[plasmalnf] Add pre-selected theme

- For OEM modes where there is already a theme, add a preselect:
   key to pick a specific theme and have that one come up as already-
   selected in the list.
 - Don't re-run the lnftool if an already-selected theme is clicked
   again. Use toggled() instead of clicked().

src/modules/plasmalnf/PlasmaLnfPage.cpp

@@ -23,6 +23,8 @@
 #include "utils/Logger.h"
 #include "utils/Retranslator.h"
 
+#include <QAbstractButton>
+
 #include <KPackage/Package>
 #include <KPackage/PackageLoader>
 
@@ -94,6 +96,14 @@ PlasmaLnfPage::setEnabledThemesAll()
     setEnabledThemes( plasma_themes() );
 }
 
+void
+PlasmaLnfPage::setPreselect( const QString& id )
+{
+    m_preselect = id;
+    if ( !m_enabledThemes.isEmpty() )
+        fillUi();
+}
+
 
 void PlasmaLnfPage::updateThemeNames()
 {
@@ -166,6 +176,11 @@ void PlasmaLnfPage::fillUi()
         {
             theme.widget->updateThemeName( theme );
         }
+        if ( theme.id == m_preselect )
+        {
+            const QSignalBlocker b( theme.widget->button() );
+            theme.widget->button()->setChecked( true );
+        }
         ++c;
     }
 }

src/modules/plasmalnf/PlasmaLnfPage.h

@@ -50,6 +50,8 @@ public:
     void setEnabledThemes( const ThemeInfoList& themes );
     /** @brief enable all installed plasma themes. */
     void setEnabledThemesAll();
+    /** @brief set which theme is to be preselected. */
+    void setPreselect( const QString& id );
 
 signals:
     void plasmaThemeSelected( const QString& id );
@@ -64,6 +66,7 @@ private:
 
     Ui::PlasmaLnfPage* ui;
     QString m_lnfPath;
+    QString m_preselect;
     ThemeInfoList m_enabledThemes;
 
     QButtonGroup *m_buttonGroup;

src/modules/plasmalnf/PlasmaLnfViewStep.cpp

@@ -137,6 +137,12 @@ PlasmaLnfViewStep::setConfigurationMap( const QVariantMap& configurationMap )
         liveUser = configurationMap.value( "liveuser" ).toString();
     m_liveUser = liveUser;
 
+    QString preselect;
+    if ( configurationMap.contains( "preselect" ) && configurationMap.value( "preselect" ).type() == QVariant::String )
+        preselect = configurationMap.value( "preselect" ).toString();
+    if ( !preselect.isEmpty() )
+        m_widget->setPreselect( preselect );
+
     if ( configurationMap.contains( "themes" ) &&
         configurationMap.value( "themes" ).type() == QVariant::List )
     {

src/modules/plasmalnf/PlasmaLnfViewStep.h

@@ -61,9 +61,9 @@ public slots:
 
 private:
     PlasmaLnfPage* m_widget;
-    QString m_lnfPath;
-    QString m_themeId;
-    QString m_liveUser;
+    QString m_lnfPath;  // Path to the lnf tool
+    QString m_themeId;  // Id of selected theme
+    QString m_liveUser; // Name of the live user (for OEM mode)
 };
 
 CALAMARES_PLUGIN_FACTORY_DECLARATION( PlasmaLnfViewStepFactory )

src/modules/plasmalnf/ThemeWidget.cpp

@@ -62,7 +62,7 @@ ThemeWidget::ThemeWidget(const ThemeInfo& info, QWidget* parent)
     layout->addWidget( image_label, 1 );
     layout->addWidget( m_description, 3 );
 
-    connect( m_check, &QRadioButton::clicked, this, &ThemeWidget::clicked );
+    connect( m_check, &QRadioButton::toggled, this, &ThemeWidget::clicked );
 }
 
 void

src/modules/plasmalnf/plasmalnf.conf

@@ -27,3 +27,15 @@ themes:
     - theme: org.kde.breezedark.desktop
       image: "breeze-dark.png"
     - org.kde.fluffy-bunny.desktop
+
+# You can pre-select one of the themes; it is not applied
+# immediately, but its radio-button is switched on to indicate
+# that that is the theme (that is most likely) currently in use.
+# Do this only on Live images where you are reasonably sure
+# that the user is not going to change the theme out from under
+# themselves before running the installer.
+#
+# If this key is present, its value should be the id of the theme
+# which should be pre-selected. If absent, empty, or the pre-selected
+# theme is not found on the live system, no theme will be pre-selected.
+preselect: org.kde.breeze.desktop