Part Revert "[Units] Make iconSizes property constant"

Summary:
Though we can make the property constant, some applications still use the
signal (for example FolderView.qml) to know that one of the icons has
changed sizes and do some processing.

Whilst it would be possible to fix folderview, we should avoid public
API changes.

Reviewers: #plasma, #frameworks

Subscribers: plasma-devel

Tags: #plasma, #frameworks

Differential Revision: https://phabricator.kde.org/D4092

src/declarativeimports/core/units.cpp

@@ -134,6 +134,8 @@ void Units::iconLoaderSettingsChanged()
     m_iconSizes->insert(QStringLiteral("large"), devicePixelIconSize(KIconLoader::SizeLarge));
     m_iconSizes->insert(QStringLiteral("huge"), devicePixelIconSize(KIconLoader::SizeHuge));
     m_iconSizes->insert(QStringLiteral("enormous"), devicePixelIconSize(KIconLoader::SizeEnormous));
+
+    emit iconSizesChanged();
 }
 
 QQmlPropertyMap *Units::iconSizes() const

src/declarativeimports/core/units.h

@@ -73,7 +73,10 @@ class Units : public QObject
      *
      * Not devicePixelRation-adjusted::
      * * desktop
+     *
      */
+    //note the iconSizeChanges signal indicates that one (or more) of these icons have changed
+    //but the property map itself remains constant
     Q_PROPERTY(QQmlPropertyMap *iconSizes READ iconSizes CONSTANT)
 
     // layout hints
@@ -176,6 +179,7 @@ public:
 Q_SIGNALS:
     void devicePixelRatioChanged();
     void gridUnitChanged();
+    void iconSizesChanged();
     void spacingChanged();
     void durationChanged();