8342098: Write a test to compare the images

Backport-of: 47ebf8d868b2e15b943a227ad3cf2ee12eed10f6

Author: GoeLin

test/jdk/java/awt/Robot/ScreenCaptureRobotTest.java

@@ -0,0 +1,166 @@
+/*
+ * Copyright (c) 2000, 2024, 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.BorderLayout;
+import java.awt.Canvas;
+import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.EventQueue;
+import java.awt.Font;
+import java.awt.Frame;
+import java.awt.Graphics;
+import java.awt.GraphicsEnvironment;
+import java.awt.Point;
+import java.awt.Rectangle;
+import java.awt.Robot;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+import javax.imageio.ImageIO;
+
+/*
+ * @test
+ * @key headful
+ * @bug 8342098
+ * @summary Verify that the image captured from the screen using a Robot
+ * and the source image are same.
+ * @run main/othervm -Dsun.java2d.uiScale=1 ScreenCaptureRobotTest
+ */
+public class ScreenCaptureRobotTest {
+
+    private static final int IMAGE_WIDTH = 200;
+    private static final int IMAGE_HEIGHT = 100;
+    private static final int OFFSET = 10;
+
+    private static Frame frame;
+    private static Canvas canvas;
+
+    private static BufferedImage realImage;
+
+    private static volatile Point point;
+
+    public static void main(String[] args) throws Exception {
+        try {
+            EventQueue.invokeAndWait(ScreenCaptureRobotTest::initializeGUI);
+            doTest();
+        } finally {
+            EventQueue.invokeAndWait(ScreenCaptureRobotTest::disposeFrame);
+        }
+    }
+
+    private static void initializeGUI() {
+        frame = new Frame("ScreenCaptureRobotTest Frame");
+        realImage = GraphicsEnvironment.getLocalGraphicsEnvironment()
+                .getDefaultScreenDevice()
+                .getDefaultConfiguration()
+                .createCompatibleImage(IMAGE_WIDTH, IMAGE_HEIGHT);
+
+        Graphics g = realImage.createGraphics();
+        g.setColor(Color.YELLOW);
+        g.fillRect(0, 0, IMAGE_WIDTH, IMAGE_HEIGHT);
+        g.setColor(Color.RED);
+        g.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 20));
+        g.drawString("Capture This", 10, 40);
+        g.dispose();
+
+        canvas = new ImageCanvas();
+        canvas.setBackground(Color.YELLOW);
+        canvas.setPreferredSize(new Dimension(IMAGE_WIDTH + (OFFSET * 2),
+                IMAGE_HEIGHT + (OFFSET * 2)));
+        frame.setLayout(new BorderLayout());
+        frame.add(canvas);
+        frame.pack();
+        frame.setLocationRelativeTo(null);
+        frame.setVisible(true);
+    }
+
+    private static void doTest() throws Exception {
+        Robot robot = new Robot();
+        robot.waitForIdle();
+        robot.delay(500);
+
+        EventQueue.invokeAndWait(() -> point = canvas.getLocationOnScreen());
+
+        Rectangle rect = new Rectangle(point.x + OFFSET, point.y + OFFSET,
+                IMAGE_WIDTH, IMAGE_HEIGHT);
+
+        BufferedImage capturedImage = robot.createScreenCapture(rect);
+
+        if (!compareImages(capturedImage, realImage)) {
+            String errorMessage = "FAIL : Captured Image is different from "
+                    + "the real image";
+            saveImage(capturedImage, "CapturedImage.png");
+            saveImage(realImage, "RealImage.png");
+            throw new RuntimeException(errorMessage);
+        }
+    }
+
+    private static boolean compareImages(BufferedImage capturedImg,
+            BufferedImage realImg) {
+        int capturedPixel;
+        int realPixel;
+        int imgWidth = capturedImg.getWidth();
+        int imgHeight = capturedImg.getHeight();
+
+        if (imgWidth != IMAGE_WIDTH || imgHeight != IMAGE_HEIGHT) {
+            System.out.println("Captured and real images are different in size");
+            return false;
+        }
+
+        for (int i = 0; i < imgWidth; i++) {
+            for (int j = 0; j < imgHeight; j++) {
+                capturedPixel = capturedImg.getRGB(i, j);
+                realPixel = realImg.getRGB(i, j);
+                if (capturedPixel != realPixel) {
+                    System.out.println("Captured pixel ("
+                            + Integer.toHexString(capturedPixel) + ") at "
+                            + "(" + i + ", " + j + ") is not equal to real pixel ("
+                            + Integer.toHexString(realPixel) + ")");
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+
+    private static class ImageCanvas extends Canvas {
+        @Override
+        public void paint(Graphics g) {
+            g.drawImage(realImage, OFFSET, OFFSET, this);
+        }
+    }
+
+    private static void saveImage(BufferedImage image, String fileName) {
+        try {
+            ImageIO.write(image, "png", new File(fileName));
+        } catch (IOException ignored) {
+            System.err.println(ignored.getMessage());
+        }
+    }
+
+    private static void disposeFrame() {
+        if (frame != null) {
+            frame.dispose();
+        }
+    }
+}