Menu: highlight items in menu bar on mouse hover (issue #49)

CHANGELOG.md

@@ -6,6 +6,7 @@ FlatLaf Change Log
 - Menus:
   - Changed menu bar and popup menu background colors (made brighter in light
     themes and darker in dark themes).
+  - Highlight items in menu bar on mouse hover. (issue #49)
   - Popup menus now have empty space at the top and bottom.
   - Menu items now have larger left and right margins.
   - Made `JMenu`, `JMenuItem`, `JCheckBoxMenuItem` and `JRadioButtonMenuItem`

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatMenuUI.java

@@ -17,11 +17,17 @@
 package com.formdev.flatlaf.ui;
 
 import static com.formdev.flatlaf.util.UIScale.scale;
+import java.awt.Color;
 import java.awt.Graphics;
 import java.awt.Rectangle;
+import java.awt.event.MouseEvent;
 import java.beans.PropertyChangeListener;
+import javax.swing.ButtonModel;
 import javax.swing.JComponent;
+import javax.swing.JMenu;
 import javax.swing.JMenuItem;
+import javax.swing.UIManager;
+import javax.swing.event.MouseInputListener;
 import javax.swing.plaf.ComponentUI;
 import javax.swing.plaf.basic.BasicMenuUI;
 
@@ -51,11 +57,17 @@ import javax.swing.plaf.basic.BasicMenuUI;
  * @uiDefault Menu.useMenuBarBackgroundForTopLevel	boolean	default is false
  * @uiDefault MenuBar.background					Color	used if Menu.useMenuBarBackgroundForTopLevel is true
  *
+ * <!-- FlatMenuUI -->
+ *
+ * @uiDefault MenuBar.hoverBackground				Color
+ *
  * @author Karl Tauber
  */
 public class FlatMenuUI
 	extends BasicMenuUI
 {
+	private Color hoverBackground;
+
 	public static ComponentUI createUI( JComponent c ) {
 		return new FlatMenuUI();
 	}
@@ -64,10 +76,21 @@ public class FlatMenuUI
 	protected void installDefaults() {
 		super.installDefaults();
 
+		menuItem.setRolloverEnabled( true );
+
+		hoverBackground = UIManager.getColor( "MenuBar.hoverBackground" );
+
 		// scale
 		defaultTextIconGap = scale( defaultTextIconGap );
 	}
 
+	@Override
+	protected void uninstallDefaults() {
+		super.uninstallDefaults();
+
+		hoverBackground = null;
+	}
+
 	/**
 	 * Scale defaultTextIconGap again if iconTextGap property has changed.
 	 */
@@ -81,6 +104,43 @@ public class FlatMenuUI
 		};
 	}
 
+	@Override
+	protected MouseInputListener createMouseInputListener( JComponent c ) {
+		return new BasicMenuUI.MouseInputHandler() {
+			@Override
+			public void mouseEntered( MouseEvent e ) {
+				super.mouseEntered( e );
+				rollover( e, true );
+			}
+
+			@Override
+			public void mouseExited( MouseEvent e ) {
+				super.mouseExited( e );
+				rollover( e, false );
+			}
+
+			private void rollover( MouseEvent e, boolean rollover ) {
+				JMenu menu = (JMenu) e.getSource();
+				if( menu.isTopLevelMenu() && menu.isRolloverEnabled() ) {
+					menu.getModel().setRollover( rollover );
+					menu.repaint();
+				}
+			}
+		};
+	}
+
+	@Override
+	protected void paintBackground( Graphics g, JMenuItem menuItem, Color bgColor ) {
+		ButtonModel model = menuItem.getModel();
+		if( model.isArmed() || model.isSelected() ) {
+			super.paintBackground( g, menuItem, bgColor );
+		} else if( model.isRollover() && model.isEnabled() && ((JMenu)menuItem).isTopLevelMenu() ) {
+			FlatUIUtils.setColor( g, hoverBackground, menuItem.getBackground() );
+			g.fillRect( 0, 0, menuItem.getWidth(), menuItem.getHeight() );
+		} else
+			super.paintBackground( g, menuItem, bgColor );
+	}
+
 	@Override
 	protected void paintText( Graphics g, JMenuItem menuItem, Rectangle textRect, String text ) {
 		FlatMenuItemUI.paintText( g, menuItem, textRect, text, disabledForeground, selectionForeground );

flatlaf-core/src/main/resources/com/formdev/flatlaf/FlatDarkLaf.properties

@@ -145,6 +145,7 @@ Menu.icon.disabledArrowColor=#606060
 #---- MenuBar ----
 
 MenuBar.borderColor=#515151
+MenuBar.hoverBackground=lighten($MenuBar.background,10%)
 
 
 #---- MenuItemCheckBox ----

flatlaf-core/src/main/resources/com/formdev/flatlaf/FlatLightLaf.properties

@@ -152,6 +152,7 @@ Menu.icon.disabledArrowColor=#ABABAB
 #---- MenuBar ----
 
 MenuBar.borderColor=#cdcdcd
+MenuBar.hoverBackground=darken($MenuBar.background,10%)
 
 
 #---- MenuItemCheckBox ----

flatlaf-testing/src/main/resources/com/formdev/flatlaf/testing/FlatTestLaf.properties

@@ -24,6 +24,7 @@
 @selectionInactiveForeground=#ffffff
 @disabledText=#000088
 @textComponentBackground=#ffffff
+@menuBackground=#fff
 @cellFocusColor=#ff0000
 @icon=#afafaf
 
@@ -157,6 +158,7 @@ Menu.icon.disabledArrowColor=#ABABAB
 #---- MenuBar ----
 
 MenuBar.borderColor=#4444ff
+MenuBar.hoverBackground=#fdd
 
 
 #---- MenuItemCheckBox ----