8280020: Underline and line-through not straight in WebView

Backport-of: 263db3d

modules/javafx.web/src/main/native/Source/WebCore/platform/graphics/java/GraphicsContextJava.cpp

@@ -343,18 +343,21 @@ void GraphicsContextJava::drawLinesForText(const FloatPoint& origin, float thick
     if (paintingDisabled())
         return;
 
-    for (const auto& width : widths) {
-        // This is a workaround for http://bugs.webkit.org/show_bug.cgi?id=15659
-        StrokeStyle savedStrokeStyle = strokeStyle();
-        setStrokeStyle(stroke);
+    // This is a workaround for http://bugs.webkit.org/show_bug.cgi?id=15659
+    StrokeStyle savedStrokeStyle = strokeStyle();
+    setStrokeStyle(stroke);
+    float savedStrokeThickness = strokeThickness();
+    setStrokeThickness(thickness);
 
-        FloatPoint endPoint = origin + FloatPoint(width, thickness);
-        drawLine(
-            IntPoint(origin.x(), origin.y()),
-            IntPoint(endPoint.x(), endPoint.y()));
+    FloatPoint startPoint = origin + FloatPoint(0, thickness / 2);
+    FloatPoint endPoint = startPoint + FloatPoint(widths.last(), 0);
+    drawLine(
+        IntPoint(startPoint.x(), startPoint.y()),
+        IntPoint(endPoint.x(), endPoint.y()));
+
+    setStrokeStyle(savedStrokeStyle);
+    setStrokeThickness(savedStrokeThickness);
 
-        setStrokeStyle(savedStrokeStyle);
-    }
 }
 
 void GraphicsContextJava::drawLineForText(const FloatRect& rect, bool printing, bool doubleLines, StrokeStyle stroke)

tests/system/src/test/java/test/javafx/scene/web/StraightLineTest.java

@@ -0,0 +1,177 @@
+/*
+ * Copyright (c) 2022, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+
+package test.javafx.scene.web;
+
+import com.sun.webkit.WebPage;
+import com.sun.webkit.WebPageShim;
+import javafx.application.Application;
+import javafx.application.Platform;
+import javafx.scene.Scene;
+import javafx.scene.image.PixelReader;
+import javafx.scene.image.WritableImage;
+import javafx.scene.paint.Color;
+import javafx.scene.web.WebEngineShim;
+import javafx.scene.web.WebView;
+import javafx.stage.Stage;
+import java.io.*;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import test.util.Util;
+
+import java.util.concurrent.CountDownLatch;
+import static org.junit.Assert.assertEquals;
+
+import static javafx.concurrent.Worker.State.SUCCEEDED;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+public class StraightLineTest {
+    private static final CountDownLatch launchLatch = new CountDownLatch(1);
+    private static final int LINE_THICKNESS = 20;
+    private static final int SKIP_TEXT_BOUNDARY = 32;
+    private static final int DELTA = 3;
+
+    // Maintain one application instance
+    static StraightLineTestApp straightLineTestApp;
+
+    private WebView webView;
+
+    public static class StraightLineTestApp extends Application {
+        Stage primaryStage = null;
+
+        @Override
+        public void init() {
+            StraightLineTest.straightLineTestApp = this;
+        }
+
+        @Override
+        public void start(Stage primaryStage) throws Exception {
+            Platform.setImplicitExit(false);
+            this.primaryStage = primaryStage;
+            launchLatch.countDown();
+        }
+    }
+
+    private static String colorToString(Color c) {
+        int r = (int)(c.getRed() * 255.0);
+        int g = (int)(c.getGreen() * 255.0);
+        int b = (int)(c.getBlue() * 255.0);
+        int a = (int)(c.getOpacity() * 255.0);
+        return "rgba(" + r + "," + g + "," + b + "," + a + ")";
+    }
+
+    @BeforeClass
+    public static void setupOnce() {
+        // Start the Test Application
+        new Thread(() -> Application.launch(StraightLineTestApp.class, (String[])null)).start();
+
+        assertTrue("Timeout waiting for FX runtime to start", Util.await(launchLatch));
+    }
+
+    @AfterClass
+    public static void tearDownOnce() {
+        Platform.exit();
+    }
+
+    @Before
+    public void setupTestObjects() {
+        Platform.runLater(() -> {
+            webView = new WebView();
+            Scene scene = new Scene(webView, 150, 100);
+            straightLineTestApp.primaryStage.setScene(scene);
+            straightLineTestApp.primaryStage.show();
+        });
+    }
+
+    @Test public void testLine() {
+        final CountDownLatch webViewStateLatch = new CountDownLatch(1);
+
+        Util.runAndWait(() -> {
+            assertNotNull(webView);
+
+            webView.getEngine().getLoadWorker().stateProperty().
+                addListener((observable, oldValue, newValue) -> {
+                if (newValue == SUCCEEDED) {
+                    webView.requestFocus();
+                }
+            });
+
+            webView.focusedProperty().
+                addListener((observable, oldValue, newValue) -> {
+                if (newValue) {
+                    webViewStateLatch.countDown();
+                }
+            });
+
+            webView.getEngine().loadContent("<!DOCTYPE html>\n" +
+                    "<html>\n" +
+                    "<head>\n" +
+                    "<style>\n" +
+                    "body {\n" +
+                    "margin:0px;\n"+
+                    "}\n" +
+                    "div {\n" +
+                    "padding:0px;\n"+
+                    "width:150px;\n"+
+                    "height:20px;\n"+
+                    "margin:0px;\n"+
+                    "text-decoration: underline;\n" +
+                    "text-decoration-thickness: 20px;\n" +
+                    "font-size: 16px; \n" +
+                    "}\n" +
+                    "</style>\n" +
+                    "</head>\n" +
+                    "<body>\n" +
+                    "<div>TEST UNDERLINE</div>\n" +
+                    "</body>\n" +
+                    "</html>");
+        });
+
+        assertTrue("Timeout when waiting for focus change ", Util.await(webViewStateLatch));
+
+        Util.runAndWait(() -> {
+            WritableImage snapshot = straightLineTestApp.primaryStage.getScene().snapshot(null);
+            PixelReader pr = snapshot.getPixelReader();
+            int start_x = (int)webView.getEngine().executeScript("document.getElementsByTagName('div')[0].getBoundingClientRect().x");
+            int start_y = (int)webView.getEngine().executeScript("document.getElementsByTagName('div')[0].getBoundingClientRect().y");
+            int width = (int)webView.getEngine().executeScript("document.getElementsByTagName('div')[0].getBoundingClientRect().width");
+            int height = (int)webView.getEngine().executeScript("document.getElementsByTagName('div')[0].getBoundingClientRect().height");
+
+            int line_start_x = start_x + DELTA;
+            int line_end_x = start_x + width - SKIP_TEXT_BOUNDARY;
+            int line_start_y = start_y + height + LINE_THICKNESS/2;
+            String line_color = "rgba(0,0,0,255)"; // color of line
+
+            for (int x = line_start_x; x < line_end_x; x++) {
+                String color = colorToString(pr.getColor(x, line_start_y));
+                assertEquals(line_color, color);
+            }
+        });
+    }
+}