Windows: Fix MDI child window titles in High-DPI displays

This change improves the appearance of MDI child windows in a High-DPI
display for applications using the WindowsVista style, with the
Qt::AA_EnableHighDpiScaling attribute set.

Task-number: QTBUG-64708
Change-Id: I5e9fbd23809b440ffd33e4948c83d115cc6e1910
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

2 files changed, 24 insertions, 20 deletions

diff --git a/src/plugins/styles/windowsvista/qwindowsvistastyle.cpp b/src/plugins/styles/windowsvista/qwindowsvistastyle.cpp
index 6add110249..bb110660a3 100644
--- a/src/plugins/styles/windowsvista/qwindowsvistastyle.cpp
+++ b/src/plugins/styles/windowsvista/qwindowsvistastyle.cpp
@@ -2171,12 +2171,12 @@ QRect QWindowsVistaStyle::subControlRect(ComplexControl control, const QStyleOpt
         if (const QStyleOptionTitleBar *tb = qstyleoption_cast<const QStyleOptionTitleBar *>(option)) {
             if (!buttonVisible(subControl, tb))
                 return rect;
+            const qreal factor = QWindowsStylePrivate::nativeMetricScaleFactor(widget);
             const bool isToolTitle = false;
             const int height = tb->rect.height();
             const int width = tb->rect.width();
             const int buttonWidth =
-                qRound(qreal(GetSystemMetrics(SM_CXSIZE)) * QWindowsStylePrivate::nativeMetricScaleFactor(widget)
-                       - QStyleHelper::dpiScaled(4));
+                qRound(qreal(GetSystemMetrics(SM_CXSIZE)) * factor - QStyleHelper::dpiScaled(4));
 
             const int frameWidth = proxy()->pixelMetric(PM_MdiSubWindowFrameWidth, option, widget);
             const bool sysmenuHint  = (tb->titleBarFlags & Qt::WindowSystemMenuHint) != 0;
@@ -2190,31 +2190,31 @@ QRect QWindowsVistaStyle::subControlRect(ComplexControl control, const QStyleOpt
                 rect = QRect(frameWidth, 0, width - (buttonWidth + frameWidth + 10), height);
                 if (isToolTitle) {
                     if (sysmenuHint) {
-                        rect.adjust(0, 0, -buttonWidth - 3, 0);
+                        rect.adjust(0, 0, int(-buttonWidth - 3 * factor), 0);
                     }
                     if (minimizeHint || maximizeHint)
-                        rect.adjust(0, 0, -buttonWidth - 2, 0);
+                        rect.adjust(0, 0, int(-buttonWidth - 2 * factor), 0);
                 } else {
                     if (sysmenuHint) {
-                        const int leftOffset = height - 8;
-                        rect.adjust(leftOffset, 0, 0, 4);
+                        const int leftOffset = int(height - 8 * factor);
+                        rect.adjust(leftOffset, 0, 0, int(4 * factor));
                     }
                     if (minimizeHint)
-                        rect.adjust(0, 0, -buttonWidth - 2, 0);
+                        rect.adjust(0, 0, int(-buttonWidth - 2 * factor), 0);
                     if (maximizeHint)
-                        rect.adjust(0, 0, -buttonWidth - 2, 0);
+                        rect.adjust(0, 0, int(-buttonWidth - 2 * factor), 0);
                     if (contextHint)
-                        rect.adjust(0, 0, -buttonWidth - 2, 0);
+                        rect.adjust(0, 0, int(-buttonWidth - 2 * factor), 0);
                     if (shadeHint)
-                        rect.adjust(0, 0, -buttonWidth - 2, 0);
+                        rect.adjust(0, 0, int(-buttonWidth - 2 * factor), 0);
                 }
-                rect.translate(0, 2);
+                rect.translate(0, int(2 * factor));
                 rect = visualRect(option->direction, option->rect, rect);
                 break;
             case SC_TitleBarSysMenu:
                 {
-                    const int controlTop = 6;
-                    const int controlHeight = height - controlTop - 3;
+                    const int controlTop = int(6 * factor);
+                    const int controlHeight = int(height - controlTop - 3 * factor);
                     int iconExtent = proxy()->pixelMetric(PM_SmallIconSize);
                     QSize iconSize = tb->icon.actualSize(QSize(iconExtent, iconExtent));
                     if (tb->icon.isNull())
@@ -2222,7 +2222,7 @@ QRect QWindowsVistaStyle::subControlRect(ComplexControl control, const QStyleOpt
                     int hPad = (controlHeight - iconSize.height())/2;
                     int vPad = (controlHeight - iconSize.width())/2;
                     rect = QRect(frameWidth + hPad, controlTop + vPad, iconSize.width(), iconSize.height());
-                    rect.translate(0, 3);
+                    rect.translate(0, int(3 * factor));
                     rect = visualRect(option->direction, option->rect, rect);
                 }
                 break;
diff --git a/src/plugins/styles/windowsvista/qwindowsxpstyle.cpp b/src/plugins/styles/windowsvista/qwindowsxpstyle.cpp
index 733b3a9e9c..ddd8a76cfd 100644
--- a/src/plugins/styles/windowsvista/qwindowsxpstyle.cpp
+++ b/src/plugins/styles/windowsvista/qwindowsxpstyle.cpp
@@ -492,7 +492,8 @@ bool QWindowsXPStylePrivate::isTransparent(XPThemeData &themeData)
 QRegion QWindowsXPStylePrivate::region(XPThemeData &themeData)
 {
     HRGN hRgn = 0;
-    RECT rect = themeData.toRECT(themeData.rect);
+    const qreal factor = QWindowsStylePrivate::nativeMetricScaleFactor(themeData.widget);
+    RECT rect = themeData.toRECT(QRect(themeData.rect.topLeft() / factor, themeData.rect.size() / factor));
     if (!SUCCEEDED(GetThemeBackgroundRegion(themeData.handle(), bufferHDC(), themeData.partId,
                                             themeData.stateId, &rect, &hRgn))) {
         return QRegion();
@@ -521,7 +522,7 @@ QRegion QWindowsXPStylePrivate::region(XPThemeData &themeData)
         RECT *r = reinterpret_cast<RECT*>(rd->Buffer);
         for (uint i = 0; i < rd->rdh.nCount; ++i) {
             QRect rect;
-            rect.setCoords(r->left, r->top, r->right - 1, r->bottom - 1);
+            rect.setCoords(int(r->left * factor), int(r->top * factor), int((r->right - 1) * factor), int((r->bottom - 1) * factor));
             ++r;
             region |= rect;
         }
@@ -1754,9 +1755,9 @@ case PE_Frame:
             else
                 stateId = FS_INACTIVE;
 
-            int fwidth = frm->lineWidth + frm->midLineWidth;
+            int fwidth = int((frm->lineWidth + frm->midLineWidth) / QWindowsStylePrivate::nativeMetricScaleFactor(widget));
 
-            XPThemeData theme(0, p, themeNumber, 0, stateId);
+            XPThemeData theme(widget, p, themeNumber, 0, stateId);
             if (!theme.isValid())
                 break;
 
@@ -2947,6 +2948,7 @@ void QWindowsXPStyle::drawComplexControl(ComplexControl cc, const QStyleOptionCo
         {
             if (const QStyleOptionTitleBar *tb = qstyleoption_cast<const QStyleOptionTitleBar *>(option))
             {
+                const qreal factor = QWindowsStylePrivate::nativeMetricScaleFactor(widget);
                 bool isActive = tb->titleBarState & QStyle::State_Active;
                 XPThemeData theme(widget, p, QWindowsXPStylePrivate::WindowTheme);
                 if (sub & SC_TitleBarLabel) {
@@ -2973,13 +2975,15 @@ void QWindowsXPStyle::drawComplexControl(ComplexControl cc, const QStyleOptionCo
                         GetThemeColor(theme.handle(), WP_CAPTION, isActive ? CS_ACTIVE : CS_INACTIVE, TMT_TEXTSHADOWCOLOR, &textShadowRef);
                         QColor textShadow = qRgb(GetRValue(textShadowRef), GetGValue(textShadowRef), GetBValue(textShadowRef));
                         p->setPen(textShadow);
-                        p->drawText(ir.x() + 3, ir.y() + 2, ir.width() - 1, ir.height(),
+                        p->drawText(int(ir.x() + 3 * factor), int(ir.y() + 2 * factor),
+                                    int(ir.width() - 1 * factor), ir.height(),
                                     Qt::AlignLeft | Qt::AlignVCenter | Qt::TextSingleLine, tb->text);
                     }
                     COLORREF captionText = GetSysColor(isActive ? COLOR_CAPTIONTEXT : COLOR_INACTIVECAPTIONTEXT);
                     QColor textColor = qRgb(GetRValue(captionText), GetGValue(captionText), GetBValue(captionText));
                     p->setPen(textColor);
-                    p->drawText(ir.x() + 2, ir.y() + 1, ir.width() - 2, ir.height(),
+                    p->drawText(int(ir.x() + 2 * factor), int(ir.y() + 1 * factor),
+                                int(ir.width() - 2 * factor), ir.height(),
                                 Qt::AlignLeft | Qt::AlignVCenter | Qt::TextSingleLine, tb->text);
                 }
                 if (sub & SC_TitleBarSysMenu && tb->titleBarFlags & Qt::WindowSystemMenuHint) {