8024061: Exception thrown when drag and drop between two components is executed quickly

Reviewed-by: pchelko, serb
Contributed-by: alexey.ivanov@oracle.com

src/share/classes/sun/awt/dnd/SunDropTargetContextPeer.java

@@ -239,6 +239,13 @@ public abstract class SunDropTargetContextPeer implements DropTargetContextPeer,
 
         if (localTransferable != null) {
             return localTransferable.getTransferData(df);
+        } else if (df.isMimeTypeEqual(DataFlavor.javaJVMLocalObjectMimeType)) {
+            // Workaround to JDK-8024061: Exception thrown when drag and drop
+            //      between two components is executed quickly.
+            // It is expected localTransferable is not null if javaJVMLocalObjectMimeType
+            // is used. Executing further results in ClassCastException, so null is
+            // returned here as no transfer data is available in this case.
+            return null;
         }
 
         if (dropStatus != STATUS_ACCEPT || dropComplete) {

test/sun/awt/dnd/8024061/bug8024061.java

+/*
+ * Copyright (c) 2014, 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 8024061
+ * @summary Checks that no exception is thrown if dragGestureRecognized
+ *          takes a while to complete.
+ */
+import sun.awt.OSInfo;
+import sun.awt.OSInfo.OSType;
+import sun.awt.SunToolkit;
+
+import java.awt.*;
+import java.awt.datatransfer.DataFlavor;
+import java.awt.datatransfer.Transferable;
+import java.awt.datatransfer.UnsupportedFlavorException;
+import java.awt.dnd.DnDConstants;
+import java.awt.dnd.DragGestureEvent;
+import java.awt.dnd.DragGestureListener;
+import java.awt.dnd.DragSource;
+import java.awt.dnd.DragSourceDragEvent;
+import java.awt.dnd.DragSourceDropEvent;
+import java.awt.dnd.DragSourceEvent;
+import java.awt.dnd.DragSourceListener;
+import java.awt.dnd.DropTarget;
+import java.awt.dnd.DropTargetDragEvent;
+import java.awt.dnd.DropTargetDropEvent;
+import java.awt.dnd.DropTargetEvent;
+import java.awt.dnd.DropTargetListener;
+import java.awt.event.InputEvent;
+
+import java.io.IOException;
+import java.lang.reflect.InvocationTargetException;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import javax.swing.*;
+
+/**
+ * If dragGestureRecognized() takes a while to complete and if user performs a drag quickly,
+ * an exception is thrown from DropTargetListener.dragEnter when it calls
+ * DropTargetDragEvent.getTransferable().
+ * <p>
+ * This class introduces a delay in dragGestureRecognized() to cause the exception.
+ */
+public class bug8024061 {
+    private static final DataFlavor DropObjectFlavor;
+    private static final int DELAY = 1000;
+
+    private final DnDPanel panel1 = new DnDPanel(Color.yellow);
+    private final DnDPanel panel2 = new DnDPanel(Color.pink);
+    private final JFrame frame;
+
+    private static final CountDownLatch lock = new CountDownLatch(1);
+    private static volatile Exception dragEnterException = null;
+
+    static {
+        DataFlavor flavor = null;
+        try {
+            flavor = new DataFlavor(DataFlavor.javaJVMLocalObjectMimeType);
+        } catch (ClassNotFoundException e) {
+            e.printStackTrace();
+        }
+        DropObjectFlavor = flavor;
+    }
+
+    bug8024061() {
+        frame = new JFrame("DnDWithRobot");
+        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
+
+        Dimension d = new Dimension(100, 100);
+
+        panel1.setPreferredSize(d);
+        panel2.setPreferredSize(d);
+
+        Container content = frame.getContentPane();
+        content.setLayout(new GridLayout(1, 2, 5, 5));
+        content.add(panel1);
+        content.add(panel2);
+
+        frame.pack();
+
+        DropObject drop = new DropObject();
+        drop.place(panel1, new Point(10, 10));
+        frame.setVisible(true);
+    }
+
+    public static void main(String[] args) throws AWTException, InvocationTargetException, InterruptedException {
+        OSType type = OSInfo.getOSType();
+        if (type != OSType.LINUX && type != OSType.SOLARIS) {
+            System.out.println("This test is for Linux and Solaris only... " +
+                               "skipping!");
+            return;
+        }
+
+        final bug8024061[] dnd = {null};
+        SwingUtilities.invokeAndWait(new Runnable() {
+            @Override
+            public void run() {
+                dnd[0] = new bug8024061();
+            }
+        });
+        final Robot robot = new Robot();
+        robot.setAutoDelay(10);
+        SunToolkit toolkit = (SunToolkit) Toolkit.getDefaultToolkit();
+        toolkit.realSync();
+
+        JFrame frame = dnd[0].frame;
+        Point point = frame.getLocationOnScreen();
+        Point here = new Point(point.x + 35, point.y + 45);
+        Point there = new Point(point.x + 120, point.y + 45);
+        here.x += 25;
+        robot.mouseMove(here.x, here.y);
+        robot.mousePress(InputEvent.BUTTON1_MASK);
+        while (here.x < there.x) {
+            here.x += 20;
+            robot.mouseMove(here.x, here.y);
+            System.out.println("x = " + here.x);
+        }
+        robot.mouseRelease(InputEvent.BUTTON1_MASK);
+        toolkit.realSync();
+        robot.mousePress(InputEvent.BUTTON1_MASK);
+        robot.mouseRelease(InputEvent.BUTTON1_MASK);
+        System.out.println("finished");
+
+        try {
+            if (lock.await(5, TimeUnit.SECONDS)) {
+                if (dragEnterException == null) {
+                    System.out.println("Test passed.");
+                } else {
+                    System.out.println("Test failed.");
+                    dragEnterException.printStackTrace();
+                    throw new RuntimeException(dragEnterException);
+                }
+            } else {
+                System.out.println("Test failed. Timeout reached");
+                throw new RuntimeException("Timed out waiting for dragEnter()");
+            }
+        } finally {
+            frame.dispose();
+        }
+    }
+
+    class DropObject implements Transferable {
+        DnDPanel panel;
+        Color color = Color.CYAN;
+        int width = 50;
+        int height = 50;
+        int x;
+        int y;
+
+        void draw(Graphics2D g) {
+            Color savedColor = g.getColor();
+            g.setColor(color);
+            g.fillRect(x, y, width, height);
+            g.setColor(Color.lightGray);
+            g.drawRect(x, y, width, height);
+            g.setColor(savedColor);
+        }
+
+        boolean contains(int x, int y) {
+            return (x > this.x && x < this.x + width)
+                    && (y > this.y && y < this.y + height);
+        }
+
+        @Override
+        public DataFlavor[] getTransferDataFlavors() {
+            return new DataFlavor[]{DropObjectFlavor};
+        }
+
+        void place(DnDPanel panel, Point location) {
+            if (panel != this.panel) {
+                x = location.x;
+                y = location.y;
+                if (this.panel != null) {
+                    this.panel.setDropObject(null);
+                    this.panel.repaint();
+                }
+                this.panel = panel;
+                this.panel.setDropObject(this);
+                this.panel.repaint();
+            }
+        }
+
+        @Override
+        public boolean isDataFlavorSupported(DataFlavor flavor) {
+            return DropObjectFlavor.equals(flavor);
+        }
+
+        @Override
+        public Object getTransferData(DataFlavor flavor)
+                throws UnsupportedFlavorException, IOException {
+            if (isDataFlavorSupported(flavor)) {
+                return this;
+            } else {
+                throw new UnsupportedFlavorException(flavor);
+            }
+        }
+    }
+
+    class DnDPanel extends JPanel {
+        DropObject dropObject;
+        final DragSource dragSource;
+        final DropTarget dropTarget;
+        final Color color;
+        final DragGestureListener dgListener;
+        final DragSourceListener dsListener;
+        final DropTargetListener dtListener;
+
+        DnDPanel(Color color) {
+            this.color = color;
+            this.dragSource = DragSource.getDefaultDragSource();
+            dgListener = new DragGestureListener() {
+                @Override
+                public void dragGestureRecognized(DragGestureEvent dge) {
+                    Point location = dge.getDragOrigin();
+                    if (dropObject != null && dropObject.contains(location.x, location.y)) {
+                        dragSource.startDrag(dge, DragSource.DefaultCopyNoDrop, dropObject, dsListener);
+                        try {
+                            Thread.sleep(DELAY);
+                        } catch (InterruptedException e) {
+                        }
+                    }
+                }
+            };
+
+            dsListener = new DragSourceListener() {
+                @Override
+                public void dragEnter(DragSourceDragEvent dsde) {
+                }
+
+                @Override
+                public void dragOver(DragSourceDragEvent dsde) {
+                }
+
+                @Override
+                public void dropActionChanged(DragSourceDragEvent dsde) {
+                }
+
+                @Override
+                public void dragExit(DragSourceEvent dse) {
+                }
+
+                @Override
+                public void dragDropEnd(DragSourceDropEvent dsde) {
+                }
+            };
+
+            dtListener = new DropTargetListener() {
+                @Override
+                public void dragEnter(DropTargetDragEvent dtde) {
+                    if (dropObject != null) {
+                        dtde.rejectDrag();
+                        return;
+                    }
+                    dtde.acceptDrag(DnDConstants.ACTION_MOVE);
+                    try {
+                        Transferable t = dtde.getTransferable();
+                        Object data = t.getTransferData(DropObjectFlavor);
+                        if (data != null) {
+                            throw new Exception("getTransferData returned non-null");
+                        }
+                    } catch (Exception e) {
+                        dragEnterException = e;
+                        e.printStackTrace();
+                    } finally {
+                        lock.countDown();
+                    }
+                }
+
+                @Override
+                public void dragOver(DropTargetDragEvent dtde) {
+                    if (dropObject != null) {
+                        dtde.rejectDrag();
+                        return;
+                    }
+                    dtde.acceptDrag(DnDConstants.ACTION_MOVE);
+                }
+
+                @Override
+                public void dropActionChanged(DropTargetDragEvent dtde) {
+                }
+
+                @Override
+                public void dragExit(DropTargetEvent dte) {
+                }
+
+                @Override
+                public void drop(DropTargetDropEvent dtde) {
+                    if (dropObject != null) {
+                        dtde.rejectDrop();
+                        return;
+                    }
+                    try {
+                        dtde.acceptDrop(DnDConstants.ACTION_MOVE);
+                        Transferable t = dtde.getTransferable();
+                        DropObject dropObject = (DropObject) t.getTransferData(DropObjectFlavor);
+                        Point location = dtde.getLocation();
+                        dropObject.place(DnDPanel.this, location);
+                        dtde.dropComplete(true);
+                    } catch (Exception e) {
+                        e.printStackTrace();
+                    }
+
+                }
+            };
+
+            dragSource.createDefaultDragGestureRecognizer(this,
+                    DnDConstants.ACTION_MOVE, dgListener);
+
+            dropTarget = new DropTarget(this, DnDConstants.ACTION_MOVE, dtListener, true);
+
+        }
+
+        public void paintComponent(Graphics g) {
+            super.paintComponent(g);
+            Color savedColor = g.getColor();
+            g.setColor(color);
+            g.fillRect(0, 0, getWidth(), getHeight());
+            g.setColor(savedColor);
+            if (dropObject != null) {
+                dropObject.draw((Graphics2D) g);
+            }
+        }
+
+        void setDropObject(DropObject dropObject) {
+            this.dropObject = dropObject;
+        }
+
+        DropObject findDropObject(int x, int y) {
+            if (dropObject != null && dropObject.contains(x, y)) {
+                return dropObject;
+            }
+            return null;
+        }
+    }
+}