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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);
+};
+