8373946: Synth ProgressBarUI implementation confuses background painting with border painting

Reviewed-by: prr, kizune, azvegint

Author: prsadhuk

src/java.desktop/share/classes/javax/swing/plaf/synth/SynthProgressBarUI.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -216,11 +216,9 @@ public void update(Graphics g, JComponent c) {
 
         SynthLookAndFeel.update(context, g);
 
-        if (((JProgressBar) c).isBorderPainted()) {
-            context.getPainter().paintProgressBarBackground(context,
-                    g, 0, 0, c.getWidth(), c.getHeight(),
-                    progressBar.getOrientation());
-        }
+        context.getPainter().paintProgressBarBackground(context,
+                g, 0, 0, c.getWidth(), c.getHeight(),
+                progressBar.getOrientation());
         paint(context, g);
     }
 

test/jdk/javax/swing/JProgressBar/TestProgressBarBorder.java

@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8192888
+ * @key headful
+ * @summary Verifies ProgressBar in Synth L&F renders background
+ *          when border is not painted
+ * @run main TestNimbusProgressBarBorder
+ */
+
+import java.io.File;
+
+import java.awt.BorderLayout;
+import java.awt.Color;
+import java.awt.Graphics2D;
+import java.awt.GridBagLayout;
+import java.awt.image.BufferedImage;
+import java.awt.Rectangle;
+import java.awt.Robot;
+
+import javax.imageio.ImageIO;
+
+import javax.swing.JFrame;
+import javax.swing.JPanel;
+import javax.swing.JProgressBar;
+import javax.swing.UIManager;
+import javax.swing.SwingUtilities;
+
+public class TestNimbusProgressBarBorder {
+
+    private static JFrame frame;
+    private static JProgressBar progressBar;
+    private static boolean failure = true;
+    private static volatile Rectangle rect;
+
+    public static void main(String[] args) throws Exception {
+        int width = 200;
+        int height = 100;
+        try {
+            Robot robot = new Robot();
+            SwingUtilities.invokeAndWait(() -> {
+                try {
+                    // Set Nimbus L&F
+                    UIManager.setLookAndFeel("javax.swing.plaf.nimbus.NimbusLookAndFeel");
+                } catch (Exception e) {
+                    throw new RuntimeException(e);
+                }
+                frame = new JFrame("Nimbus JProgressBar Test");
+                frame.setSize(width, height);
+
+                // ProgressBar setup
+                progressBar = new JProgressBar(0, 100);
+                progressBar.setValue(0);
+                progressBar.setBorderPainted(false);
+
+                JPanel center = new JPanel(new GridBagLayout());
+                center.setBackground(Color.WHITE);
+                center.add(progressBar);
+
+                frame.add(center, BorderLayout.CENTER);
+                frame.setLocationRelativeTo(null);
+                frame.setVisible(true);
+            });
+            robot.waitForIdle();
+            robot.delay(1000);
+            SwingUtilities.invokeAndWait(() -> {
+                rect = progressBar.getBounds();
+            });
+
+            BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
+            Graphics2D g2d = (Graphics2D) img.getGraphics();
+            g2d.setColor(Color.WHITE);
+            g2d.fillRect(0, 0, rect.width, rect.height);
+            progressBar.paint(g2d);
+            g2d.dispose();
+
+            robot.waitForIdle();
+            robot.delay(100);
+
+            for (int x = 10; x < (10 + rect.width / 2); x++) {
+                for (int y = 10; y < (10 + rect.height / 2); y++) {
+                    Color col = new Color(img.getRGB(x, y));
+                    if (!col.equals(Color.WHITE)) {
+                        failure = false;
+                        break;
+                    }
+                }
+            }
+            if (failure) {
+                ImageIO.write(img, "png", new File("ProgressBarTest.png"));
+                throw new RuntimeException("ProgressBar background not drawn");
+            }
+        } finally {
+            SwingUtilities.invokeAndWait(() -> {
+                if (frame != null) {
+                    frame.dispose();
+                }
+            });
+        }
+    }
+}