content/events/src/nsDOMDataTransfer.h

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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
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  21  * Contributor(s):
  22  *   Neil Deakin <enndeakin@gmail.com>
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  36  * ***** END LICENSE BLOCK ***** */
  37
  38 #ifndef nsDOMDataTransfer_h__
  39 #define nsDOMDataTransfer_h__
  40
  41 #include "nsString.h"
  42 #include "nsTArray.h"
  43 #include "nsIVariant.h"
  44 #include "nsIPrincipal.h"
  45 #include "nsIDOMDataTransfer.h"
  46 #include "nsIDragService.h"
  47 #include "nsIDOMElement.h"
  48 #include "nsCycleCollectionParticipant.h"
  49
  50 class nsITransferable;
  51
  52 /**
  53  * TransferItem is used to hold data for a particular format. Each piece of
  54  * data has a principal set from the caller which added it. This allows a
  55  * caller that wishes to retrieve the data to only be able to access the data
  56  * it is allowed to, yet still allow a chrome caller to retrieve any of the
  57  * data.
  58  */
  59 struct TransferItem {
  60   nsString mFormat;
  61   nsCOMPtr<nsIPrincipal> mPrincipal;
  62   nsCOMPtr<nsIVariant> mData;
  63 };
  64
  65 class nsDOMDataTransfer : public nsIDOMDataTransfer,
  66                           public nsIDOMNSDataTransfer
  67 {
  68 public:
  69   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  70   NS_DECL_NSIDOMDATATRANSFER
  71   NS_DECL_NSIDOMNSDATATRANSFER
  72
  73   NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(nsDOMDataTransfer, nsIDOMDataTransfer)
  74
  75   friend class nsDOMDragEvent;
  76   friend class nsEventStateManager;
  77
  78 protected:
  79
  80   // the constructors are protected so only our friends can call them
  81
  82   // default constructor used for the dragstart/draggesture event and
  83   // synthetic events
  84   nsDOMDataTransfer();
  85
  86   // this constructor must only be used to create a dataTransfer for a drag
  87   // that was started without using a data transfer, either an external drag,
  88   // that is, a drag where the source is another application, or a drag
  89   // started by calling the drag service directly.
  90   nsDOMDataTransfer(PRUint32 aEventType, PRUint32 aAction);
  91
  92   // this constructor is used only by the Clone method to copy the fields as
  93   // needed to a new data transfer.
  94   nsDOMDataTransfer(PRUint32 aEventType,
  95                     const PRUint32 aEffectAllowed,
  96                     PRBool aIsExternal,
  97                     nsTArray<nsTArray<TransferItem> >& aItems,
  98                     nsIDOMElement* aDragImage,
  99                     PRUint32 aDragImageX,
 100                     PRUint32 aDragImageY);
 101
 102   static const char sEffects[8][9];
 103
 104 public:
 105
 106   void GetDragTarget(nsIDOMElement** aDragTarget)
 107   {
 108     *aDragTarget = mDragTarget;
 109     NS_IF_ADDREF(*aDragTarget);
 110   }
 111
 112   // a readonly dataTransfer cannot have new data added or existing data removed.
 113   // Only the dropEffect and effectAllowed may be modified.
 114   void SetReadOnly() { mReadOnly = PR_TRUE; }
 115
 116   // converts the data into an array of nsITransferable objects to be used for
 117   // drag and drop or clipboard operations.
 118   void GetTransferables(nsISupportsArray** transferables);
 119
 120   // converts the data in the variant to an nsISupportString if possible or
 121   // an nsISupports or null otherwise.
 122   PRBool ConvertFromVariant(nsIVariant* aVariant,
 123                             nsISupports** aSupports,
 124                             PRUint32* aLength);
 125
 126   // clears all of the data
 127   void ClearAll();
 128
 129   // Similar to SetData except also specifies the principal to store.
 130   // aData may be null when called from CacheExternalFormats.
 131   nsresult SetDataWithPrincipal(const nsAString& aFormat,
 132                                 nsIVariant* aData,
 133                                 PRUint32 aIndex,
 134                                 nsIPrincipal* aPrincipal);
 135
 136 protected:
 137
 138   // returns a weak reference to the drag image
 139   nsIDOMElement* GetDragImage(PRInt32* aX, PRInt32* aY)
 140   {
 141     *aX = mDragImageX;
 142     *aY = mDragImageY;
 143     return mDragImage;
 144   }
 145
 146   // returns a weak reference to the current principal
 147   nsIPrincipal* GetCurrentPrincipal();
 148
 149   // converts some formats used for compatibility in aInFormat into aOutFormat.
 150   // Text and text/unicode become text/plain, and URL becomes text/uri-list
 151   void GetRealFormat(const nsAString& aInFormat, nsAString& aOutFormat);
 152
 153   // caches the formats that exist in the drag service that were added by an
 154   // external drag
 155   void CacheExternalFormats();
 156
 157   // fills in the data field of aItem with the data from the drag service for
 158   // a given index.
 159   void FillInExternalDragData(TransferItem& aItem, PRUint32 aIndex);
 160
 161   // the event type this data transfer is for. This will correspond to an
 162   // event->message value.
 163   PRUint32 mEventType;
 164
 165   // the drop effect and effect allowed
 166   PRUint32 mDropEffect;
 167   PRUint32 mEffectAllowed;
 168
 169   // readonly data transfers may not be modified except the drop effect and
 170   // effect allowed.
 171   PRPackedBool mReadOnly;
 172
 173   // true for drags started without a data transfer, for example, those from
 174   // another application.
 175   PRPackedBool mIsExternal;
 176
 177   // array of items, each containing an array of format->data pairs
 178   nsTArray<nsTArray<TransferItem> > mItems;
 179
 180   // the target of the drag. The drag and dragend events will fire at this.
 181   nsCOMPtr<nsIDOMElement> mDragTarget;
 182
 183   // the custom drag image and coordinates within the image. If mDragImage is
 184   // null, the default image is created from the drag target.
 185   nsCOMPtr<nsIDOMElement> mDragImage;
 186   PRUint32 mDragImageX;
 187   PRUint32 mDragImageY;
 188 };
 189
 190 #endif // nsDOMDataTransfer_h__
 191