Fix HiDPI rendering issues in the WindowsVista style

Fixing miscellaneous rendering issues to make the WindowsVista
style look good on High DPI displays:
- Fixed size/resolution of combo box arrows, and changed to native look.
- Fixed vanishing horizontal line in the frame of line edit widgets.
- Fixed gaps in combo box popup.
- Fixed size/resolution of arrow in push button menu.

Task-number: QTBUG-49374
Task-number: QTBUG-65237
Task-number: QTBUG-65238
Change-Id: If68c2fae7472def3c19636483af741ca8ed2c490
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

2 files changed, 44 insertions, 28 deletions

diff --git a/src/plugins/styles/windowsvista/qwindowsvistastyle.cpp b/src/plugins/styles/windowsvista/qwindowsvistastyle.cpp
index 078875033f..6add110249 100644
--- a/src/plugins/styles/windowsvista/qwindowsvistastyle.cpp
+++ b/src/plugins/styles/windowsvista/qwindowsvistastyle.cpp
@@ -990,7 +990,7 @@ void QWindowsVistaStyle::drawControl(ControlElement element, const QStyleOption
                 XPThemeData theme(widget, 0, QWindowsXPStylePrivate::ToolBarTheme,
                                   TP_DROPDOWNBUTTON);
                 if (theme.isValid()) {
-                    const QSizeF size = theme.size() * QWindowsStylePrivate::nativeMetricScaleFactor(widget);
+                    const QSizeF size = theme.size() * QStyleHelper::dpiScaled(1);
                     if (!size.isEmpty()) {
                         mbiw = qRound(size.width());
                         mbih = qRound(size.height());
@@ -1513,7 +1513,7 @@ void QWindowsVistaStyle::drawComplexControl(ComplexControl control, const QStyle
     if (d->transitionsEnabled() && canAnimate(option))
     {
 
-        if (control == CC_ScrollBar || control == CC_SpinBox ) {
+        if (control == CC_ScrollBar || control == CC_SpinBox || control == CC_ComboBox) {
 
             QObject *styleObject = option->styleObject; // Can be widget or qquickitem
 
@@ -1643,12 +1643,28 @@ void QWindowsVistaStyle::drawComplexControl(ComplexControl control, const QStyle
 
             } else {
                 if (sub & SC_ComboBoxFrame) {
-                    QStyleOptionButton btn;
-                    btn.QStyleOption::operator=(*option);
-                    btn.rect = option->rect.adjusted(-1, -1, 1, 1);
-                    if (sub & SC_ComboBoxArrow)
-                        btn.features = QStyleOptionButton::HasMenu;
-                    proxy()->drawControl(QStyle::CE_PushButton, &btn, painter, widget);
+                    XPThemeData theme(widget, painter, QWindowsXPStylePrivate::ComboboxTheme);
+                    theme.rect = option->rect;
+                    theme.partId = CP_READONLY;
+                    if (!(cmb->state & State_Enabled))
+                        theme.stateId = CBXS_DISABLED;
+                    else if (cmb->state & State_Sunken || cmb->state & State_On)
+                        theme.stateId = CBXS_PRESSED;
+                    else if (cmb->state & State_MouseOver)
+                        theme.stateId = CBXS_HOT;
+                    else
+                        theme.stateId = CBXS_NORMAL;
+                    d->drawBackground(theme);
+                }
+                if (sub & SC_ComboBoxArrow) {
+                    XPThemeData theme(widget, painter, QWindowsXPStylePrivate::ComboboxTheme);
+                    theme.rect = proxy()->subControlRect(CC_ComboBox, option, SC_ComboBoxArrow, widget);
+                    theme.partId = option->direction == Qt::RightToLeft ? CP_DROPDOWNBUTTONLEFT : CP_DROPDOWNBUTTONRIGHT;
+                    if (!(cmb->state & State_Enabled))
+                        theme.stateId = CBXS_DISABLED;
+                    else
+                        theme.stateId = CBXS_NORMAL;
+                    d->drawBackground(theme);
                 }
             }
        }
@@ -2123,15 +2139,12 @@ QRect QWindowsVistaStyle::subControlRect(ComplexControl control, const QStyleOpt
 #if QT_CONFIG(combobox)
     case CC_ComboBox:
         if (const QStyleOptionComboBox *cb = qstyleoption_cast<const QStyleOptionComboBox *>(option)) {
-            int x = cb->rect.x(),
-                y = cb->rect.y(),
-                wi = cb->rect.width(),
-                he = cb->rect.height();
-            int xpos = x;
-            int margin = cb->frame ? 3 : 0;
-            int bmarg = cb->frame ? 2 : 0;
-            int arrowButtonWidth = bmarg + 16;
-            xpos += wi - arrowButtonWidth;
+            const int x = cb->rect.x(), y = cb->rect.y(), wi = cb->rect.width(), he = cb->rect.height();
+            const int margin = cb->frame ? 3 : 0;
+            const int bmarg = cb->frame ? 2 : 0;
+            const int arrowWidth = qRound(QStyleHelper::dpiScaled(16));
+            const int arrowButtonWidth = bmarg + arrowWidth;
+            const int xpos = x + wi - arrowButtonWidth;
 
             switch (subControl) {
             case SC_ComboBoxFrame:
@@ -2141,7 +2154,7 @@ QRect QWindowsVistaStyle::subControlRect(ComplexControl control, const QStyleOpt
                 rect.setRect(xpos, y , arrowButtonWidth, he);
                 break;
             case SC_ComboBoxEditField:
-                rect.setRect(x + margin, y + margin, wi - 2 * margin - 16, he - 2 * margin);
+                rect.setRect(x + margin, y + margin, wi - 2 * margin - arrowWidth, he - 2 * margin);
                 break;
             case SC_ComboBoxListBoxPopup:
                 rect = cb->rect;
diff --git a/src/plugins/styles/windowsvista/qwindowsxpstyle.cpp b/src/plugins/styles/windowsvista/qwindowsxpstyle.cpp
index cf344c8f88..ff27cab98a 100644
--- a/src/plugins/styles/windowsvista/qwindowsxpstyle.cpp
+++ b/src/plugins/styles/windowsvista/qwindowsxpstyle.cpp
@@ -887,6 +887,7 @@ bool QWindowsXPStylePrivate::drawBackgroundThruNativeBuffer(XPThemeData &themeDa
         PROPERTYORIGIN origin = PO_NOTFOUND;
         GetThemePropertyOrigin(themeData.handle(), themeData.partId, themeData.stateId, TMT_BORDERSIZE, &origin);
         GetThemeInt(themeData.handle(), themeData.partId, themeData.stateId, TMT_BORDERSIZE, &borderSize);
+        borderSize *= additionalDevicePixelRatio;
 
         // Clip away border region
         if ((origin == PO_CLASS || origin == PO_PART || origin == PO_STATE) && borderSize > 0) {
@@ -996,7 +997,7 @@ bool QWindowsXPStylePrivate::drawBackgroundThruNativeBuffer(XPThemeData &themeDa
     }
 
     if (addBorderContentClipping)
-        painter->setClipRegion(extraClip, Qt::IntersectClip);
+        painter->setClipRegion(scaleRegion(extraClip, 1.0 / additionalDevicePixelRatio), Qt::IntersectClip);
 
     if (!themeData.mirrorHorizontally && !themeData.mirrorVertically && !themeData.rotate) {
         if (!haveCachedPixmap)
@@ -1479,11 +1480,12 @@ case PE_Frame:
                 // GetThemeInt(theme.handle(), partId, stateId, TMT_BORDERCOLOR, &borderSize);
 
                 // Inner white border
-                p->setPen(QPen(option->palette.base().color(), 1));
-                p->drawRect(option->rect.adjusted(1, 1, -2, -2));
+                p->setPen(QPen(option->palette.base().color(), 0));
+                p->drawRect(QRectF(option->rect).adjusted(QStyleHelper::dpiScaled(0.5), QStyleHelper::dpiScaled(0.5),
+                                                          QStyleHelper::dpiScaled(-1), QStyleHelper::dpiScaled(-1)));
                 // Outer dark border
-                p->setPen(QPen(bordercolor, 1));
-                p->drawRect(option->rect.adjusted(0, 0, -1, -1));
+                p->setPen(QPen(bordercolor, 0));
+                p->drawRect(QRectF(option->rect).adjusted(0, 0, QStyleHelper::dpiScaled(-0.5), QStyleHelper::dpiScaled(-0.5)));
                 p->setPen(oldPen);
                 return;
             } else if (fillType == BT_NONE) {
@@ -3511,9 +3513,8 @@ QRect QWindowsXPStyle::subControlRect(ComplexControl cc, const QStyleOptionCompl
 
     case CC_ComboBox:
         if (const QStyleOptionComboBox *cmb = qstyleoption_cast<const QStyleOptionComboBox *>(option)) {
-            int x = cmb->rect.x(), y = cmb->rect.y(), wi = cmb->rect.width(), he = cmb->rect.height();
-            int xpos = x;
-            xpos += wi - 1 - 16;
+            const int x = cmb->rect.x(), y = cmb->rect.y(), wi = cmb->rect.width(), he = cmb->rect.height();
+            const int xpos = x + wi - qRound(QStyleHelper::dpiScaled(1 + 16));
 
             switch (subControl) {
             case SC_ComboBoxFrame:
@@ -3521,11 +3522,13 @@ QRect QWindowsXPStyle::subControlRect(ComplexControl cc, const QStyleOptionCompl
                 break;
 
             case SC_ComboBoxArrow:
-                rect = QRect(xpos, y+1, 16, he-2);
+                rect = QRect(xpos, y + qRound(QStyleHelper::dpiScaled(1)),
+                             qRound(QStyleHelper::dpiScaled(16)), he - qRound(QStyleHelper::dpiScaled(2)));
                 break;
 
             case SC_ComboBoxEditField:
-                rect = QRect(x+2, y+2, wi-3-16, he-4);
+                rect = QRect(x + qRound(QStyleHelper::dpiScaled(2)), y + qRound(QStyleHelper::dpiScaled(2)),
+                             wi - qRound(QStyleHelper::dpiScaled(3 + 16)), he - qRound(QStyleHelper::dpiScaled(4)));
                 break;
 
             case SC_ComboBoxListBoxPopup: