4 files changed, 53 insertions, 6 deletions

diff --git a/src/gui/image/qicon.cpp b/src/gui/image/qicon.cpp
index 32fa9e75ac..14a0248600 100644
--- a/src/gui/image/qicon.cpp
+++ b/src/gui/image/qicon.cpp
@@ -1194,7 +1194,7 @@ void QIcon::setFallbackSearchPaths(const QStringList &paths)
 
     The \a name should correspond to a directory name in the
     themeSearchPath() containing an index.theme
-    file describing it's contents.
+    file describing its contents.
 
     \sa themeSearchPaths(), themeName()
 */
@@ -1220,6 +1220,37 @@ QString QIcon::themeName()
 }
 
 /*!
+    \since 5.12
+
+    Returns the name of the fallback icon theme.
+
+    On X11, if not set, the fallback icon theme depends on your desktop
+    settings. On other platforms it is not set by default.
+
+    \sa setFallbackThemeName(), themeName()
+*/
+QString QIcon::fallbackThemeName()
+{
+    return QIconLoader::instance()->fallbackThemeName();
+}
+
+/*!
+    \since 5.12
+
+    Sets the fallback icon theme to \a name.
+
+    The \a name should correspond to a directory name in the
+    themeSearchPath() containing an index.theme
+    file describing its contents.
+
+    \sa fallbackThemeName(), themeSearchPaths(), themeName()
+*/
+void QIcon::setFallbackThemeName(const QString &name)
+{
+    QIconLoader::instance()->setFallbackThemeName(name);
+}
+
+/*!
     \since 4.6
 
     Returns the QIcon corresponding to \a name in the current
diff --git a/src/gui/image/qicon.h b/src/gui/image/qicon.h
index 653ba6fda4..6a4fc8927a 100644
--- a/src/gui/image/qicon.h
+++ b/src/gui/image/qicon.h
@@ -124,6 +124,9 @@ public:
     static QString themeName();
     static void setThemeName(const QString &path);
 
+    static QString fallbackThemeName();
+    static void setFallbackThemeName(const QString &name);
+
     Q_DUMMY_COMPARISON_OPERATOR(QIcon)
 
 private:
diff --git a/src/gui/image/qiconloader.cpp b/src/gui/image/qiconloader.cpp
index 1ea4f1340b..228de3adc3 100644
--- a/src/gui/image/qiconloader.cpp
+++ b/src/gui/image/qiconloader.cpp
@@ -60,7 +60,7 @@ QT_BEGIN_NAMESPACE
 Q_GLOBAL_STATIC(QIconLoader, iconLoaderInstance)
 
 /* Theme to use in last resort, if the theme does not have the icon, neither the parents  */
-static QString fallbackTheme()
+static QString systemFallbackThemeName()
 {
     if (const QPlatformTheme *theme = QGuiApplicationPrivate::platformTheme()) {
         const QVariant themeHint = theme->themeHint(QPlatformTheme::SystemIconFallbackThemeName);
@@ -117,7 +117,7 @@ void QIconLoader::ensureInitialized()
         m_systemTheme = systemThemeName();
 
         if (m_systemTheme.isEmpty())
-            m_systemTheme = fallbackTheme();
+            m_systemTheme = systemFallbackThemeName();
         if (qt_iconEngineFactoryLoader()->keyMap().key(QLatin1String("svg"), -1) != -1)
             m_supportsSvg = true;
     }
@@ -137,7 +137,7 @@ void QIconLoader::updateSystemTheme()
     if (m_userTheme.isEmpty()) {
         QString theme = systemThemeName();
         if (theme.isEmpty())
-            theme = fallbackTheme();
+            theme = fallbackThemeName();
         if (theme != m_systemTheme) {
             m_systemTheme = theme;
             invalidateKey();
@@ -151,6 +151,16 @@ void QIconLoader::setThemeName(const QString &themeName)
     invalidateKey();
 }
 
+QString QIconLoader::fallbackThemeName() const
+{
+    return m_userFallbackTheme.isEmpty() ? systemFallbackThemeName() : m_userFallbackTheme;
+}
+
+void QIconLoader::setFallbackThemeName(const QString &themeName)
+{
+    m_userFallbackTheme = themeName;
+}
+
 void QIconLoader::setThemeSearchPath(const QStringList &searchPaths)
 {
     m_iconDirs = searchPaths;
@@ -388,7 +398,7 @@ QIconTheme::QIconTheme(const QString &themeName)
 
         // Ensure a default platform fallback for all themes
         if (m_parents.isEmpty()) {
-            const QString fallback = fallbackTheme();
+            const QString fallback = QIconLoader::instance()->fallbackThemeName();
             if (!fallback.isEmpty())
                 m_parents.append(fallback);
         }
@@ -414,7 +424,7 @@ QThemeIconInfo QIconLoader::findIconHelper(const QString &themeName,
     if (!theme.isValid()) {
         theme = QIconTheme(themeName);
         if (!theme.isValid())
-            theme = QIconTheme(fallbackTheme());
+            theme = QIconTheme(fallbackThemeName());
     }
 
     const QStringList contentDirs = theme.contentDirs();
diff --git a/src/gui/image/qiconloader_p.h b/src/gui/image/qiconloader_p.h
index 746e871fb1..fac18b5d79 100644
--- a/src/gui/image/qiconloader_p.h
+++ b/src/gui/image/qiconloader_p.h
@@ -177,6 +177,8 @@ public:
 
     QString themeName() const { return m_userTheme.isEmpty() ? m_systemTheme : m_userTheme; }
     void setThemeName(const QString &themeName);
+    QString fallbackThemeName() const;
+    void setFallbackThemeName(const QString &themeName);
     QIconTheme theme() { return themeList.value(themeName()); }
     void setThemeSearchPath(const QStringList &searchPaths);
     QStringList themeSearchPaths() const;
@@ -200,6 +202,7 @@ private:
     bool m_initialized;
 
     mutable QString m_userTheme;
+    mutable QString m_userFallbackTheme;
     mutable QString m_systemTheme;
     mutable QStringList m_iconDirs;
     mutable QHash <QString, QIconTheme> themeList;