support changing default font used for all components with automatic …

…scaling UI if using larger font

CHANGELOG.md

@@ -6,6 +6,8 @@ FlatLaf Change Log
 - Linux: Fixed scaling if `GDK_SCALE` environment variable is set or if running
   on JetBrains Runtime. (issue #69)
 - Tree: Fixed repainting wide selection on focus gained/lost.
+- Support changing default font used for all components with automatic scaling
+  UI if using larger font. Use `UIManager.put( "defaultFont", myFont );`
 - No longer use system property `sun.java2d.uiScale`. (Java 8 only)
 - Demo: Support using own FlatLaf themes (`.properties` files) that are located
   in working directory of Demo application. Shown in the "Themes" list under

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

@@ -49,8 +49,10 @@
 import javax.swing.UIDefaults;
 import javax.swing.UIManager;
 import javax.swing.UnsupportedLookAndFeelException;
+import javax.swing.UIDefaults.ActiveValue;
 import javax.swing.plaf.ColorUIResource;
 import javax.swing.plaf.FontUIResource;
+import javax.swing.plaf.UIResource;
 import javax.swing.plaf.basic.BasicLookAndFeel;
 import javax.swing.text.html.HTMLEditorKit;
 import com.formdev.flatlaf.util.SystemInfo;
@@ -345,14 +347,22 @@ private void initFonts( UIDefaults defaults ) {
 
 		uiFont = UIScale.applyCustomScaleFactor( uiFont );
 
+		// use active value for all fonts to allow changing fonts in all components
+		// (similar as in Nimbus L&F) with:
+		//     UIManager.put( "defaultFont", myFont );
+		Object activeFont =  new ActiveFont( 1 );
+
 		// override fonts
 		for( Object key : defaults.keySet() ) {
 			if( key instanceof String && (((String)key).endsWith( ".font" ) || ((String)key).endsWith( "Font" )) )
-				defaults.put( key, uiFont );
+				defaults.put( key, activeFont );
 		}
 
 		// use smaller font for progress bar
-		defaults.put( "ProgressBar.font", UIScale.scaleFont( uiFont, 0.85f ) );
+		defaults.put( "ProgressBar.font", new ActiveFont( 0.85f ) );
+
+		// set default font
+		defaults.put( "defaultFont", uiFont );
 	}
 
 	/**
@@ -562,4 +572,42 @@ private static boolean hasMnemonic( Component c ) {
 
 		return false;
 	}
+
+	//---- class ActiveFont ---------------------------------------------------
+
+	private static class ActiveFont
+		implements ActiveValue
+	{
+		private final float scaleFactor;
+
+		// cache (scaled) font
+		private Font font;
+		private Font lastDefaultFont;
+
+		ActiveFont( float scaleFactor ) {
+			this.scaleFactor = scaleFactor;
+		}
+
+		@Override
+		public Object createValue( UIDefaults table ) {
+			Font defaultFont = UIManager.getFont( "defaultFont" );
+
+			if( lastDefaultFont != defaultFont ) {
+				lastDefaultFont = defaultFont;
+
+				if( scaleFactor != 1 ) {
+					// scale font
+					int newFontSize = Math.round( defaultFont.getSize() * scaleFactor );
+					font = new FontUIResource( defaultFont.deriveFont( (float) newFontSize ) );
+				} else {
+					// make sure that font is a UIResource for LaF switching
+					font = (defaultFont instanceof UIResource)
+						? defaultFont
+						: new FontUIResource( defaultFont );
+				}
+			}
+
+			return font;
+		}
+	}
 }

flatlaf-core/src/main/java/com/formdev/flatlaf/util/UIScale.java

@@ -24,6 +24,7 @@
 import java.awt.Insets;
 import java.beans.PropertyChangeEvent;
 import java.beans.PropertyChangeListener;
+import java.beans.PropertyChangeSupport;
 import java.lang.reflect.Method;
 import javax.swing.LookAndFeel;
 import javax.swing.UIManager;
@@ -48,19 +49,36 @@
  *
  * 2) user scaling mode
  *
- * This mode is mainly for Java 8 compatibility, but is also used on Linux.
+ * This mode is mainly for Java 8 compatibility, but is also used on Linux
+ * or if the default font is changed.
  * The user scale factor is computed based on the used font.
  * The JRE does not scale anything.
  * So we have to invoke {@link #scale(float)} where necessary.
  * There is only one user scale factor for all displays.
- * The user scale factor may change if the active LaF or "Label.font" has changed.
+ * The user scale factor may change if the active LaF, "defaultFont" or "Label.font" has changed.
+ * If system scaling mode is available the user scale factor is usually 1,
+ * but may be larger on Linux or if the default font is changed.
  *
  * @author Karl Tauber
  */
 public class UIScale
 {
 	private static final boolean DEBUG = false;
 
+	private static PropertyChangeSupport changeSupport;
+
+	public static void addPropertyChangeListener( PropertyChangeListener listener ) {
+		if( changeSupport == null )
+			changeSupport = new PropertyChangeSupport( UIScale.class );
+		changeSupport.addPropertyChangeListener( listener );
+	}
+
+	public static void removePropertyChangeListener( PropertyChangeListener listener ) {
+		if( changeSupport == null )
+			return;
+		changeSupport.removePropertyChangeListener( listener );
+	}
+
 	//---- system scaling (Java 9) --------------------------------------------
 
 	private static Boolean jreHiDPI;
@@ -110,27 +128,33 @@ private static void initialize() {
 			return;
 		initialized = true;
 
-		if( isUserScalingEnabled() ) {
-			// listener to update scale factor if LaF changed or if Label.font changed
-			// (e.g. option "Override default fonts" in IntelliJ IDEA)
-			PropertyChangeListener listener = new PropertyChangeListener() {
-				@Override
-				public void propertyChange( PropertyChangeEvent e ) {
-					String propName = e.getPropertyName();
-					if( "lookAndFeel".equals( propName ) ) {
+		if( !isUserScalingEnabled() )
+			return;
+
+		// listener to update scale factor if LaF changed, "defaultFont" or "Label.font" changed
+		PropertyChangeListener listener = new PropertyChangeListener() {
+			@Override
+			public void propertyChange( PropertyChangeEvent e ) {
+				switch( e.getPropertyName() ) {
+					case "lookAndFeel":
 						// it is not necessary (and possible) to remove listener of old LaF defaults
 						if( e.getNewValue() instanceof LookAndFeel )
 							UIManager.getLookAndFeelDefaults().addPropertyChangeListener( this );
 						updateScaleFactor();
-					} else if( "Label.font".equals( propName ) )
+						break;
+
+					case "defaultFont":
+					case "Label.font":
 						updateScaleFactor();
+						break;
 				}
-			};
-			UIManager.addPropertyChangeListener( listener );
-			UIManager.getLookAndFeelDefaults().addPropertyChangeListener( listener );
+			}
+		};
+		UIManager.addPropertyChangeListener( listener );
+		UIManager.getDefaults().addPropertyChangeListener( listener );
+		UIManager.getLookAndFeelDefaults().addPropertyChangeListener( listener );
 
-			updateScaleFactor();
-		}
+		updateScaleFactor();
 	}
 
 	private static void updateScaleFactor() {
@@ -141,7 +165,9 @@ private static void updateScaleFactor() {
 		// because even if we are on a HiDPI display it is not sure
 		// that a larger font size is set by the current LaF
 		// (e.g. can avoid large icons with small text)
-		Font font = UIManager.getFont( "Label.font" );
+		Font font = UIManager.getFont( "defaultFont" );
+		if( font == null )
+			font = UIManager.getFont( "Label.font" );
 
 		setUserScaleFactor( computeScaleFactor( font ) );
 	}
@@ -168,9 +194,6 @@ private static float computeScaleFactor( Font font ) {
 	}
 
 	private static boolean isUserScalingEnabled() {
-		if( isSystemScalingEnabled() && !SystemInfo.IS_LINUX )
-			return false; // disable user scaling if JRE scales
-
 		// same as in IntelliJ IDEA
 		String hidpi = System.getProperty( "hidpi" );
 		return (hidpi != null) ? Boolean.parseBoolean( hidpi ) : true;
@@ -197,14 +220,6 @@ public static FontUIResource applyCustomScaleFactor( FontUIResource font ) {
 		return new FontUIResource( font.deriveFont( (float) newFontSize ) );
 	}
 
-	/**
-	 * Scales the given font.
-	 */
-	public static FontUIResource scaleFont( FontUIResource font, float scaleFactor ) {
-		int newFontSize = Math.round( font.getSize() * scaleFactor );
-		return new FontUIResource( font.deriveFont( (float) newFontSize ) );
-	}
-
 	/**
 	 * Similar to sun.java2d.SunGraphicsEnvironment.getScaleFactor(String)
 	 */
@@ -242,10 +257,14 @@ private static void setUserScaleFactor( float scaleFactor ) {
 		else // round scale factor to 1/4
 			scaleFactor = Math.round( scaleFactor * 4f ) / 4f;
 
+		float oldScaleFactor = UIScale.scaleFactor;
 		UIScale.scaleFactor = scaleFactor;
 
 		if( DEBUG )
 			System.out.println( "HiDPI scale factor " + scaleFactor );
+
+		if( changeSupport != null )
+			changeSupport.firePropertyChange( "userScaleFactor", oldScaleFactor, scaleFactor );
 	}
 
 	public static float scale( float value ) {

flatlaf-demo/src/main/java/com/formdev/flatlaf/demo/ControlBar.java

@@ -83,6 +83,11 @@ else if( className.equals( NimbusLookAndFeel.class.getName() ) )
 				} );
 			}
 		} );
+
+		UIScale.addPropertyChangeListener( e -> {
+			// update info label because user scale factor may change
+			updateInfoLabel();
+		} );
 	}
 
 	void initialize( JFrame frame, JTabbedPane tabbedPane ) {

flatlaf-demo/src/main/java/com/formdev/flatlaf/demo/DemoFrame.java

@@ -20,6 +20,7 @@
 import java.awt.event.*;
 import javax.swing.*;
 import javax.swing.text.DefaultEditorKit;
+import com.formdev.flatlaf.FlatLaf;
 import com.formdev.flatlaf.demo.intellijthemes.*;
 import com.formdev.flatlaf.extras.FlatSVGIcon;
 import net.miginfocom.swing.*;
@@ -52,12 +53,53 @@ private void selectedTabChanged() {
 		DemoPrefs.getState().putInt( FlatLafDemo.KEY_TAB, tabbedPane.getSelectedIndex() );
 	}
 
-	private void menuItemActionPerformed(ActionEvent e) {
+	private void menuItemActionPerformed( ActionEvent e ) {
 		SwingUtilities.invokeLater( () -> {
 			JOptionPane.showMessageDialog( this, e.getActionCommand(), "Menu Item", JOptionPane.PLAIN_MESSAGE );
 		} );
 	}
 
+	private void fontFamilyChanged( ActionEvent e ) {
+		String fontFamily = e.getActionCommand();
+
+		Font font = UIManager.getFont( "defaultFont" );
+		Font newFont = new Font( fontFamily, font.getStyle(), font.getSize() );
+		UIManager.put( "defaultFont", newFont );
+
+		FlatLaf.updateUI();
+	}
+
+	private void fontSizeChanged( ActionEvent e ) {
+		String fontSizeStr = e.getActionCommand();
+
+		Font font = UIManager.getFont( "defaultFont" );
+		Font newFont = font.deriveFont( (float) Integer.parseInt( fontSizeStr ) );
+		UIManager.put( "defaultFont", newFont );
+
+		FlatLaf.updateUI();
+	}
+
+	private void restoreFont() {
+		UIManager.put( "defaultFont", null );
+		FlatLaf.updateUI();
+	}
+
+	private void incrFont() {
+		Font font = UIManager.getFont( "defaultFont" );
+		Font newFont = font.deriveFont( (float) (font.getSize() + 1) );
+		UIManager.put( "defaultFont", newFont );
+
+		FlatLaf.updateUI();
+	}
+
+	private void decrFont() {
+		Font font = UIManager.getFont( "defaultFont" );
+		Font newFont = font.deriveFont( (float) Math.max( font.getSize() - 1, 8 ) );
+		UIManager.put( "defaultFont", newFont );
+
+		FlatLaf.updateUI();
+	}
+
 	private void initComponents() {
 		// JFormDesigner - Component initialization - DO NOT MODIFY  //GEN-BEGIN:initComponents
 		JMenuBar menuBar1 = new JMenuBar();
@@ -86,6 +128,10 @@ private void initComponents() {
 		JRadioButtonMenuItem radioButtonMenuItem1 = new JRadioButtonMenuItem();
 		JRadioButtonMenuItem radioButtonMenuItem2 = new JRadioButtonMenuItem();
 		JRadioButtonMenuItem radioButtonMenuItem3 = new JRadioButtonMenuItem();
+		fontMenu = new JMenu();
+		JMenuItem restoreFontMenuItem = new JMenuItem();
+		JMenuItem incrFontMenuItem = new JMenuItem();
+		JMenuItem decrFontMenuItem = new JMenuItem();
 		JMenu helpMenu = new JMenu();
 		JMenuItem aboutMenuItem = new JMenuItem();
 		JToolBar toolBar1 = new JToolBar();
@@ -285,6 +331,30 @@ private void initComponents() {
 			}
 			menuBar1.add(viewMenu);
 
+			//======== fontMenu ========
+			{
+				fontMenu.setText("Font");
+
+				//---- restoreFontMenuItem ----
+				restoreFontMenuItem.setText("Restore Font");
+				restoreFontMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_0, KeyEvent.CTRL_MASK));
+				restoreFontMenuItem.addActionListener(e -> restoreFont());
+				fontMenu.add(restoreFontMenuItem);
+
+				//---- incrFontMenuItem ----
+				incrFontMenuItem.setText("Increase Font Size");
+				incrFontMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_PLUS, KeyEvent.CTRL_MASK));
+				incrFontMenuItem.addActionListener(e -> incrFont());
+				fontMenu.add(incrFontMenuItem);
+
+				//---- decrFontMenuItem ----
+				decrFontMenuItem.setText("Decrease Font Size");
+				decrFontMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_MINUS, KeyEvent.CTRL_MASK));
+				decrFontMenuItem.addActionListener(e -> decrFont());
+				fontMenu.add(decrFontMenuItem);
+			}
+			menuBar1.add(fontMenu);
+
 			//======== helpMenu ========
 			{
 				helpMenu.setText("Help");
@@ -387,9 +457,30 @@ private void initComponents() {
 		cutMenuItem.addActionListener( new DefaultEditorKit.CutAction() );
 		copyMenuItem.addActionListener( new DefaultEditorKit.CopyAction() );
 		pasteMenuItem.addActionListener( new DefaultEditorKit.PasteAction() );
+
+		// add font families
+		fontMenu.addSeparator();
+		String[] fontFamilies = { "Arial", "Comic Sans MS", "Courier New", "Dialog",
+			"Monospaced", "SansSerif", "Serif", "Tahoma", "Verdana" };
+		for( String fontFamily : fontFamilies ) {
+			JMenuItem fontItem = new JMenuItem( fontFamily );
+			fontItem.addActionListener( this::fontFamilyChanged );
+			fontMenu.add( fontItem );
+		}
+
+		// add font sizes
+		fontMenu.addSeparator();
+		int[] fontSizes = { 8, 10, 12, 14, 16, 18, 20, 24, 28 };
+		for( int fontSize : fontSizes ) {
+			String fontSizeStr = Integer.toString( fontSize );
+			JMenuItem fontItem = new JMenuItem( fontSizeStr );
+			fontItem.addActionListener( this::fontSizeChanged );
+			fontMenu.add( fontItem );
+		}
 	}
 
 	// JFormDesigner - Variables declaration - DO NOT MODIFY  //GEN-BEGIN:variables
+	private JMenu fontMenu;
 	private JTabbedPane tabbedPane;
 	private ControlBar controlBar;
 	// JFormDesigner - End of variables declaration  //GEN-END:variables