Theme: added ability to access root Theme via attached property

Author: micieslak

ui/StatusQ/include/StatusQ/theme.h

@@ -58,6 +58,8 @@ class Theme : public QQuickAttachedPropertyPropagator
 
     const ThemePalette* palette() const;
 
+    Q_INVOKABLE Theme* rootTheme();
+
     static Theme *qmlAttachedProperties(QObject *object);
 
 signals:

ui/StatusQ/src/theme.cpp

@@ -1,5 +1,7 @@
 #include "StatusQ/theme.h"
 
+#include <QQmlApplicationEngine>
+
 namespace {
 
 constexpr qreal s_defaultPadding = 16;
@@ -165,6 +167,23 @@ const ThemePalette* Theme::palette() const
                                    : s_paletteDark.get();
 }
 
+Theme *Theme::rootTheme()
+{
+    auto theme = qobject_cast<Theme*>(attachedParent());
+
+    if (!theme)
+        return this;
+
+    while (true) {
+        auto next = qobject_cast<Theme*>(theme->attachedParent());
+
+        if (!next || qobject_cast<QQmlApplicationEngine*>(next->parent()))
+            return theme;
+        else
+            theme = next;
+    }
+}
+
 Theme* Theme::qmlAttachedProperties(QObject *object)
 {
     return new Theme(object);