8199441: Wrong caret position in multiline text components on Windows with a screen resolution higher than 100%

Reviewed-by: prr, jdv

src/java.desktop/share/classes/javax/swing/text/WrappedPlainView.java

@@ -364,8 +364,9 @@ public class WrappedPlainView extends BoxView implements TabExpander {
                                                 this, p0);
         } else {
             p = p0 + Utilities.getTabbedTextOffset(segment, metrics,
-                                                   tabBase, tabBase + currentWidth,
-                                                   this, p0, false);
+                                               (float)tabBase,
+                                               (float)(tabBase + currentWidth),
+                                               this, p0, false);
         }
         SegmentCache.releaseSharedSegment(segment);
         return p;
@@ -847,8 +848,8 @@ public class WrappedPlainView extends BoxView implements TabExpander {
                         Segment segment = SegmentCache.getSharedSegment();
                         loadText(segment, p0, p1);
                         int n = Utilities.getTabbedTextOffset(segment, metrics,
-                                                   alloc.x, x,
-                                                   WrappedPlainView.this, p0);
+                                                   (float)alloc.x, (float)x,
+                                                   WrappedPlainView.this, p0, false);
                         SegmentCache.releaseSharedSegment(segment);
                         return Math.min(p0 + n, p1 - 1);
                     }

test/jdk/javax/swing/text/Caret/TestCaretPosition.java

@@ -0,0 +1,125 @@
+/*
+ * Copyright (c) 2018, 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 8199441
+ * @key headful
+ * @summary  Verifies caret position in multiline line-wrapped text component
+ *           in hidpi mode should be in sync with mouse press position.
+ * @run main/othervm -Dsun.java2d.uiScale=1.5 TestCaretPosition
+ */
+
+import javax.swing.JTextArea;
+import javax.swing.JFrame;
+import javax.swing.JScrollPane;
+import javax.swing.SwingUtilities;
+import javax.swing.text.BadLocationException;
+import javax.swing.text.Caret;
+import java.awt.Font;
+import java.awt.BorderLayout;
+import java.awt.Point;
+import java.awt.Robot;
+import java.awt.event.InputEvent;
+import java.awt.event.MouseEvent;
+import java.awt.event.MouseListener;
+import java.awt.geom.Rectangle2D;
+
+public class TestCaretPosition {
+    private static JTextArea jTextArea1;
+    private static JFrame f;
+
+    private static void createUI() {
+        jTextArea1 = new JTextArea(5, 80);
+        f = new JFrame();
+        jTextArea1.setFont(new java.awt.Font("Arial", Font.PLAIN, 12));
+
+        fillTextArea(jTextArea1);
+        jTextArea1.setLineWrap(true);
+        jTextArea1.addMouseListener(new MouseListener() {
+            @Override
+            public void mouseClicked(MouseEvent e) {}
+
+            @Override
+            public void mousePressed(MouseEvent e) {
+                try {
+                    Caret caret = jTextArea1.getCaret();
+                    Rectangle2D rect = jTextArea1.modelToView2D(caret.getDot());
+
+                    if (Math.abs(e.getPoint().x - rect.getX()) > 5) {
+                        System.out.println("mouse point " + e.getPoint());
+                        System.out.println("caret position " + rect);
+                        throw new RuntimeException(" Wrong caret position");
+                    }
+                } catch (BadLocationException ex) {}
+            }
+
+            @Override
+            public void mouseReleased(MouseEvent e) {}
+
+            @Override
+            public void mouseEntered(MouseEvent e) {}
+
+            @Override
+            public void mouseExited(MouseEvent e) {}
+        });
+        f.add(new JScrollPane(jTextArea1), BorderLayout.CENTER);
+        f.pack();
+        f.setVisible(true);
+    }
+
+    public static void main(String args[]) throws Exception {
+        try {
+
+            SwingUtilities.invokeAndWait(() -> createUI());
+
+            Point p = jTextArea1.getLocationOnScreen();
+            Robot robot = new Robot();
+            robot.setAutoDelay(200);
+            robot.mouseMove(p.x+ 480, p.y+6);
+            robot.waitForIdle();
+            robot.mousePress(InputEvent.BUTTON1_DOWN_MASK);
+            robot.waitForIdle();
+            robot.mouseRelease(InputEvent.BUTTON1_DOWN_MASK);
+            robot.waitForIdle();
+        } finally {
+             SwingUtilities.invokeAndWait(() -> f.dispose());
+        }
+    }
+
+    private static void fillTextArea(JTextArea area) {
+        StringBuilder buf = new StringBuilder();
+
+        for (int i = 0; i < 3; i++) {
+            StringBuilder row = new StringBuilder();
+            for (int j = 0; j < 50; j++) {
+                row.append(j);
+                if (j % 5 == 0) {
+                    row.append(" ");
+                }
+            }
+            buf.append(row).append(System.lineSeparator());
+        }
+        area.setText(buf.toString());
+        area.setCaretPosition(0);
+    }
+}