michael@0: // -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0: 
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: ////////////////////////////////////////////////////////////////////////
michael@0: //
michael@0: // USE OF THIS API FOR DRAG AND DROP IS DEPRECATED!
michael@0: // Do not use this file for new code.
michael@0: //
michael@0: // For documentation about what to use instead, see:
michael@0: //   http://developer.mozilla.org/En/DragDrop/Drag_and_Drop
michael@0: //
michael@0: ////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: 
michael@0: /** 
michael@0:  *  nsTransferable - a wrapper for nsITransferable that simplifies
michael@0:  *                   javascript clipboard and drag&drop. for use in
michael@0:  *                   these situations you should use the nsClipboard
michael@0:  *                   and nsDragAndDrop wrappers for more convenience
michael@0:  **/ 
michael@0:  
michael@0: var nsTransferable = {
michael@0:   /**
michael@0:    * nsITransferable set (TransferData aTransferData) ;
michael@0:    *
michael@0:    * Creates a transferable with data for a list of supported types ("flavours")
michael@0:    * 
michael@0:    * @param TransferData aTransferData
michael@0:    *        a javascript object in the format described above 
michael@0:    **/ 
michael@0:   set: function (aTransferDataSet)
michael@0:     {
michael@0:       var trans = this.createTransferable();
michael@0:       for (var i = 0; i < aTransferDataSet.dataList.length; ++i) 
michael@0:         {
michael@0:           var currData = aTransferDataSet.dataList[i];
michael@0:           var currFlavour = currData.flavour.contentType;
michael@0:           trans.addDataFlavor(currFlavour);
michael@0:           var supports = null; // nsISupports data
michael@0:           var length = 0;
michael@0:           if (currData.flavour.dataIIDKey == "nsISupportsString")
michael@0:             {
michael@0:               supports = Components.classes["@mozilla.org/supports-string;1"]
michael@0:                                    .createInstance(Components.interfaces.nsISupportsString);
michael@0: 
michael@0:               supports.data = currData.supports;
michael@0:               length = supports.data.length;
michael@0:             }
michael@0:           else 
michael@0:             {
michael@0:               // non-string data.
michael@0:               supports = currData.supports;
michael@0:               length = 0; // kFlavorHasDataProvider
michael@0:             }
michael@0:           trans.setTransferData(currFlavour, supports, length * 2);
michael@0:         }
michael@0:       return trans;
michael@0:     },
michael@0:   
michael@0:   /**
michael@0:    * TransferData/TransferDataSet get (FlavourSet aFlavourSet, 
michael@0:    *                                   Function aRetrievalFunc, Boolean aAnyFlag) ;
michael@0:    *
michael@0:    * Retrieves data from the transferable provided in aRetrievalFunc, formatted
michael@0:    * for more convenient access.
michael@0:    *
michael@0:    * @param FlavourSet aFlavourSet
michael@0:    *        a FlavourSet object that contains a list of supported flavours.
michael@0:    * @param Function aRetrievalFunc
michael@0:    *        a reference to a function that returns a nsISupportsArray of nsITransferables
michael@0:    *        for each item from the specified source (clipboard/drag&drop etc)
michael@0:    * @param Boolean aAnyFlag
michael@0:    *        a flag specifying whether or not a specific flavour is requested. If false,
michael@0:    *        data of the type of the first flavour in the flavourlist parameter is returned,
michael@0:    *        otherwise the best flavour supported will be returned.
michael@0:    **/
michael@0:   get: function (aFlavourSet, aRetrievalFunc, aAnyFlag)
michael@0:     {
michael@0:       if (!aRetrievalFunc) 
michael@0:         throw "No data retrieval handler provided!";
michael@0:       
michael@0:       var supportsArray = aRetrievalFunc(aFlavourSet);
michael@0:       var dataArray = [];
michael@0:       var count = supportsArray.Count();
michael@0:       
michael@0:       // Iterate over the number of items returned from aRetrievalFunc. For
michael@0:       // clipboard operations, this is 1, for drag and drop (where multiple
michael@0:       // items may have been dragged) this could be >1.
michael@0:       for (var i = 0; i < count; i++)
michael@0:         {
michael@0:           var trans = supportsArray.GetElementAt(i);
michael@0:           if (!trans) continue;
michael@0:           trans = trans.QueryInterface(Components.interfaces.nsITransferable);
michael@0:             
michael@0:           var data = { };
michael@0:           var length = { };
michael@0:           
michael@0:           var currData = null;
michael@0:           if (aAnyFlag)
michael@0:             { 
michael@0:               var flavour = { };
michael@0:               trans.getAnyTransferData(flavour, data, length);
michael@0:               if (data && flavour)
michael@0:                 {
michael@0:                   var selectedFlavour = aFlavourSet.flavourTable[flavour.value];
michael@0:                   if (selectedFlavour) 
michael@0:                     dataArray[i] = FlavourToXfer(data.value, length.value, selectedFlavour);
michael@0:                 }
michael@0:             }
michael@0:           else
michael@0:             {
michael@0:               var firstFlavour = aFlavourSet.flavours[0];
michael@0:               trans.getTransferData(firstFlavour, data, length);
michael@0:               if (data && firstFlavour)
michael@0:                 dataArray[i] = FlavourToXfer(data.value, length.value, firstFlavour);
michael@0:             }
michael@0:         }
michael@0:       return new TransferDataSet(dataArray);
michael@0:     },
michael@0: 
michael@0:   /** 
michael@0:    * nsITransferable createTransferable (void) ;
michael@0:    *
michael@0:    * Creates and returns a transferable object.
michael@0:    **/    
michael@0:   createTransferable: function ()
michael@0:     {
michael@0:       const kXferableContractID = "@mozilla.org/widget/transferable;1";
michael@0:       const kXferableIID = Components.interfaces.nsITransferable;
michael@0:       var trans = Components.classes[kXferableContractID].createInstance(kXferableIID);
michael@0:       trans.init(null);
michael@0:       return trans;
michael@0:     }
michael@0: };  
michael@0: 
michael@0: /** 
michael@0:  * A FlavourSet is a simple type that represents a collection of Flavour objects.
michael@0:  * FlavourSet is constructed from an array of Flavours, and stores this list as
michael@0:  * an array and a hashtable. The rationale for the dual storage is as follows:
michael@0:  * 
michael@0:  * Array: Ordering is important when adding data flavours to a transferable. 
michael@0:  *        Flavours added first are deemed to be 'preferred' by the client. 
michael@0:  * Hash:  Convenient lookup of flavour data using the content type (MIME type)
michael@0:  *        of data as a key. 
michael@0:  */
michael@0: function FlavourSet(aFlavourList)
michael@0: {
michael@0:   this.flavours = aFlavourList || [];
michael@0:   this.flavourTable = { };
michael@0: 
michael@0:   this._XferID = "FlavourSet";
michael@0:   
michael@0:   for (var i = 0; i < this.flavours.length; ++i)
michael@0:     this.flavourTable[this.flavours[i].contentType] = this.flavours[i];
michael@0: }
michael@0: 
michael@0: FlavourSet.prototype = {
michael@0:   appendFlavour: function (aFlavour, aFlavourIIDKey)
michael@0:   {
michael@0:     var flavour = new Flavour (aFlavour, aFlavourIIDKey);
michael@0:     this.flavours.push(flavour);
michael@0:     this.flavourTable[flavour.contentType] = flavour;
michael@0:   }
michael@0: };
michael@0: 
michael@0: /** 
michael@0:  * A Flavour is a simple type that represents a data type that can be handled. 
michael@0:  * It takes a content type (MIME type) which is used when storing data on the
michael@0:  * system clipboard/drag and drop, and an IIDKey (string interface name
michael@0:  * which is used to QI data to an appropriate form. The default interface is
michael@0:  * assumed to be wide-string.
michael@0:  */ 
michael@0: function Flavour(aContentType, aDataIIDKey)
michael@0: {
michael@0:   this.contentType = aContentType;
michael@0:   this.dataIIDKey = aDataIIDKey || "nsISupportsString";
michael@0: 
michael@0:   this._XferID = "Flavour";
michael@0: }
michael@0: 
michael@0: function TransferDataBase() {}
michael@0: TransferDataBase.prototype = {
michael@0:   push: function (aItems)
michael@0:   {
michael@0:     this.dataList.push(aItems);
michael@0:   },
michael@0: 
michael@0:   get first ()
michael@0:   {
michael@0:     return "dataList" in this && this.dataList.length ? this.dataList[0] : null;
michael@0:   }
michael@0: };
michael@0: 
michael@0: /** 
michael@0:  * TransferDataSet is a list (array) of TransferData objects, which represents
michael@0:  * data dragged from one or more elements. 
michael@0:  */
michael@0: function TransferDataSet(aTransferDataList)
michael@0: {
michael@0:   this.dataList = aTransferDataList || [];
michael@0: 
michael@0:   this._XferID = "TransferDataSet";
michael@0: }
michael@0: TransferDataSet.prototype = TransferDataBase.prototype;
michael@0: 
michael@0: /** 
michael@0:  * TransferData is a list (array) of FlavourData for all the applicable content
michael@0:  * types associated with a drag from a single item. 
michael@0:  */
michael@0: function TransferData(aFlavourDataList)
michael@0: {
michael@0:   this.dataList = aFlavourDataList || [];
michael@0: 
michael@0:   this._XferID = "TransferData";
michael@0: }
michael@0: TransferData.prototype = {
michael@0:   __proto__: TransferDataBase.prototype,
michael@0:   
michael@0:   addDataForFlavour: function (aFlavourString, aData, aLength, aDataIIDKey)
michael@0:   {
michael@0:     this.dataList.push(new FlavourData(aData, aLength, 
michael@0:                        new Flavour(aFlavourString, aDataIIDKey)));
michael@0:   }
michael@0: };
michael@0: 
michael@0: /** 
michael@0:  * FlavourData is a type that represents data retrieved from the system 
michael@0:  * clipboard or drag and drop. It is constructed internally by the Transferable
michael@0:  * using the raw (nsISupports) data from the clipboard, the length of the data,
michael@0:  * and an object of type Flavour representing the type. Clients implementing
michael@0:  * IDragDropObserver receive an object of this type in their implementation of
michael@0:  * onDrop. They access the 'data' property to retrieve data, which is either data 
michael@0:  * QI'ed to a usable form, or unicode string. 
michael@0:  */
michael@0: function FlavourData(aData, aLength, aFlavour) 
michael@0: {
michael@0:   this.supports = aData;
michael@0:   this.contentLength = aLength;
michael@0:   this.flavour = aFlavour || null;
michael@0:   
michael@0:   this._XferID = "FlavourData";
michael@0: }
michael@0: 
michael@0: FlavourData.prototype = {
michael@0:   get data ()
michael@0:   {
michael@0:     if (this.flavour &&
michael@0:         this.flavour.dataIIDKey != "nsISupportsString")
michael@0:       return this.supports.QueryInterface(Components.interfaces[this.flavour.dataIIDKey]); 
michael@0: 
michael@0:     var supports = this.supports;
michael@0:     if (supports instanceof Components.interfaces.nsISupportsString)
michael@0:       return supports.data.substring(0, this.contentLength/2);
michael@0:      
michael@0:     return supports;
michael@0:   }
michael@0: }
michael@0: 
michael@0: /** 
michael@0:  * Create a TransferData object with a single FlavourData entry. Used when 
michael@0:  * unwrapping data of a specific flavour from the drag service. 
michael@0:  */
michael@0: function FlavourToXfer(aData, aLength, aFlavour) 
michael@0: {
michael@0:   return new TransferData([new FlavourData(aData, aLength, aFlavour)]);
michael@0: }
michael@0: 
michael@0: var transferUtils = {
michael@0: 
michael@0:   retrieveURLFromData: function (aData, flavour)
michael@0:   {
michael@0:     switch (flavour) {
michael@0:       case "text/unicode":
michael@0:       case "text/plain":
michael@0:       case "text/x-moz-text-internal":
michael@0:         return aData.replace(/^\s+|\s+$/g, "");
michael@0:       case "text/x-moz-url":
michael@0:         return ((aData instanceof Components.interfaces.nsISupportsString) ? aData.toString() : aData).split("\n")[0];
michael@0:       case "application/x-moz-file":
michael@0:         var ioService = Components.classes["@mozilla.org/network/io-service;1"]
michael@0:                                   .getService(Components.interfaces.nsIIOService);
michael@0:         var fileHandler = ioService.getProtocolHandler("file")
michael@0:                                    .QueryInterface(Components.interfaces.nsIFileProtocolHandler);
michael@0:         return fileHandler.getURLSpecFromFile(aData);
michael@0:     }
michael@0:     return null;                                                   
michael@0:   }
michael@0: 
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * nsDragAndDrop - a convenience wrapper for nsTransferable, nsITransferable
michael@0:  *                 and nsIDragService/nsIDragSession. 
michael@0:  *
michael@0:  * Use: map the handler functions to the 'ondraggesture', 'ondragover' and
michael@0:  *   'ondragdrop' event handlers on your XML element, e.g.                   
michael@0:  *   <xmlelement ondraggesture="nsDragAndDrop.startDrag(event, observer);"   
michael@0:  *               ondragover="nsDragAndDrop.dragOver(event, observer);"      
michael@0:  *               ondragdrop="nsDragAndDrop.drop(event, observer);"/>         
michael@0:  *                                                                           
michael@0:  *   You need to create an observer js object with the following member      
michael@0:  *   functions:                                                              
michael@0:  *     Object onDragStart (event)        // called when drag initiated,      
michael@0:  *                                       // returns flavour list with data   
michael@0:  *                                       // to stuff into transferable      
michael@0:  *     void onDragOver (Object flavour)  // called when element is dragged   
michael@0:  *                                       // over, so that it can perform     
michael@0:  *                                       // any drag-over feedback for provided
michael@0:  *                                       // flavour                          
michael@0:  *     void onDrop (Object data)         // formatted data object dropped.   
michael@0:  *     Object getSupportedFlavours ()    // returns a flavour list so that   
michael@0:  *                                       // nsTransferable can determine
michael@0:  *                                       // whether or not to accept drop. 
michael@0:  **/   
michael@0: 
michael@0: var nsDragAndDrop = {
michael@0:   
michael@0:   _mDS: null,
michael@0:   get mDragService()
michael@0:     {
michael@0:       if (!this._mDS) 
michael@0:         {
michael@0:           const kDSContractID = "@mozilla.org/widget/dragservice;1";
michael@0:           const kDSIID = Components.interfaces.nsIDragService;
michael@0:           this._mDS = Components.classes[kDSContractID].getService(kDSIID);
michael@0:         }
michael@0:       return this._mDS;
michael@0:     },
michael@0: 
michael@0:   /**
michael@0:    * void startDrag (DOMEvent aEvent, Object aDragDropObserver) ;
michael@0:    *
michael@0:    * called when a drag on an element is started.
michael@0:    *
michael@0:    * @param DOMEvent aEvent
michael@0:    *        the DOM event fired by the drag init
michael@0:    * @param Object aDragDropObserver
michael@0:    *        javascript object of format described above that specifies
michael@0:    *        the way in which the element responds to drag events.
michael@0:    **/  
michael@0:   startDrag: function (aEvent, aDragDropObserver)
michael@0:     {
michael@0:       if (!("onDragStart" in aDragDropObserver))
michael@0:         return;
michael@0: 
michael@0:       const kDSIID = Components.interfaces.nsIDragService;
michael@0:       var dragAction = { action: kDSIID.DRAGDROP_ACTION_COPY + kDSIID.DRAGDROP_ACTION_MOVE + kDSIID.DRAGDROP_ACTION_LINK };
michael@0: 
michael@0:       var transferData = { data: null };
michael@0:       try 
michael@0:         {
michael@0:           aDragDropObserver.onDragStart(aEvent, transferData, dragAction);
michael@0:         }
michael@0:       catch (e) 
michael@0:         {
michael@0:           return;  // not a draggable item, bail!
michael@0:         }
michael@0: 
michael@0:       if (!transferData.data) return;
michael@0:       transferData = transferData.data;
michael@0: 
michael@0:       var dt = aEvent.dataTransfer;
michael@0:       var count = 0;
michael@0:       do {
michael@0:         var tds = transferData._XferID == "TransferData" 
michael@0:                                          ? transferData 
michael@0:                                          : transferData.dataList[count]
michael@0:         for (var i = 0; i < tds.dataList.length; ++i) 
michael@0:         {
michael@0:           var currData = tds.dataList[i];
michael@0:           var currFlavour = currData.flavour.contentType;
michael@0:           var value = currData.supports;
michael@0:           if (value instanceof Components.interfaces.nsISupportsString)
michael@0:             value = value.toString();
michael@0:           dt.mozSetDataAt(currFlavour, value, count);
michael@0:         }
michael@0: 
michael@0:         count++;
michael@0:       }
michael@0:       while (transferData._XferID == "TransferDataSet" && 
michael@0:              count < transferData.dataList.length);
michael@0: 
michael@0:       dt.effectAllowed = "all";
michael@0:       // a drag targeted at a tree should instead use the treechildren so that
michael@0:       // the current selection is used as the drag feedback
michael@0:       dt.addElement(aEvent.originalTarget.localName == "treechildren" ?
michael@0:                     aEvent.originalTarget : aEvent.target);
michael@0:       aEvent.stopPropagation();
michael@0:     },
michael@0: 
michael@0:   /** 
michael@0:    * void dragOver (DOMEvent aEvent, Object aDragDropObserver) ;
michael@0:    *
michael@0:    * called when a drag passes over this element
michael@0:    *
michael@0:    * @param DOMEvent aEvent
michael@0:    *        the DOM event fired by passing over the element
michael@0:    * @param Object aDragDropObserver
michael@0:    *        javascript object of format described above that specifies
michael@0:    *        the way in which the element responds to drag events.
michael@0:    **/
michael@0:   dragOver: function (aEvent, aDragDropObserver)
michael@0:     { 
michael@0:       if (!("onDragOver" in aDragDropObserver)) 
michael@0:         return;
michael@0:       if (!this.checkCanDrop(aEvent, aDragDropObserver))
michael@0:         return;
michael@0:       var flavourSet = aDragDropObserver.getSupportedFlavours();
michael@0:       for (var flavour in flavourSet.flavourTable)
michael@0:         {
michael@0:           if (this.mDragSession.isDataFlavorSupported(flavour))
michael@0:             {
michael@0:               aDragDropObserver.onDragOver(aEvent, 
michael@0:                                            flavourSet.flavourTable[flavour], 
michael@0:                                            this.mDragSession);
michael@0:               aEvent.stopPropagation();
michael@0:               aEvent.preventDefault();
michael@0:               break;
michael@0:             }
michael@0:         }
michael@0:     },
michael@0: 
michael@0:   mDragSession: null,
michael@0: 
michael@0:   /** 
michael@0:    * void drop (DOMEvent aEvent, Object aDragDropObserver) ;
michael@0:    *
michael@0:    * called when the user drops on the element
michael@0:    *
michael@0:    * @param DOMEvent aEvent
michael@0:    *        the DOM event fired by the drop
michael@0:    * @param Object aDragDropObserver
michael@0:    *        javascript object of format described above that specifies
michael@0:    *        the way in which the element responds to drag events.
michael@0:    **/
michael@0:   drop: function (aEvent, aDragDropObserver)
michael@0:     {
michael@0:       if (!("onDrop" in aDragDropObserver))
michael@0:         return;
michael@0:       if (!this.checkCanDrop(aEvent, aDragDropObserver))
michael@0:         return;  
michael@0: 
michael@0:       var flavourSet = aDragDropObserver.getSupportedFlavours();
michael@0: 
michael@0:       var dt = aEvent.dataTransfer;
michael@0:       var dataArray = [];
michael@0:       var count = dt.mozItemCount;
michael@0:       for (var i = 0; i < count; ++i) {
michael@0:         var types = dt.mozTypesAt(i);
michael@0:         for (var j = 0; j < flavourSet.flavours.length; j++) {
michael@0:           var type = flavourSet.flavours[j].contentType;
michael@0:           // dataTransfer uses text/plain but older code used text/unicode, so
michael@0:           // switch this for compatibility
michael@0:           var modtype = (type == "text/unicode") ? "text/plain" : type;
michael@0:           if (Array.indexOf(types, modtype) >= 0) {
michael@0:             var data = dt.mozGetDataAt(modtype, i);
michael@0:             if (data) {
michael@0:               // Non-strings need some non-zero value used for their data length.
michael@0:               const kNonStringDataLength = 4;
michael@0: 
michael@0:               var length = (typeof data == "string") ? data.length : kNonStringDataLength;
michael@0:               dataArray[i] = FlavourToXfer(data, length, flavourSet.flavourTable[type]);
michael@0:               break;
michael@0:             }
michael@0:           }
michael@0:         }
michael@0:       }
michael@0: 
michael@0:       var transferData = new TransferDataSet(dataArray)
michael@0: 
michael@0:       // hand over to the client to respond to dropped data
michael@0:       var multiple = "canHandleMultipleItems" in aDragDropObserver && aDragDropObserver.canHandleMultipleItems;
michael@0:       var dropData = multiple ? transferData : transferData.first.first;
michael@0:       aDragDropObserver.onDrop(aEvent, dropData, this.mDragSession);
michael@0:       aEvent.stopPropagation();
michael@0:     },
michael@0: 
michael@0:   /** 
michael@0:    * void dragExit (DOMEvent aEvent, Object aDragDropObserver) ;
michael@0:    *
michael@0:    * called when a drag leaves this element
michael@0:    *
michael@0:    * @param DOMEvent aEvent
michael@0:    *        the DOM event fired by leaving the element
michael@0:    * @param Object aDragDropObserver
michael@0:    *        javascript object of format described above that specifies
michael@0:    *        the way in which the element responds to drag events.
michael@0:    **/
michael@0:   dragExit: function (aEvent, aDragDropObserver)
michael@0:     {
michael@0:       if (!this.checkCanDrop(aEvent, aDragDropObserver))
michael@0:         return;
michael@0:       if ("onDragExit" in aDragDropObserver)
michael@0:         aDragDropObserver.onDragExit(aEvent, this.mDragSession);
michael@0:     },  
michael@0:     
michael@0:   /** 
michael@0:    * void dragEnter (DOMEvent aEvent, Object aDragDropObserver) ;
michael@0:    *
michael@0:    * called when a drag enters in this element
michael@0:    *
michael@0:    * @param DOMEvent aEvent
michael@0:    *        the DOM event fired by entering in the element
michael@0:    * @param Object aDragDropObserver
michael@0:    *        javascript object of format described above that specifies
michael@0:    *        the way in which the element responds to drag events.
michael@0:    **/
michael@0:   dragEnter: function (aEvent, aDragDropObserver)
michael@0:     {
michael@0:       if (!this.checkCanDrop(aEvent, aDragDropObserver))
michael@0:         return;
michael@0:       if ("onDragEnter" in aDragDropObserver)
michael@0:         aDragDropObserver.onDragEnter(aEvent, this.mDragSession);
michael@0:     },  
michael@0: 
michael@0:   /** 
michael@0:    * Boolean checkCanDrop (DOMEvent aEvent, Object aDragDropObserver) ;
michael@0:    *
michael@0:    * Sets the canDrop attribute for the drag session.
michael@0:    * returns false if there is no current drag session.
michael@0:    *
michael@0:    * @param DOMEvent aEvent
michael@0:    *        the DOM event fired by the drop
michael@0:    * @param Object aDragDropObserver
michael@0:    *        javascript object of format described above that specifies
michael@0:    *        the way in which the element responds to drag events.
michael@0:    **/
michael@0:   checkCanDrop: function (aEvent, aDragDropObserver)
michael@0:     {
michael@0:       if (!this.mDragSession) 
michael@0:         this.mDragSession = this.mDragService.getCurrentSession();
michael@0:       if (!this.mDragSession) 
michael@0:         return false;
michael@0:       this.mDragSession.canDrop = this.mDragSession.sourceNode != aEvent.target;
michael@0:       if ("canDrop" in aDragDropObserver)
michael@0:         this.mDragSession.canDrop &= aDragDropObserver.canDrop(aEvent, this.mDragSession);
michael@0:       return true;
michael@0:     },
michael@0: 
michael@0:   /**
michael@0:    * Do a security check for drag n' drop. Make sure the source document
michael@0:    * can load the dragged link.
michael@0:    *
michael@0:    * @param DOMEvent aEvent
michael@0:    *        the DOM event fired by leaving the element
michael@0:    * @param Object aDragDropObserver
michael@0:    *        javascript object of format described above that specifies
michael@0:    *        the way in which the element responds to drag events.
michael@0:    * @param String aDraggedText
michael@0:    *        the text being dragged
michael@0:    **/
michael@0:   dragDropSecurityCheck: function (aEvent, aDragSession, aDraggedText)
michael@0:     {
michael@0:       // Strip leading and trailing whitespace, then try to create a
michael@0:       // URI from the dropped string. If that succeeds, we're
michael@0:       // dropping a URI and we need to do a security check to make
michael@0:       // sure the source document can load the dropped URI. We don't
michael@0:       // so much care about creating the real URI here
michael@0:       // (i.e. encoding differences etc don't matter), we just want
michael@0:       // to know if aDraggedText really is a URI.
michael@0: 
michael@0:       aDraggedText = aDraggedText.replace(/^\s*|\s*$/g, '');
michael@0: 
michael@0:       var uri;
michael@0:       var ioService = Components.classes["@mozilla.org/network/io-service;1"]
michael@0:                                 .getService(Components.interfaces.nsIIOService);
michael@0:       try {
michael@0:         uri = ioService.newURI(aDraggedText, null, null);
michael@0:       } catch (e) {
michael@0:       }
michael@0: 
michael@0:       if (!uri)
michael@0:         return;
michael@0: 
michael@0:       // aDraggedText is a URI, do the security check.
michael@0:       const nsIScriptSecurityManager = Components.interfaces
michael@0:                                                  .nsIScriptSecurityManager;
michael@0:       var secMan = Components.classes["@mozilla.org/scriptsecuritymanager;1"]
michael@0:                              .getService(nsIScriptSecurityManager);
michael@0: 
michael@0:       if (!aDragSession)
michael@0:         aDragSession = this.mDragService.getCurrentSession();
michael@0: 
michael@0:       var sourceDoc = aDragSession.sourceDocument;
michael@0:       // Use "file:///" as the default sourceURI so that drops of file:// URIs
michael@0:       // are always allowed.
michael@0:       var principal = sourceDoc ? sourceDoc.nodePrincipal
michael@0:                                 : secMan.getSimpleCodebasePrincipal(ioService.newURI("file:///", null, null));
michael@0: 
michael@0:       try {
michael@0:         secMan.checkLoadURIStrWithPrincipal(principal, aDraggedText,
michael@0:                                             nsIScriptSecurityManager.STANDARD);
michael@0:       } catch (e) {
michael@0:         // Stop event propagation right here.
michael@0:         aEvent.stopPropagation();
michael@0: 
michael@0:         throw "Drop of " + aDraggedText + " denied.";
michael@0:       }
michael@0:     }
michael@0: };
michael@0: