[libcalamaresui] Add branding-aware function for loading image by name

src/libcalamaresui/Branding.cpp

@@ -186,6 +186,7 @@ Branding::Branding( const QString& brandingFilePath,
             loadStrings( m_images, doc, "images",
                 [&]( const QString& s ) -> QString
                 {
+                    // See also image()
                     const QString imageName( expand( s ) );
                     QFileInfo imageFi( componentDir.absoluteFilePath( imageName ) );
                     if ( !imageFi.exists() )
@@ -314,6 +315,22 @@ Branding::image( Branding::ImageEntry imageEntry, const QSize& size ) const
     }
 }
 
+QPixmap
+Branding::image(const QString& imageName, const QSize& size) const
+{
+    QDir componentDir( componentDirectory() );
+    QFileInfo imageFi( componentDir.absoluteFilePath( imageName ) );
+    if ( !imageFi.exists() )
+    {
+        const auto icon = QIcon::fromTheme( imageName );
+        // Not found, bail out with the filename used
+        if ( icon.isNull() )
+            return QPixmap();
+        return icon.pixmap( size );
+    }
+    return ImageRegistry::instance()->pixmap( imageFi.absoluteFilePath(), size );
+}
+
 QString
 Branding::stylesheet() const
 {

src/libcalamaresui/Branding.h

@@ -123,6 +123,16 @@ public:
     QString styleString( Branding::StyleEntry styleEntry ) const;
     QString imagePath( Branding::ImageEntry imageEntry ) const;
     QPixmap image( Branding::ImageEntry imageEntry, const QSize& size ) const;
+
+    /** @brief Look up an image in the branding directory or as an icon
+     *
+     * The @p name is checked in the branding directory: if it is an image
+     * file, return the pixmap from that file, at the requested size.
+     * If it isn't a file, look it up as an icon name in the current theme.
+     * May return a null pixmap if nothing is found.
+     */
+    QPixmap image( const QString& name, const QSize& size ) const;
+
     /** @brief Stylesheet to apply for this branding. May be empty.
      *
      * The file is loaded every time this function is called, so