QQuickTheme: don't inherit QPlatformTheme

Use QPlatformTheme as a fallback instead of inheriting from it. This
way, Qt Quick Controls 2 themes don't mess up the fonts and palettes
of Qt Quick Controls 1 and Qt Widgets applications.

Note: QQuickTheme::Font and QQuickTheme::Palette enums are copies of
the respective enums in QPlatformTheme, for now. This is the simplest
first step, but later on, we can have our own set of enums that cover
controls, such as Switch, that were previously entirely missing from
QPlatformTheme.

Task-number: QTBUG-51921
Change-Id: I8efe0ba2d03d65bc12b55b533ba9f2fab5320348
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 6 insertions, 15 deletions

diff --git a/tests/auto/font/tst_font.cpp b/tests/auto/font/tst_font.cpp
index a585e970..f3f9dbf5 100644
--- a/tests/auto/font/tst_font.cpp
+++ b/tests/auto/font/tst_font.cpp
@@ -180,10 +180,10 @@ void tst_font::inheritance()
     QCOMPARE(grandChild->property("font").value<QFont>(), windowFont);
 }
 
-class TestFontTheme : public QQuickProxyTheme
+class TestFontTheme : public QQuickTheme
 {
 public:
-    TestFontTheme(QPlatformTheme *theme) : QQuickProxyTheme(theme)
+    TestFontTheme()
     {
         std::fill(fonts, fonts + QQuickTheme::NFonts, static_cast<QFont *>(0));
 
@@ -192,8 +192,6 @@ public:
             font.setPixelSize(i + 10);
             fonts[i] = new QFont(font);
         }
-
-        QGuiApplicationPrivate::platform_theme = this;
     }
 
     const QFont *font(Font type = SystemFont) const override
@@ -266,9 +264,9 @@ void tst_font::defaultFont()
     QQmlComponent component(&engine);
     component.setData(QString("import QtQuick.Controls 2.2; %1 { }").arg(control).toUtf8(), QUrl());
 
-    // The call to setData() above causes QQuickDefaultTheme to be set as the platform theme,
+    // The call to setData() above causes QQuickDefaultTheme to be set as the current theme,
     // so we must make sure we only set our theme afterwards.
-    TestFontTheme theme(QGuiApplicationPrivate::platform_theme);
+    QQuickTheme::setCurrent(new TestFontTheme);
 
     QScopedPointer<QObject> object(component.create());
     QVERIFY2(!object.isNull(), qPrintable(component.errorString()));
@@ -276,16 +274,9 @@ void tst_font::defaultFont()
     QVariant var = object->property("font");
     QVERIFY(var.isValid());
 
-    const QFont *expectedFont = theme.font(fontType);
-    QVERIFY(expectedFont);
-
+    QFont expectedFont = QQuickTheme::themeFont(fontType);
     QFont actualFont = var.value<QFont>();
-
-    if (actualFont != *expectedFont) {
-        qDebug() << QTest::currentDataTag() << actualFont << *expectedFont;
-    }
-
-    QCOMPARE(actualFont, *expectedFont);
+    QCOMPARE(actualFont, expectedFont);
 }
 
 void tst_font::listView_data()