Add attribute to enable font and palette propagation in QSS.

By default when using Qt Style Sheets, a widget does not inherit its
font and palette from its parent widget. With the
Qt::AA_UseStyleSheetPropagationInWidgetStyles application attribute set,
propagation when using Qt Style Sheets behaves like it does with regular
QWidget::setPalette() and QWidget::setFont() calls.

[ChangeLog][QtWidgets] Added the
Qt::AA_UseStyleSheetPropagationInWidgetStyles attribute which enables
font and palette propagation for Qt Style Sheets.

Task-number: QTBUG-37580
Change-Id: I3038c13d61e32625a1a05291c5394eaefd376a68
Reviewed-by: Samuel Nevala <samuel.nevala@intopalo.com>
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>

1 files changed, 214 insertions, 14 deletions

diff --git a/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp b/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
index 5b0ae29dc1..b52aa30239 100644
--- a/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
+++ b/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
@@ -55,6 +55,7 @@ public:
     ~tst_QStyleSheetStyle();
 
 private slots:
+    void init();
     void repolish();
     void numinstances();
     void widgetsBeforeAppStyleSheet();
@@ -71,8 +72,12 @@ private slots:
     void layoutSpacing();
 #endif
     void qproperty();
+    void palettePropagation_data();
     void palettePropagation();
+    void fontPropagation_data();
     void fontPropagation();
+    void widgetStylePropagation_data();
+    void widgetStylePropagation();
     void onWidgetDestroyed();
     void fontPrecedence();
     void focusColors();
@@ -137,6 +142,12 @@ tst_QStyleSheetStyle::~tst_QStyleSheetStyle()
 {
 }
 
+void tst_QStyleSheetStyle::init()
+{
+    qApp->setStyleSheet(QString());
+    QCoreApplication::setAttribute(Qt::AA_UseStyleSheetPropagationInWidgetStyles, false);
+}
+
 void tst_QStyleSheetStyle::numinstances()
 {
     QWidget w;
@@ -627,31 +638,80 @@ void tst_QStyleSheetStyle::namespaces()
     QCOMPARE(BACKGROUND(pb2), red);
 }
 
+void tst_QStyleSheetStyle::palettePropagation_data()
+{
+    QTest::addColumn<QString>("applicationStyleSheet");
+    QTest::addColumn<bool>("widgetStylePropagation");
+    QTest::newRow("Widget style propagation") << " " << true;
+    QTest::newRow("Widget style propagation, no application style sheet") << QString() << true;
+    QTest::newRow("Default propagation") << " " << false;
+    QTest::newRow("Default propagation, no application style sheet") << QString() << false;
+}
+
 void tst_QStyleSheetStyle::palettePropagation()
 {
-    qApp->setStyleSheet("");
+    QFETCH(QString, applicationStyleSheet);
+    QFETCH(bool, widgetStylePropagation);
+
+    qApp->setStyleSheet(applicationStyleSheet);
+    QCoreApplication::setAttribute(Qt::AA_UseStyleSheetPropagationInWidgetStyles, widgetStylePropagation);
+
     QGroupBox gb;
-    QPushButton *push = new QPushButton(&gb);
-    QPushButton &pb = *push;
-    push->setText("AsdF");
+    QLabel *label = new QLabel(&gb);
+    QLabel &lb = *label;
+    label->setText("AsdF");
 
     gb.setStyleSheet("QGroupBox { color: red }");
-    QVERIFY(COLOR(gb) == Qt::red);
-    QVERIFY(COLOR(pb) == APPCOLOR(pb)); // palette shouldn't propagate
-    gb.setStyleSheet("QGroupBox * { color: red }");
+    QCOMPARE(COLOR(gb), QColor(Qt::red));
 
-    QVERIFY(COLOR(pb) == Qt::red);
-    QVERIFY(COLOR(gb) == APPCOLOR(gb));
+    if (widgetStylePropagation) {
+        QCOMPARE(COLOR(lb), QColor(Qt::red)); // palette should propagate in standard mode
+    } else {
+        QCOMPARE(COLOR(lb), APPCOLOR(lb)); // palette shouldn't propagate
+    }
 
     QWidget window;
+    lb.setParent(&window);
+    if (widgetStylePropagation) {
+        // In standard propagation mode, widgets that are not explicitly
+        // targeted do not have their propagated palette unset when they are
+        // unpolished by changing parents.  This is consistent with regular Qt
+        // widgets, who also maintain their propagated palette when changing
+        // parents
+        QCOMPARE(COLOR(lb), QColor(Qt::red));
+    } else {
+        QCOMPARE(COLOR(lb), APPCOLOR(lb));
+    }
+    lb.setParent(&gb);
+
+    gb.setStyleSheet("QGroupBox * { color: red }");
+
+    QCOMPARE(COLOR(lb), QColor(Qt::red));
+    QCOMPARE(COLOR(gb), APPCOLOR(gb));
+
     window.setStyleSheet("* { color: white; }");
-    pb.setParent(&window);
-    QVERIFY(COLOR(pb) == Qt::white);
+    lb.setParent(&window);
+    QCOMPARE(COLOR(lb), QColor(Qt::white));
+}
+
+void tst_QStyleSheetStyle::fontPropagation_data()
+{
+    QTest::addColumn<QString>("applicationStyleSheet");
+    QTest::addColumn<bool>("widgetStylePropagation");
+    QTest::newRow("Widget style propagation") << " " << true;
+    QTest::newRow("Widget style propagation, no application style sheet") << QString() << true;
+    QTest::newRow("Default propagation") << " " << false;
+    QTest::newRow("Default propagation, no application style sheet") << QString() << false;
 }
 
 void tst_QStyleSheetStyle::fontPropagation()
 {
-    qApp->setStyleSheet("");
+    QFETCH(QString, applicationStyleSheet);
+    QFETCH(bool, widgetStylePropagation);
+
+    qApp->setStyleSheet(applicationStyleSheet);
+    QCoreApplication::setAttribute(Qt::AA_UseStyleSheetPropagationInWidgetStyles, widgetStylePropagation);
+
     QComboBox cb;
     cb.addItem("item1");
     cb.addItem("item2");
@@ -661,7 +721,11 @@ void tst_QStyleSheetStyle::fontPropagation()
 
     cb.setStyleSheet("QComboBox { font-size: 20pt; }");
     QCOMPARE(FONTSIZE(cb), 20);
-    QCOMPARE(FONTSIZE(*popup), viewFontSize);
+    if (widgetStylePropagation) {
+        QCOMPARE(FONTSIZE(*popup), 20);
+    } else {
+        QCOMPARE(FONTSIZE(*popup), viewFontSize);
+    }
     QGroupBox gb;
     QPushButton *push = new QPushButton(&gb);
     QPushButton &pb = *push;
@@ -670,7 +734,11 @@ void tst_QStyleSheetStyle::fontPropagation()
 
     gb.setStyleSheet("QGroupBox { font-size: 20pt }");
     QCOMPARE(FONTSIZE(gb), 20);
-    QVERIFY(FONTSIZE(pb) == buttonFontSize); // font does not propagate
+    if (widgetStylePropagation) {
+        QCOMPARE(FONTSIZE(pb), 20);
+    } else {
+        QCOMPARE(FONTSIZE(pb), buttonFontSize); // font does not propagate
+    }
     gb.setStyleSheet("QGroupBox * { font-size: 20pt; }");
     QCOMPARE(FONTSIZE(gb), gbFontSize);
     QCOMPARE(FONTSIZE(pb), 20);
@@ -1796,6 +1864,138 @@ void tst_QStyleSheetStyle::styleSheetChangeBeforePolish()
     QVERIFY(testForColors(image2, QColor(0x00, 0xFF, 0x00)));
 }
 
+void tst_QStyleSheetStyle::widgetStylePropagation_data()
+{
+    QTest::addColumn<QString>("applicationStyleSheet");
+    QTest::addColumn<QString>("parentStyleSheet");
+    QTest::addColumn<QString>("childStyleSheet");
+    QTest::addColumn<QFont>("parentFont");
+    QTest::addColumn<QFont>("childFont");
+    QTest::addColumn<QPalette>("parentPalette");
+    QTest::addColumn<QPalette>("childPalette");
+    QTest::addColumn<int>("parentExpectedSize");
+    QTest::addColumn<int>("childExpectedSize");
+    QTest::addColumn<QColor>("parentExpectedColor");
+    QTest::addColumn<QColor>("childExpectedColor");
+
+    QFont noFont;
+    QFont font45; font45.setPointSize(45);
+    QFont font32; font32.setPointSize(32);
+
+    QPalette noPalette;
+    QPalette redPalette; redPalette.setColor(QPalette::WindowText, QColor("red"));
+    QPalette greenPalette; greenPalette.setColor(QPalette::WindowText, QColor("green"));
+
+    QLabel defaultLabel;
+
+    int defaultSize = defaultLabel.font().pointSize();
+    QColor defaultColor = defaultLabel.palette().color(defaultLabel.foregroundRole());
+    QColor redColor("red");
+    QColor greenColor("green");
+
+    // Check regular Qt propagation works as expected, with and without a
+    // non-interfering application stylesheet
+    QTest::newRow("defaults")
+        << QString() << QString() << QString()
+        << noFont << noFont << noPalette << noPalette
+        << defaultSize << defaultSize << defaultColor << defaultColor;
+    QTest::newRow("parent font propagation, no application style sheet")
+        << QString() << QString() << QString()
+        << font45 << noFont << noPalette << noPalette
+        << 45 << 45 << defaultColor << defaultColor;
+    QTest::newRow("parent font propagation, dummy application style sheet")
+        << "QGroupBox { font-size: 64pt }" << QString() << QString()
+        << font45 << noFont << noPalette << noPalette
+        << 45 << 45 << defaultColor << defaultColor;
+    QTest::newRow("parent color propagation, no application style sheet")
+        << QString() << QString() << QString()
+        << noFont << noFont << redPalette << noPalette
+        << defaultSize << defaultSize << redColor << redColor;
+    QTest::newRow("parent color propagation, dummy application style sheet")
+        << "QGroupBox { color: blue }" << QString() << QString()
+        << noFont << noFont << redPalette << noPalette
+        << defaultSize << defaultSize << redColor << redColor;
+
+    // Parent style sheet propagates to child if child has not explicitly
+    // set a value
+    QTest::newRow("parent style sheet color propagation")
+        << "#parentLabel { color: red }" << QString() << QString()
+        << noFont << noFont << noPalette << noPalette
+        << defaultSize << defaultSize << redColor << redColor;
+    QTest::newRow("parent style sheet font propagation")
+        << "#parentLabel { font-size: 45pt }" << QString() << QString()
+        << noFont << noFont << noPalette << noPalette
+        << 45 << 45 << defaultColor << defaultColor;
+
+    // Parent style sheet does not propagate to child if child has explicitly
+    // set a value
+    QTest::newRow("parent style sheet color propagation, child explicitly set")
+        << "#parentLabel { color: red }" << QString() << QString()
+        << noFont << noFont << noPalette << greenPalette
+        << defaultSize << defaultSize << redColor << greenColor;
+    QTest::newRow("parent style sheet font propagation, child explicitly set")
+        << "#parentLabel { font-size: 45pt }" << QString() << QString()
+        << noFont << font32 << noPalette << noPalette
+        << 45 << 32 << defaultColor << defaultColor;
+
+    // Parent does not propagate to child when child is target of style sheet
+    QTest::newRow("parent style sheet font propagation, child application style sheet")
+        << "#childLabel { font-size: 32pt }" << QString() << QString()
+        << font45 << noFont << noPalette << noPalette
+        << 45 << 32 << defaultColor << defaultColor;
+    QTest::newRow("parent style sheet color propagation, child application style sheet")
+        << "#childLabel { color: green }" << QString() << QString()
+        << noFont << noFont << redPalette << noPalette
+        << defaultSize << defaultSize << redColor << greenColor;
+}
+
+void tst_QStyleSheetStyle::widgetStylePropagation()
+{
+    QFETCH(QString, applicationStyleSheet);
+    QFETCH(QString, parentStyleSheet);
+    QFETCH(QString, childStyleSheet);
+
+    QFETCH(QFont, parentFont);
+    QFETCH(QFont, childFont);
+    QFETCH(QPalette, parentPalette);
+    QFETCH(QPalette, childPalette);
+
+    QFETCH(int, parentExpectedSize);
+    QFETCH(int, childExpectedSize);
+    QFETCH(QColor, parentExpectedColor);
+    QFETCH(QColor, childExpectedColor);
+
+    QCoreApplication::setAttribute(Qt::AA_UseStyleSheetPropagationInWidgetStyles, true);
+
+    qApp->setStyleSheet(applicationStyleSheet);
+
+    QLabel parentLabel;
+    parentLabel.setObjectName("parentLabel");
+    QLabel childLabel(&parentLabel);
+    childLabel.setObjectName("childLabel");
+
+    if (parentFont.resolve())
+        parentLabel.setFont(parentFont);
+    if (childFont.resolve())
+        childLabel.setFont(childFont);
+    if (parentPalette.resolve())
+        parentLabel.setPalette(parentPalette);
+    if (childPalette.resolve())
+        childLabel.setPalette(childPalette);
+    if (!parentStyleSheet.isEmpty())
+        parentLabel.setStyleSheet(parentStyleSheet);
+    if (!childStyleSheet.isEmpty())
+        childLabel.setStyleSheet(childStyleSheet);
+
+    parentLabel.ensurePolished();
+    childLabel.ensurePolished();
+
+    QCOMPARE(FONTSIZE(parentLabel), parentExpectedSize);
+    QCOMPARE(FONTSIZE(childLabel), childExpectedSize);
+    QCOMPARE(COLOR(parentLabel), parentExpectedColor);
+    QCOMPARE(COLOR(childLabel), childExpectedColor);
+}
+
 QTEST_MAIN(tst_QStyleSheetStyle)
 #include "tst_qstylesheetstyle.moc"