Deprecate QGuiApplication::fontChanged() signal

Rather than have a fontChanged() signal which can be connected to for
tracking when the application font has changed, then it is better to
use the event that is sent to all windows and the application itself.
That way it is easy for a window/widget or item that cares about the
change to the application font to catch it in the event() function.

[ChangeLog][QtGui][QGuiApplication] Deprecated fontChanged() signal in
favor of QEvent::ApplicationFontChanged.

Change-Id: Iae8e832238fc85e385a52305bc04f16e597454b0
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 42 insertions, 8 deletions

diff --git a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
index 833111644e..2e0d293399 100644
--- a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
+++ b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
@@ -417,6 +417,7 @@ private slots:
 
     void winIdAfterClose();
     void receivesLanguageChangeEvent();
+    void receivesApplicationFontChangeEvent();
 
 private:
     bool ensureScreenSize(int width, int height);
@@ -11626,30 +11627,36 @@ void tst_QWidget::winIdAfterClose()
     delete spy;
 }
 
-class LanguageChangeEventWidget : public QWidget
+class ChangeEventWidget : public QWidget
 {
 public:
-    LanguageChangeEventWidget(QWidget *parent = nullptr) : QWidget(parent) {}
+    ChangeEventWidget(QWidget *parent = nullptr) : QWidget(parent) {}
     int languageChangeCount = 0;
+    int applicationFontChangeCount = 0;
 protected:
     bool event(QEvent *e) override
     {
         if (e->type() == QEvent::LanguageChange)
             languageChangeCount++;
+        else if (e->type() == QEvent::ApplicationFontChange)
+            applicationFontChangeCount++;
         return QWidget::event(e);
     }
 };
 
-class LanguageChangeEventWindow : public QWindow
+class ChangeEventWindow : public QWindow
 {
 public:
-    LanguageChangeEventWindow(QWindow *parent = nullptr) : QWindow(parent) {}
+    ChangeEventWindow(QWindow *parent = nullptr) : QWindow(parent) {}
     int languageChangeCount = 0;
+    int applicationFontChangeCount = 0;
 protected:
     bool event(QEvent *e) override
     {
         if (e->type() == QEvent::LanguageChange)
             languageChangeCount++;
+        else if (e->type() == QEvent::ApplicationFontChange)
+            applicationFontChangeCount++;
         return QWindow::event(e);
     }
 };
@@ -11658,14 +11665,14 @@ void tst_QWidget::receivesLanguageChangeEvent()
 {
     // Confirm that any QWindow or QWidget only gets a single
     // LanguageChange event when a translator is installed
-    LanguageChangeEventWidget topLevel;
-    auto childWidget = new LanguageChangeEventWidget(&topLevel);
+    ChangeEventWidget topLevel;
+    auto childWidget = new ChangeEventWidget(&topLevel);
     topLevel.show();
     QVERIFY(QTest::qWaitForWindowExposed(&topLevel));
-    LanguageChangeEventWindow ww;
+    ChangeEventWindow ww;
     ww.show();
     QVERIFY(QTest::qWaitForWindowExposed(&ww));
-    LanguageChangeEventWidget topLevelNotShown;
+    ChangeEventWidget topLevelNotShown;
     QTranslator t;
     QVERIFY(t.load("hellotr_la.qm", ":/"));
     QVERIFY(qApp->installTranslator(&t));
@@ -11676,5 +11683,32 @@ void tst_QWidget::receivesLanguageChangeEvent()
     QCOMPARE(ww.languageChangeCount, 1);
 }
 
+void tst_QWidget::receivesApplicationFontChangeEvent()
+{
+    // Confirm that any QWindow or top level QWidget only gets a single
+    // ApplicationFontChange event when the font is changed
+    const QFont origFont = QApplication::font();
+
+    ChangeEventWidget topLevel;
+    auto childWidget = new ChangeEventWidget(&topLevel);
+    topLevel.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&topLevel));
+    ChangeEventWindow ww;
+    ww.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&ww));
+    ChangeEventWidget topLevelNotShown;
+    QFont changedFont = origFont;
+    changedFont.setPointSize(changedFont.pointSize() + 2);
+    QApplication::setFont(changedFont);
+    QCoreApplication::sendPostedEvents(0, QEvent::ApplicationFontChange);
+    QCOMPARE(topLevel.applicationFontChangeCount, 1);
+    QCOMPARE(topLevelNotShown.applicationFontChangeCount, 1);
+    // QWidget should not be passing the event on automatically
+    QCOMPARE(childWidget->applicationFontChangeCount, 0);
+    QCOMPARE(ww.applicationFontChangeCount, 1);
+
+    QApplication::setFont(origFont);
+}
+
 QTEST_MAIN(tst_QWidget)
 #include "tst_qwidget.moc"