect.width();
-            int buttonWidth = GetSystemMetrics(SM_CXSIZE) / QWindowsStylePrivate::devicePixelRatio(widget)
-                - int(QStyleHelper::dpiScaled(4));
+            const int buttonWidth =
+                qRound(qreal(GetSystemMetrics(SM_CXSIZE)) * QWindowsStylePrivate::nativeMetricScaleFactor(widget)
+                       - QStyleHelper::dpiScaled(4));
 
             const int frameWidth = proxy()->pixelMetric(PM_MdiSubWindowFrameWidth, option, widget);
             const bool sysmenuHint  = (tb->titleBarFlags & Qt::WindowSystemMenuHint) != 0;
diff --git a/src/widgets/styles/qwindowsxpstyle.cpp b/src/widgets/styles/qwindowsxpstyle.cpp
index f2ee8e0b47..3017707117 100644
--- a/src/widgets/styles/qwindowsxpstyle.cpp
+++ b/src/widgets/styles/qwindowsxpstyle.cpp
@@ -2098,7 +2098,7 @@ void QWindowsXPStyle::drawControl(ControlElement element, const QStyleOption *op
             themeNumber = QWindowsXPStylePrivate::StatusTheme;
             partId = SP_GRIPPER;
             XPThemeData theme(0, p, themeNumber, partId, 0);
-            QSize size = (theme.size() / QWindowsStylePrivate::devicePixelRatio(widget)).toSize();
+            QSize size = (theme.size() * QWindowsStylePrivate::nativeMetricScaleFactor(widget)).toSize();
             size.rheight()--;
             if (const QStyleOptionSizeGrip *sg = qstyleoption_cast<const QStyleOptionSizeGrip *>(option)) {
                 switch (sg->corner) {
@@ -2169,7 +2169,7 @@ void QWindowsXPStyle::drawControl(ControlElement element, const QStyleOption *op
                                   QWindowsXPStylePrivate::ToolBarTheme,
                                   TP_SPLITBUTTONDROPDOWN);
                 if (theme.isValid()) {
-                    const QSize size = (theme.size() / QWindowsStylePrivate::devicePixelRatio(widget)).toSize();
+                    const QSize size = (theme.size() * QWindowsStylePrivate::nativeMetricScaleFactor(widget)).toSize();
                     mbiw = size.width();
                     mbih = size.height();
                 }
@@ -2632,10 +2632,11 @@ void QWindowsXPStyle::drawControl(ControlElement element, const QStyleOption *op
 QRect QWindowsXPStylePrivate::scrollBarGripperBounds(QStyle::State flags, const QWidget *widget, XPThemeData *theme)
 {
     const bool horizontal = flags & QStyle::State_Horizontal;
-    const QMargins contentsMargin = (theme->margins(theme->rect, TMT_SIZINGMARGINS)
-                                     / QWindowsStylePrivate::devicePixelRatio(widget)).toMargins();
+    const qreal factor = QWindowsStylePrivate::nativeMetricScaleFactor(widget);
+    const QMargins contentsMargin =
+        (theme->margins(theme->rect, TMT_SIZINGMARGINS) * factor).toMargins();
     theme->partId = horizontal ? SBP_GRIPPERHORZ : SBP_GRIPPERVERT;
-    const QSize size = (theme->size() / QWindowsStylePrivate::devicePixelRatio(widget)).toSize();
+    const QSize size = (theme->size() * factor).toSize();
 
     const int hSpace = theme->rect.width() - size.width();
     const int vSpace = theme->rect.height() - size.height();
@@ -3793,12 +3794,13 @@ QSize QWindowsXPStyle::sizeFromContents(ContentsType ct, const QStyleOption *opt
         {
             XPThemeData buttontheme(widget, 0, QWindowsXPStylePrivate::ButtonTheme, BP_PUSHBUTTON, PBS_NORMAL);
             if (buttontheme.isValid()) {
-                const qreal devicePixelRatio = QWindowsXPStylePrivate::devicePixelRatio(widget);
-                const QMarginsF borderSize = buttontheme.margins() / devicePixelRatio;
+                const qreal factor = QWindowsXPStylePrivate::nativeMetricScaleFactor(widget);
+                const QMarginsF borderSize = buttontheme.margins() * factor;
                 if (!borderSize.isNull()) {
-                    const qreal margin = qreal(2) / devicePixelRatio;
+                    const qreal margin = qreal(2) * factor;
                     sz.rwidth() += qRound(borderSize.left() + borderSize.right() - margin);
-                    sz.rheight() += int(borderSize.bottom() + borderSize.top() - margin + devicePixelRatio - 1);
+                    sz.rheight() += int(borderSize.bottom() + borderSize.top() - margin
+                        + qreal(1) / factor - 1);
                 }
                 const int textMargins = 2*(proxy()->pixelMetric(PM_FocusFrameHMargin) + 1);
                 sz += QSize(qMax(pixelMetric(QStyle::PM_ScrollBarExtent, option, widget)
@@ -4072,7 +4074,7 @@ QIcon QWindowsXPStyle::standardIcon(StandardPixmap standardIcon,
                 XPThemeData theme(0, 0, QWindowsXPStylePrivate::WindowTheme,
                                   WP_RESTOREBUTTON, RBS_NORMAL);
                 if (theme.isValid()) {
-                    const QSize size = (themeSize.size() / QWindowsStylePrivate::devicePixelRatio(widget)).toSize();
+                    const QSize size = (themeSize.size() * QWindowsStylePrivate::nativeMetricScaleFactor(widget)).toSize();
                     QPixmap pm(size);
                     pm.fill(Qt::transparent);
                     QPainter p(&pm);