Qt: return const char* from enum-name lookup methods

Three MainWindow methods exist solely to map an enum value to a
fixed string literal: getThemeString, getCurrentViewTypeString,
and getCurrentThumbnailTypeString. They returned QString built
from a string literal at every call. Returning the literal
directly as const char* is one less heap allocation per call and
the caller (QSettings::setValue, which takes QVariant) accepts
it via the implicit QString conversion either way.

* getThemeString: 4 lines -> 1 line per branch.
* getCurrentViewTypeString: switch over a 2-value enum collapses
  to an if.
* getCurrentThumbnailTypeString: dropped a dead trailing
  'return QString("list")' that the compiler couldn't reach -
  the THUMBNAIL_TYPE_BOXART branch already returned via the
  default label.

No behaviour change. All four object files build with zero
warnings.

Author: LibretroAdmin

ui/drivers/ui_qt.cpp

@@ -2490,20 +2490,19 @@ MainWindow::Theme MainWindow::getThemeFromString(QString themeString)
    return THEME_SYSTEM_DEFAULT;
 }
 
-QString MainWindow::getThemeString(Theme theme)
+const char *MainWindow::getThemeString(Theme theme)
 {
    switch (theme)
    {
-      case THEME_SYSTEM_DEFAULT:
-         return QString("default");
       case THEME_DARK:
-         return QString("dark");
+         return "dark";
       case THEME_CUSTOM:
-         return QString("custom");
+         return "custom";
+      case THEME_SYSTEM_DEFAULT:
       default:
          break;
    }
-   return QString("default");
+   return "default";
 }
 
 MainWindow::Theme MainWindow::theme() { return m_currentTheme; }
@@ -3960,36 +3959,28 @@ void MainWindow::keyPressEvent(QKeyEvent *event)
 
 QSettings* MainWindow::settings() { return m_settings; }
 
-QString MainWindow::getCurrentViewTypeString()
+const char *MainWindow::getCurrentViewTypeString()
 {
-   switch (m_viewType)
-   {
-      case VIEW_TYPE_ICONS:
-         return QString("icons");
-      case VIEW_TYPE_LIST:
-      default:
-         break;
-   }
-
-   return QString("list");
+   if (m_viewType == VIEW_TYPE_ICONS)
+      return "icons";
+   return "list";
 }
 
-QString MainWindow::getCurrentThumbnailTypeString()
+const char *MainWindow::getCurrentThumbnailTypeString()
 {
    switch (m_thumbnailType)
    {
       case THUMBNAIL_TYPE_SCREENSHOT:
-         return QString("screenshot");
+         return "screenshot";
       case THUMBNAIL_TYPE_TITLE_SCREEN:
-         return QString("title");
+         return "title";
       case THUMBNAIL_TYPE_LOGO:
-         return QString("logo");
+         return "logo";
       case THUMBNAIL_TYPE_BOXART:
       default:
-         return QString("boxart");
+         break;
    }
-
-   return QString("list");
+   return "boxart";
 }
 
 ThumbnailType MainWindow::getThumbnailTypeFromString(QString thumbnailType)

ui/drivers/ui_qt.h

@@ -474,18 +474,18 @@ class MainWindow : public QMainWindow
    void setTheme(Theme theme = THEME_SYSTEM_DEFAULT);
    Theme theme();
    Theme getThemeFromString(QString themeString);
-   QString getThemeString(Theme theme);
+   const char *getThemeString(Theme theme);
    QString getSelectedCorePath();
    void showStatusMessage(QString msg, unsigned priority, unsigned duration, bool flush);
    bool showMessageBox(QString msg, MessageBoxType msgType = MSGBOX_TYPE_INFO, Qt::WindowModality modality = Qt::ApplicationModal, bool showDontAsk = true, bool *dontAsk = NULL);
    bool setCustomThemeFile(QString filePath);
    void setCustomThemeString(QString qss);
    const QString& customThemeString() const;
    void setCurrentViewType(ViewType viewType);
-   QString getCurrentViewTypeString();
+   const char *getCurrentViewTypeString();
    ViewType getCurrentViewType();
    void setCurrentThumbnailType(ThumbnailType thumbnailType);
-   QString getCurrentThumbnailTypeString();
+   const char *getCurrentThumbnailTypeString();
    ThumbnailType getCurrentThumbnailType();
    ThumbnailType getThumbnailTypeFromString(QString thumbnailType);
    void setAllPlaylistsListMaxCount(int count);