1 files changed, 103 insertions, 21 deletions

diff --git a/java/awt/dnd/DropTarget.java b/java/awt/dnd/DropTarget.java
index 1e7b2c4cd..63be5ac04 100644
--- a/java/awt/dnd/DropTarget.java
+++ b/java/awt/dnd/DropTarget.java
@@ -38,12 +38,12 @@ exception statement from your version. */
 
 package java.awt.dnd;
 
-import gnu.classpath.NotImplementedException;
-
 import java.awt.Component;
 import java.awt.GraphicsEnvironment;
 import java.awt.HeadlessException;
+import java.awt.Insets;
 import java.awt.Point;
+import java.awt.Rectangle;
 import java.awt.datatransfer.FlavorMap;
 import java.awt.datatransfer.SystemFlavorMap;
 import java.awt.dnd.peer.DropTargetPeer;
@@ -55,6 +55,8 @@ import java.io.Serializable;
 import java.util.EventListener;
 import java.util.TooManyListenersException;
 
+import javax.swing.Timer;
+
 /**
  * @author Michael Koch
  * @since 1.2
@@ -70,30 +72,87 @@ public class DropTarget
   protected static class DropTargetAutoScroller
     implements ActionListener
   {
+    /**
+     * The threshold that keeps the autoscroller running.
+     */
+    private static final int HYSTERESIS = 10;
+
+    /**
+     * The initial timer delay.
+     */
+    private static final int DELAY = 100;
+
     private Component component;
     private Point point;
-    
+
+    /**
+     * The timer that triggers autoscrolling.
+     */
+    private Timer timer;
+
+    /**
+     * The outer region of the scroller. This is the component's size.
+     */
+    private Rectangle outer;
+
+    /**
+     * The inner region of the scroller. This is the component size without
+     * the autoscroll insets.
+     */
+    private Rectangle inner;
+
     protected DropTargetAutoScroller (Component c, Point p)
     {
       component = c;
       point = p;
+      timer = new Timer(DELAY, this);
+      timer.setCoalesce(true);
+      timer.start();
     }
 
     protected void updateLocation (Point newLocn)
     {
+      Point previous = point;
       point = newLocn;
+      if (Math.abs(point.x - previous.x) > HYSTERESIS
+          || Math.abs(point.y - previous.y) > HYSTERESIS)
+        {
+          if (timer.isRunning())
+            timer.stop();
+        }
+      else
+        {
+          if (! timer.isRunning())
+            timer.start();
+        }
     }
 
     protected void stop ()
-      throws NotImplementedException
     {
-      // FIXME: implement this
+      timer.start();
     }
 
     public void actionPerformed (ActionEvent e)
-      throws NotImplementedException
     {
-      // FIXME: implement this
+      Autoscroll autoScroll = (Autoscroll) component;
+
+      // First synchronize the inner and outer rectangles.
+      Insets i = autoScroll.getAutoscrollInsets();
+      int width = component.getWidth();
+      int height = component.getHeight();
+      if (width != outer.width || height != outer.height)
+        outer.setBounds(0, 0, width, height);
+      if (inner.x != i.left || inner.y != i.top)
+        inner.setLocation(i.left, i.top);
+      int inWidth = width - i.left - i.right;
+      int inHeight = height - i.top - i.bottom;
+      if (inWidth != inner.width || inHeight != inner.height)
+        inner.setSize(inWidth, inHeight);
+
+      // Scroll if the outer rectangle contains the location, but the
+      // inner doesn't.
+      if (outer.contains(point) && ! inner.contains(point))
+        autoScroll.autoscroll(point);
     }
   }
 
@@ -182,6 +241,8 @@ public class DropTarget
    */
   public void setComponent (Component c)
   {
+    if (component != null)
+      clearAutoscroll();
     component = c;
   }
 
@@ -212,6 +273,8 @@ public class DropTarget
   public void setActive (boolean active)
   {
     this.active = active;
+    if (! active)
+      clearAutoscroll();
   }
 
   public boolean isActive()
@@ -250,30 +313,47 @@ public class DropTarget
 
   public void dragEnter(DropTargetDragEvent dtde)
   {
-    if (dropTargetListener != null)
-      dropTargetListener.dragEnter(dtde);
+    if (active)
+      {
+        if (dropTargetListener != null)
+          dropTargetListener.dragEnter(dtde);
+        initializeAutoscrolling(dtde.getLocation());
+      }
   }
 
   public void dragOver(DropTargetDragEvent dtde)
   {
-    if (dropTargetListener != null)
-      dropTargetListener.dragOver(dtde);
+    if (active)
+      {
+        if (dropTargetListener != null)
+          dropTargetListener.dragOver(dtde);
+        updateAutoscroll(dtde.getLocation());
+      }
   }
 
   public void dropActionChanged(DropTargetDragEvent dtde)
   {
-    if (dropTargetListener != null)
-      dropTargetListener.dropActionChanged(dtde);
+    if (active)
+      {
+        if (dropTargetListener != null)
+          dropTargetListener.dropActionChanged(dtde);
+        updateAutoscroll(dtde.getLocation());
+      }
   }
 
   public void dragExit(DropTargetEvent dte)
   {
-    if (dropTargetListener != null)
-      dropTargetListener.dragExit(dte);
+    if (active)
+      {
+        if (dropTargetListener != null)
+          dropTargetListener.dragExit(dte);
+        clearAutoscroll();
+      }
   }
 
   public void drop(DropTargetDropEvent dtde)
   {
+    clearAutoscroll();
     if (dropTargetListener != null)
       dropTargetListener.drop(dtde);
   }
@@ -332,15 +412,13 @@ public class DropTarget
   protected DropTarget.DropTargetAutoScroller createDropTargetAutoScroller
                                                        (Component c, Point p)
   {
-    if (autoscroller == null)
-      autoscroller = new DropTarget.DropTargetAutoScroller (c, p);
-    
-    return autoscroller;
+    return new DropTarget.DropTargetAutoScroller (c, p);
   }
 
   protected void initializeAutoscrolling(Point p)
   {
-    createDropTargetAutoScroller (component, p);
+    if (component instanceof Autoscroll) // Checks for null too.
+      autoscroller = createDropTargetAutoScroller (component, p);
   }
 
   protected void updateAutoscroll(Point dragCursorLocn)
@@ -351,6 +429,10 @@ public class DropTarget
 
   protected void clearAutoscroll()
   {
-    autoscroller = null;
+    if (autoscroller != null)
+      {
+        autoscroller.stop();
+        autoscroller = null;
+      }
   }
 } // class DropTarget