content: // ===============================================================================
  // Authors: AFRL/RQQD
  // Organization: Air Force Research Laboratory, Aerospace Systems Directorate, Power and Control Division
  // 
  // Copyright (c) 2017 Government of the United State of America, as represented by
  // the Secretary of the Air Force.  No copyright is claimed in the United States under
  // Title 17, U.S. Code.  All Other Rights Reserved.
  // ===============================================================================
  
  package org.flexdock.docking.drag;
  
  import java.awt.Component;
  import java.awt.Dimension;
  import java.awt.Point;
  import java.awt.Rectangle;
  import java.awt.event.MouseEvent;
  import java.util.EventListener;
  
  import javax.swing.SwingUtilities;
  
  import org.flexdock.docking.Dockable;
  import org.flexdock.docking.DockingConstants;
  import org.flexdock.docking.DockingManager;
  import org.flexdock.docking.DockingPort;
  
  public class DragOperation implements DockingConstants {
      public static final String DRAG_IMAGE = "DragOperation.DRAG_IMAGE";
  
      private Component dragSource;
      private Component dockable;
      private DockingPort parentDockingPort;
      private Point mouseOffset;
      private Point currentMouse;
      private EventListener[] cachedListeners;
      private DragManager dragListener;
      private DockingPort targetPort;
      private String targetRegion;
      private boolean overWindow;
      private boolean pseudoDrag;
      private long started;
      private Dockable dockableRef;
      private DockingPort sourcePort;
  
  
      public DragOperation(Component dockable, Point dragOrigin, MouseEvent evt) {
          if(dockable==null)
              throw new NullPointerException("'dockable' parameter cannot be null.");
          if(evt==null)
              throw new NullPointerException("'evt' parameter cannot be null.");
          if(!(evt.getSource() instanceof Component))
              throw new IllegalArgumentException("'evt.getSource()' must be an instance of java.awt.Component.");
  
          if(dragOrigin==null)
              dragOrigin = evt.getPoint();
          init(dockable, (Component)evt.getSource(), dragOrigin, false);
      }
  
      public DragOperation(Component dockable, Component dragSource, Point currentMouse) {
          init(dockable, dragSource, currentMouse, true);
      }
  
      private void init(Component dockable, Component dragSource, Point currentMouse, boolean fakeDrag) {
          this.dockable = dockable;
          this.dragSource = dragSource;
          this.currentMouse = currentMouse;
          mouseOffset = calculateMouseOffset(currentMouse);
          pseudoDrag = fakeDrag;
          if(!fakeDrag)
              parentDockingPort = (DockingPort)SwingUtilities.getAncestorOfClass(DockingPort.class, dockable);
  
          sourcePort = DockingManager.getDockingPort(dockable);
          started = -1;
      }
  
      private Point calculateMouseOffset(Point evtPoint) {
          if(evtPoint==null)
              return null;
  
          Point dockableLoc = dockable.getLocationOnScreen();
          SwingUtilities.convertPointToScreen(evtPoint, dragSource);
          Point offset = new Point();
          offset.x = dockableLoc.x - evtPoint.x;
          offset.y = dockableLoc.y - evtPoint.y;
          return offset;
      }
  
      public Component getDockable() {
          return dockable;
      }
  
      public Dockable getDockableReference() {
          if(dockableRef==null)
              dockableRef = DockingManager.getDockable(dockable);
          return dockableRef;
      }
  
      public Point getMouseOffset() {
          return (Point)mouseOffset.clone();
      }
  
      public void updateMouse(MouseEvent me) {
          if(me!=null && me.getSource()==dragSource)
              currentMouse = me.getPoint();
      }
  
      public Point getCurrentMouse() {
          return getCurrentMouse(false);
      }
  
      public Point getCurrentMouse(boolean relativeToScreen) {
          Point p = (Point)currentMouse.clone();
          if(relativeToScreen)
              SwingUtilities.convertPointToScreen(p, dragSource);
          return p;
      }
  
      public Rectangle getDragRect(boolean relativeToScreen) {
          Point p = getCurrentMouse(relativeToScreen);
          Point offset = getMouseOffset();
          p.x += offset.x;
          p.y += offset.y;
  
          Rectangle r = new Rectangle(getDragSize());
          r.setLocation(p);
          return r;
  
      }
  
      public Point getCurrentMouse(Component target) {
          if(target==null || !target.isVisible())
              return null;
          return SwingUtilities.convertPoint(dragSource, currentMouse, target);
      }
  
      public Dimension getDragSize() {
          return ((Component)dockable).getSize();
      }
  
      public Component getDragSource() {
          return dragSource;
      }
  
      public void setTarget(DockingPort port, String region) {
          targetPort = port;
          targetRegion = region==null? UNKNOWN_REGION: region;
      }
  
      public DockingPort getTargetPort() {
          return targetPort;
      }
  
      public String getTargetRegion() {
          return targetRegion;
      }
  
      public EventListener[] getCachedListeners() {
          return cachedListeners==null? new EventListener[0]: cachedListeners;
      }
  
      public void setCachedListeners(EventListener[] listeners) {
          cachedListeners = listeners;
      }
  
      public DragManager getDragListener() {
          return dragListener;
      }
  
      public void setDragListener(DragManager listener) {
          this.dragListener = listener;
      }
  
      public boolean isOverWindow() {
          return overWindow;
      }
  
      public void setOverWindow(boolean overWindow) {
          this.overWindow = overWindow;
      }
  
      public boolean isPseudoDrag() {
          return pseudoDrag;
      }
  
      public DockingPort getParentDockingPort() {
          return parentDockingPort;
      }
  
      public void start() {
          if(started==-1)
              started = System.currentTimeMillis();
      }
  
      public long getStartTime() {
          return started;
      }
  
      public DockingPort getSourcePort() {
          return sourcePort;
      }
  }