content/events/src/nsDOMDragEvent.cpp

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   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
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   5  * The contents of this file are subject to the Mozilla Public License Version
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  15  * The Original Code is mozilla.org code.
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  17  * The Initial Developer of the Original Code is the Mozilla Corporation.
  18  * Portions created by the Initial Developer are Copyright (C) 2008
  19  * the Initial Developer. All Rights Reserved.
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  21  * Contributor(s):
  22  *   Neil Deakin <enndeakin@gmail.com>
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  24  * Alternatively, the contents of this file may be used under the terms of
  25  * either of the GNU General Public License Version 2 or later (the "GPL"),
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  36  * ***** END LICENSE BLOCK ***** */
  37
  38 #include "nsDOMDragEvent.h"
  39 #include "nsIServiceManager.h"
  40 #include "nsGUIEvent.h"
  41 #include "nsContentUtils.h"
  42 #include "nsIEventStateManager.h"
  43 #include "nsDOMDataTransfer.h"
  44 #include "nsIDragService.h"
  45
  46 nsDOMDragEvent::nsDOMDragEvent(nsPresContext* aPresContext,
  47                                nsInputEvent* aEvent)
  48   : nsDOMMouseEvent(aPresContext, aEvent ? aEvent :
  49                     new nsDragEvent(PR_FALSE, 0, nsnull))
  50 {
  51   if (aEvent) {
  52     mEventIsInternal = PR_FALSE;
  53   }
  54   else {
  55     mEventIsInternal = PR_TRUE;
  56     mEvent->time = PR_Now();
  57     mEvent->refPoint.x = mEvent->refPoint.y = 0;
  58   }
  59 }
  60
  61 nsDOMDragEvent::~nsDOMDragEvent()
  62 {
  63   if (mEventIsInternal) {
  64     if (mEvent->eventStructType == NS_DRAG_EVENT)
  65       delete static_cast<nsDragEvent*>(mEvent);
  66     mEvent = nsnull;
  67   }
  68 }
  69
  70 NS_IMPL_ADDREF_INHERITED(nsDOMDragEvent, nsDOMMouseEvent)
  71 NS_IMPL_RELEASE_INHERITED(nsDOMDragEvent, nsDOMMouseEvent)
  72
  73 NS_INTERFACE_MAP_BEGIN(nsDOMDragEvent)
  74   NS_INTERFACE_MAP_ENTRY(nsIDOMDragEvent)
  75   NS_INTERFACE_MAP_ENTRY_CONTENT_CLASSINFO(DragEvent)
  76 NS_INTERFACE_MAP_END_INHERITING(nsDOMMouseEvent)
  77
  78 NS_IMETHODIMP
  79 nsDOMDragEvent::InitDragEvent(const nsAString & aType,
  80                               PRBool aCanBubble,
  81                               PRBool aCancelable,
  82                               nsIDOMAbstractView* aView,
  83                               PRInt32 aDetail,
  84                               nsIDOMDataTransfer* aDataTransfer)
  85 {
  86   nsresult rv = nsDOMUIEvent::InitUIEvent(aType, aCanBubble, aCancelable, aView, aDetail);
  87   NS_ENSURE_SUCCESS(rv, rv);
  88
  89   if (mEventIsInternal && mEvent) {
  90     nsDragEvent* dragEvent = static_cast<nsDragEvent*>(mEvent);
  91     dragEvent->dataTransfer = aDataTransfer;
  92   }
  93
  94   return NS_OK;
  95 }
  96
  97 NS_IMETHODIMP
  98 nsDOMDragEvent::InitDragEventNS(const nsAString & aNamespaceURIArg,
  99                                 const nsAString & aType,
 100                                 PRBool aCanBubble,
 101                                 PRBool aCancelable,
 102                                 nsIDOMAbstractView* aView,
 103                                 PRInt32 aDetail,
 104                                 nsIDOMDataTransfer* aDataTransfer)
 105 {
 106   return NS_ERROR_NOT_IMPLEMENTED;
 107 }
 108
 109 NS_IMETHODIMP
 110 nsDOMDragEvent::GetDataTransfer(nsIDOMDataTransfer** aDataTransfer)
 111 {
 112   *aDataTransfer = nsnull;
 113
 114   if (!mEvent || mEvent->eventStructType != NS_DRAG_EVENT) {
 115     NS_WARNING("Tried to get dataTransfer from non-drag event!");
 116     return NS_OK;
 117   }
 118
 119   // the dataTransfer field of the event caches the DataTransfer associated
 120   // with the drag. It is initialized when an attempt is made to retrieve it
 121   // rather that when the event is created to avoid duplicating the data when
 122   // no listener ever uses it.
 123   nsDragEvent* dragEvent = static_cast<nsDragEvent*>(mEvent);
 124   if (dragEvent->dataTransfer) {
 125     CallQueryInterface(dragEvent->dataTransfer, aDataTransfer);
 126     return NS_OK;
 127   }
 128
 129   // for synthetic events, just use the supplied data transfer object
 130   if (mEventIsInternal) {
 131     NS_IF_ADDREF(*aDataTransfer = dragEvent->dataTransfer);
 132     return NS_OK;
 133   }
 134
 135   // For draggesture and dragstart events, the data transfer object is
 136   // created before the event fires, so it should already be set. For other
 137   // drag events, get the object from the drag session.
 138   NS_ASSERTION(mEvent->message != NS_DRAGDROP_GESTURE &&
 139                mEvent->message != NS_DRAGDROP_START,
 140                "draggesture event created without a dataTransfer");
 141
 142   nsCOMPtr<nsIDragSession> dragSession = nsContentUtils::GetDragSession();
 143   NS_ENSURE_TRUE(dragSession, NS_OK); // no drag in progress
 144
 145   nsCOMPtr<nsIDOMDataTransfer> initialDataTransfer;
 146   dragSession->GetDataTransfer(getter_AddRefs(initialDataTransfer));
 147   if (!initialDataTransfer) {
 148     // A dataTransfer won't exist when a drag was started by some other
 149     // means, for instance calling the drag service directly, or a drag
 150     // from another application. In either case, a new dataTransfer should
 151     // be created that reflects the data. Pass true to the constructor for
 152     // the aIsExternal argument, so that only system access is allowed.
 153     PRUint32 action = 0;
 154     dragSession->GetDragAction(&action);
 155     initialDataTransfer =
 156       new nsDOMDataTransfer(mEvent->message, action);
 157     NS_ENSURE_TRUE(initialDataTransfer, NS_ERROR_OUT_OF_MEMORY);
 158
 159     // now set it in the drag session so we don't need to create it again
 160     dragSession->SetDataTransfer(initialDataTransfer);
 161   }
 162
 163   // each event should use a clone of the original dataTransfer.
 164   nsCOMPtr<nsIDOMNSDataTransfer> initialDataTransferNS =
 165     do_QueryInterface(initialDataTransfer);
 166   NS_ENSURE_TRUE(initialDataTransferNS, NS_ERROR_FAILURE);
 167   initialDataTransferNS->Clone(mEvent->message,
 168                                getter_AddRefs(dragEvent->dataTransfer));
 169   NS_ENSURE_TRUE(dragEvent->dataTransfer, NS_ERROR_OUT_OF_MEMORY);
 170
 171   // for the dragenter and dragover events, initialize the drop effect
 172   // from the drop action, which platform specific widget code sets before
 173   // the event is fired based on the keyboard state.
 174   if (mEvent->message == NS_DRAGDROP_ENTER ||
 175       mEvent->message == NS_DRAGDROP_OVER) {
 176     nsCOMPtr<nsIDOMNSDataTransfer> newDataTransfer =
 177       do_QueryInterface(dragEvent->dataTransfer);
 178     NS_ENSURE_TRUE(newDataTransfer, NS_ERROR_FAILURE);
 179
 180     PRUint32 action, effectAllowed;
 181     dragSession->GetDragAction(&action);
 182     newDataTransfer->GetEffectAllowedInt(&effectAllowed);
 183     newDataTransfer->SetDropEffectInt(FilterDropEffect(action, effectAllowed));
 184   }
 185   else if (mEvent->message == NS_DRAGDROP_DROP ||
 186            mEvent->message == NS_DRAGDROP_DRAGDROP ||
 187            mEvent->message == NS_DRAGDROP_END) {
 188     // For the drop and dragend events, set the drop effect based on the
 189     // last value that the dropEffect had. This will have been set in
 190     // nsEventStateManager::PostHandleEvent for the last dragenter or
 191     // dragover event.
 192     nsCOMPtr<nsIDOMNSDataTransfer> newDataTransfer =
 193       do_QueryInterface(dragEvent->dataTransfer);
 194     NS_ENSURE_TRUE(newDataTransfer, NS_ERROR_FAILURE);
 195
 196     PRUint32 dropEffect;
 197     initialDataTransferNS->GetDropEffectInt(&dropEffect);
 198     newDataTransfer->SetDropEffectInt(dropEffect);
 199   }
 200
 201   NS_IF_ADDREF(*aDataTransfer = dragEvent->dataTransfer);
 202   return NS_OK;
 203 }
 204
 205 // static
 206 PRUint32
 207 nsDOMDragEvent::FilterDropEffect(PRUint32 aAction, PRUint32 aEffectAllowed)
 208 {
 209   // It is possible for the drag action to include more than one action, but
 210   // the widget code which sets the action from the keyboard state should only
 211   // be including one. If multiple actions were set, we just consider them in
 212   //  the following order:
 213   //   copy, link, move
 214   if (aAction & nsIDragService::DRAGDROP_ACTION_COPY)
 215     aAction = nsIDragService::DRAGDROP_ACTION_COPY;
 216   else if (aAction & nsIDragService::DRAGDROP_ACTION_LINK)
 217     aAction = nsIDragService::DRAGDROP_ACTION_LINK;
 218   else if (aAction & nsIDragService::DRAGDROP_ACTION_MOVE)
 219     aAction = nsIDragService::DRAGDROP_ACTION_MOVE;
 220
 221   // Filter the action based on the effectAllowed. If the effectAllowed
 222   // doesn't include the action, then that action cannot be done, so adjust
 223   // the action to something that is allowed. For a copy, adjust to move or
 224   // link. For a move, adjust to copy or link. For a link, adjust to move or
 225   // link. Otherwise, use none.
 226   if (aAction & aEffectAllowed ||
 227       aEffectAllowed == nsIDragService::DRAGDROP_ACTION_UNINITIALIZED)
 228     return aAction;
 229   if (aEffectAllowed & nsIDragService::DRAGDROP_ACTION_MOVE)
 230     return nsIDragService::DRAGDROP_ACTION_MOVE;
 231   if (aEffectAllowed & nsIDragService::DRAGDROP_ACTION_COPY)
 232     return nsIDragService::DRAGDROP_ACTION_COPY;
 233   if (aEffectAllowed & nsIDragService::DRAGDROP_ACTION_LINK)
 234     return nsIDragService::DRAGDROP_ACTION_LINK;
 235   return nsIDragService::DRAGDROP_ACTION_NONE;
 236 }
 237
 238 nsresult NS_NewDOMDragEvent(nsIDOMEvent** aInstancePtrResult,
 239                             nsPresContext* aPresContext,
 240                             nsDragEvent *aEvent)
 241 {
 242   nsDOMDragEvent* event = new nsDOMDragEvent(aPresContext, aEvent);
 243   NS_ENSURE_TRUE(event, NS_ERROR_OUT_OF_MEMORY);
 244
 245   return CallQueryInterface(event, aInstancePtrResult);
 246 }