8187759: Background not refreshed when painting over a transparent JF…

…rame

Reviewed-by: azvegint, abhiscxk, serb

src/java.desktop/share/classes/javax/swing/BufferStrategyPaintManager.java

@@ -243,6 +243,15 @@ public boolean paint(JComponent paintingComponent,
                 ((SunGraphics2D)bsg).constrain(xOffset + cx, yOffset + cy,
                                                x + w, y + h);
                 bsg.setClip(x, y, w, h);
+
+                if (!bufferComponent.isOpaque()) {
+                    final SunGraphics2D g2d = (SunGraphics2D) bsg;
+                    final Color oldBg = g2d.getBackground();
+                    g2d.setBackground(paintingComponent.getBackground());
+                    g2d.clearRect(x, y, w, h);
+                    g2d.setBackground(oldBg);
+                }
+
                 paintingComponent.paintToOffscreen(bsg, x, y, w, h,
                                                    x + w, y + h);
                 accumulate(xOffset + x, yOffset + y, w, h);

test/jdk/javax/swing/JFrame/JFrameBackgroundRefreshTest.java

@@ -0,0 +1,210 @@
+/*
+ * Copyright (c) 2023, 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.
+ */
+
+import java.awt.Color;
+import java.awt.Component;
+import java.awt.Font;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.MouseInfo;
+import java.awt.Point;
+import java.awt.Rectangle;
+import java.awt.Robot;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+import javax.imageio.ImageIO;
+import javax.swing.JFrame;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.SwingUtilities;
+
+/*
+ * @test
+ * @key headful
+ * @bug 8187759
+ * @summary Test to check if JFrame background is refreshed in Linux.
+ * @requires (os.family == "linux")
+ * @run main JFrameBackgroundRefreshTest
+ */
+
+public class JFrameBackgroundRefreshTest {
+    public static JFrame frame;
+    private static final BufferedImage test = generateImage();
+    private static Point p = new Point();
+    private static Robot robot;
+    private static JFrame whiteFrame;
+    private static Point frameLocation;
+    private static int frameCenterX, frameCenterY, awayX, awayY;
+    private static int imageCenterX, imageCenterY;
+
+    public static void main(String[] args) throws Exception {
+        try {
+            SwingUtilities.invokeAndWait(() -> {
+                try {
+                    JFrameBackgroundRefreshTest.initialize();
+                } catch (Exception e) {
+                    throw new RuntimeException(e);
+                }
+            });
+
+            SwingUtilities.invokeAndWait(() -> {
+                frameLocation = whiteFrame.getLocationOnScreen();
+                frameCenterX = frameLocation.x + whiteFrame.getWidth() / 2;
+                frameCenterY = frameLocation.y + whiteFrame.getHeight() / 2;
+                awayX = frameLocation.x + whiteFrame.getWidth() + 100;
+                awayY = frameLocation.y + whiteFrame.getHeight() / 2;
+                imageCenterX = p.x + test.getWidth() / 2;
+                imageCenterY = p.y + test.getHeight() / 2;
+            });
+            robot.delay(100);
+            robot.waitForIdle();
+            robot.mouseMove(imageCenterX, imageCenterY);
+            robot.delay(100);
+            robot.waitForIdle();
+            moveMouseSlowly(frameCenterX, frameCenterY);
+            robot.delay(1000);
+            robot.waitForIdle();
+
+            moveMouseSlowly(awayX, awayY);
+            robot.delay(100);
+            robot.waitForIdle();
+            Rectangle screenCaptureRect = new Rectangle(frameCenterX - 50,
+                    frameCenterY - 50, 100, 100);
+            BufferedImage bufferedImage = robot.createScreenCapture(screenCaptureRect);
+
+            if (!compareImages(bufferedImage)) {
+                try {
+                    ImageIO.write(bufferedImage, "png",
+                            new File("FailureImage.png"));
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+                throw new RuntimeException("Test Failed!");
+            }
+            System.out.println("Test Passed!");
+        } finally {
+            SwingUtilities.invokeAndWait(() -> {
+                if (frame != null) {
+                    frame.dispose();
+                }
+                if (whiteFrame != null) {
+                    whiteFrame.dispose();
+                }
+            });
+        }
+    }
+
+    private static void moveMouseSlowly( int targetX, int targetY) {
+        Point currentMousePos = MouseInfo.getPointerInfo().getLocation();
+        int currentX = currentMousePos.x;
+        int currentY = currentMousePos.y;
+        int deltaX = targetX - currentX;
+        int deltaY = targetY - currentY;
+        int steps = 50;
+        double stepX = (double) deltaX / steps;
+        double stepY = (double) deltaY / steps;
+        for (int i = 1; i <= steps; i++) {
+            int nextX = currentX + (int) Math.round(i * stepX);
+            int nextY = currentY + (int) Math.round(i * stepY);
+            robot.mouseMove(nextX, nextY);
+            robot.delay(10);
+        }
+        robot.mouseMove(targetX, targetY);
+    }
+
+    private static boolean compareImages(BufferedImage bufferedImage) {
+        int sampleRGB = bufferedImage.getRGB(0,0);
+        for (int x = 0; x < bufferedImage.getWidth(); x++) {
+            for (int y = 0; y < bufferedImage.getHeight(); y++) {
+                if (bufferedImage.getRGB(x, y) != sampleRGB) {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+
+    public static void initialize() throws Exception {
+        frame = new JFrame("JFrame Background refresh test");
+        whiteFrame = new JFrame("White Frame");
+        robot = new Robot();
+        whiteFrame.setSize(200, 200);
+        whiteFrame.setBackground(Color.WHITE);
+        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        frame.setUndecorated(true);
+        frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
+        frame.setBackground(new Color(0, 0, 0, 0));
+        frame.setContentPane(new TranslucentPane());
+        frame.addMouseMotionListener(new MouseDragListener());
+        whiteFrame.setLocationRelativeTo(null);
+        whiteFrame.setVisible(true);
+        frame.setVisible(true);
+        frame.setAlwaysOnTop(true);
+    }
+    private static class MouseDragListener extends MouseAdapter {
+        @Override
+        public void mouseMoved(MouseEvent e) {
+            p = e.getPoint();
+            frame.repaint();
+        }
+    }
+
+    /** Capture an image of any component **/
+    private static BufferedImage getImage(Component c) {
+        if (c == null) {
+            return null;
+        }
+        BufferedImage image = new BufferedImage(c.getWidth(),
+                c.getHeight(), BufferedImage.TYPE_INT_ARGB);
+        Graphics2D g = image.createGraphics();
+        c.printAll(g);
+        g.dispose();
+        return image;
+    }
+
+    /** Generates a dummy image to be painted on the frame **/
+    private static BufferedImage generateImage() {
+        JLabel label = new JLabel("test");
+        label.setFont(new Font("Arial", Font.BOLD, 24));
+        label.setSize(label.getPreferredSize());
+        return getImage(label);
+    }
+
+    public static class TranslucentPane extends JPanel {
+        public TranslucentPane() {
+            setOpaque(false);
+        }
+        @Override
+        protected void paintComponent(Graphics g) {
+            super.paintComponent(g);
+            Graphics2D g2d = (Graphics2D) g.create();
+            g2d.setColor(new Color(0,0,0,0));
+            g2d.fillRect(0, 0, getWidth(), getHeight());
+            g2d.drawImage(test, p.x, p.y, this);
+            g2d.dispose();
+        }
+    }
+}