Window decorations:

- support customizing of window title alignment: left aligned or centered (default is left without embedded menubar and centered with embedded menubar)
- improved centering of window title with embedded menubar (issue #252)

CHANGELOG.md

@@ -9,8 +9,10 @@ FlatLaf Change Log
   and embedded menu bar with all JREs, while still having native Windows 10
   border drop shadows, resize behavior, window snapping and system window menu.
   (PR #267)
-- Support right aligned components in `JFrame` title bar with embedded menu bar
+- Custom window decorations: Support right aligned components in `JFrame` title
-  (using `Box.createHorizontalGlue()`). (PR #268)
+  bar with embedded menu bar (using `Box.createHorizontalGlue()`). (PR #268)
+- Custom window decorations: Improved centering of window title with embedded
+  menu bar. (issue #252)
 
 #### Fixed bugs
 

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

@@ -83,6 +83,9 @@ import com.formdev.flatlaf.util.UIScale;
  * @uiDefault TitlePane.titleMargins						Insets
  * @uiDefault TitlePane.menuBarEmbedded						boolean
  * @uiDefault TitlePane.buttonMaximizedHeight				int
+ * @uiDefault TitlePane.centerTitle							boolean
+ * @uiDefault TitlePane.centerTitleIfMenuBarEmbedded		boolean
+ * @uiDefault TitlePane.menuBarTitleGap						int
  * @uiDefault TitlePane.closeIcon							Icon
  * @uiDefault TitlePane.iconifyIcon							Icon
  * @uiDefault TitlePane.maximizeIcon						Icon
@@ -102,6 +105,9 @@ public class FlatTitlePane
 
 	protected final Dimension iconSize = UIManager.getDimension( "TitlePane.iconSize" );
 	protected final int buttonMaximizedHeight = UIManager.getInt( "TitlePane.buttonMaximizedHeight" );
+	protected final boolean centerTitle = UIManager.getBoolean( "TitlePane.centerTitle" );
+	protected final boolean centerTitleIfMenuBarEmbedded = FlatUIUtils.getUIBoolean( "TitlePane.centerTitleIfMenuBarEmbedded", true );
+	protected final int menuBarTitleGap = FlatUIUtils.getUIInt( "TitlePane.menuBarTitleGap", 20 );
 
 	protected final JRootPane rootPane;
 
@@ -146,9 +152,15 @@ public class FlatTitlePane
 	protected void addSubComponents() {
 		leftPanel = new JPanel();
 		iconLabel = new JLabel();
-		titleLabel = new JLabel();
+		titleLabel = new JLabel() {
+			@Override
+			public void updateUI() {
+				setUI( new FlatTitleLabelUI() );
+			}
+		};
 		iconLabel.setBorder( new FlatEmptyBorder( UIManager.getInsets( "TitlePane.iconMargins" ) ) );
 		titleLabel.setBorder( new FlatEmptyBorder( UIManager.getInsets( "TitlePane.titleMargins" ) ) );
+		titleLabel.setHorizontalAlignment( SwingConstants.CENTER );
 
 		leftPanel.setLayout( new BoxLayout( leftPanel, BoxLayout.LINE_AXIS ) );
 		leftPanel.setOpaque( false );
@@ -261,8 +273,6 @@ public class FlatTitlePane
 		restoreButton.setForeground( foreground );
 		closeButton.setForeground( foreground );
 
-		titleLabel.setHorizontalAlignment( hasEmbeddedMenuBar ? SwingConstants.CENTER : SwingConstants.LEADING );
-
 		// this is necessary because hover/pressed colors are derived from background color
 		iconifyButton.setBackground( background );
 		maximizeButton.setBackground( background );
@@ -472,6 +482,7 @@ public class FlatTitlePane
 
 	protected void menuBarLayouted() {
 		updateNativeTitleBarHeightAndHitTestSpotsLater();
+		revalidate();
 	}
 
 /*debug
@@ -798,6 +809,41 @@ debug*/
 		}
 	}
 
+	//---- class FlatTitleLabelUI ---------------------------------------------
+
+	protected class FlatTitleLabelUI
+		extends FlatLabelUI
+	{
+		@Override
+		protected void paintEnabledText( JLabel l, Graphics g, String s, int textX, int textY ) {
+			boolean hasEmbeddedMenuBar = hasVisibleEmbeddedMenuBar( rootPane.getJMenuBar() );
+			int labelWidth = l.getWidth();
+			int textWidth = labelWidth - (textX * 2);
+			int gap = UIScale.scale( menuBarTitleGap );
+
+			// The passed in textX coordinate is always to horizontally center the text within the label bounds.
+			// Modify textX so that the text is painted either centered within the window bounds or leading aligned.
+			boolean center = hasEmbeddedMenuBar ? centerTitleIfMenuBarEmbedded : centerTitle;
+			if( center ) {
+				// If window is wide enough, center title within window bounds.
+				// Otherwise leave it centered within free space (label bounds).
+				int centeredTextX = ((l.getParent().getWidth() - textWidth) / 2) - l.getX();
+				if( centeredTextX >= gap && centeredTextX + textWidth <= labelWidth - gap )
+					textX = centeredTextX;
+			} else {
+				// leading aligned
+				boolean leftToRight = getComponentOrientation().isLeftToRight();
+				Insets insets = l.getInsets();
+				int leadingInset = hasEmbeddedMenuBar ? gap : (leftToRight ? insets.left : insets.right);
+				int leadingTextX = leftToRight ? leadingInset : labelWidth - leadingInset - textWidth;
+				if( leftToRight ? leadingTextX < textX : leadingTextX > textX )
+					textX = leadingTextX;
+			}
+
+			super.paintEnabledText( l, g, s, textX, textY );
+		}
+	}
+
 	//---- class Handler ------------------------------------------------------
 
 	protected class Handler

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

@@ -119,6 +119,11 @@ public class FlatUIUtils
 		return (color != null) ? color : UIManager.getColor( defaultKey );
 	}
 
+	public static boolean getUIBoolean( String key, boolean defaultValue ) {
+		Object value = UIManager.get( key );
+		return (value instanceof Boolean) ? (Boolean) value : defaultValue;
+	}
+
 	public static int getUIInt( String key, int defaultValue ) {
 		Object value = UIManager.get( key );
 		return (value instanceof Integer) ? (Integer) value : defaultValue;

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

@@ -692,6 +692,9 @@ TitlePane.iconMargins = 3,8,3,8
 TitlePane.titleMargins = 3,0,3,0
 TitlePane.buttonSize = 44,30
 TitlePane.buttonMaximizedHeight = 22
+TitlePane.centerTitle = false
+TitlePane.centerTitleIfMenuBarEmbedded = true
+TitlePane.menuBarTitleGap = 20
 TitlePane.closeIcon = com.formdev.flatlaf.icons.FlatWindowCloseIcon
 TitlePane.iconifyIcon = com.formdev.flatlaf.icons.FlatWindowIconifyIcon
 TitlePane.maximizeIcon = com.formdev.flatlaf.icons.FlatWindowMaximizeIcon

flatlaf-testing/dumps/uidefaults/FlatDarkLaf_1.8.0_202.txt

@@ -1126,6 +1126,8 @@ TitlePane.buttonHoverBackground #484c4f    com.formdev.flatlaf.util.DerivedColor
 TitlePane.buttonMaximizedHeight 22
 TitlePane.buttonPressedBackground #616569    com.formdev.flatlaf.util.DerivedColor [UI]    lighten(20% autoInverse)
 TitlePane.buttonSize           44,30    javax.swing.plaf.DimensionUIResource [UI]
+TitlePane.centerTitle          false
+TitlePane.centerTitleIfMenuBarEmbedded true
 TitlePane.closeHoverBackground #e81123    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.closeHoverForeground #ffffff    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.closeIcon            [lazy] 44,30    com.formdev.flatlaf.icons.FlatWindowCloseIcon [UI]
@@ -1140,6 +1142,7 @@ TitlePane.inactiveBackground   #303234    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.inactiveForeground   #888888    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.maximizeIcon         [lazy] 44,30    com.formdev.flatlaf.icons.FlatWindowMaximizeIcon [UI]
 TitlePane.menuBarEmbedded      true
+TitlePane.menuBarTitleGap      20
 TitlePane.restoreIcon          [lazy] 44,30    com.formdev.flatlaf.icons.FlatWindowRestoreIcon [UI]
 TitlePane.titleMargins         3,0,3,0    javax.swing.plaf.InsetsUIResource [UI]
 TitlePane.useWindowDecorations true

flatlaf-testing/dumps/uidefaults/FlatLightLaf_1.8.0_202.txt

@@ -1131,6 +1131,8 @@ TitlePane.buttonHoverBackground #e6e6e6    com.formdev.flatlaf.util.DerivedColor
 TitlePane.buttonMaximizedHeight 22
 TitlePane.buttonPressedBackground #cccccc    com.formdev.flatlaf.util.DerivedColor [UI]    darken(20% autoInverse)
 TitlePane.buttonSize           44,30    javax.swing.plaf.DimensionUIResource [UI]
+TitlePane.centerTitle          false
+TitlePane.centerTitleIfMenuBarEmbedded true
 TitlePane.closeHoverBackground #e81123    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.closeHoverForeground #ffffff    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.closeIcon            [lazy] 44,30    com.formdev.flatlaf.icons.FlatWindowCloseIcon [UI]
@@ -1145,6 +1147,7 @@ TitlePane.inactiveBackground   #ffffff    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.inactiveForeground   #8c8c8c    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.maximizeIcon         [lazy] 44,30    com.formdev.flatlaf.icons.FlatWindowMaximizeIcon [UI]
 TitlePane.menuBarEmbedded      true
+TitlePane.menuBarTitleGap      20
 TitlePane.restoreIcon          [lazy] 44,30    com.formdev.flatlaf.icons.FlatWindowRestoreIcon [UI]
 TitlePane.titleMargins         3,0,3,0    javax.swing.plaf.InsetsUIResource [UI]
 TitlePane.useWindowDecorations true

flatlaf-testing/dumps/uidefaults/FlatTestLaf_1.8.0_202.txt

@@ -1124,6 +1124,8 @@ TextPaneUI                     com.formdev.flatlaf.ui.FlatTextPaneUI
 TitlePane.background           #00ff00    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.buttonMaximizedHeight 22
 TitlePane.buttonSize           44,30    javax.swing.plaf.DimensionUIResource [UI]
+TitlePane.centerTitle          false
+TitlePane.centerTitleIfMenuBarEmbedded true
 TitlePane.closeHoverBackground #e81123    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.closeHoverForeground #ffffff    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.closeIcon            [lazy] 44,30    com.formdev.flatlaf.icons.FlatWindowCloseIcon [UI]
@@ -1137,6 +1139,7 @@ TitlePane.inactiveBackground   #008800    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.inactiveForeground   #ffffff    javax.swing.plaf.ColorUIResource [UI]
 TitlePane.maximizeIcon         [lazy] 44,30    com.formdev.flatlaf.icons.FlatWindowMaximizeIcon [UI]
 TitlePane.menuBarEmbedded      true
+TitlePane.menuBarTitleGap      20
 TitlePane.restoreIcon          [lazy] 44,30    com.formdev.flatlaf.icons.FlatWindowRestoreIcon [UI]
 TitlePane.titleMargins         3,0,3,0    javax.swing.plaf.InsetsUIResource [UI]
 TitlePane.useWindowDecorations true

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatWindowDecorationsTest.java

@@ -189,6 +189,14 @@ public class FlatWindowDecorationsTest
 		menuBar.getMenu( menuCount - 1 ).setText( text );
 	}
 
+	private void changeTitle() {
+		Window window = SwingUtilities.windowForComponent( this );
+		if( window instanceof Frame )
+			((Frame)window).setTitle( ((Frame)window).getTitle() + " bla" );
+		else if( window instanceof Dialog )
+			((Dialog)window).setTitle( ((Dialog)window).getTitle() + " bla" );
+	}
+
 	private void resizableChanged() {
 		Window window = SwingUtilities.windowForComponent( this );
 		if( window instanceof Frame )
@@ -308,6 +316,8 @@ public class FlatWindowDecorationsTest
 		colorizeMenusCheckBox = new JCheckBox();
 		resizableCheckBox = new JCheckBox();
 		maximizedBoundsCheckBox = new JCheckBox();
+		JPanel hSpacer1 = new JPanel(null);
+		JButton changeTitleButton = new JButton();
 		undecoratedCheckBox = new JCheckBox();
 		fullScreenCheckBox = new JCheckBox();
 		JLabel label1 = new JLabel();
@@ -428,6 +438,12 @@ public class FlatWindowDecorationsTest
 		maximizedBoundsCheckBox.setText("maximized bounds (50,100, 1000,700)");
 		maximizedBoundsCheckBox.addActionListener(e -> maximizedBoundsChanged());
 		add(maximizedBoundsCheckBox, "cell 1 3");
+		add(hSpacer1, "cell 1 3,growx");
+
+		//---- changeTitleButton ----
+		changeTitleButton.setText("Change title");
+		changeTitleButton.addActionListener(e -> changeTitle());
+		add(changeTitleButton, "cell 1 3");
 
 		//---- undecoratedCheckBox ----
 		undecoratedCheckBox.setText("undecorated");

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatWindowDecorationsTest.jfd

@@ -123,6 +123,18 @@ new FormModel {
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 				"value": "cell 1 3"
 			} )
+			add( new FormComponent( "com.jformdesigner.designer.wrapper.HSpacer" ) {
+				name: "hSpacer1"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 1 3,growx"
+			} )
+			add( new FormComponent( "javax.swing.JButton" ) {
+				name: "changeTitleButton"
+				"text": "Change title"
+				addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "changeTitle", false ) )
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 1 3"
+			} )
 			add( new FormComponent( "javax.swing.JCheckBox" ) {
 				name: "undecoratedCheckBox"
 				"text": "undecorated"
@@ -316,7 +328,7 @@ new FormModel {
 			} )
 		}, new FormLayoutConstraints( null ) {
 			"location": new java.awt.Point( 0, 0 )
-			"size": new java.awt.Dimension( 550, 440 )
+			"size": new java.awt.Dimension( 580, 440 )
 		} )
 		add( new FormContainer( "javax.swing.JMenuBar", new FormLayoutManager( class javax.swing.JMenuBar ) ) {
 			name: "menuBar"

flatlaf-theme-editor/src/main/resources/com/formdev/flatlaf/themeeditor/FlatLafUIKeys.txt

@@ -836,6 +836,8 @@ TitlePane.buttonHoverBackground
 TitlePane.buttonMaximizedHeight
 TitlePane.buttonPressedBackground
 TitlePane.buttonSize
+TitlePane.centerTitle
+TitlePane.centerTitleIfMenuBarEmbedded
 TitlePane.closeHoverBackground
 TitlePane.closeHoverForeground
 TitlePane.closeIcon
@@ -850,6 +852,7 @@ TitlePane.inactiveBackground
 TitlePane.inactiveForeground
 TitlePane.maximizeIcon
 TitlePane.menuBarEmbedded
+TitlePane.menuBarTitleGap
 TitlePane.restoreIcon
 TitlePane.titleMargins
 TitlePane.useWindowDecorations