fixed/improved vertical position of text when scaled on HiDPI screens on Windows when running on Java 9 or later

CHANGELOG.md

@@ -18,6 +18,8 @@ FlatLaf Change Log
   `Spinner.buttonStyle` to `button` (default) or `none`).
 - TableHeader: Support top/bottom/left positioned sort arrow when using
   [Glazed Lists](https://github.com/glazedlists/glazedlists). (issue #113)
+- Fixed/improved vertical position of text when scaled on HiDPI screens on
+  Windows when running on Java 9 or later.
 
 
 ## 0.36

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

@@ -19,6 +19,7 @@ package com.formdev.flatlaf.ui;
 import static com.formdev.flatlaf.util.UIScale.scale;
 import java.awt.Dimension;
 import java.awt.Graphics;
+import java.awt.Graphics2D;
 import java.beans.PropertyChangeEvent;
 import javax.swing.JComponent;
 import javax.swing.JEditorPane;
@@ -28,6 +29,7 @@ import javax.swing.plaf.UIResource;
 import javax.swing.plaf.basic.BasicEditorPaneUI;
 import javax.swing.text.JTextComponent;
 import com.formdev.flatlaf.FlatClientProperties;
+import com.formdev.flatlaf.util.HiDPIUtils;
 
 /**
  * Provides the Flat LaF UI delegate for {@link javax.swing.JEditorPane}.
@@ -119,6 +121,11 @@ public class FlatEditorPaneUI
 		return size;
 	}
 
+	@Override
+	protected void paintSafely( Graphics g ) {
+		super.paintSafely( HiDPIUtils.createGraphicsTextYCorrection( (Graphics2D) g ) );
+	}
+
 	@Override
 	protected void paintBackground( Graphics g ) {
 		JTextComponent c = getComponent();

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

@@ -19,6 +19,7 @@ package com.formdev.flatlaf.ui;
 import java.awt.Color;
 import java.awt.FontMetrics;
 import java.awt.Graphics;
+import java.awt.Graphics2D;
 import java.awt.Rectangle;
 import java.beans.PropertyChangeEvent;
 import javax.swing.Icon;
@@ -29,7 +30,9 @@ import javax.swing.UIManager;
 import javax.swing.plaf.ComponentUI;
 import javax.swing.plaf.basic.BasicHTML;
 import javax.swing.plaf.basic.BasicLabelUI;
+import javax.swing.text.View;
 import com.formdev.flatlaf.FlatLaf;
+import com.formdev.flatlaf.util.HiDPIUtils;
 import com.formdev.flatlaf.util.UIScale;
 
 /**
@@ -124,6 +127,12 @@ public class FlatLabelUI
 		BasicHTML.updateRenderer( c, text );
 	}
 
+	@Override
+	public void paint( Graphics g, JComponent c ) {
+		View v = (View) c.getClientProperty( BasicHTML.propertyKey );
+		super.paint( (v != null) ? HiDPIUtils.createGraphicsTextYCorrection( (Graphics2D) g ) : g, c );
+	}
+
 	@Override
 	protected void paintEnabledText( JLabel l, Graphics g, String s, int textX, int textY ) {
 		int mnemIndex = FlatLaf.isShowMnemonics() ? l.getDisplayedMnemonicIndex() : -1;

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

@@ -19,6 +19,7 @@ package com.formdev.flatlaf.ui;
 import java.awt.Color;
 import java.awt.Dimension;
 import java.awt.Graphics;
+import java.awt.Graphics2D;
 import java.awt.Toolkit;
 import java.awt.event.FocusListener;
 import java.awt.event.KeyAdapter;
@@ -33,6 +34,7 @@ import javax.swing.plaf.ComponentUI;
 import javax.swing.plaf.basic.BasicPasswordFieldUI;
 import javax.swing.text.Caret;
 import javax.swing.text.JTextComponent;
+import com.formdev.flatlaf.util.HiDPIUtils;
 
 /**
  * Provides the Flat LaF UI delegate for {@link javax.swing.JPasswordField}.
@@ -153,7 +155,8 @@ public class FlatPasswordFieldUI
 		FlatTextFieldUI.paintBackground( g, getComponent(), isIntelliJTheme );
 		FlatTextFieldUI.paintPlaceholder( g, getComponent(), placeholderForeground );
 		paintCapsLock( g );
-		super.paintSafely( g );
+
+		super.paintSafely( HiDPIUtils.createGraphicsTextYCorrection( (Graphics2D) g ) );
 	}
 
 	protected void paintCapsLock( Graphics g ) {

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

@@ -19,6 +19,7 @@ package com.formdev.flatlaf.ui;
 import java.awt.Color;
 import java.awt.Dimension;
 import java.awt.Graphics;
+import java.awt.Graphics2D;
 import java.beans.PropertyChangeEvent;
 import javax.swing.JComponent;
 import javax.swing.JTextArea;
@@ -27,6 +28,7 @@ import javax.swing.plaf.ComponentUI;
 import javax.swing.plaf.UIResource;
 import javax.swing.plaf.basic.BasicTextAreaUI;
 import javax.swing.text.JTextComponent;
+import com.formdev.flatlaf.util.HiDPIUtils;
 
 /**
  * Provides the Flat LaF UI delegate for {@link javax.swing.JTextArea}.
@@ -89,6 +91,11 @@ public class FlatTextAreaUI
 		FlatEditorPaneUI.propertyChange( getComponent(), e );
 	}
 
+	@Override
+	protected void paintSafely( Graphics g ) {
+		super.paintSafely( HiDPIUtils.createGraphicsTextYCorrection( (Graphics2D) g ) );
+	}
+
 	@Override
 	protected void paintBackground( Graphics g ) {
 		JTextComponent c = getComponent();

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

@@ -38,6 +38,7 @@ import javax.swing.plaf.basic.BasicTextFieldUI;
 import javax.swing.text.Caret;
 import javax.swing.text.JTextComponent;
 import com.formdev.flatlaf.FlatClientProperties;
+import com.formdev.flatlaf.util.HiDPIUtils;
 
 /**
  * Provides the Flat LaF UI delegate for {@link javax.swing.JTextField}.
@@ -146,7 +147,8 @@ public class FlatTextFieldUI
 	protected void paintSafely( Graphics g ) {
 		paintBackground( g, getComponent(), isIntelliJTheme );
 		paintPlaceholder( g, getComponent(), placeholderForeground );
-		super.paintSafely( g );
+
+		super.paintSafely( HiDPIUtils.createGraphicsTextYCorrection( (Graphics2D) g ) );
 	}
 
 	@Override

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

@@ -18,6 +18,7 @@ package com.formdev.flatlaf.ui;
 
 import java.awt.Dimension;
 import java.awt.Graphics;
+import java.awt.Graphics2D;
 import java.beans.PropertyChangeEvent;
 import javax.swing.JComponent;
 import javax.swing.JEditorPane;
@@ -26,6 +27,7 @@ import javax.swing.plaf.ComponentUI;
 import javax.swing.plaf.UIResource;
 import javax.swing.plaf.basic.BasicTextPaneUI;
 import javax.swing.text.JTextComponent;
+import com.formdev.flatlaf.util.HiDPIUtils;
 
 /**
  * Provides the Flat LaF UI delegate for {@link javax.swing.JTextPane}.
@@ -99,6 +101,11 @@ public class FlatTextPaneUI
 		return FlatEditorPaneUI.applyMinimumWidth( c, super.getMinimumSize( c ), minimumWidth );
 	}
 
+	@Override
+	protected void paintSafely( Graphics g ) {
+		super.paintSafely( HiDPIUtils.createGraphicsTextYCorrection( (Graphics2D) g ) );
+	}
+
 	@Override
 	protected void paintBackground( Graphics g ) {
 		JTextComponent c = getComponent();

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

@@ -29,6 +29,7 @@ import javax.swing.SwingUtilities;
 import javax.swing.plaf.ComponentUI;
 import javax.swing.plaf.basic.BasicHTML;
 import javax.swing.plaf.basic.BasicToolTipUI;
+import com.formdev.flatlaf.util.HiDPIUtils;
 import com.formdev.flatlaf.util.StringUtils;
 
 /**
@@ -130,7 +131,7 @@ public class FlatToolTipUI
 				FlatUIUtils.drawString( c, g, line, leftToRight ? x : x2 - SwingUtilities.computeStringWidth( fm, line ), y );
 			}
 		} else
-			super.paint( g, c );
+			super.paint( HiDPIUtils.createGraphicsTextYCorrection( (Graphics2D) g ), c );
 	}
 
 	private boolean isMultiLine( JComponent c ) {

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

@@ -46,7 +46,6 @@ import com.formdev.flatlaf.FlatClientProperties;
 import com.formdev.flatlaf.util.DerivedColor;
 import com.formdev.flatlaf.util.Graphics2DProxy;
 import com.formdev.flatlaf.util.HiDPIUtils;
-import com.formdev.flatlaf.util.JavaCompatibility;
 import com.formdev.flatlaf.util.UIScale;
 
 /**
@@ -449,23 +448,24 @@ public class FlatUIUtils
 	}
 
 	/**
-	 * Draws the given string at the specified location using text properties
+	 * Draws the given string at the specified location.
-	 * and anti-aliasing hints from the provided component.
+	 * The provided component is used to query text properties and anti-aliasing hints.
-	 *
+	 * <p>
-	 * Use this method instead of Graphics.drawString() for correct anti-aliasing.
+	 * Use this method instead of {@link Graphics#drawString(String, int, int)} for correct anti-aliasing.
-	 *
+	 * <p>
-	 * Replacement for SwingUtilities2.drawString()
+	 * Replacement for {@code SwingUtilities2.drawString()}.
+	 * Uses {@link HiDPIUtils#drawStringWithYCorrection(JComponent, Graphics2D, String, int, int)}.
 	 */
 	public static void drawString( JComponent c, Graphics g, String text, int x, int y ) {
-		JavaCompatibility.drawStringUnderlineCharAt( c, g, text, -1, x, y );
+		HiDPIUtils.drawStringWithYCorrection( c, (Graphics2D) g, text, x, y );
 	}
 
 	/**
-	 * Draws the given string at the specified location underlining the specified
+	 * Draws the given string at the specified location underlining the specified character.
-	 * character. The provided component is used to query text properties and
+	 * The provided component is used to query text properties and anti-aliasing hints.
-	 * anti-aliasing hints.
+	 * <p>
-	 *
+	 * Replacement for {@code SwingUtilities2.drawStringUnderlineCharAt()}.
-	 * Replacement for SwingUtilities2.drawStringUnderlineCharAt()
+	 * Uses {@link HiDPIUtils#drawStringUnderlineCharAtWithYCorrection(JComponent, Graphics2D, String, int, int, int)}.
 	 */
 	public static void drawStringUnderlineCharAt( JComponent c, Graphics g,
 		String text, int underlinedIndex, int x, int y )
@@ -487,7 +487,7 @@ public class FlatUIUtils
 			};
 		}
 
-		JavaCompatibility.drawStringUnderlineCharAt( c, g, text, underlinedIndex, x, y );
+		HiDPIUtils.drawStringUnderlineCharAtWithYCorrection( c, (Graphics2D) g, text, underlinedIndex, x, y );
 	}
 
 	public static boolean hasOpaqueBeenExplicitlySet( JComponent c ) {

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

@@ -16,9 +16,11 @@
 
 package com.formdev.flatlaf.util;
 
+import java.awt.Graphics;
 import java.awt.Graphics2D;
 import java.awt.geom.AffineTransform;
 import java.awt.geom.Rectangle2D;
+import java.text.AttributedCharacterIterator;
 import javax.swing.JComponent;
 
 /**
@@ -95,4 +97,116 @@ public class HiDPIUtils
 	private static double normalize( double value ) {
 		return Math.floor( value + 0.25 ) + 0.25;
 	}
+
+
+	private static Boolean useTextYCorrection;
+
+	private static boolean useTextYCorrection() {
+		if( useTextYCorrection == null )
+			useTextYCorrection = Boolean.valueOf( System.getProperty( "flatlaf.useTextYCorrection", "true" ) );
+		return useTextYCorrection;
+	}
+
+	/**
+	 * When painting text on HiDPI screens and the JRE scales, then the text is
+	 * painted too far down on some operating systems.
+	 * The higher the system scale factor is, the more.
+	 * <p>
+	 * This methods computes a correction value for the Y position.
+	 */
+	public static float computeTextYCorrection( Graphics2D g ) {
+		if( !useTextYCorrection() || !SystemInfo.IS_WINDOWS || !SystemInfo.IS_JAVA_9_OR_LATER )
+			return 0;
+
+		AffineTransform t = g.getTransform();
+		double scaleY = t.getScaleY();
+		if( scaleY < 1.25 )
+			return 0;
+
+		// Text is painted at slightly different Y positions depending on scale factor
+		// and Y position of component.
+		// The exact reason is not yet known (to me), but there are several factors:
+		// - fractional scale factors result in fractional component Y device coordinates
+		// - fractional text Y device coordinates are rounded for horizontal lines of characters
+		// - maybe different rounding methods for drawing primitives (e.g. rectangle) and text
+		// - Java adds 0.5 to X/Y positions in before drawing string in BufferedTextPipe.enqueueGlyphList()
+
+		// this is not the optimal solution, but works very good in most cases
+		// (tested with class FlatPaintingStringTest on Windows 10 with font "Segoe UI")
+		if( scaleY <= 1.25 )
+			return -0.875f;
+		if( scaleY <= 1.5 )
+			return -0.625f;
+		if( scaleY <= 1.75 )
+			return -0.875f;
+		if( scaleY <= 2.0 )
+			return -0.75f;
+		if( scaleY <= 2.25 )
+			return -0.875f;
+		if( scaleY <= 3.5 )
+			return -0.75f;
+		return -0.875f;
+	}
+
+	/**
+	 * Applies Y correction and draws the given string at the specified location.
+	 * The provided component is used to query text properties and anti-aliasing hints.
+	 * <p>
+	 * Use this method instead of {@link Graphics#drawString(String, int, int)} for correct anti-aliasing.
+	 * <p>
+	 * Replacement for {@code SwingUtilities2.drawString()}.
+	 */
+	public static void drawStringWithYCorrection( JComponent c, Graphics2D g, String text, int x, int y ) {
+		drawStringUnderlineCharAtWithYCorrection( c, g, text, -1, x, y );
+	}
+
+	/**
+	 * Applies Y correction and draws the given string at the specified location underlining the specified character.
+	 * The provided component is used to query text properties and anti-aliasing hints.
+	 * <p>
+	 * Replacement for {@code SwingUtilities2.drawStringUnderlineCharAt()}.
+	 */
+	public static void drawStringUnderlineCharAtWithYCorrection( JComponent c,
+		Graphics2D g, String text, int underlinedIndex, int x, int y )
+	{
+		float yCorrection = computeTextYCorrection( g );
+		if( yCorrection != 0 ) {
+			g.translate( 0, yCorrection );
+			JavaCompatibility.drawStringUnderlineCharAt( c, g, text, underlinedIndex, x, y );
+			g.translate( 0, -yCorrection );
+		} else
+			JavaCompatibility.drawStringUnderlineCharAt( c, g, text, underlinedIndex, x, y );
+	}
+
+	/**
+	 * Creates a graphics object and applies Y correction to string drawing methods.
+	 * If no Y correction is necessary, the passed in graphics object is returned.
+	 */
+	public static Graphics2D createGraphicsTextYCorrection( Graphics2D g ) {
+		float yCorrection = computeTextYCorrection( g );
+		if( yCorrection == 0 )
+			return g;
+
+		return new Graphics2DProxy( g ) {
+			@Override
+			public void drawString( String str, int x, int y ) {
+				super.drawString( str, x, y + yCorrection );
+			}
+
+			@Override
+			public void drawString( String str, float x, float y ) {
+				super.drawString( str, x, y + yCorrection );
+			}
+
+			@Override
+			public void drawString( AttributedCharacterIterator iterator, int x, int y ) {
+				super.drawString( iterator, x, y + yCorrection );
+			}
+
+			@Override
+			public void drawString( AttributedCharacterIterator iterator, float x, float y ) {
+				super.drawString( iterator, x, y + yCorrection );
+			}
+		};
+	}
 }

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

@@ -0,0 +1,223 @@
+/*
+ * Copyright 2020 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.formdev.flatlaf.testing;
+
+import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.FontMetrics;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Insets;
+import java.awt.geom.AffineTransform;
+import javax.swing.*;
+import javax.swing.border.EmptyBorder;
+import com.formdev.flatlaf.ui.FlatUIUtils;
+import com.formdev.flatlaf.util.Graphics2DProxy;
+import com.formdev.flatlaf.util.HiDPIUtils;
+import com.formdev.flatlaf.util.JavaCompatibility;
+import com.formdev.flatlaf.util.SystemInfo;
+import net.miginfocom.swing.*;
+
+/**
+ * @author Karl Tauber
+ */
+public class FlatPaintingStringTest
+	extends JPanel
+{
+	public static void main( String[] args ) {
+		System.setProperty( "sun.java2d.uiScale", "1x" );
+
+		SwingUtilities.invokeLater( () -> {
+			FlatTestFrame frame = FlatTestFrame.create( args, "FlatPaintingStringTest" );
+
+			ToolTipManager.sharedInstance().setInitialDelay( 0 );
+			ToolTipManager.sharedInstance().setDismissDelay( 10000 );
+
+			frame.showFrame( FlatPaintingStringTest::new );
+		} );
+	}
+
+	FlatPaintingStringTest() {
+		initComponents();
+
+		if( !SystemInfo.IS_JAVA_9_OR_LATER ) {
+			add( new JLabel( "requires Java 9 or later" ) );
+			return;
+		}
+
+		add( new JLabel() );
+		add( new JLabel( "none" ) );
+		add( new JLabel( "flatlaf" ) );
+		add( new JLabel( "0.25*scale" ) );
+		add( new JLabel( "0.5*scale" ) );
+		add( new JLabel( "0.25" ) );
+		add( new JLabel( "0.5" ) );
+		add( new JLabel( "0.625" ) );
+		add( new JLabel( "0.75" ) );
+		add( new JLabel( "0.875" ) );
+
+		YCorrectionFunction none = (g, scaleFactor) -> 0;
+		YCorrectionFunction flatlaf = (g, scaleFactor) -> HiDPIUtils.computeTextYCorrection( g );
+		YCorrectionFunction oneQSysScale = (g, scaleFactor) -> -(0.25f * scaleFactor);
+		YCorrectionFunction halfSysScale = (g, scaleFactor) -> -(0.5f * scaleFactor);
+		YCorrectionFunction oneQ = (g, scaleFactor) -> -0.25f;
+		YCorrectionFunction half = (g, scaleFactor) -> -0.5f;
+		YCorrectionFunction fiveEights = (g, scaleFactor) -> -0.625f;
+		YCorrectionFunction threeQ = (g, scaleFactor) -> -0.75f;
+		YCorrectionFunction sevenEights = (g, scaleFactor) -> -0.875f;
+
+		float[] scaleFactors = new float[] { 1f, 1.25f, 1.5f, 1.75f, 2f, 2.25f, 2.5f, 3f, 3.5f, 4f };
+
+		for( float scaleFactor : scaleFactors ) {
+			add( new JLabel( String.valueOf( scaleFactor ) ), "newLine" );
+
+			add( scaleFactor, none );
+			add( scaleFactor, flatlaf );
+			add( scaleFactor, oneQSysScale );
+			add( scaleFactor, halfSysScale );
+			add( scaleFactor, oneQ );
+			add( scaleFactor, half );
+			add( scaleFactor, fiveEights );
+			add( scaleFactor, threeQ );
+			add( scaleFactor, sevenEights );
+		}
+	}
+
+	private void add( float scaleFactor, YCorrectionFunction correctionFunction ) {
+		add( new Painter( scaleFactor, correctionFunction, 0 ), "split 4, gapx 0 0" );
+		add( new Painter( scaleFactor, correctionFunction, 0.25f ), "gapx 0 0" );
+		add( new Painter( scaleFactor, correctionFunction, 0.5f ), "gapx 0 0" );
+		add( new Painter( scaleFactor, correctionFunction, 0.75f ), "gapx 0 0" );
+	}
+
+	private void initComponents() {
+		// JFormDesigner - Component initialization - DO NOT MODIFY  //GEN-BEGIN:initComponents
+
+		//======== this ========
+		setBorder(null);
+		setLayout(new MigLayout(
+			"insets dialog,hidemode 3",
+			// columns
+			"[fill]",
+			// rows
+			"[fill]"));
+		// JFormDesigner - End of component initialization  //GEN-END:initComponents
+	}
+
+	// JFormDesigner - Variables declaration - DO NOT MODIFY  //GEN-BEGIN:variables
+	// JFormDesigner - End of variables declaration  //GEN-END:variables
+
+	private interface YCorrectionFunction {
+		float computeTextYCorrection( Graphics2D g, float scaleFactor );
+	}
+
+	//---- class Painter ------------------------------------------------------
+
+	public static class Painter
+		extends JLabel
+	{
+		private final float scaleFactor;
+		private final YCorrectionFunction correctionFunction;
+		private final float yOffset;
+
+		public Painter( float scaleFactor, YCorrectionFunction correctionFunction, float yOffset ) {
+			super( "E" );
+			this.scaleFactor = scaleFactor;
+			this.correctionFunction = correctionFunction;
+			this.yOffset = yOffset;
+			setBorder( new EmptyBorder( 2, 4, 2, 0 ) );
+		}
+
+		@Override
+		public Dimension getPreferredSize() {
+			Dimension size = super.getPreferredSize();
+			Insets insets = getInsets();
+			int leftRight = insets.left + insets.right;
+			return new Dimension(
+				scale( size.width -leftRight ) + leftRight,
+				scale( size.height ) );
+		}
+
+		@Override
+		protected void paintComponent( Graphics g ) {
+			Graphics2D g2 = (Graphics2D) g;
+			FlatUIUtils.setRenderingHints( g2 );
+
+			// simulate component y position at a fraction
+			if( scaleFactor > 1 )
+				g2.translate( 0, yOffset );
+
+			int width = getWidth();
+			int height = getHeight();
+			Insets insets = getInsets();
+			FontMetrics fm = getFontMetrics( getFont() );
+
+			// paint lines at 1x
+			HiDPIUtils.paintAtScale1x( g2, 0, 0, width, height,
+				(g2d, x2, y2, width2, height2, scaleFactor2) -> {
+//					g.setColor( Color.blue );
+//					g.drawLine( 0, 0, width2, 0 );
+//					g.drawLine( 0, height2 - 1, width2, height2 - 1 );
+
+					int baseline = (int) Math.round( (insets.top + fm.getAscent()) * scaleFactor2 * scaleFactor ) - 1;
+					int topline = height2 - baseline - 1;
+
+					g.setColor( Color.red );
+					g.drawLine( 0, baseline, width2, baseline );
+					g.drawLine( 0, topline, width2, topline );
+				} );
+
+			// move x before scaling to have same left inset at all scale factors
+			g.translate( insets.left, 0 );
+
+			// scale
+			((Graphics2D)g).scale( scaleFactor, scaleFactor );
+
+			// compute Y correction
+			float yCorrection = correctionFunction.computeTextYCorrection( g2, scaleFactor );
+
+			// create graphics that applies Y correction
+			Graphics2D cg = new Graphics2DProxy( g2 ) {
+				@Override
+				public void drawString( String str, int x, int y ) {
+					super.drawString( str, x, y + yCorrection );
+				}
+
+				@Override
+				public void drawString( String str, float x, float y ) {
+					super.drawString( str, x, y + yCorrection );
+				}
+			};
+
+			// draw string
+			g.setColor( getForeground() );
+			int y = insets.top + fm.getAscent();
+			JavaCompatibility.drawStringUnderlineCharAt( this, cg, "E", -1, 0, y );
+
+			// set tooltip text
+			if( getToolTipText() == null ) {
+				AffineTransform t = g2.getTransform();
+				double textY = t.getTranslateY() + (y * t.getScaleY());
+				setToolTipText( textY + " + " + yCorrection + " = " + (textY + yCorrection) );
+			}
+		}
+
+		private int scale( int value ) {
+			return Math.round( value * scaleFactor );
+		}
+	}
+}

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

@@ -0,0 +1,21 @@
+JFDML JFormDesigner: "7.0.2.0.298" Java: "14" encoding: "UTF-8"
+
+new FormModel {
+	contentType: "form/swing"
+	root: new FormRoot {
+		auxiliary() {
+			"JavaCodeGenerator.defaultVariableLocal": true
+		}
+		add( new FormContainer( "javax.swing.JPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
+			"$layoutConstraints": "insets dialog,hidemode 3"
+			"$columnConstraints": "[fill]"
+			"$rowConstraints": "[fill]"
+		} ) {
+			name: "this"
+			"border": sfield com.jformdesigner.model.FormObject NULL_VALUE
+		}, new FormLayoutConstraints( null ) {
+			"location": new java.awt.Point( 0, 0 )
+			"size": new java.awt.Dimension( 450, 300 )
+		} )
+	}
+}