7175397: The divider color is not changed to green when dragging for Nimbus LaF.

Reviewed-by: jdv

src/java.desktop/share/classes/javax/swing/plaf/synth/SynthSplitPaneUI.java

@@ -65,6 +65,8 @@ public class SynthSplitPaneUI extends BasicSplitPaneUI
      */
     private SynthStyle dividerStyle;
 
+    private Color dividerDraggingColor;
+
     /**
      *
      * Constructs a {@code SynthSplitPaneUI}.
@@ -89,6 +91,8 @@ public class SynthSplitPaneUI extends BasicSplitPaneUI
     protected void installDefaults() {
         updateStyle(splitPane);
 
+        dividerDraggingColor = UIManager.getColor("SplitPaneDivider.draggingColor");
+
         setOrientation(splitPane.getOrientation());
         setContinuousLayout(splitPane.isContinuousLayout());
 
@@ -256,6 +260,19 @@ public class SynthSplitPaneUI extends BasicSplitPaneUI
         return divider;
     }
 
+    private void setDividerDraggingColor(Graphics g, int loc) {
+        if (!isContinuousLayout() && getLastDragLocation() != -1 &&
+               dividerDraggingColor != null) {
+
+            g.setColor(dividerDraggingColor);
+            if (getOrientation() == JSplitPane.HORIZONTAL_SPLIT) {
+                g.fillRect(loc, 0, dividerSize - 1, splitPane.getHeight() - 1);
+            } else {
+                g.fillRect(0, loc, splitPane.getWidth() - 1, dividerSize - 1);
+            }
+        }
+    }
+
     /**
      * {@inheritDoc}
      */
@@ -265,6 +282,7 @@ public class SynthSplitPaneUI extends BasicSplitPaneUI
         return new Canvas() {
             public void paint(Graphics g) {
                 paintDragDivider(g, 0, 0, getWidth(), getHeight());
+                setDividerDraggingColor(g, 0);
             }
         };
     }
@@ -345,8 +363,10 @@ public class SynthSplitPaneUI extends BasicSplitPaneUI
      */
     @Override
     public void finishedPaintingChildren(JSplitPane jc, Graphics g) {
+
         if(jc == splitPane && getLastDragLocation() != -1 &&
                               !isContinuousLayout() && !draggingHW) {
+
             if(jc.getOrientation() == JSplitPane.HORIZONTAL_SPLIT) {
                 paintDragDivider(g, getLastDragLocation(), 0, dividerSize - 1,
                                  splitPane.getHeight() - 1);
@@ -354,6 +374,7 @@ public class SynthSplitPaneUI extends BasicSplitPaneUI
                 paintDragDivider(g, 0, getLastDragLocation(),
                                  splitPane.getWidth() - 1, dividerSize - 1);
             }
+            setDividerDraggingColor(g, getLastDragLocation());
         }
     }
 }

test/jdk/javax/swing/plaf/nimbus/TestNimbusDividerDragColor.java

@@ -0,0 +1,95 @@
+/*
+ * 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.
+ *
+ * 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 4820080
+   @summary RFE: Cannot Change the JSplitPane Divider Color while dragging
+   @key headful
+   @library /java/awt/regtesthelpers
+   @build PassFailJFrame
+   @run main/manual TestNimbusDividerDragColor
+*/
+
+import java.awt.Color;
+import java.awt.Panel;
+import javax.swing.Box;
+import javax.swing.BoxLayout;
+import javax.swing.JFrame;
+import javax.swing.JPanel;
+import javax.swing.JSeparator;
+import javax.swing.JSplitPane;
+import javax.swing.SwingUtilities;
+import javax.swing.UIManager;
+
+public class TestNimbusDividerDragColor {
+
+    private static JFrame frame;
+
+    private static final String INSTRUCTIONS =
+        "Drag the dividers of the splitpanes (both top and bottom).\n " +
+        " If the divider color is green while dragging\n " +
+        " then test passes, otherwise test fails";
+
+    public static void init() {
+        UIManager.put("SplitPaneDivider.draggingColor", Color.green);
+
+        frame = new JFrame();
+        Box box = new Box(BoxLayout.Y_AXIS);
+        frame.getContentPane().add(box);
+
+        JPanel jleft = new JPanel();
+        jleft.setBackground(Color.darkGray);
+        JPanel jright = new JPanel();
+        jright.setBackground(Color.darkGray);
+        JSplitPane jsp = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, jleft, jright);
+        jsp.setContinuousLayout(false);
+        box.add(jsp);
+
+        box.add(Box.createVerticalStrut(5));
+        box.add(new JSeparator());
+        box.add(Box.createVerticalStrut(5));
+
+        Panel left = new Panel();
+        left.setBackground(Color.darkGray);
+        Panel right = new Panel();
+        right.setBackground(Color.darkGray);
+        JSplitPane sp = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, left, right);
+        sp.setContinuousLayout(false);
+        box.add(sp);
+        frame.add(box);
+        frame.setSize(200, 200);
+        frame.setVisible(true);
+    }
+
+
+    public static void main(String[] argv) throws Exception {
+        UIManager.setLookAndFeel("javax.swing.plaf.nimbus.NimbusLookAndFeel");
+        PassFailJFrame passFailJFrame = new PassFailJFrame(
+                "JFileChooser Test Instructions", INSTRUCTIONS, 5);
+        SwingUtilities.invokeAndWait(() -> init());
+        PassFailJFrame.addTestWindow(frame);
+        PassFailJFrame.positionTestWindow(
+                frame, PassFailJFrame.Position.HORIZONTAL);
+        passFailJFrame.awaitAndCheck();
+    }
+}