content/events/public/nsEventDispatcher.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* ***** BEGIN LICENSE BLOCK *****
   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
   9  *
  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12  * for the specific language governing rights and limitations under the
  13  * License.
  14  *
  15  * The Original Code is mozilla.org code.
  16  *
  17  * The Initial Developer of the Original Code is
  18  * Olli Pettay (Olli.Pettay@helsinki.fi)
  19  * Portions created by the Initial Developer are Copyright (C) 2006
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *
  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"),
  26  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  27  * in which case the provisions of the GPL or the LGPL are applicable instead
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  33  * the provisions above, a recipient may use your version of this file under
  34  * the terms of any one of the MPL, the GPL or the LGPL.
  35  *
  36  * ***** END LICENSE BLOCK ***** */
  37
  38 #ifdef MOZILLA_INTERNAL_API
  39 #ifndef nsEventDispatcher_h___
  40 #define nsEventDispatcher_h___
  41
  42 #include "nsGUIEvent.h"
  43
  44 class nsIContent;
  45 class nsIDocument;
  46 class nsPresContext;
  47 class nsPIDOMEventTarget;
  48 class nsIScriptGlobalObject;
  49 class nsEventTargetChainItem;
  50
  51
  52 /**
  53  * About event dispatching:
  54  * When either nsEventDispatcher::Dispatch or
  55  * nsEventDispatcher::DispatchDOMEvent is called an event target chain is
  56  * created. nsEventDispatcher creates the chain by calling PreHandleEvent
  57  * on each event target and the creation continues until either the mCanHandle
  58  * member of the nsEventChainPreVisitor object is PR_FALSE or the mParentTarget
  59  * does not point to a new target. The event target chain is created in the
  60  * heap.
  61  *
  62  * If the event needs retargeting, mEventTargetAtParent must be set in
  63  * PreHandleEvent.
  64  *
  65  * The capture, target and bubble phases of the event dispatch are handled
  66  * by iterating through the event target chain. Iteration happens twice,
  67  * first for the default event group and then for the system event group.
  68  * While dispatching the event for the system event group PostHandleEvent
  69  * is called right after calling event listener for the current event target.
  70  */
  71
  72 class nsEventChainVisitor {
  73 public:
  74   nsEventChainVisitor(nsPresContext* aPresContext,
  75                       nsEvent* aEvent,
  76                       nsIDOMEvent* aDOMEvent,
  77                       nsEventStatus aEventStatus = nsEventStatus_eIgnore)
  78   : mPresContext(aPresContext), mEvent(aEvent), mDOMEvent(aDOMEvent),
  79     mEventStatus(aEventStatus), mItemFlags(0)
  80   {}
  81
  82   /**
  83    * The prescontext, possibly nsnull.
  84    */
  85   nsPresContext* const  mPresContext;
  86
  87   /**
  88    * The nsEvent which is being dispatched. Never nsnull.
  89    */
  90   nsEvent* const        mEvent;
  91
  92   /**
  93    * The DOM Event assiciated with the mEvent. Possibly nsnull if a DOM Event
  94    * is not (yet) created.
  95    */
  96   nsIDOMEvent*          mDOMEvent;
  97
  98   /**
  99    * The status of the event.
 100    * @see nsEventStatus.h
 101    */
 102   nsEventStatus         mEventStatus;
 103
 104   /**
 105    * Bits for items in the event target chain.
 106    * Set in PreHandleEvent() and used in PostHandleEvent().
 107    *
 108    * @note These bits are different for each item in the event target chain.
 109    *       It is up to the Pre/PostHandleEvent implementation to decide how to
 110    *       use these bits.
 111    *
 112    * @note Using PRUint16 because that is used also in nsEventTargetChainItem.
 113    */
 114   PRUint16              mItemFlags;
 115
 116   /**
 117    * Data for items in the event target chain.
 118    * Set in PreHandleEvent() and used in PostHandleEvent().
 119    *
 120    * @note This data is different for each item in the event target chain.
 121    *       It is up to the Pre/PostHandleEvent implementation to decide how to
 122    *       use this.
 123    */
 124   nsCOMPtr<nsISupports> mItemData;
 125 };
 126
 127 class nsEventChainPreVisitor : public nsEventChainVisitor {
 128 public:
 129   nsEventChainPreVisitor(nsPresContext* aPresContext,
 130                          nsEvent* aEvent,
 131                          nsIDOMEvent* aDOMEvent,
 132                          nsEventStatus aEventStatus = nsEventStatus_eIgnore)
 133   : nsEventChainVisitor(aPresContext, aEvent, aDOMEvent, aEventStatus),
 134     mCanHandle(PR_TRUE), mForceContentDispatch(PR_FALSE),
 135     mRelatedTargetIsInAnon(PR_FALSE), mWantsWillHandleEvent(PR_FALSE),
 136     mParentTarget(nsnull), mEventTargetAtParent(nsnull) {}
 137
 138   void Reset() {
 139     mItemFlags = 0;
 140     mItemData = nsnull;
 141     mCanHandle = PR_TRUE;
 142     mForceContentDispatch = PR_FALSE;
 143     mWantsWillHandleEvent = PR_FALSE;
 144     mParentTarget = nsnull;
 145     mEventTargetAtParent = nsnull;
 146   }
 147
 148   /**
 149    * Member that must be set in PreHandleEvent by event targets. If set to false,
 150    * indicates that this event target will not be handling the event and
 151    * construction of the event target chain is complete. The target that sets
 152    * mCanHandle to false is NOT included in the event target chain.
 153    */
 154   PRPackedBool          mCanHandle;
 155
 156   /**
 157    * If mForceContentDispatch is set to PR_TRUE,
 158    * content dispatching is not disabled for this event target.
 159    * FIXME! This is here for backward compatibility. Bug 329119
 160    */
 161   PRPackedBool          mForceContentDispatch;
 162
 163   /**
 164    * PR_TRUE if it is known that related target is or is a descendant of an
 165    * element which is anonymous for events.
 166    */
 167   PRPackedBool          mRelatedTargetIsInAnon;
 168
 169
 170   /**
 171    * Whether or not nsPIDOMEventTarget::WillHandleEvent will be
 172    * called. Default is PR_FALSE;
 173    */
 174   PRPackedBool          mWantsWillHandleEvent;
 175
 176   /**
 177    * Parent item in the event target chain.
 178    */
 179   nsPIDOMEventTarget*   mParentTarget;
 180
 181   /**
 182    * If the event needs to be retargeted, this is the event target,
 183    * which should be used when the event is handled at mParentTarget.
 184    */
 185   nsPIDOMEventTarget*   mEventTargetAtParent;
 186 };
 187
 188 class nsEventChainPostVisitor : public nsEventChainVisitor {
 189 public:
 190   nsEventChainPostVisitor(nsEventChainVisitor& aOther)
 191   : nsEventChainVisitor(aOther.mPresContext, aOther.mEvent, aOther.mDOMEvent,
 192                         aOther.mEventStatus)
 193   {}
 194 };
 195
 196 /**
 197  * If an nsDispatchingCallback object is passed to Dispatch,
 198  * its HandleEvent method is called after handling the default event group,
 199  * before handling the system event group.
 200  * This is used in nsPresShell.
 201  */
 202 class NS_STACK_CLASS nsDispatchingCallback {
 203 public:
 204   virtual void HandleEvent(nsEventChainPostVisitor& aVisitor) = 0;
 205 };
 206
 207 /**
 208  * The generic class for event dispatching.
 209  * Must not be used outside Gecko!
 210  */
 211 class nsEventDispatcher
 212 {
 213 public:
 214   /**
 215    * aTarget should QI to nsPIDOMEventTarget.
 216    * If the target of aEvent is set before calling this method, the target of
 217    * aEvent is used as the target (unless there is event
 218    * retargeting) and the originalTarget of the DOM Event.
 219    * aTarget is always used as the starting point for constructing the event
 220    * target chain, no matter what the value of aEvent->target is.
 221    * In other words, aEvent->target is only a property of the event and it has
 222    * nothing to do with the construction of the event target chain.
 223    * Neither aTarget nor aEvent is allowed to be nsnull.
 224    * @note Use this method when dispatching an nsEvent.
 225    */
 226   static nsresult Dispatch(nsISupports* aTarget,
 227                            nsPresContext* aPresContext,
 228                            nsEvent* aEvent,
 229                            nsIDOMEvent* aDOMEvent = nsnull,
 230                            nsEventStatus* aEventStatus = nsnull,
 231                            nsDispatchingCallback* aCallback = nsnull);
 232
 233   /**
 234    * Dispatches an event.
 235    * If aDOMEvent is not nsnull, it is used for dispatching
 236    * (aEvent can then be nsnull) and (if aDOMEvent is not |trusted| already),
 237    * the |trusted| flag is set based on the UniversalBrowserWrite capability.
 238    * Otherwise this works like nsEventDispatcher::Dispatch.
 239    * @note Use this method when dispatching nsIDOMEvent.
 240    */
 241   static nsresult DispatchDOMEvent(nsISupports* aTarget,
 242                                    nsEvent* aEvent, nsIDOMEvent* aDOMEvent,
 243                                    nsPresContext* aPresContext,
 244                                    nsEventStatus* aEventStatus);
 245
 246   /**
 247    * Creates a DOM Event.
 248    */
 249   static nsresult CreateEvent(nsPresContext* aPresContext,
 250                               nsEvent* aEvent,
 251                               const nsAString& aEventType,
 252                               nsIDOMEvent** aDOMEvent);
 253
 254 };
 255
 256 #endif
 257 #endif