7045593: Possible Regression : JTextfield cursor placement behavior algorithm has changed

Reviewed-by: peterz

jdk/src/share/classes/javax/swing/text/Utilities.java

@@ -337,8 +337,7 @@ public class Utilities {
             // x before x0, return.
             return 0;
         }
-        int currX = x0;
-        int nextX = currX;
+        int nextX = x0;
         // s may be a shared segment, so it is copied prior to calling
         // the tab expander
         char[] txt = s.array;
@@ -388,19 +387,45 @@ public class Utilities {
             } else {
                 nextX += metrics.charWidth(txt[i]);
             }
-            if ((x >= currX) && (x < nextX)) {
+            if (x < nextX) {
                 // found the hit position... return the appropriate side
-                int offset = ((round == false) || ((x - currX) < (nextX - x))) ?
-                        (i - txtOffset) : (i + 1 - txtOffset);
+                int offset;
+
                 // the length of the string measured as a whole may differ from
                 // the sum of individual character lengths, for example if
                 // fractional metrics are enabled; and we must guard from this.
-                while (offset > 0 && metrics.charsWidth(txt, txtOffset, offset) > (x - x0)) {
-                    offset--;
+                if (round) {
+                    offset = i + 1 - txtOffset;
+
+                    int width = metrics.charsWidth(txt, txtOffset, offset);
+                    int span = x - x0;
+
+                    if (span < width) {
+                        while (offset > 0) {
+                            int nextWidth = offset > 1 ? metrics.charsWidth(txt, txtOffset, offset - 1) : 0;
+
+                            if (span >= nextWidth) {
+                                if (span - nextWidth < width - span) {
+                                    offset--;
+                                }
+
+                                break;
+                            }
+
+                            width = nextWidth;
+                            offset--;
+                        }
+                    }
+                } else {
+                    offset = i - txtOffset;
+
+                    while (offset > 0 && metrics.charsWidth(txt, txtOffset, offset) > (x - x0)) {
+                        offset--;
+                    }
                 }
+
                 return offset;
             }
-            currX = nextX;
         }
 
         // didn't find, return end offset

jdk/test/javax/swing/text/Utilities/bug7045593.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2011, 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 7045593
+ * @summary Possible Regression : JTextfield cursor placement behavior algorithm has changed
+ * @author Pavel Porvatov
+ */
+
+import sun.awt.SunToolkit;
+
+import javax.swing.*;
+import javax.swing.text.BadLocationException;
+import java.awt.*;
+
+public class bug7045593 {
+    private static volatile JTextField jtf;
+
+    public static void main(String[] args) throws Exception {
+        SwingUtilities.invokeAndWait(new Runnable() {
+            public void run() {
+                jtf = new JTextField("WW");
+
+                JFrame frame = new JFrame();
+                frame.getContentPane().add(jtf);
+                frame.pack();
+                frame.setVisible(true);
+            }
+        });
+
+        ((SunToolkit) SunToolkit.getDefaultToolkit()).realSync();
+
+        SwingUtilities.invokeAndWait(new Runnable() {
+            public void run() {
+                try {
+                    Rectangle r = jtf.modelToView(1);
+
+                    int delta = 2;
+
+                    for (int x = r.x - delta; x < r.x + delta; x++) {
+                        assertEquals(jtf.viewToModel(new Point(x, r.y)), 1);
+                    }
+
+                    System.out.println("Passed.");
+                } catch (BadLocationException e) {
+                    throw new RuntimeException("Test failed", e);
+                }
+            }
+        });
+    }
+
+    private static void assertEquals(int i1, int i2) {
+        if (i1 != i2) {
+            throw new RuntimeException("Test failed, " + i1 + " != " + i2);
+        }
+    }
+}