import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

widget/nsIClipboardDragDropHooks.idl

@@ -0,0 +1,101 @@
+/* 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);
+};
+