Add attribute to indicate a widget was the target of a style sheet

Qt already has the widget attribute WA_StyleSheet to which indicates that
a widget was subject to a style sheet, but it doesn't indicate that the
widget was actually affected by the style sheet. For example, an application
style sheet will set the WA_StyleSheet attribute on all widgets, even if it
only targets QPushButtons. The WA_StyleSheetTarget new attribute pairs with
WA_StyleSheet to give this extra information.

[ChangeLog][QtWidgets] Added the Qt::WA_StyleSheetTarget attribute to
indicate that a widget was affected by a style sheet.

Change-Id: I7cca18ddec8fbb69f294ae2ef990672a5f4f1d83
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@qt.io>
Reviewed-by: Sérgio Martins <sergio.martins@kdab.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp b/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
index 28a099de83..6a4d972baf 100644
--- a/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
+++ b/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
@@ -98,6 +98,8 @@ private slots:
     void widgetStyle();
     void appStyle();
     void QTBUG11658_cachecrash();
+    void styleSheetTargetAttribute();
+
 private:
     QColor COLOR(const QWidget& w) {
         w.ensurePolished();
@@ -1999,6 +2001,59 @@ void tst_QStyleSheetStyle::widgetStylePropagation()
     QCOMPARE(COLOR(childLabel), childExpectedColor);
 }
 
+void tst_QStyleSheetStyle::styleSheetTargetAttribute()
+{
+    QGroupBox gb;
+    QLabel lb(&gb);
+    QPushButton pb(&lb);
+
+    gb.ensurePolished(); lb.ensurePolished(); pb.ensurePolished();
+    QCOMPARE(gb.testAttribute(Qt::WA_StyleSheetTarget), false);
+    QCOMPARE(lb.testAttribute(Qt::WA_StyleSheetTarget), false);
+    QCOMPARE(pb.testAttribute(Qt::WA_StyleSheetTarget), false);
+
+    qApp->setStyleSheet("QPushButton { background-color: blue; }");
+
+    gb.ensurePolished(); lb.ensurePolished(); pb.ensurePolished();
+    QCOMPARE(gb.testAttribute(Qt::WA_StyleSheetTarget), false);
+    QCOMPARE(lb.testAttribute(Qt::WA_StyleSheetTarget), false);
+    QCOMPARE(pb.testAttribute(Qt::WA_StyleSheetTarget), true);
+
+    qApp->setStyleSheet("QGroupBox { background-color: blue; }");
+
+    gb.ensurePolished(); lb.ensurePolished(); pb.ensurePolished();
+    QCOMPARE(gb.testAttribute(Qt::WA_StyleSheetTarget), true);
+    QCOMPARE(lb.testAttribute(Qt::WA_StyleSheetTarget), false);
+    QCOMPARE(pb.testAttribute(Qt::WA_StyleSheetTarget), false);
+
+    qApp->setStyleSheet("QGroupBox * { background-color: blue; }");
+
+    gb.ensurePolished(); lb.ensurePolished(); pb.ensurePolished();
+    QCOMPARE(gb.testAttribute(Qt::WA_StyleSheetTarget), false);
+    QCOMPARE(lb.testAttribute(Qt::WA_StyleSheetTarget), true);
+    QCOMPARE(pb.testAttribute(Qt::WA_StyleSheetTarget), true);
+
+    qApp->setStyleSheet("* { background-color: blue; }");
+    gb.ensurePolished(); lb.ensurePolished(); pb.ensurePolished();
+    QCOMPARE(gb.testAttribute(Qt::WA_StyleSheetTarget), true);
+    QCOMPARE(lb.testAttribute(Qt::WA_StyleSheetTarget), true);
+    QCOMPARE(pb.testAttribute(Qt::WA_StyleSheetTarget), true);
+
+    qApp->setStyleSheet("QLabel { font-size: 32pt; }");
+
+    gb.ensurePolished(); lb.ensurePolished(); pb.ensurePolished();
+    QCOMPARE(gb.testAttribute(Qt::WA_StyleSheetTarget), false);
+    QCOMPARE(lb.testAttribute(Qt::WA_StyleSheetTarget), true);
+    QCOMPARE(pb.testAttribute(Qt::WA_StyleSheetTarget), false);
+
+    qApp->setStyleSheet("");
+
+    gb.ensurePolished(); lb.ensurePolished(); pb.ensurePolished();
+    QCOMPARE(gb.testAttribute(Qt::WA_StyleSheetTarget), false);
+    QCOMPARE(lb.testAttribute(Qt::WA_StyleSheetTarget), false);
+    QCOMPARE(pb.testAttribute(Qt::WA_StyleSheetTarget), false);
+}
+
 QTEST_MAIN(tst_QStyleSheetStyle)
 #include "tst_qstylesheetstyle.moc"