michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "nsISupports.idl"
michael@0: 
michael@0: interface nsITransferable;
michael@0: interface nsIDragSession;
michael@0: interface nsIDOMEvent;
michael@0: 
michael@0: 
michael@0: /**
michael@0:  * Interfaces for overriding the built-in drag, drop, copy, and paste
michael@0:  * implementations in the content area and editors. Use this to do things
michael@0:  * such as prevent a drag from starting, adding or removing
michael@0:  * data and flavors, or preventing the drop.
michael@0:  *
michael@0:  * Embedders who want to have these hooks made available should implement
michael@0:  * nsIClipboardDragDropHooks and use the command manager to send the
michael@0:  * appropriate commands with these parameters/settings: 
michael@0:  *      command:  cmd_clipboardDragDropHook
michael@0:  *
michael@0:  *      params        value type   possible values
michael@0:  *      "addhook"     isupports    nsIClipboardDragDropHooks as nsISupports
michael@0:  *      "removehook"  isupports    nsIClipboardDragDropHooks as nsISupports
michael@0:  *
michael@0:  * Notes:
michael@0:  *  * Overrides/hooks need to be added to each window (as appropriate).
michael@0:  *    Adding them to the first window does not enable them for every window.
michael@0:  *  * If more than one implementation is set for a window, the hooks will be
michael@0:  *    called in the order they are added.
michael@0:  *  * Adding the same hook to the same window will not add a second call.
michael@0:  *    Each hook can only be called once per user action/api.
michael@0:  *  * Not all hooks are guaranteed to be called.  If there are multiple hooks
michael@0:  *    set for a window, any of them has an opportunity to cancel the action
michael@0:  *    so no further processing will occur.
michael@0:  *  * If any errors occur (without setting the boolean result) the default
michael@0:  *    action will occur.
michael@0:  *  * AllowDrop will be called MANY times during drag so ensure that it is
michael@0:  *    efficient. 
michael@0:  */
michael@0: 
michael@0: 
michael@0: [scriptable,uuid(e03e6c5e-0d84-4c0b-8739-e6b8d51922de)]
michael@0: interface nsIClipboardDragDropHooks : nsISupports
michael@0: {
michael@0:   /**
michael@0:    * Prevents the drag from starting
michael@0:    *
michael@0:    * @param event DOM event (drag gesture)
michael@0:    *
michael@0:    * @return TRUE  drag can proceed
michael@0:    * @return FALSE drag is cancelled, does not go to OS
michael@0:    */
michael@0:   boolean allowStartDrag(in nsIDOMEvent event);
michael@0:   
michael@0:   /**
michael@0:    * Tells gecko whether a drop is allowed on this content area
michael@0:    *
michael@0:    * @param event   DOM event (drag over)
michael@0:    * @param session the drag session from which client can get
michael@0:    *                   the flavors present or the actual data
michael@0:    *
michael@0:    * @return TRUE  indicates to OS that if a drop does happen on this
michael@0:    *                browser, it will be accepted.
michael@0:    * @return FALSE indicates to OS drop is not allowed. On win32, this
michael@0:    *                will change the cursor to "reject".
michael@0:    */
michael@0:   boolean allowDrop(in nsIDOMEvent event, in nsIDragSession session);
michael@0: 
michael@0:   /**
michael@0:    * Alter the flavors or data presented to the OS
michael@0:    * Used for drag and copy actions
michael@0:    * Because this can be called many times, it is highly recommended
michael@0:    * that the implementation be very efficient so user feedback is
michael@0:    * not negatively impacted.
michael@0:    *
michael@0:    * @param event  DOM event (drag drop); null if triggered by copy.
michael@0:    * @param trans  the transferable holding the list of flavors
michael@0:    *               and the data for each flavor
michael@0:    *
michael@0:    * @return TRUE  copy/drag can proceed
michael@0:    * @return FALSE copy/drag is cancelled, does not go to OS
michael@0:    */
michael@0:   boolean onCopyOrDrag(in nsIDOMEvent aEvent, in nsITransferable trans);
michael@0: 
michael@0:   /**
michael@0:    * Provide an alternative action to the built-in behavior when
michael@0:    * something is dropped on the browser or in an editor
michael@0:    *
michael@0:    * @param event  DOM event (drag drop); null if triggered by paste.
michael@0:    * @param trans  the transferable holding the list of flavors
michael@0:    *               and the data for each flavor
michael@0:    *
michael@0:    * @return TRUE  action was handled, do not perform built-in
michael@0:    *                behavior
michael@0:    * @return FALSE action was not overridden, do built-in behavior
michael@0:    */
michael@0:   boolean onPasteOrDrop(in nsIDOMEvent event, in nsITransferable trans);
michael@0: };
michael@0: