UI: Use the new theming system to set Vivy's theme

src/VivyApplication.cc

 #include "VivyApplication.hh"
 #include "UI/MainWindow.hh"
+#include "UI/Theme/Theme.hh"
 
 using namespace Vivy;
 
@@ -8,12 +9,22 @@ VivyApplication::VivyApplication(int &argc, char **argv)
 {
 }
 
+VivyApplication::~VivyApplication() noexcept {}
+
 void
 VivyApplication::setTheme(Theme theme) noexcept
 {
     if (theme == Theme::System)
         return;
 
+    else if (theme == Theme::QtCreator) {
+        qtCreatorThemePtr.reset(new Vivy::Theme("QtCreator"));
+        QSettings settings(QStringLiteral(":theme/design.creatortheme"), QSettings::IniFormat);
+        qtCreatorThemePtr->readSettings(&settings);
+        qtCreatorThemePtr->applyToApplication();
+        return;
+    }
+
     const QString sheet = theme == Theme::Dark ? QStringLiteral(":qdarkstyle/dark/style.qss")
                                                : QStringLiteral(":qdarkstyle/light/style.qss");
 
@@ -46,7 +57,7 @@ VivyApplication::exec() noexcept
     setAttribute(Qt::AA_DontShowIconsInMenus, false);
     setAttribute(Qt::AA_DontShowShortcutsInContextMenus, false);
     setFont(getApplicationFont(Font::Default));
-    setTheme(Theme::Dark); // TODO: Set system theme for now (because we
+    setTheme(Theme::QtCreator); // TODO: Set system theme for now (because we
                                 // don't have a central theme provider).
 
     // Cursor blinking

src/VivyApplication.hh

@@ -36,6 +36,7 @@
 namespace Vivy
 {
 class MainWindow;
+class Theme;
 
 // Vivy application class
 class VivyApplication : public QApplication {
@@ -54,7 +55,7 @@ public:
         DefaultBoldItalic
     };
 
-    enum class Theme { System, Dark, Light };
+    enum class Theme { System, Dark, Light, QtCreator };
 
 private:
     int fontIdMonospace;
@@ -64,11 +65,13 @@ private:
     int fontIdBold;
     int fontIdBoldItalic;
 
+    std::unique_ptr<Vivy::Theme> qtCreatorThemePtr{ nullptr };
     std::unique_ptr<MainWindow> mainWindowPtr{ nullptr };
     bool useFakeVim{ false };
 
 public:
     VivyApplication(int &argc, char **argv);
+    ~VivyApplication() noexcept override;
 
     int exec() noexcept;