QStyleSheetStyle: introduce class Tampered<QPalette|QFont>

... as a replacement for two QPairs and move some common
QFont/QPalette functionality into it.

Change-Id: Iaab92130dd54eaa7900ac2048014a80cbd04bfb6
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

2 files changed, 34 insertions, 30 deletions

diff --git a/src/widgets/styles/qstylesheetstyle.cpp b/src/widgets/styles/qstylesheetstyle.cpp
index ba05155b74..0c7a3e692c 100644
--- a/src/widgets/styles/qstylesheetstyle.cpp
+++ b/src/widgets/styles/qstylesheetstyle.cpp
@@ -2594,7 +2594,7 @@ void QStyleSheetStyle::setPalette(QWidget *w)
 
     if (!useStyleSheetPropagationInWidgetStyles || p.resolve() != 0) {
         QPalette wp = w->palette();
-        styleSheetCaches->customPaletteWidgets.insert(w, qMakePair(wp, p.resolve()));
+        styleSheetCaches->customPaletteWidgets.insert(w, {wp, p.resolve()});
 
         if (useStyleSheetPropagationInWidgetStyles) {
             p = p.resolve(wp);
@@ -2614,20 +2614,14 @@ void QStyleSheetStyle::unsetPalette(QWidget *w)
 
     const auto it = styleSheetCaches->customPaletteWidgets.find(w);
     if (it != styleSheetCaches->customPaletteWidgets.end()) {
-        QPair<QPalette, uint> p = std::move(*it);
+        auto customizedPalette = std::move(*it);
         styleSheetCaches->customPaletteWidgets.erase(it);
 
-        QPalette original = p.first;
-
-        if (useStyleSheetPropagationInWidgetStyles) {
-            original.resolve(original.resolve() & p.second);
-
-            QPalette wp = w->palette();
-            wp.resolve(wp.resolve() & ~p.second);
-            wp.resolve(original);
-            wp.resolve(wp.resolve() | original.resolve());
-            original = wp;
-        }
+        QPalette original;
+        if (useStyleSheetPropagationInWidgetStyles)
+            original = std::move(customizedPalette).reverted(w->palette());
+        else
+            original = customizedPalette.oldWidgetValue;
 
         w->setPalette(original);
         QWidget *ew = embeddedWidget(w);
@@ -2657,18 +2651,9 @@ void QStyleSheetStyle::unsetStyleSheetFont(QWidget *w) const
 {
     const auto it = styleSheetCaches->customFontWidgets.find(w);
     if (it != styleSheetCaches->customFontWidgets.end()) {
-        QPair<QFont, uint> f = std::move(*it);
+        auto customizedFont = std::move(*it);
         styleSheetCaches->customFontWidgets.erase(it);
-
-        QFont original = f.first;
-        original.resolve(original.resolve() & f.second);
-
-        QFont font = w->font();
-        font.resolve(font.resolve() & ~f.second);
-        font.resolve(original);
-        font.resolve(font.resolve() | original.resolve());
-
-        w->setFont(font);
+        w->setFont(std::move(customizedFont).reverted(w->font()));
     }
 }
 
@@ -5953,7 +5938,7 @@ void QStyleSheetStyle::updateStyleSheetFont(QWidget* w) const
 
         if (rule.font.resolve()) {
             QFont wf = w->font();
-            styleSheetCaches->customFontWidgets.insert(w, qMakePair(wf, rule.font.resolve()));
+            styleSheetCaches->customFontWidgets.insert(w, {wf, rule.font.resolve()});
 
             QFont font = rule.font.resolve(wf);
             font.resolve(wf.resolve() | rule.font.resolve());
diff --git a/src/widgets/styles/qstylesheetstyle_p.h b/src/widgets/styles/qstylesheetstyle_p.h
index 55dd2df329..2d302305bd 100644
--- a/src/widgets/styles/qstylesheetstyle_p.h
+++ b/src/widgets/styles/qstylesheetstyle_p.h
@@ -189,12 +189,31 @@ public:
     QHash<const QObject *, QRenderRules> renderRulesCache;
     QHash<const void *, QCss::StyleSheet> styleSheetCache; // parsed style sheets
     QSet<const QWidget *> autoFillDisabledWidgets;
-    // widgets whose palettes and fonts we have tampered. stored value pair is
-    // QPair<old widget value, resolve mask of stylesheet value>
-    QHash<const QWidget *, QPair<QPalette, uint> > customPaletteWidgets;
-    QHash<const QWidget *, QPair<QFont, uint> > customFontWidgets;
+    // widgets with whose palettes and fonts we have tampered:
+    template <typename T>
+    struct Tampered {
+        T oldWidgetValue;
+        uint resolveMask;
+
+        // only call this function on an rvalue *this (it mangles oldWidgetValue)
+        T reverted(T current)
+#ifdef Q_COMPILER_REF_QUALIFIERS
+        &&
+#endif
+        {
+            oldWidgetValue.resolve(oldWidgetValue.resolve() & resolveMask);
+            current.resolve(current.resolve() & ~resolveMask);
+            current.resolve(oldWidgetValue);
+            current.resolve(current.resolve() | oldWidgetValue.resolve());
+            return current;
+        }
+    };
+    QHash<const QWidget *, Tampered<QPalette>> customPaletteWidgets;
+    QHash<const QWidget *, Tampered<QFont>> customFontWidgets;
 };
-
+template <typename T>
+class QTypeInfo<QStyleSheetStyleCaches::Tampered<T>>
+    : QTypeInfoMerger<QStyleSheetStyleCaches::Tampered<T>, T> {};
 
 QT_END_NAMESPACE
 #endif // QT_NO_STYLE_STYLESHEET