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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 */
#ifndef mozilla_dom_DataTransfer_h
#define mozilla_dom_DataTransfer_h
#include "nsString.h"
#include "nsTArray.h"
#include "nsIVariant.h"
#include "nsIPrincipal.h"
#include "nsIDragService.h"
#include "nsITransferable.h"
#include "nsCycleCollectionParticipant.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/EventForwards.h"
#include "mozilla/dom/BindingDeclarations.h"
#include "mozilla/dom/DataTransferItemList.h"
#include "mozilla/dom/File.h"
class nsINode;
class nsITransferable;
class nsILoadContext;
namespace mozilla {
class EventStateManager;
namespace dom {
class DataTransferItem;
class DataTransferItemList;
class DOMStringList;
class Element;
class FileList;
class Promise;
template <typename T>
class Optional;
{ \
0x6c5f90d1, 0xa886, 0x42c8, { \
0x85, 0x06, 0x10, 0xbe, 0x5c, 0x0d, 0xc6, 0x77 \
} \
class DataTransfer final : public nsISupports, public nsWrapperCache {
friend class mozilla::EventStateManager;
/// An enum which represents which "Drag Data Store Mode" the DataTransfer is
/// in according to the spec.
enum class Mode : uint8_t {
// hide the default constructor
// this constructor is used only by the Clone method to copy the fields as
// needed to a new data transfer.
// NOTE: Do not call this method directly.
DataTransfer(nsISupports* aParent, EventMessage aEventMessage,
const uint32_t aEffectAllowed, bool aCursorState,
bool aIsExternal, bool aUserCancelled,
bool aIsCrossDomainSubFrameDrop, int32_t aClipboardType,
DataTransferItemList* aItems, Element* aDragImage,
uint32_t aDragImageX, uint32_t aDragImageY);
static const char sEffects[8][9];
// Constructor for DataTransfer.
// aIsExternal must only be true when used to create a dataTransfer for a
// paste, a drag or an input that was started without using a data transfer.
// The case of a drag will occur when an external drag occurs, that is, a
// drag where the source is another application, or a drag is started by
// calling the drag service directly. For clipboard operations,
// aClipboardType indicates which clipboard to use, from nsIClipboard, or -1
// for non-clipboard operations, or if access to the system clipboard should
// not be allowed.
DataTransfer(nsISupports* aParent, EventMessage aEventMessage,
bool aIsExternal, int32_t aClipboardType);
DataTransfer(nsISupports* aParent, EventMessage aEventMessage,
nsITransferable* aTransferable);
DataTransfer(nsISupports* aParent, EventMessage aEventMessage,
const nsAString& aString);
virtual JSObject* WrapObject(JSContext* aCx,
JS::Handle<JSObject*> aGivenProto) override;
nsISupports* GetParentObject() const { return mParent; }
void SetParentObject(nsISupports* aNewParent) {
// Setting the parent after we've been wrapped is pointless, so
// make sure we aren't wrapped yet.
mParent = aNewParent;
static already_AddRefed<DataTransfer> Constructor(
const GlobalObject& aGlobal);
* The actual effect that will be used, and should always be one of the
* possible values of effectAllowed.
* For dragstart, drag and dragleave events, the dropEffect is initialized
* to none. Any value assigned to the dropEffect will be set, but the value
* isn't used for anything.
* For the dragenter and dragover events, the dropEffect will be initialized
* based on what action the user is requesting. How this is determined is
* platform specific, but typically the user can press modifier keys to
* adjust which action is desired. Within an event handler for the dragenter
* and dragover events, the dropEffect should be modified if the action the
* user is requesting is not the one that is desired.
* For the drop and dragend events, the dropEffect will be initialized to
* the action that was desired, which will be the value that the dropEffect
* had after the last dragenter or dragover event.
* Possible values:
* copy - a copy of the source item is made at the new location
* move - an item is moved to a new location
* link - a link is established to the source at the new location
* none - the item may not be dropped
* Assigning any other value has no effect and retains the old value.
void GetDropEffect(nsAString& aDropEffect) {
void SetDropEffect(const nsAString& aDropEffect);
* Specifies the effects that are allowed for this drag. You may set this in
* the dragstart event to set the desired effects for the source, and within
* the dragenter and dragover events to set the desired effects for the
* target. The value is not used for other events.
* Possible values:
* copy - a copy of the source item is made at the new location
* move - an item is moved to a new location
* link - a link is established to the source at the new location
* copyLink, copyMove, linkMove, all - combinations of the above
* none - the item may not be dropped
* uninitialized - the default value when the effect has not been set,
* equivalent to all.
* Assigning any other value has no effect and retains the old value.
void GetEffectAllowed(nsAString& aEffectAllowed) {
if (mEffectAllowed == nsIDragService::DRAGDROP_ACTION_UNINITIALIZED) {
} else {
void SetEffectAllowed(const nsAString& aEffectAllowed);
* Set the image to be used for dragging if a custom one is desired. Most of
* the time, this would not be set, as a default image is created from the
* node that was dragged.
* If the node is an HTML img element, an HTML canvas element or a XUL image
* element, the image data is used. Otherwise, image should be a visible
* node and the drag image will be created from this. If image is null, any
* custom drag image is cleared and the default is used instead.
* The coordinates specify the offset into the image where the mouse cursor
* should be. To center the image for instance, use values that are half the
* width and height.
* @param image a node to use
* @param x the horizontal offset
* @param y the vertical offset
void SetDragImage(Element& aElement, int32_t aX, int32_t aY);
void UpdateDragImage(Element& aElement, int32_t aX, int32_t aY);
void GetTypes(nsTArray<nsString>& aTypes, CallerType aCallerType) const;
bool HasType(const nsAString& aType) const;
bool HasFile() const;
void GetData(const nsAString& aFormat, nsAString& aData,
nsIPrincipal& aSubjectPrincipal, ErrorResult& aRv) const;
void SetData(const nsAString& aFormat, const nsAString& aData,
nsIPrincipal& aSubjectPrincipal, ErrorResult& aRv);
void ClearData(const mozilla::dom::Optional<nsAString>& aFormat,
nsIPrincipal& aSubjectPrincipal, mozilla::ErrorResult& aRv);
* Holds a list of all the local files available on this data transfer.
* A dataTransfer containing no files will return an empty list, and an
* invalid index access on the resulting file list will return null.
already_AddRefed<FileList> GetFiles(nsIPrincipal& aSubjectPrincipal);
already_AddRefed<Promise> GetFilesAndDirectories(
nsIPrincipal& aSubjectPrincipal, mozilla::ErrorResult& aRv);
already_AddRefed<Promise> GetFiles(bool aRecursiveFlag,
nsIPrincipal& aSubjectPrincipal,
ErrorResult& aRv);
void AddElement(Element& aElement, mozilla::ErrorResult& aRv);
uint32_t MozItemCount() const;
void GetMozCursor(nsAString& aCursor) {
if (mCursorState) {
} else {
void SetMozCursor(const nsAString& aCursor);
already_AddRefed<DOMStringList> MozTypesAt(uint32_t aIndex,
CallerType aCallerType,
mozilla::ErrorResult& aRv) const;
void MozClearDataAt(const nsAString& aFormat, uint32_t aIndex,
nsIPrincipal& aSubjectPrincipal,
mozilla::ErrorResult& aRv);
void MozSetDataAt(JSContext* aCx, const nsAString& aFormat,
JS::Handle<JS::Value> aData, uint32_t aIndex,
nsIPrincipal& aSubjectPrincipal, mozilla::ErrorResult& aRv);
void MozGetDataAt(JSContext* aCx, const nsAString& aFormat, uint32_t aIndex,
JS::MutableHandle<JS::Value> aRetval,
nsIPrincipal& aSubjectPrincipal, mozilla::ErrorResult& aRv);
bool MozUserCancelled() const { return mUserCancelled; }
already_AddRefed<nsINode> GetMozSourceNode();
* Integer version of dropEffect, set to one of the constants in
* nsIDragService.
uint32_t DropEffectInt() const { return mDropEffect; }
void SetDropEffectInt(uint32_t aDropEffectInt) {
MOZ_RELEASE_ASSERT(aDropEffectInt < ArrayLength(sEffects),
"Bogus drop effect value");
mDropEffect = aDropEffectInt;
* Integer version of effectAllowed, set to one or a combination of the
* constants in nsIDragService.
uint32_t EffectAllowedInt() const { return mEffectAllowed; }
void GetMozTriggeringPrincipalURISpec(nsAString& aPrincipalURISpec);
nsIContentSecurityPolicy* GetMozCSP();
mozilla::dom::Element* GetDragTarget() const { return mDragTarget; }
nsresult GetDataAtNoSecurityCheck(const nsAString& aFormat, uint32_t aIndex,
nsIVariant** aData) const;
DataTransferItemList* Items() const { return mItems; }
// Returns the current "Drag Data Store Mode" of the DataTransfer. This
// determines what modifications may be performed on the DataTransfer, and
// what data may be read from it.
Mode GetMode() const { return mMode; }
void SetMode(Mode aMode);
// Helper method. Is true if the DataTransfer's mode is ReadOnly or Protected,
// which means that the DataTransfer cannot be modified.
bool IsReadOnly() const { return mMode != Mode::ReadWrite; }
// Helper method. Is true if the DataTransfer's mode is Protected, which means
// that DataTransfer type information may be read, but data may not be.
bool IsProtected() const { return mMode == Mode::Protected; }
nsITransferable* GetTransferable() const { return mTransferable; }
int32_t ClipboardType() const { return mClipboardType; }
EventMessage GetEventMessage() const { return mEventMessage; }
bool IsCrossDomainSubFrameDrop() const { return mIsCrossDomainSubFrameDrop; }
// converts the data into an array of nsITransferable objects to be used for
// drag and drop or clipboard operations.
already_AddRefed<nsIArray> GetTransferables(nsINode* aDragTarget);
already_AddRefed<nsIArray> GetTransferables(nsILoadContext* aLoadContext);
// converts the data for a single item at aIndex into an nsITransferable
// object.
already_AddRefed<nsITransferable> GetTransferable(
uint32_t aIndex, nsILoadContext* aLoadContext);
// converts the data in the variant to an nsISupportString if possible or
// an nsISupports or null otherwise.
bool ConvertFromVariant(nsIVariant* aVariant, nsISupports** aSupports,
uint32_t* aLength) const;
// Disconnects the DataTransfer from the Drag Data Store. If the
// dom.dataTransfer.disconnect pref is enabled, this will clear the
// DataTransfer and set it to the `Protected` state, otherwise this method is
// a no-op.
void Disconnect();
// clears all of the data
void ClearAll();
// Similar to SetData except also specifies the principal to store.
// aData may be null when called from CacheExternalDragFormats or
// CacheExternalClipboardFormats.
nsresult SetDataWithPrincipal(const nsAString& aFormat, nsIVariant* aData,
uint32_t aIndex, nsIPrincipal* aPrincipal,
bool aHidden = false);
// Variation of SetDataWithPrincipal with handles extracting
// kCustomTypesMime data into separate types.
void SetDataWithPrincipalFromOtherProcess(const nsAString& aFormat,
nsIVariant* aData, uint32_t aIndex,
nsIPrincipal* aPrincipal,
bool aHidden);
// returns a weak reference to the drag image
Element* GetDragImage(int32_t* aX, int32_t* aY) const {
*aX = mDragImageX;
*aY = mDragImageY;
return mDragImage;
// This method makes a copy of the DataTransfer object, with a few properties
// changed, and the mode updated to reflect the correct mode for the given
// event. This method is used during the drag operation to generate the
// DataTransfer objects for each event after `dragstart`. Event objects will
// lazily clone the DataTransfer stored in the DragSession (which is a clone
// of the DataTransfer used in the `dragstart` event) when requested.
nsresult Clone(nsISupports* aParent, EventMessage aEventMessage,
bool aUserCancelled, bool aIsCrossDomainSubFrameDrop,
DataTransfer** aResult);
// converts some formats used for compatibility in aInFormat into aOutFormat.
// Text and text/unicode become text/plain, and URL becomes text/uri-list
void GetRealFormat(const nsAString& aInFormat, nsAString& aOutFormat) const;
static bool PrincipalMaySetData(const nsAString& aFormat, nsIVariant* aData,
nsIPrincipal* aPrincipal);
// Notify the DataTransfer that the list returned from GetTypes may have
// changed. This can happen due to items we care about for purposes of
// GetTypes being added or removed or changing item kinds.
void TypesListMayHaveChanged();
// Testing method used to emulate internal DataTransfer management.
// NOTE: Please don't use this. See the comments in the webidl for more.
already_AddRefed<DataTransfer> MozCloneForEvent(const nsAString& aEvent,
ErrorResult& aRv);
// Retrieve a list of clipboard formats supported
// If kFileMime is supported, then it will be placed either at
// index 0 or at index 1 in aResult
static void GetExternalClipboardFormats(const int32_t& aWhichClipboard,
const bool& aPlainTextOnly,
nsTArray<nsCString>* aResult);
// Retrieve a list of supporting formats in aTransferable.
// If kFileMime is supported, then it will be placed either at
// index 0 or at index 1 in aResult
static void GetExternalTransferableFormats(nsITransferable* aTransferable,
bool aPlainTextOnly,
nsTArray<nsCString>* aResult);
// caches text and uri-list data formats that exist in the drag service or
// clipboard for retrieval later.
nsresult CacheExternalData(const char* aFormat, uint32_t aIndex,
nsIPrincipal* aPrincipal, bool aHidden);
// caches the formats that exist in the drag service that were added by an
// external drag
void CacheExternalDragFormats();
// caches the formats that exist in the clipboard
void CacheExternalClipboardFormats(bool aPlainTextOnly);
// caches the formats that exist in mTransferable
void CacheTransferableFormats();
// caches the formats specified by aTypes.
void CacheExternalData(const nsTArray<nsCString>& aTypes,
nsIPrincipal* aPrincipal);
FileList* GetFilesInternal(ErrorResult& aRv, nsIPrincipal* aSubjectPrincipal);
nsresult GetDataAtInternal(const nsAString& aFormat, uint32_t aIndex,
nsIPrincipal* aSubjectPrincipal,
nsIVariant** aData) const;
nsresult SetDataAtInternal(const nsAString& aFormat, nsIVariant* aData,
uint32_t aIndex, nsIPrincipal* aSubjectPrincipal);
friend class ContentParent;
friend class Clipboard;
void FillAllExternalData();
void FillInExternalCustomTypes(uint32_t aIndex, nsIPrincipal* aPrincipal);
void FillInExternalCustomTypes(nsIVariant* aData, uint32_t aIndex,
nsIPrincipal* aPrincipal);
void MozClearDataAtHelper(const nsAString& aFormat, uint32_t aIndex,
nsIPrincipal& aSubjectPrincipal,
mozilla::ErrorResult& aRv);
nsCOMPtr<nsISupports> mParent;
// If DataTransfer is initialized with an instance of nsITransferable, it's
// grabbed with this member **until** the constructor fills all data of all
// items.
nsCOMPtr<nsITransferable> mTransferable;
// the drop effect and effect allowed
uint32_t mDropEffect;
uint32_t mEffectAllowed;
// the event message this data transfer is for. This will correspond to an
// event->mMessage value.
EventMessage mEventMessage;
// Indicates the behavior of the cursor during drag operations
bool mCursorState;
// The current "Drag Data Store Mode" which the DataTransfer is in.
Mode mMode;
// true for drags started without a data transfer, for example, those from
// another application.
bool mIsExternal;
// true if the user cancelled the drag. Used only for the dragend event.
bool mUserCancelled;
// true if this is a cross-domain drop from a subframe where access to the
// data should be prevented
bool mIsCrossDomainSubFrameDrop;
// Indicates which clipboard type to use for clipboard operations. Ignored for
// drag and drop.
int32_t mClipboardType;
// The items contained with the DataTransfer
RefPtr<DataTransferItemList> mItems;
// the target of the drag. The drag and dragend events will fire at this.
nsCOMPtr<mozilla::dom::Element> mDragTarget;
// the custom drag image and coordinates within the image. If mDragImage is
// null, the default image is created from the drag target.
nsCOMPtr<mozilla::dom::Element> mDragImage;
uint32_t mDragImageX;
uint32_t mDragImageY;
} // namespace dom
} // namespace mozilla
#endif /* mozilla_dom_DataTransfer_h */