Implement color role AccentColor in QStyleSheetStyle and QCssParser

The color role AccentColor has been added to QPalette.

This patch implements the new color role in QCssParser and subsequently
in QStyleSheetStyle.
The QBrush variable names used to populate brushes, have been changed
into speaking names for better code readability.

tst_QCssParser has been adapted accordingly.
The test function accentColor() has been added in tst_QStyleSheetStyle.

Documentation has been updated.

Change-Id: Ib09ddc1b61868f2bb8f70f654e83ea1c35276d30
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

src/gui/text/qcssparser.cpp

@@ -47,6 +47,7 @@ static const QCssKnownValue properties[NumProperties - 1] = {
     { "-qt-style-features", QtStyleFeatures },
     { "-qt-table-type", QtTableType },
     { "-qt-user-state", QtUserState },
+    { "accent-color", QtAccentColor },
     { "alternate-background-color", QtAlternateBackground },
     { "background", Background },
     { "background-attachment", BackgroundAttachment },
@@ -1341,17 +1342,23 @@ bool ValueExtractor::extractFont(QFont *font, int *fontSizeAdjustment)
     return hit;
 }
 
-bool ValueExtractor::extractPalette(QBrush *fg, QBrush *sfg, QBrush *sbg, QBrush *abg, QBrush *pfg)
+bool ValueExtractor::extractPalette(QBrush *foreground,
+                                    QBrush *selectedForeground,
+                                    QBrush *selectedBackground,
+                                    QBrush *alternateBackground,
+                                    QBrush *placeHolderTextForeground,
+                                    QBrush *accentColor)
 {
     bool hit = false;
     for (int i = 0; i < declarations.size(); ++i) {
         const Declaration &decl = declarations.at(i);
         switch (decl.d->propertyId) {
-        case Color: *fg = decl.brushValue(pal); break;
+        case Color: *foreground = decl.brushValue(pal); break;
-        case QtSelectionForeground: *sfg = decl.brushValue(pal); break;
+        case QtSelectionForeground: *selectedForeground = decl.brushValue(pal); break;
-        case QtSelectionBackground: *sbg = decl.brushValue(pal); break;
+        case QtSelectionBackground: *selectedBackground = decl.brushValue(pal); break;
-        case QtAlternateBackground: *abg = decl.brushValue(pal); break;
+        case QtAlternateBackground: *alternateBackground = decl.brushValue(pal); break;
-        case QtPlaceHolderTextColor: *pfg = decl.brushValue(pal); break;
+        case QtPlaceHolderTextColor: *placeHolderTextForeground = decl.brushValue(pal); break;
+        case QtAccentColor: *accentColor = decl.brushValue(pal); break;
         default: continue;
         }
         hit = true;

src/gui/text/qcssparser_p.h

@@ -166,6 +166,7 @@ enum Property {
     WordSpacing,
     TextDecorationColor,
     QtPlaceHolderTextColor,
+    QtAccentColor,
     NumProperties
 };
 
@@ -823,7 +824,9 @@ struct Q_GUI_EXPORT ValueExtractor
     bool extractBox(int *margins, int *paddings, int *spacing = nullptr);
     bool extractBorder(int *borders, QBrush *colors, BorderStyle *Styles, QSize *radii);
     bool extractOutline(int *borders, QBrush *colors, BorderStyle *Styles, QSize *radii, int *offsets);
-    bool extractPalette(QBrush *fg, QBrush *sfg, QBrush *sbg, QBrush *abg, QBrush *pfg);
+    bool extractPalette(QBrush *foreground, QBrush *selectedForeground, QBrush *selectedBackground,
+                        QBrush *alternateBackground, QBrush *placeHolderTextForeground,
+                        QBrush *accentColor);
     int  extractStyleFeatures();
     bool extractImage(QIcon *icon, Qt::Alignment *a, QSize *size);
     bool extractIcon(QIcon *icon, QSize *size);

src/widgets/doc/src/widgets-and-layouts/stylesheet.qdoc

@@ -1357,6 +1357,13 @@
         \li Type
         \li Description
 
+    \row
+        \li \b{\c accent-color}
+        \li \l{#Brush}{Brush} \br
+        \li The property sets the \c AccentColor, which is used to emphasize
+           interactive UI elements.
+           If this property is not set, it defaults to the \c highlight color.
+
     \row
         \li \b{\c alternate-background-color} \target alternate-background-color-prop
         \li \l{#Brush}{Brush} \br
@@ -3064,6 +3071,7 @@
     \row
         \li \b{PaletteRole} \target PaletteRole
         \li \c alternate-base \br
+              | \c accentColor \br
               | \c base \br
               | \c bright-text \br
               | \c button \br

src/widgets/styles/qstylesheetstyle.cpp

@@ -434,16 +434,26 @@ struct QStyleSheetBoxData : public QSharedData
 
 struct QStyleSheetPaletteData : public QSharedData
 {
-    QStyleSheetPaletteData(const QBrush &fg, const QBrush &sfg, const QBrush &sbg,
+     QStyleSheetPaletteData(const QBrush &foreground,
-                           const QBrush &abg, const QBrush &pfg)
+                            const QBrush &selectedForeground,
-        : foreground(fg), selectionForeground(sfg), selectionBackground(sbg),
+                            const QBrush &selectedBackground,
-          alternateBackground(abg), placeholderForeground(pfg) { }
+                            const QBrush &alternateBackground,
+                            const QBrush &placeHolderTextForeground,
+                            const QBrush &accentColor)
+        : foreground(foreground)
+        , selectionForeground(selectedForeground)
+        , selectionBackground(selectedBackground)
+        , alternateBackground(alternateBackground)
+        , placeholderForeground(placeHolderTextForeground)
+        , accentColor(accentColor)
+     { }
 
     QBrush foreground;
     QBrush selectionForeground;
     QBrush selectionBackground;
     QBrush alternateBackground;
     QBrush placeholderForeground;
+    QBrush accentColor;
 };
 
 struct QStyleSheetGeometryData : public QSharedData
@@ -955,10 +965,17 @@ QRenderRule::QRenderRule(const QList<Declaration> &declarations, const QObject *
         bg = new QStyleSheetBackgroundData(brush, pixmap, repeat, alignment, origin, attachment, clip);
     }
 
-    QBrush sfg, fg, pfg;
+    QBrush foreground;
-    QBrush sbg, abg;
+    QBrush selectedForeground;
-    if (v.extractPalette(&fg, &sfg, &sbg, &abg, &pfg))
+    QBrush selectedBackground;
-        pal = new QStyleSheetPaletteData(fg, sfg, sbg, abg, pfg);
+    QBrush alternateBackground;
+    QBrush placeHolderTextForeground;
+    QBrush accentColor;
+    if (v.extractPalette(&foreground, &selectedForeground, &selectedBackground,
+                         &alternateBackground, &placeHolderTextForeground, &accentColor)) {
+        pal = new QStyleSheetPaletteData(foreground, selectedForeground, selectedBackground,
+                                         alternateBackground, placeHolderTextForeground, accentColor);
+    }
 
     QIcon imgIcon;
     alignment = Qt::AlignCenter;
@@ -1487,6 +1504,8 @@ void QRenderRule::configurePalette(QPalette *p, QPalette::ColorGroup cg, const Q
         p->setBrush(cg, QPalette::AlternateBase, pal->alternateBackground);
     if (pal->placeholderForeground.style() != Qt::NoBrush)
         p->setBrush(cg, QPalette::PlaceholderText, pal->placeholderForeground);
+    if (pal->accentColor.style() != Qt::NoBrush)
+        p->setBrush(cg, QPalette::AccentColor, pal->accentColor);
 }
 
 bool QRenderRule::hasModification() const

tests/auto/gui/text/qcssparser/tst_qcssparser.cpp

@@ -1543,20 +1543,26 @@ void tst_QCssParser::gradient()
     QList<QCss::StyleRule> rules = testSelector.styleRulesForNode(n);
     QList<QCss::Declaration> decls = rules.at(0).declarations;
     QCss::ValueExtractor ve(decls);
-    QBrush fg, sfg, pfg;
+    QBrush foreground;
-    QBrush sbg, abg;
+    QBrush selectedForeground;
-    QVERIFY(ve.extractPalette(&fg, &sfg, &sbg, &abg, &pfg));
+    QBrush selectedBackground;
+    QBrush alternateBackground;
+    QBrush placeHolderTextForeground;
+    QBrush accentColor;
+    QVERIFY(ve.extractPalette(&foreground, &selectedForeground, &selectedBackground,
+                              &alternateBackground, &placeHolderTextForeground, &accentColor));
+
     if (type == "linear") {
-        QCOMPARE(sbg.style(), Qt::LinearGradientPattern);
+        QCOMPARE(selectedBackground.style(), Qt::LinearGradientPattern);
-        const QLinearGradient *lg = static_cast<const QLinearGradient *>(sbg.gradient());
+        const auto *lg = static_cast<const QLinearGradient *>(selectedBackground.gradient());
         QCOMPARE(lg->start(), start);
         QCOMPARE(lg->finalStop(), finalStop);
     } else if (type == "conical") {
-        QCOMPARE(sbg.style(), Qt::ConicalGradientPattern);
+        QCOMPARE(selectedBackground.style(), Qt::ConicalGradientPattern);
-        const QConicalGradient *cg = static_cast<const QConicalGradient *>(sbg.gradient());
+        const auto *cg = static_cast<const QConicalGradient *>(selectedBackground.gradient());
         QCOMPARE(cg->center(), start);
     }
-    const QGradient *g = sbg.gradient();
+    const QGradient *g = selectedBackground.gradient();
     QCOMPARE(g->spread(), QGradient::Spread(spread));
     QCOMPARE(g->stops().at(0).first, stop0);
     QCOMPARE(g->stops().at(0).second, color0);

tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp

@@ -106,6 +106,7 @@ private slots:
     void QTBUG36933_brokenPseudoClassLookup();
     void styleSheetChangeBeforePolish();
     void placeholderColor();
+    void accentColor();
     void enumPropertySelector_data();
     void enumPropertySelector();
     //at the end because it mess with the style.
@@ -2360,6 +2361,15 @@ void tst_QStyleSheetStyle::placeholderColor()
     QCOMPARE(le1.palette().placeholderText().color(), QColor(phSpec));
 }
 
+void tst_QStyleSheetStyle::accentColor()
+{
+    QLineEdit lineEdit;
+    const QColor universe(42, 42, 42);
+    lineEdit.setStyleSheet(QString("QLineEdit { accent-color: %1; }").arg(universe.name()));
+    lineEdit.ensurePolished();
+    QCOMPARE(lineEdit.palette().accentColor().color(), universe);
+}
+
 void tst_QStyleSheetStyle::enumPropertySelector_data()
 {
     QTest::addColumn<QString>("styleSheet");