Refactor theme plugin loading.

In the old implementation, the QPlatformIntegration was asked
for the theme first, so there was no way of overriding that
by a custom plugin. Also, there was a memory leak in case
the platform theme was actually created by a plugin.

QGuiApplication now asks the QPlatformIntegration for a list
of potential theme names first, tries to load them using
the plugin loader and finally invokes a factory method of
QPlatformIntegration in case that fails. The theme is now
owned by QGuiApplication.

In the XCB plugin, the environment variable DESKTOP_SESSION
is queried and appended to the list of themes, making it possible
to load plugins for other session types.

Change-Id: I1a4b4e061815bca16c65b23e591bb7563a3e44e2
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/src/platformsupport/themes/genericunix/qgenericunixthemes_p.h b/src/platformsupport/themes/genericunix/qgenericunixthemes_p.h
index a9db29e8cd..cabffc0212 100644
--- a/src/platformsupport/themes/genericunix/qgenericunixthemes_p.h
+++ b/src/platformsupport/themes/genericunix/qgenericunixthemes_p.h
@@ -67,11 +67,14 @@ class QGenericUnixTheme : public QPlatformTheme
 public:
     QGenericUnixTheme() {}
 
-    static QPlatformTheme *createUnixTheme();
+    static QPlatformTheme *createUnixTheme(const QString &name);
+    static QStringList themeNames();
 
     virtual QVariant themeHint(ThemeHint hint) const;
 
     static QStringList xdgIconThemePaths();
+
+    static const char *name;
 };
 
 class QKdeTheme : public QPlatformTheme
@@ -88,6 +91,8 @@ public:
     virtual const QFont *font(Font type) const
         { return m_resources.fonts[type]; }
 
+    static const char *name;
+
 private:
     QString globalSettingsFile() const;
     void refresh();
@@ -109,6 +114,8 @@ public:
     QGnomeTheme() {}
     virtual QVariant themeHint(ThemeHint hint) const;
 
+    static const char *name;
+
 private:
 };