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/* 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"
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);
};
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