gecko/content/events/public/nsPIDOMEventTarget.h

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 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
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 *
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 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla.org code.
 *
 * The Initial Developer of the Original Code is Mozilla.org.
 * Portions created by the Initial Developer are Copyright (C) 2006
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 *
 * Contributor(s):
 *     Olli Pettay <Olli.Pettay@helsinki.fi> (Original Author)
 *
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 * either the GNU General Public License Version 2 or later (the "GPL"), or
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#ifndef nsPIDOMEventTarget_h_
#define nsPIDOMEventTarget_h_

#include "nsISupports.h"
#include "nsEvent.h"

class nsIDOMEvent;
class nsPresContext;
class nsEventChainPreVisitor;
class nsEventChainPostVisitor;
class nsIEventListenerManager;
class nsIDOMEventListener;
class nsIDOMEventGroup;
class nsIScriptContext;
struct JSContext;

// 89292f3a-535d-4ba0-882a-10cff9e21bcc
#define NS_PIDOMEVENTTARGET_IID \
  { 0x89292f3a, 0x535d, 0x4ba0, \
    { 0x88, 0x2a, 0x10, 0xcf, 0xf9, 0xe2, 0x1b, 0xcc } }

class nsPIDOMEventTarget : public nsISupports
{
public:
  NS_DECLARE_STATIC_IID_ACCESSOR(NS_PIDOMEVENTTARGET_IID)

  /**
   * Returns the nsPIDOMEventTarget object which should be used as the target
   * of DOMEvents.
   * Usually |this| is returned, but for example global object returns
   * the outer object.
   */
   virtual nsPIDOMEventTarget* GetTargetForDOMEvent() { return this; }

  /**
   * Returns the nsPIDOMEventTarget object which should be used as the target
   * of the event and when constructing event target chain.
   * Usually |this| is returned, but for example global object returns
   * the inner object.
   */
   virtual nsPIDOMEventTarget* GetTargetForEventTargetChain() { return this; }

  /**
   * Called before the capture phase of the event flow.
   * This is used to create the event target chain and implementations
   * should set the necessary members of nsEventChainPreVisitor.
   * At least aVisitor.mCanHandle must be set,
   * usually also aVisitor.mParentTarget if mCanHandle is PR_TRUE.
   * First one tells that this object can handle the aVisitor.mEvent event and
   * the latter one is the possible parent object for the event target chain.
   * @see nsEventDispatcher.h for more documentation about aVisitor.
   *
   * @param aVisitor the visitor object which is used to create the
   *                 event target chain for event dispatching.
   *
   * @note Only nsEventDispatcher should call this method.
   */
  virtual nsresult PreHandleEvent(nsEventChainPreVisitor& aVisitor) = 0;

  /**
   * If nsEventChainPreVisitor.mWantsWillHandleEvent is set PR_TRUE,
   * called just before possible event handlers on this object will be called.
   */
  virtual nsresult WillHandleEvent(nsEventChainPostVisitor& aVisitor)
  {
    return NS_OK;
  }

  /**
   * Called after the bubble phase of the system event group.
   * The default handling of the event should happen here.
   * @param aVisitor the visitor object which is used during post handling.
   *
   * @see nsEventDispatcher.h for documentation about aVisitor.
   * @note Only nsEventDispatcher should call this method.
   */
  virtual nsresult PostHandleEvent(nsEventChainPostVisitor& aVisitor) = 0;

  /**
   * Dispatch an event.
   * @param aEvent the event that is being dispatched.
   * @param aDOMEvent the event that is being dispatched, use if you want to
   *                  dispatch nsIDOMEvent, not only nsEvent.
   * @param aPresContext the current presentation context, can be nsnull.
   * @param aEventStatus the status returned from the function, can be nsnull.
   *
   * @note If both aEvent and aDOMEvent are used, aEvent must be the internal
   *       event of the aDOMEvent.
   *
   * If aDOMEvent is not nsnull (in which case aEvent can be nsnull) it is used
   * for dispatching, otherwise aEvent is used.
   *
   * @deprecated This method is here just until all the callers outside Gecko
   *             have been converted to use nsIDOMEventTarget::dispatchEvent.
   */
  virtual nsresult DispatchDOMEvent(nsEvent* aEvent,
                                    nsIDOMEvent* aDOMEvent,
                                    nsPresContext* aPresContext,
                                    nsEventStatus* aEventStatus) = 0;

  /**
   * Get the event listener manager, the guy you talk to to register for events
   * on this node.
   * @param aMayCreate If PR_FALSE, returns a listener manager only if
   *                   one already exists.
   */
  virtual nsIEventListenerManager* GetListenerManager(PRBool aMayCreate) = 0;

  /**
   * Add an event listener for nsIID.
   */
  virtual nsresult AddEventListenerByIID(nsIDOMEventListener *aListener,
                                         const nsIID& aIID) = 0;
  /**
   * Remove event listener for nsIID.
   */
  virtual nsresult RemoveEventListenerByIID(nsIDOMEventListener *aListener,
                                            const nsIID& aIID) = 0;
  
  /**
   * Get the system event group.
   */
  virtual nsresult GetSystemEventGroup(nsIDOMEventGroup** aGroup) = 0;

  /**
   * Get the script context in which the event handlers should be run.
   * May return null.
   * @note Caller *must* check the value of aRv.
   */
  virtual nsIScriptContext* GetContextForEventHandlers(nsresult* aRv) = 0;

  /**
   * If the method above returns null, but a success code, this method
   * is called.
   */
   virtual JSContext* GetJSContextForEventHandlers() { return nsnull; }
};

NS_DEFINE_STATIC_IID_ACCESSOR(nsPIDOMEventTarget, NS_PIDOMEVENTTARGET_IID)

#endif // !defined(nsPIDOMEventTarget_h_)