Testing: FlatPaintingStringTest:

- added "Fonts" combobox to test various fonts
- reworked/fixed text painting/sizing to get correct results

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

@@ -22,12 +22,14 @@ import java.awt.Font;
 import java.awt.FontMetrics;
 import java.awt.Graphics;
 import java.awt.Graphics2D;
-import java.awt.Insets;
+import java.awt.GraphicsEnvironment;
+import java.awt.Rectangle;
 import java.awt.geom.AffineTransform;
+import java.util.Arrays;
 import javax.swing.*;
-import javax.swing.border.EmptyBorder;
+import javax.swing.text.StyleContext;
+import com.formdev.flatlaf.FlatLaf;
 import com.formdev.flatlaf.FlatSystemProperties;
-import com.formdev.flatlaf.ui.FlatUIUtils;
 import com.formdev.flatlaf.util.Graphics2DProxy;
 import com.formdev.flatlaf.util.HiDPIUtils;
 import com.formdev.flatlaf.util.JavaCompatibility;
@@ -57,18 +59,49 @@ public class FlatPaintingStringTest
 	FlatPaintingStringTest() {
 		initComponents();
 
+		String[] availableFontFamilyNames = GraphicsEnvironment.getLocalGraphicsEnvironment()
+			.getAvailableFontFamilyNames().clone();
+		Arrays.sort( availableFontFamilyNames );
+
+		Font currentFont = UIManager.getFont( "Label.font" );
+		String currentFamily = currentFont.getFamily();
+
+		// initialize font families combobox
+		String[] families = {
+			"Arial", "Cantarell", "DejaVu Sans",
+			"Dialog", "Inter", "Liberation Sans", "Noto Sans", "Open Sans", "Roboto",
+			"SansSerif", "Segoe UI", "Tahoma", "Ubuntu", "Verdana" };
+		Arrays.sort( families, String.CASE_INSENSITIVE_ORDER );
+		DefaultComboBoxModel<String> model = new DefaultComboBoxModel<>();
+		model.addElement( currentFamily );
+		for( String family : families ) {
+			if( !family.equals( currentFamily ) && Arrays.binarySearch( availableFontFamilyNames, family ) >= 0 )
+				model.addElement( family );
+		}
+		fontField.setModel( model );
+		fontField.setSelectedItem( currentFamily );
+		updateFontMetricsLabel();
+
 		add( new JLabel() );
 		add( new JLabel( "none" ) );
 		add( new JLabel( "flatlaf" ) );
-		add( new JLabel( "0.25*scale" ) );
+		add( new JLabel() );
-		add( new JLabel( "0.5*scale" ) );
 		if( SystemInfo.isJava_9_orLater ) {
+			add( new JLabel( "0.125" ) );
 			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" ) );
+			add( new JLabel( "1" ) );
+			add( new JLabel( "1.25" ) );
+			add( new JLabel() );
+			add( new JLabel( "0.25*scale" ) );
+			add( new JLabel( "0.5*scale" ) );
+			add( new JLabel( "ty" ) );
 		} else {
+			add( new JLabel( "0.25*scale" ) );
+			add( new JLabel( "0.5*scale" ) );
 			add( new JLabel( "0.625*scale" ) );
 			add( new JLabel( "0.75*scale" ) );
 			add( new JLabel( "0.875*scale" ) );
@@ -80,16 +113,14 @@ public class FlatPaintingStringTest
 				? HiDPIUtils.computeTextYCorrection( g )
 				: (scaleFactor > 1 ? -(0.625f * scaleFactor) : 0);
 		};
-		YCorrectionFunction oneQSysScale = (g, scaleFactor) -> -(0.25f * scaleFactor);
+		YCorrectionFunction ty = (g, scaleFactor) -> {
-		YCorrectionFunction halfSysScale = (g, scaleFactor) -> -(0.5f * scaleFactor);
+			// Based on translateY, which is the scaled Y coordinate translation of the graphics context.
-		YCorrectionFunction fiveEightsQSysScale = (g, scaleFactor) -> -(0.625f * scaleFactor);
+			// When painting whole window, translateY is from top of window, and this works fine.
-		YCorrectionFunction threeQSysScale = (g, scaleFactor) -> -(0.75f * scaleFactor);
+			// But when repainting only parts of the window, then translateY starts somewhere
-		YCorrectionFunction sevenEightsSysScale = (g, scaleFactor) -> -(0.875f * scaleFactor);
+			// else and the text if (re-)painted at the wrong Y location.
-		YCorrectionFunction oneQ = (g, scaleFactor) -> -0.25f;
+			double y = g.getTransform().getTranslateY();
-		YCorrectionFunction half = (g, scaleFactor) -> -0.5f;
+			return (float) -(y - (int) y);
-		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 };
 
@@ -98,34 +129,72 @@ public class FlatPaintingStringTest
 
 			add( scaleFactor, none );
 			add( scaleFactor, flatlaf );
-			add( scaleFactor, oneQSysScale );
+			add( new JLabel( "  " ) );
-			add( scaleFactor, halfSysScale );
 			if( SystemInfo.isJava_9_orLater ) {
-				add( scaleFactor, oneQ );
+				add( scaleFactor, (g, sf) -> -0.125f );
-				add( scaleFactor, half );
+				add( scaleFactor, (g, sf) -> -0.25f );
-				add( scaleFactor, fiveEights );
+				add( scaleFactor, (g, sf) -> -0.5f );
-				add( scaleFactor, threeQ );
+				add( scaleFactor, (g, sf) -> -0.625f );
-				add( scaleFactor, sevenEights );
+				add( scaleFactor, (g, sf) -> -0.75f );
+				add( scaleFactor, (g, sf) -> -0.875f );
+				add( scaleFactor, (g, sf) -> -1f );
+				add( scaleFactor, (g, sf) -> -1.25f );
+				add( new JLabel( "  " ) );
+				add( scaleFactor, (g, sf) -> -(0.25f * sf) );
+				add( scaleFactor, (g, sf) -> -(0.5f * sf) );
+				add( scaleFactor, ty );
 			} else {
-				add( scaleFactor, fiveEightsQSysScale );
+				add( scaleFactor, (g, sf) -> -(0.25f * sf) );
-				add( scaleFactor, threeQSysScale );
+				add( scaleFactor, (g, sf) -> -(0.5f * sf) );
-				add( scaleFactor, sevenEightsSysScale );
+				add( scaleFactor, (g, sf) -> -(0.625f * sf) );
+				add( scaleFactor, (g, sf) -> -(0.75f * sf) );
+				add( scaleFactor, (g, sf) -> -(0.875f * sf) );
 			}
+
+			add( new JLabel( String.valueOf( scaleFactor ) ) );
 		}
 	}
 
 	private void add( float scaleFactor, YCorrectionFunction correctionFunction ) {
 		if( SystemInfo.isJava_9_orLater ) {
 			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, 1 ), "gapx 0 0" );
-			add( new Painter( scaleFactor, correctionFunction, 0.5f ), "gapx 0 0" );
+			add( new Painter( scaleFactor, correctionFunction, 2 ), "gapx 0 0" );
-			add( new Painter( scaleFactor, correctionFunction, 0.75f ), "gapx 0 0" );
+			add( new Painter( scaleFactor, correctionFunction, 3 ), "gapx 0 0" );
 		} else
 			add( new Painter( scaleFactor, correctionFunction, 0 ) );
 	}
 
+	private void fontChanged() {
+		String family = (String) fontField.getSelectedItem();
+
+		Font font = UIManager.getFont( "defaultFont" );
+		if( font.getFamily().equals( family ) )
+			return;
+
+		Font newFont = StyleContext.getDefaultStyleContext().getFont( family, font.getStyle(), font.getSize() );
+		UIManager.put( "defaultFont", newFont );
+		updateFontMetricsLabel();
+
+		FlatLaf.updateUILater();
+	}
+
+	private void updateFontMetricsLabel() {
+		Font font = UIManager.getFont( "defaultFont" );
+		FontMetrics fm = getFontMetrics( font );
+		fontMetricsLabel.setText( String.format( "%s %d    height %d   ascent %d   descent %d   max ascent %d   max descent %d   leading %d",
+			font.getFamily(), font.getSize(),
+			fm.getHeight(), fm.getAscent(), fm.getDescent(),
+			fm.getMaxAscent(), fm.getMaxDescent(), fm.getLeading()
+		) );
+	}
+
 	private void initComponents() {
 		// JFormDesigner - Component initialization - DO NOT MODIFY  //GEN-BEGIN:initComponents
+		JPanel panel1 = new JPanel();
+		JLabel fontLabel = new JLabel();
+		fontField = new JComboBox<>();
+		fontMetricsLabel = new JLabel();
 
 		//======== this ========
 		setBorder(null);
@@ -134,11 +203,40 @@ public class FlatPaintingStringTest
 			// columns
 			"[fill]",
 			// rows
+			"[top]unrel" +
 			"[top]"));
+
+		//======== panel1 ========
+		{
+			panel1.setLayout(new MigLayout(
+				"hidemode 3",
+				// columns
+				"[fill]" +
+				"[fill]" +
+				"[fill]",
+				// rows
+				"[]"));
+
+			//---- fontLabel ----
+			fontLabel.setText("Font:");
+			panel1.add(fontLabel, "cell 0 0");
+
+			//---- fontField ----
+			fontField.setMaximumRowCount(20);
+			fontField.addActionListener(e -> fontChanged());
+			panel1.add(fontField, "cell 1 0");
+
+			//---- fontMetricsLabel ----
+			fontMetricsLabel.setText("text");
+			panel1.add(fontMetricsLabel, "cell 2 0");
+		}
+		add(panel1, "north");
 		// JFormDesigner - End of component initialization  //GEN-END:initComponents
 	}
 
 	// JFormDesigner - Variables declaration - DO NOT MODIFY  //GEN-BEGIN:variables
+	private JComboBox<String> fontField;
+	private JLabel fontMetricsLabel;
 	// JFormDesigner - End of variables declaration  //GEN-END:variables
 
 	private interface YCorrectionFunction {
@@ -152,17 +250,29 @@ public class FlatPaintingStringTest
 	{
 		private final float scaleFactor;
 		private final YCorrectionFunction correctionFunction;
-		private final float yOffset;
+		private final int yOffset;
 
-		public Painter( float scaleFactor, YCorrectionFunction correctionFunction, float yOffset ) {
+		public Painter( float scaleFactor, YCorrectionFunction correctionFunction, int yOffset ) {
 			super( "E" );
 			this.scaleFactor = scaleFactor;
 			this.correctionFunction = correctionFunction;
 			this.yOffset = yOffset;
-			setBorder( new EmptyBorder( 2, 0, 2, 0 ) );
+
+			updateFont();
+		}
+
+		@Override
+		public void updateUI() {
+			super.updateUI();
+			updateFont();
+		}
+
+		private void updateFont() {
+			if( scaleFactor == 0 )
+				return; // invoked from super constructor
 
 			if( !SystemInfo.isJava_9_orLater ) {
-				Font font = getFont();
+				Font font = UIManager.getFont( "defaultFont" );
 				setFont( font.deriveFont( (float) Math.round( font.getSize() * scaleFactor ) ) );
 			}
 		}
@@ -170,35 +280,36 @@ public class FlatPaintingStringTest
 		@Override
 		public Dimension getPreferredSize() {
 			Dimension size = super.getPreferredSize();
-			Insets insets = getInsets();
+			if( SystemInfo.isJava_9_orLater ) {
-			int leftRight = insets.left + insets.right;
+				// compute component size using JRE scaling
-			return new Dimension(
+				//
-				scale( size.width -leftRight ) + leftRight,
+				// The y offset is used to simulate different vertical component positions,
-				scale( size.height ) );
+				// which may result in different component heights.
+				// E.g. scaling following bounds by 150% results in different heights:
+				//   0,0, 10,15  -->  [x=0,y=0,width=15,height=22]
+				//   0,1, 10,15  -->  [x=0,y=1,width=15,height=23]
+				Rectangle r = scaleTo1x( scaleFactor, 0, yOffset, size.width, size.height );
+				return new Dimension( r.width, r.height );
+			} else
+				return size;
 		}
 
 		@Override
 		protected void paintComponent( Graphics g ) {
 			Graphics2D g2 = (Graphics2D) g;
-			Object[] oldRenderingHints = FlatUIUtils.setRenderingHints( g2 );
-
-			// simulate component y position at a fraction
-			if( scaleFactor > 1 && SystemInfo.isJava_9_orLater )
-				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.setColor( Color.blue );
-//					g.drawLine( 0, 0, width2, 0 );
+					g.drawLine( 0, 0, width2, 0 );
-//					g.drawLine( 0, height2 - 1, width2, height2 - 1 );
+					g.drawLine( 0, height2 - 1, width2, height2 - 1 );
 
-					int baseline = (int) Math.round( (insets.top + fm.getAscent()) * scaleFactor2
+					int baseline = (int) Math.round( fm.getAscent() * scaleFactor2
 						* (SystemInfo.isJava_9_orLater ? scaleFactor : 1f) ) - 1;
 					int topline = height2 - baseline - 1;
 
@@ -207,8 +318,15 @@ public class FlatPaintingStringTest
 					g.drawLine( 0, topline, width2, topline );
 				} );
 
-			// move x before scaling to have same left inset at all scale factors
+			// simulate different vertical component positions
-			g.translate( insets.left, 0 );
+			if( yOffset > 0 && SystemInfo.isJava_9_orLater ) {
+				double ty = yOffset * scaleFactor;
+				ty -= (int) ty;
+				if( ty == 0 )
+					return; // no need to paint
+
+				g2.translate( 0, ty );
+			}
 
 			// scale
 			if( SystemInfo.isJava_9_orLater )
@@ -232,21 +350,36 @@ public class FlatPaintingStringTest
 
 			// draw string
 			g.setColor( getForeground() );
-			int y = insets.top + fm.getAscent();
+			int y = 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) );
 		}
 
-			FlatUIUtils.resetRenderingHints( g2, oldRenderingHints );
+		/**
+		 * Scales a rectangle in the same way as the JRE does in
+		 * sun.java2d.pipe.PixelToParallelogramConverter.fillRectangle(),
+		 * which is used by Graphics.fillRect().
+		 *
+		 * This is a copy of HiDPIUtils.scale()
+		 */
+		public static Rectangle scaleTo1x( double scaleFactor, int x, int y, int width, int height ) {
+			double px = (x * scaleFactor);
+			double py = (y * scaleFactor);
+
+			double newX = normalize( px );
+			double newY = normalize( py );
+			double newWidth  = normalize( px + (width * scaleFactor) ) - newX;
+			double newHeight = normalize( py + (height * scaleFactor) ) - newY;
+
+			return new Rectangle( (int) Math.floor( newX ), (int) Math.floor( newY ), (int) newWidth, (int) newHeight );
 		}
 
-		private int scale( int value ) {
+		private static double normalize( double value ) {
-			return SystemInfo.isJava_9_orLater ? Math.round( value * scaleFactor ) : value;
+			return Math.floor( value + 0.25 ) + 0.25;
 		}
 	}
 }

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

@@ -1,4 +1,4 @@
-JFDML JFormDesigner: "7.0.2.0.298" Java: "14" encoding: "UTF-8"
+JFDML JFormDesigner: "7.0.5.0.404" Java: "17.0.2" encoding: "UTF-8"
 
 new FormModel {
 	contentType: "form/swing"
@@ -9,10 +9,45 @@ new FormModel {
 		add( new FormContainer( "javax.swing.JPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
 			"$layoutConstraints": "insets dialog,hidemode 3"
 			"$columnConstraints": "[fill]"
-			"$rowConstraints": "[top]"
+			"$rowConstraints": "[top]unrel[top]"
 		} ) {
 			name: "this"
 			"border": sfield com.jformdesigner.model.FormObject NULL_VALUE
+			add( new FormContainer( "javax.swing.JPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
+				"$layoutConstraints": "hidemode 3"
+				"$columnConstraints": "[fill][fill][fill]"
+				"$rowConstraints": "[]"
+			} ) {
+				name: "panel1"
+				add( new FormComponent( "javax.swing.JLabel" ) {
+					name: "fontLabel"
+					"text": "Font:"
+				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+					"value": "cell 0 0"
+				} )
+				add( new FormComponent( "javax.swing.JComboBox" ) {
+					name: "fontField"
+					"maximumRowCount": 20
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+						"JavaCodeGenerator.typeParameters": "String"
+					}
+					addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "fontChanged", false ) )
+				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+					"value": "cell 1 0"
+				} )
+				add( new FormComponent( "javax.swing.JLabel" ) {
+					name: "fontMetricsLabel"
+					"text": "text"
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+					}
+				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+					"value": "cell 2 0"
+				} )
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "north"
+			} )
 		}, new FormLayoutConstraints( null ) {
 			"location": new java.awt.Point( 0, 0 )
 			"size": new java.awt.Dimension( 450, 300 )