/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsISupports.idl"
#include "nsISupportsArray.idl"
#include "nsIDragSession.idl"
#include "nsIScriptableRegion.idl"


interface nsIDOMNode;
interface nsIDOMDragEvent;
interface nsIDOMDataTransfer;
interface nsISelection;

[scriptable, uuid(82B58ADA-F490-4C3D-B737-1057C4F1D052), builtinclass]
interface nsIDragService : nsISupports
{
  const long DRAGDROP_ACTION_NONE = 0;
  const long DRAGDROP_ACTION_COPY = 1;
  const long DRAGDROP_ACTION_MOVE = 2;
  const long DRAGDROP_ACTION_LINK = 4;
  const long DRAGDROP_ACTION_UNINITIALIZED = 64;

  /**
    * Starts a modal drag session with an array of transaferables 
    *
    * @param  aTransferables - an array of transferables to be dragged
    * @param  aRegion - a region containing rectangles for cursor feedback, 
    *            in window coordinates.
    * @param  aActionType - specified which of copy/move/link are allowed
    */
  void invokeDragSession ( in nsIDOMNode aDOMNode, in nsISupportsArray aTransferables, 
                             in nsIScriptableRegion aRegion, in unsigned long aActionType );

  /**
   * Starts a modal drag session using an image. The first four arguments are
   * the same as invokeDragSession.
   *
   * A custom image may be specified using the aImage argument. If this is
   * supplied, the aImageX and aImageY arguments specify the offset within
   * the image where the cursor would be positioned. That is, when the image
   * is drawn, it is offset up and left the amount so that the cursor appears
   * at that location within the image.
   *
   * If aImage is null, aImageX and aImageY are not used and the image is instead
   * determined from the source node aDOMNode, and the offset calculated so that
   * the initial location for the image appears in the same screen position as
   * where the element is located. The node must be within a document.
   *
   * Currently, supported images are all DOM nodes. If this is an HTML <image> or
   * <canvas>, the drag image is taken from the image data. If the element is in
   * a document, it will be rendered at its displayed size, othewise, it will be
   * rendered at its real size. For other types of elements, the element is
   * rendered into an offscreen buffer in the same manner as it is currently
   * displayed. The document selection is hidden while drawing.
   *
   * The aDragEvent must be supplied as the current screen coordinates of the
   * event are needed to calculate the image location.
   */
  void invokeDragSessionWithImage(in nsIDOMNode aDOMNode,
                                  in nsISupportsArray aTransferableArray,
                                  in nsIScriptableRegion aRegion,
                                  in unsigned long aActionType,
                                  in nsIDOMNode aImage,
                                  in long aImageX,
                                  in long aImageY,
                                  in nsIDOMDragEvent aDragEvent,
                                  in nsIDOMDataTransfer aDataTransfer);

  /**
   * Start a modal drag session using the selection as the drag image.
   * The aDragEvent must be supplied as the current screen coordinates of the
   * event are needed to calculate the image location.
   */
  void invokeDragSessionWithSelection(in nsISelection aSelection,
                                      in nsISupportsArray aTransferableArray,
                                      in unsigned long aActionType,
                                      in nsIDOMDragEvent aDragEvent,
                                      in nsIDOMDataTransfer aDataTransfer);

  /**
    * Returns the current Drag Session  
    */
  nsIDragSession getCurrentSession ( ) ;

  /**
    * Tells the Drag Service to start a drag session. This is called when
    * an external drag occurs
    */
  void startDragSession ( ) ;

  /**
    * Tells the Drag Service to end a drag session. This is called when
    * an external drag occurs
    *
    * If aDoneDrag is true, the drag has finished, otherwise the drag has
    * just left the window.
    */
  void endDragSession ( in boolean aDoneDrag ) ;

  /**
   * Fire a drag event at the source of the drag
   */
  void fireDragEventAtSource ( in unsigned long aMsg );

  /**
   * Increase/decrease dragging suppress level by one.
   * If level is greater than one, dragging is disabled.
   */
  void suppress();
  void unsuppress();

  [noscript] void dragMoved(in long aX, in long aY);
};


%{ C++

%}
