QMacStyle: smooth QMenu corners for real

It's been for years that QMenu's rounded corners in qmacstyle_mac were
done via QWidget::setMask(QRegion). Unfortunately, QRegion mask does not
work well with retina displays and also does not support translucency.
That's why in this change we explicitly make QMenu's background
transparent and then draw a rectangle with rounded corners in
QMacStyle::drawPrimitive(PE_PanelMenu). This not only gives much better
result than the mask-based approach, but also de-HIThemes QMenu.

As a consequence, QComboBoxPrivateContainer doesn't get any mask from
QMacStyle anymore. Therefore, when the mask is empty, we need to paint
PE_PanelMenu before invoking QFrame's paint event handler.

Made-with: Gabriel de Dietrich <gabriel.dedietrich@qt.io>
Change-Id: Ia9236176113f23b86e45507fa6ddf77236084ce3
Reviewed-by: Oleg Yadrov <oleg.yadrov@qt.io>
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@qt.io>

4 files changed, 56 insertions, 52 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoasystemsettings.mm b/src/plugins/platforms/cocoa/qcocoasystemsettings.mm
index 91fb6e973d..7c6f879b18 100644
--- a/src/plugins/platforms/cocoa/qcocoasystemsettings.mm
+++ b/src/plugins/platforms/cocoa/qcocoasystemsettings.mm
@@ -144,7 +144,6 @@ QHash<QPlatformTheme::Palette, QPalette*> qt_mac_createRolePalettes()
         }
         if (mac_widget_colors[i].paletteRole == QPlatformTheme::MenuPalette
                 || mac_widget_colors[i].paletteRole == QPlatformTheme::MenuBarPalette) {
-            pal.setBrush(QPalette::Background, qt_mac_toQColor([NSColor windowBackgroundColor]));
             pal.setBrush(QPalette::Highlight, qt_mac_toQColor([NSColor selectedMenuItemColor]));
             qc = qt_mac_toQColor([NSColor labelColor]);
             pal.setBrush(QPalette::ButtonText, qc);
diff --git a/src/plugins/styles/mac/qmacstyle_mac.mm b/src/plugins/styles/mac/qmacstyle_mac.mm
index d9e622c28a..b24ecee102 100644
--- a/src/plugins/styles/mac/qmacstyle_mac.mm
+++ b/src/plugins/styles/mac/qmacstyle_mac.mm
@@ -663,14 +663,6 @@ HIMutableShapeRef qt_mac_toHIMutableShape(const QRegion &region)
     return shape;
 }
 
-QRegion qt_mac_fromHIShapeRef(HIShapeRef shape)
-{
-    QRegion returnRegion;
-    //returnRegion.detach();
-    HIShapeEnumerate(shape, kHIShapeParseFromTopLeft, qt_mac_shape2QRegionHelper, &returnRegion);
-    return returnRegion;
-}
-
 bool qt_macWindowIsTextured(const QWidget *window)
 {
     if (QWindow *w = window->windowHandle())
@@ -2291,24 +2283,7 @@ void QMacStyle::polish(QWidget* w)
             || qobject_cast<QComboBoxPrivateContainer *>(w)
 #endif
             ) {
-        w->setWindowOpacity(0.985);
-        if (!w->testAttribute(Qt::WA_SetPalette)) {
-            QPixmap px(64, 64);
-            px.fill(Qt::white);
-            HIThemeMenuDrawInfo mtinfo;
-            mtinfo.version = qt_mac_hitheme_version;
-            mtinfo.menuType = kThemeMenuTypePopUp;
-            // HIRect rect = CGRectMake(0, 0, px.width(), px.height());
-            // ###
-            //HIThemeDrawMenuBackground(&rect, &mtinfo, QMacCGContext(&px)),
-            //                          kHIThemeOrientationNormal);
-            QPalette pal = w->palette();
-            QBrush background(px);
-            pal.setBrush(QPalette::All, QPalette::Window, background);
-            pal.setBrush(QPalette::All, QPalette::Button, background);
-            w->setPalette(pal);
-            w->setAttribute(Qt::WA_SetPalette, false);
-        }
+        w->setAttribute(Qt::WA_TranslucentBackground, true);
     }
 #endif
 
@@ -3023,7 +2998,7 @@ int QMacStyle::styleHint(StyleHint sh, const QStyleOption *opt, const QWidget *w
         ret = Qt::AlignRight;
         break;
     case SH_ComboBox_PopupFrameStyle:
-        ret = QFrame::NoFrame | QFrame::Plain;
+        ret = QFrame::NoFrame;
         break;
     case SH_MessageBox_TextInteractionFlags:
         ret = Qt::TextSelectableByMouse | Qt::LinksAccessibleByMouse | Qt::TextSelectableByKeyboard;
@@ -3057,27 +3032,6 @@ int QMacStyle::styleHint(StyleHint sh, const QStyleOption *opt, const QWidget *w
     case SH_Menu_FadeOutOnHide:
         ret = true;
         break;
-    case SH_Menu_Mask:
-        if (opt) {
-            if (QStyleHintReturnMask *mask = qstyleoption_cast<QStyleHintReturnMask*>(hret)) {
-                ret = true;
-                CGRect menuRect = CGRectMake(opt->rect.x(), opt->rect.y() + 4,
-                                             opt->rect.width(), opt->rect.height() - 8);
-                HIThemeMenuDrawInfo mdi;
-                mdi.version = 0;
-#if QT_CONFIG(menu)
-                if (w && qobject_cast<QMenu *>(w->parentWidget()))
-                    mdi.menuType = kThemeMenuTypeHierarchical;
-                else
-#endif
-                    mdi.menuType = kThemeMenuTypePopUp;
-                QCFType<HIShapeRef> shape;
-                HIThemeGetMenuBackgroundShape(&menuRect, &mdi, &shape);
-
-                mask->region = qt_mac_fromHIShapeRef(shape);
-            }
-        }
-        break;
     case SH_ItemView_PaintAlternatingRowColorsForEmptyArea:
         ret = true;
         break;
@@ -3587,6 +3541,40 @@ void QMacStyle::drawPrimitive(PrimitiveElement pe, const QStyleOption *opt, QPai
 
         break;
     }
+    case PE_PanelMenu: {
+        p->save();
+        p->fillRect(opt->rect, Qt::transparent);
+        p->setPen(Qt::transparent);
+        p->setBrush(opt->palette.window());
+        p->setRenderHint(QPainter::Antialiasing, true);
+        QPainterPath path;
+        static const qreal CornerPointOffset = 5.5;
+        static const qreal CornerControlOffset = 2.1;
+        QRectF r = opt->rect;
+        // Top-left corner
+        path.moveTo(r.left(), r.top() + CornerPointOffset);
+        path.cubicTo(r.left(), r.top() + CornerControlOffset,
+                     r.left() + CornerControlOffset, r.top(),
+                     r.left() + CornerPointOffset, r.top());
+        // Top-right corner
+        path.lineTo(r.right() - CornerPointOffset, r.top());
+        path.cubicTo(r.right() - CornerControlOffset, r.top(),
+                     r.right(), r.top() + CornerControlOffset,
+                     r.right(), r.top() + CornerPointOffset);
+        // Bottom-right corner
+        path.lineTo(r.right(), r.bottom() - CornerPointOffset);
+        path.cubicTo(r.right(), r.bottom() - CornerControlOffset,
+                     r.right() - CornerControlOffset, r.bottom(),
+                     r.right() - CornerPointOffset, r.bottom());
+        // Bottom-right corner
+        path.lineTo(r.left() + CornerPointOffset, r.bottom());
+        path.cubicTo(r.left() + CornerControlOffset, r.bottom(),
+                     r.left(), r.bottom() - CornerControlOffset,
+                     r.left(), r.bottom() - CornerPointOffset);
+        path.lineTo(r.left(), r.top() + CornerPointOffset);
+        p->drawPath(path);
+        p->restore();
+        } break;
 
     default:
         QCommonStyle::drawPrimitive(pe, opt, p, w);
@@ -4269,16 +4257,18 @@ void QMacStyle::drawControl(ControlElement ce, const QStyleOption *opt, QPainter
         const int vMargin = proxy()->pixelMetric(QStyle::PM_FocusFrameVMargin, opt, w);
         d->drawFocusRing(p, opt->rect, hMargin, vMargin);
         break; }
+    case CE_MenuEmptyArea:
+        // Skip: PE_PanelMenu fills in everything
+        break;
     case CE_MenuItem:
     case CE_MenuHMargin:
     case CE_MenuVMargin:
-    case CE_MenuEmptyArea:
     case CE_MenuTearoff:
     case CE_MenuScroller:
         if (const QStyleOptionMenuItem *mi = qstyleoption_cast<const QStyleOptionMenuItem *>(opt)) {
             const bool active = mi->state & State_Selected;
-            const QBrush bg = active ? mi->palette.highlight() : mi->palette.background();
-            p->fillRect(mi->rect, bg);
+            if (active)
+                p->fillRect(mi->rect, mi->palette.highlight());
 
             const QStyleHelper::WidgetSizePolicy widgetSize = d->aquaSizeConstrain(opt, w);
 
diff --git a/src/widgets/widgets/qcombobox.cpp b/src/widgets/widgets/qcombobox.cpp
index 1338a496e6..9afb4b3ae6 100644
--- a/src/widgets/widgets/qcombobox.cpp
+++ b/src/widgets/widgets/qcombobox.cpp
@@ -428,6 +428,20 @@ void QComboBoxPrivateContainer::resizeEvent(QResizeEvent *e)
     QFrame::resizeEvent(e);
 }
 
+void QComboBoxPrivateContainer::paintEvent(QPaintEvent *e)
+{
+    QStyleOptionComboBox cbOpt = comboStyleOption();
+    if (combo->style()->styleHint(QStyle::SH_ComboBox_Popup, &cbOpt, combo)
+            && mask().isEmpty()) {
+        QStyleOption opt;
+        opt.initFrom(this);
+        QPainter p(this);
+        style()->drawPrimitive(QStyle::PE_PanelMenu, &opt, &p, this);
+    }
+
+    QFrame::paintEvent(e);
+}
+
 void QComboBoxPrivateContainer::leaveEvent(QEvent *)
 {
 // On Mac using the Mac style we want to clear the selection
diff --git a/src/widgets/widgets/qcombobox_p.h b/src/widgets/widgets/qcombobox_p.h
index 835bbf866e..3f75a357e4 100644
--- a/src/widgets/widgets/qcombobox_p.h
+++ b/src/widgets/widgets/qcombobox_p.h
@@ -248,6 +248,7 @@ protected:
     void timerEvent(QTimerEvent *timerEvent) override;
     void leaveEvent(QEvent *e) override;
     void resizeEvent(QResizeEvent *e) override;
+    void paintEvent(QPaintEvent *e) override;
     QStyleOptionComboBox comboStyleOption() const;
 
 Q_SIGNALS: