gecko/widget/nsIClipboardDragDropHooks.idl

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/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Communicator.
*
* The Initial Developer of the Original Code is
* Netscape Communications.
* Portions created by the Initial Developer are Copyright (C) 2002
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Mike Pinkerton <pinkerton@netscape.com>
* Kathleen Brade <brade@netscape.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include "nsISupports.idl"
interface nsITransferable;
interface nsIDragSession;
interface nsIDOMEvent;
/**
* Interfaces for overriding the built-in drag, drop, copy, and paste
* implementations in the content area and editors. Use this to do things
* such as prevent a drag from starting, adding or removing
* data and flavors, or preventing the drop.
*
* Embedders who want to have these hooks made available should implement
* nsIClipboardDragDropHooks and use the command manager to send the
* appropriate commands with these parameters/settings:
* command: cmd_clipboardDragDropHook
*
* params value type possible values
* "addhook" isupports nsIClipboardDragDropHooks as nsISupports
* "removehook" isupports nsIClipboardDragDropHooks as nsISupports
*
* Notes:
* * Overrides/hooks need to be added to each window (as appropriate).
* Adding them to the first window does not enable them for every window.
* * If more than one implementation is set for a window, the hooks will be
* called in the order they are added.
* * Adding the same hook to the same window will not add a second call.
* Each hook can only be called once per user action/api.
* * Not all hooks are guaranteed to be called. If there are multiple hooks
* set for a window, any of them has an opportunity to cancel the action
* so no further processing will occur.
* * If any errors occur (without setting the boolean result) the default
* action will occur.
* * AllowDrop will be called MANY times during drag so ensure that it is
* efficient.
*/
[scriptable,uuid(e03e6c5e-0d84-4c0b-8739-e6b8d51922de)]
interface nsIClipboardDragDropHooks : nsISupports
{
/**
* Prevents the drag from starting
*
* @param event DOM event (drag gesture)
*
* @return TRUE drag can proceed
* @return FALSE drag is cancelled, does not go to OS
*/
boolean allowStartDrag(in nsIDOMEvent event);
/**
* Tells gecko whether a drop is allowed on this content area
*
* @param event DOM event (drag over)
* @param session the drag session from which client can get
* the flavors present or the actual data
*
* @return TRUE indicates to OS that if a drop does happen on this
* browser, it will be accepted.
* @return FALSE indicates to OS drop is not allowed. On win32, this
* will change the cursor to "reject".
*/
boolean allowDrop(in nsIDOMEvent event, in nsIDragSession session);
/**
* Alter the flavors or data presented to the OS
* Used for drag and copy actions
* Because this can be called many times, it is highly recommended
* that the implementation be very efficient so user feedback is
* not negatively impacted.
*
* @param event DOM event (drag drop); null if triggered by copy.
* @param trans the transferable holding the list of flavors
* and the data for each flavor
*
* @return TRUE copy/drag can proceed
* @return FALSE copy/drag is cancelled, does not go to OS
*/
boolean onCopyOrDrag(in nsIDOMEvent aEvent, in nsITransferable trans);
/**
* Provide an alternative action to the built-in behavior when
* something is dropped on the browser or in an editor
*
* @param event DOM event (drag drop); null if triggered by paste.
* @param trans the transferable holding the list of flavors
* and the data for each flavor
*
* @return TRUE action was handled, do not perform built-in
* behavior
* @return FALSE action was not overridden, do built-in behavior
*/
boolean onPasteOrDrop(in nsIDOMEvent event, in nsITransferable trans);
};