QGuiApplication::paletteChanged(const QPalette &palette) [signal]

This allows QQuickSystemPalette to listen to palette changes without
installing an expensive event filter on the application object.

Change-Id: I8b693e047d993c444e393d7a714a5709692c3560
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>

src/gui/kernel/qguiapplication.cpp

@@ -2652,6 +2652,15 @@ QClipboard * QGuiApplication::clipboard()
 }
 #endif
 
+/*!
+    \since 5.4
+    \fn void QGuiApplication::paletteChanged(const QPalette &palette)
+
+    This signal is emitted when the \a palette of the application changes.
+
+    \sa palette()
+*/
+
 /*!
     Returns the default application palette.
 
@@ -2678,6 +2687,7 @@ void QGuiApplication::setPalette(const QPalette &pal)
     else
         *QGuiApplicationPrivate::app_pal = pal;
     applicationResourceFlags |= ApplicationPaletteExplicitlySet;
+    emit qGuiApp->paletteChanged(*QGuiApplicationPrivate::app_pal);
 }
 
 QRect QGuiApplicationPrivate::applyWindowGeometrySpecification(const QRect &windowGeometry, const QWindow *window)

src/gui/kernel/qguiapplication.h

@@ -174,6 +174,7 @@ Q_SIGNALS:
     void commitDataRequest(QSessionManager &sessionManager);
     void saveStateRequest(QSessionManager &sessionManager);
 #endif
+    void paletteChanged(const QPalette &pal);
 
 protected:
     bool event(QEvent *);

tests/auto/gui/kernel/qguiapplication/tst_qguiapplication.cpp

@@ -45,6 +45,7 @@
 #include <QtGui/QWindow>
 #include <QtGui/QScreen>
 #include <QtGui/QCursor>
+#include <QtGui/QPalette>
 #include <qpa/qwindowsysteminterface.h>
 #include <qgenericplugin.h>
 
@@ -72,6 +73,7 @@ private slots:
     void abortQuitOnShow();
     void changeFocusWindow();
     void keyboardModifiers();
+    void palette();
     void modalWindow();
     void quitOnLastWindowClosed();
     void genericPluginsAndWindowSystemEvents();
@@ -434,6 +436,31 @@ void tst_QGuiApplication::keyboardModifiers()
     window->close();
 }
 
+void tst_QGuiApplication::palette()
+{
+    int argc = 1;
+    char *argv[] = { const_cast<char*>("tst_qguiapplication") };
+    QGuiApplication app(argc, argv);
+    QSignalSpy signalSpy(&app, SIGNAL(paletteChanged(QPalette)));
+
+    QPalette oldPalette = QGuiApplication::palette();
+    QPalette newPalette = QPalette(Qt::red);
+
+    QGuiApplication::setPalette(newPalette);
+    QCOMPARE(QGuiApplication::palette(), newPalette);
+    QCOMPARE(signalSpy.count(), 1);
+    QCOMPARE(signalSpy.at(0).at(0), QVariant(newPalette));
+
+    QGuiApplication::setPalette(oldPalette);
+    QCOMPARE(QGuiApplication::palette(), oldPalette);
+    QCOMPARE(signalSpy.count(), 2);
+    QCOMPARE(signalSpy.at(1).at(0), QVariant(oldPalette));
+
+    QGuiApplication::setPalette(oldPalette);
+    QCOMPARE(QGuiApplication::palette(), oldPalette);
+    QCOMPARE(signalSpy.count(), 2);
+}
+
 class BlockableWindow : public QWindow
 {
     Q_OBJECT