[packagechooser] Allow to override some of AppData

- The ID and Screenshot entries might be weird in AppData (in particular,
   a remove URL) so put those back under the control of Calamares even
   when using AppData as the source of descriptions.

src/modules/packagechooser/PackageChooserViewStep.cpp

@@ -234,7 +234,7 @@ PackageChooserViewStep::fillModel( const QVariantList& items )
 
         if ( item_map.contains( "appdata" ) )
         {
-            m_model->addPackage( PackageItem::fromAppData( CalamaresUtils::getString( item_map, "appdata" ) ) );
+            m_model->addPackage( PackageItem::fromAppData( item_map ) );
         }
         else
         {

src/modules/packagechooser/PackageModel.cpp

@@ -257,9 +257,15 @@ getNameAndSummary( const QDomNode& n )
 #endif
 
 PackageItem
-PackageItem::fromAppData( const QString& fileName )
+PackageItem::fromAppData( const QVariantMap& item_map )
 {
 #ifdef HAVE_XML
+    QString fileName = CalamaresUtils::getString( item_map, "appdata" );
+    if ( fileName.isEmpty() )
+    {
+        cWarning() << "Can't load AppData without a suitable key.";
+        return PackageItem();
+    }
     cDebug() << "Loading AppData XML from" << fileName;
 
     QDomDocument doc = loadAppData( fileName );
@@ -271,17 +277,28 @@ PackageItem::fromAppData( const QString& fileName )
     QDomElement componentNode = doc.documentElement();
     if ( !componentNode.isNull() && componentNode.tagName() == "component" )
     {
-        QString id = getChildText( componentNode, "id" );
+        // An "id" entry in the Calamares config overrides ID in the AppData
+        QString id = CalamaresUtils::getString( item_map, "id" );
+        if ( id.isEmpty() )
+        {
+            id = getChildText( componentNode, "id" );
+        }
         if ( id.isEmpty() )
         {
             return PackageItem();
         }
 
-        QString screenshotPath = getScreenshotPath( componentNode );
+        // A "screenshot" entry in the Calamares config overrides AppData
+        QString screenshotPath = CalamaresUtils::getString( item_map, "screenshot" );
+        if ( screenshotPath.isEmpty() )
+        {
+            screenshotPath = getScreenshotPath( componentNode );
+        }
 
         QVariantMap map = getNameAndSummary( componentNode );
         map.insert( "id", id );
         map.insert( "screenshot", screenshotPath );
+
         return PackageItem( map );
     }
 

src/modules/packagechooser/PackageModel.h

@@ -82,11 +82,17 @@ struct PackageItem
     bool isValid() const { return !name.isEmpty(); }
 
     /** @brief Loads an AppData XML file and returns a PackageItem
+     *
+     * The @p map must have a key *appdata*. That is used as the
+     * primary source of information, but keys *id* and *screenshotPath*
+     * may be used to override parts of the AppData -- so that the
+     * ID is under the control of Calamares, and the screenshot can be
+     * forced to a local path available on the installation medium.
      *
      * Requires XML support in libcalamares, if not present will
      * return invalid PackageItems.
      */
-    static PackageItem fromAppData( const QString& filename );
+    static PackageItem fromAppData( const QVariantMap& map );
 };
 
 using PackageList = QVector< PackageItem >;