8217263: Automate DashOffset test

Reviewed-by: prr, serb

test/java/awt/BasicStroke/DashOffset.java

+/*
+ * Copyright (c) 2001, 2019, 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.BasicStroke;
+import java.awt.Color;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.GraphicsConfiguration;
+import java.awt.GraphicsEnvironment;
+import java.awt.Image;
+import java.awt.image.BufferedImage;
+import java.awt.image.VolatileImage;
+import java.io.File;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.stream.Collectors;
+import javax.imageio.ImageIO;
+
+import static java.awt.image.BufferedImage.TYPE_INT_RGB;
+
+/*
+ * @test
+ * @bug 4469881 8217263
+ * @summary Verifies that dashed rectangles drawn to the screen line
+ *          up with their undashed counterparts
+ * @author flar
+ * @run main/othervm -Dsun.java2d.uiScale=1 DashOffset
+ */
+public class DashOffset {
+
+    private static final BasicStroke dash =
+            new BasicStroke(1.0f, BasicStroke.CAP_BUTT,
+                            BasicStroke.JOIN_MITER, 10.0f,
+                            new float[] {2.0f, 2.0f}, 0.0f);
+
+    private static final Color COLOR1 = Color.BLUE;
+    private static final Color COLOR2 = Color.GREEN;
+
+    private static final Color BACKGROUND = Color.WHITE;
+
+    private static final int WIDTH = 20;
+    private static final int HEIGHT = 20;
+
+    private static final int OFFSET = 2;
+
+    private static final int MAX_DASH_LENGTH = 3;
+
+    public static void main(String[] argv) throws Exception {
+        final boolean saveImage = argv.length > 0 && "-save".equals(argv[0]);
+
+        final BufferedImage img = new BufferedImage(WIDTH, HEIGHT,
+                                                    TYPE_INT_RGB);
+        try {
+            draw(img);
+            validate(img);
+        } finally {
+            if (saveImage) {
+                save(img, "bufferedImage.png");
+            }
+        }
+
+        if (GraphicsEnvironment.isHeadless()) {
+            return;
+        }
+
+        BufferedImage snapshot = null;
+        try {
+            final GraphicsConfiguration gc =
+                    GraphicsEnvironment.getLocalGraphicsEnvironment()
+                                       .getDefaultScreenDevice()
+                                       .getDefaultConfiguration();
+
+            VolatileImage vi = gc.createCompatibleVolatileImage(WIDTH, HEIGHT);
+            int attempt = 0;
+            do {
+                vi.validate(gc);
+                draw(vi);
+                snapshot = vi.getSnapshot();
+            } while (vi.contentsLost() && ++attempt <= 10);
+            if (attempt > 10) {
+                throw new RuntimeException("Too many attempts: " + attempt);
+            }
+            validate(snapshot);
+        } finally {
+            if (saveImage) {
+                save(snapshot, "volatileImage.png");
+            }
+        }
+    }
+
+    private static void draw(final Image img) {
+        Graphics g = img.getGraphics();
+        g.setColor(BACKGROUND);
+        g.fillRect(0, 0, WIDTH, HEIGHT);
+        g.setColor(COLOR1);
+        g.drawRect(OFFSET, OFFSET, WIDTH - OFFSET * 2, HEIGHT - OFFSET * 2);
+        g.setColor(COLOR2);
+        g.clipRect(OFFSET, OFFSET, WIDTH - OFFSET * 2 + 1, HEIGHT - OFFSET * 2 + 1);
+        ((Graphics2D) g).setStroke(dash);
+        g.drawRect(OFFSET, OFFSET, WIDTH - OFFSET * 2, HEIGHT - OFFSET * 2);
+        g.dispose();
+    }
+
+    private static void validate(final BufferedImage img) {
+        checkHorizontalLine(img, OFFSET);
+        checkHorizontalLine(img, HEIGHT - OFFSET);
+        checkVerticalLine(img, OFFSET);
+        checkVerticalLine(img, WIDTH - OFFSET);
+        checkCorners(img);
+    }
+
+    private static void checkHorizontalLine(final BufferedImage img,
+                                            final int y) {
+        int prev = img.getRGB(OFFSET, y);
+        int curr;
+        int count = 1;
+        checkColor(OFFSET, y, prev, COLOR1, COLOR2);
+        for (int x = OFFSET + 1; x <= WIDTH - OFFSET; x++) {
+            curr = img.getRGB(x, y);
+            if (curr != prev) {
+                checkColor(x, y, curr, COLOR1, COLOR2);
+                checkCount(x, y, count);
+                prev = curr;
+                count = 1;
+            } else {
+                count++;
+            }
+            if (x < WIDTH - OFFSET) {
+                checkColor(x, y - 1, img.getRGB(x, y - 1), BACKGROUND);
+                checkColor(x, y + 1, img.getRGB(x, y + 1), BACKGROUND);
+            }
+        }
+        checkCount(WIDTH - OFFSET, y, count);
+    }
+
+    private static void checkVerticalLine(final BufferedImage img,
+                                          final int x) {
+        int prev = img.getRGB(x, OFFSET);
+        checkColor(x, OFFSET, prev, COLOR1, COLOR2);
+        int count = 1;
+        for (int y = OFFSET + 1; y <= HEIGHT - OFFSET; y++) {
+            int curr = img.getRGB(x, y);
+            if (curr != prev) {
+                checkColor(x, y, curr, COLOR1, COLOR2);
+                checkCount(x, y, count);
+                prev = curr;
+                count = 1;
+            } else {
+                count++;
+            }
+            if (y < HEIGHT - OFFSET) {
+                checkColor(x - 1, y, img.getRGB(x - 1, y), BACKGROUND);
+                checkColor(x + 1, y, img.getRGB(x + 1, y), BACKGROUND);
+            }
+        }
+        checkCount(x, HEIGHT - OFFSET, count);
+    }
+
+    private static void checkCorners(final BufferedImage img) {
+        int[][] corners = {
+                {OFFSET - 1, OFFSET - 1},
+                {OFFSET,     OFFSET - 1},
+                {OFFSET - 1, OFFSET + 1},
+
+                {OFFSET - 1, HEIGHT - OFFSET},
+                {OFFSET - 1, HEIGHT - OFFSET + 1},
+                {OFFSET,     HEIGHT - OFFSET + 1},
+
+                {WIDTH - OFFSET,     OFFSET - 1},
+                {WIDTH - OFFSET + 1, OFFSET - 1},
+                {WIDTH - OFFSET + 1, OFFSET},
+
+                {WIDTH - OFFSET + 1, HEIGHT - OFFSET},
+                {WIDTH - OFFSET + 1, HEIGHT - OFFSET + 1},
+                {WIDTH - OFFSET,     HEIGHT - OFFSET + 1},
+        };
+
+        for (int[] corner : corners) {
+            int color = img.getRGB(corner[0], corner[1]);
+            checkColor(corner[0], corner[1], color, BACKGROUND);
+        }
+    }
+
+    private static void checkColor(final int x, final int y,
+                                   final int color,
+                                   final Color... validColors) {
+        checkColor(x, y, color, Arrays.stream(validColors)
+                                      .mapToInt(Color::getRGB)
+                                      .toArray());
+    }
+
+    private static void checkColor(final int x, final int y,
+                                   final int color,
+                                   final int... validColors) {
+        for (int valid : validColors) {
+            if (color == valid) {
+                return;
+            }
+        }
+        throw new RuntimeException("Unexpected color at " + x + ", " + y
+                + ": " + Integer.toHexString(color) + "; expected: "
+                + Arrays.stream(validColors)
+                        .mapToObj(Integer::toHexString)
+                        .collect(Collectors.joining(", ")));
+    }
+
+    private static void checkCount(final int x, final int y, final int count) {
+        if (count > MAX_DASH_LENGTH) {
+            throw new RuntimeException("Dash is longer than " + MAX_DASH_LENGTH
+                    + " at " + x + ", " + y);
+        }
+    }
+
+    private static void save(final BufferedImage img,
+                             final String fileName) throws IOException {
+        ImageIO.write(img, "png", new File(fileName));
+    }
+
+}