Linux: enable text anti-aliasing if no Gnome or KDE Desktop propertie…

…s are available (issue #218)

CHANGELOG.md

@@ -21,6 +21,8 @@ FlatLaf Change Log
 - TableHeader: Moved table header column border painting from
  `FlatTableHeaderUI` to new border `FlatTableHeaderBorder` to improve
  compatibility with custom table header implementations. (issue #228)
+- Linux: Enable text anti-aliasing if no Gnome or KDE Desktop properties are
+ available. (issue #218)
 - IntelliJ Themes: Added "Material Theme UI Lite / GitHub Dark" theme.
 - JIDE Common Layer: Improved support for `JideTabbedPane`. (PR #306)
 - Extras: `FlatSVGIcon` improvements:

flatlaf-core/src/main/java/com/formdev/flatlaf/FlatLaf.java

@@ -32,6 +32,7 @@
 import java.io.File;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
@@ -561,6 +562,8 @@ private void putAATextInfo( UIDefaults defaults ) {
  defaults.put( RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON );
  } else if( SystemInfo.isJava_9_orLater ) {
  Object desktopHints = Toolkit.getDefaultToolkit().getDesktopProperty( DESKTOPFONTHINTS );
+ if( desktopHints == null )
+ desktopHints = fallbackAATextInfo();
  if( desktopHints instanceof Map ) {
  @SuppressWarnings( "unchecked" )
  Map<Object, Object> hints = (Map<Object, Object>) desktopHints;
@@ -583,6 +586,8 @@ private void putAATextInfo( UIDefaults defaults ) {
  Object value = Class.forName( "sun.swing.SwingUtilities2$AATextInfo" )
  .getMethod( "getAATextInfo", boolean.class )
  .invoke( null, true );
+ if( value == null )
+ value = fallbackAATextInfo();
  defaults.put( key, value );
  } catch( Exception ex ) {
  LoggingFacade.INSTANCE.logSevere( null, ex );
@@ -591,6 +596,47 @@ private void putAATextInfo( UIDefaults defaults ) {
  }
  }
 
+ private Object fallbackAATextInfo() {
+ // do nothing if explicitly overridden
+ if( System.getProperty( "awt.useSystemAAFontSettings" ) != null )
+ return null;
+
+ Object aaHint = null;
+ Integer lcdContrastHint = null;
+
+ if( SystemInfo.isLinux ) {
+ // see sun.awt.UNIXToolkit.getDesktopAAHints()
+ Toolkit toolkit = Toolkit.getDefaultToolkit();
+ if( toolkit.getDesktopProperty( "gnome.Xft/Antialias" ) == null &&
+ toolkit.getDesktopProperty( "fontconfig/Antialias" ) == null )
+ {
+ // no Gnome or KDE Desktop properties available
+ // --> enable antialiasing
+ aaHint = RenderingHints.VALUE_TEXT_ANTIALIAS_ON;
+ }
+ }
+
+ if( aaHint == null )
+ return null;
+
+ if( SystemInfo.isJava_9_orLater ) {
+ Map<Object, Object> hints = new HashMap<>();
+ hints.put( RenderingHints.KEY_TEXT_ANTIALIASING, aaHint );
+ hints.put( RenderingHints.KEY_TEXT_LCD_CONTRAST, lcdContrastHint );
+ return hints;
+ } else {
+ // Java 8
+ try {
+ return Class.forName( "sun.swing.SwingUtilities2$AATextInfo" )
+ .getConstructor( Object.class, Integer.class )
+ .newInstance( aaHint, lcdContrastHint );
+ } catch( Exception ex ) {
+ LoggingFacade.INSTANCE.logSevere( null, ex );
+ throw new RuntimeException( ex );
+ }
+ }
+ }
+
  private void putDefaults( UIDefaults defaults, Object value, String... keys ) {
  for( String key : keys )
  defaults.put( key, value );