dom/events/JSEventHandler.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_JSEventHandler_h_
   8 #define mozilla_JSEventHandler_h_
   9
  10 #include "mozilla/Attributes.h"
  11 #include "mozilla/MemoryReporting.h"
  12 #include "mozilla/dom/EventHandlerBinding.h"
  13 #include "nsCOMPtr.h"
  14 #include "nsCycleCollectionParticipant.h"
  15 #include "nsAtom.h"
  16 #include "nsIDOMEventListener.h"
  17 #include "nsIScriptContext.h"
  18
  19 namespace mozilla {
  20
  21 class TypedEventHandler {
  22  public:
  23   enum HandlerType {
  24     eUnset = 0,
  25     eNormal = 0x1,
  26     eOnError = 0x2,
  27     eOnBeforeUnload = 0x3,
  28     eTypeBits = 0x3
  29   };
  30
  31   TypedEventHandler() : mBits(0) {}
  32
  33   explicit TypedEventHandler(dom::EventHandlerNonNull* aHandler) : mBits(0) {
  34     Assign(aHandler, eNormal);
  35   }
  36
  37   explicit TypedEventHandler(dom::OnErrorEventHandlerNonNull* aHandler)
  38       : mBits(0) {
  39     Assign(aHandler, eOnError);
  40   }
  41
  42   explicit TypedEventHandler(dom::OnBeforeUnloadEventHandlerNonNull* aHandler)
  43       : mBits(0) {
  44     Assign(aHandler, eOnBeforeUnload);
  45   }
  46
  47   TypedEventHandler(const TypedEventHandler& aOther) {
  48     if (aOther.HasEventHandler()) {
  49       // Have to make sure we take our own ref
  50       Assign(aOther.Ptr(), aOther.Type());
  51     } else {
  52       mBits = 0;
  53     }
  54   }
  55
  56   ~TypedEventHandler() { ReleaseHandler(); }
  57
  58   HandlerType Type() const { return HandlerType(mBits & eTypeBits); }
  59
  60   bool HasEventHandler() const { return !!Ptr(); }
  61
  62   void SetHandler(const TypedEventHandler& aHandler) {
  63     if (aHandler.HasEventHandler()) {
  64       ReleaseHandler();
  65       Assign(aHandler.Ptr(), aHandler.Type());
  66     } else {
  67       ForgetHandler();
  68     }
  69   }
  70
  71   dom::EventHandlerNonNull* NormalEventHandler() const {
  72     MOZ_ASSERT(Type() == eNormal && Ptr());
  73     return reinterpret_cast<dom::EventHandlerNonNull*>(Ptr());
  74   }
  75
  76   void SetHandler(dom::EventHandlerNonNull* aHandler) {
  77     ReleaseHandler();
  78     Assign(aHandler, eNormal);
  79   }
  80
  81   dom::OnBeforeUnloadEventHandlerNonNull* OnBeforeUnloadEventHandler() const {
  82     MOZ_ASSERT(Type() == eOnBeforeUnload);
  83     return reinterpret_cast<dom::OnBeforeUnloadEventHandlerNonNull*>(Ptr());
  84   }
  85
  86   void SetHandler(dom::OnBeforeUnloadEventHandlerNonNull* aHandler) {
  87     ReleaseHandler();
  88     Assign(aHandler, eOnBeforeUnload);
  89   }
  90
  91   dom::OnErrorEventHandlerNonNull* OnErrorEventHandler() const {
  92     MOZ_ASSERT(Type() == eOnError);
  93     return reinterpret_cast<dom::OnErrorEventHandlerNonNull*>(Ptr());
  94   }
  95
  96   void SetHandler(dom::OnErrorEventHandlerNonNull* aHandler) {
  97     ReleaseHandler();
  98     Assign(aHandler, eOnError);
  99   }
 100
 101   dom::CallbackFunction* Ptr() const {
 102     // Have to cast eTypeBits so we don't have to worry about
 103     // promotion issues after the bitflip.
 104     return reinterpret_cast<dom::CallbackFunction*>(mBits &
 105                                                     ~uintptr_t(eTypeBits));
 106   }
 107
 108   void ForgetHandler() {
 109     ReleaseHandler();
 110     mBits = 0;
 111   }
 112
 113   bool operator==(const TypedEventHandler& aOther) const {
 114     return Ptr() && aOther.Ptr() &&
 115            Ptr()->CallbackPreserveColor() ==
 116                aOther.Ptr()->CallbackPreserveColor();
 117   }
 118
 119  private:
 120   void operator=(const TypedEventHandler&) = delete;
 121
 122   void ReleaseHandler() {
 123     nsISupports* ptr = Ptr();
 124     NS_IF_RELEASE(ptr);
 125   }
 126
 127   void Assign(nsISupports* aHandler, HandlerType aType) {
 128     MOZ_ASSERT(aHandler, "Must have handler");
 129     NS_ADDREF(aHandler);
 130     mBits = uintptr_t(aHandler) | uintptr_t(aType);
 131   }
 132
 133   uintptr_t mBits;
 134 };
 135
 136 /**
 137  * Implemented by script event listeners. Used to retrieve the script object
 138  * corresponding to the event target and the handler itself.
 139  *
 140  * Note, mTarget is a raw pointer and the owner of the JSEventHandler object
 141  * is expected to call Disconnect()!
 142  */
 143
 144 #define NS_JSEVENTHANDLER_IID                        \
 145   {                                                  \
 146     0x4f486881, 0x1956, 0x4079, {                    \
 147       0x8c, 0xa0, 0xf3, 0xbd, 0x60, 0x5c, 0xc2, 0x79 \
 148     }                                                \
 149   }
 150
 151 class JSEventHandler : public nsIDOMEventListener {
 152  public:
 153   NS_DECLARE_STATIC_IID_ACCESSOR(NS_JSEVENTHANDLER_IID)
 154
 155   JSEventHandler(nsISupports* aTarget, nsAtom* aType,
 156                  const TypedEventHandler& aTypedHandler);
 157
 158   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
 159
 160   // nsIDOMEventListener interface
 161   NS_DECL_NSIDOMEVENTLISTENER
 162
 163   nsISupports* GetEventTarget() const { return mTarget; }
 164
 165   void Disconnect() { mTarget = nullptr; }
 166
 167   const TypedEventHandler& GetTypedEventHandler() const {
 168     return mTypedHandler;
 169   }
 170
 171   void ForgetHandler() { mTypedHandler.ForgetHandler(); }
 172
 173   nsAtom* EventName() const { return mEventName; }
 174
 175   // Set a handler for this event listener.  The handler must already
 176   // be bound to the right target.
 177   void SetHandler(const TypedEventHandler& aTypedHandler) {
 178     mTypedHandler.SetHandler(aTypedHandler);
 179   }
 180   void SetHandler(dom::EventHandlerNonNull* aHandler) {
 181     mTypedHandler.SetHandler(aHandler);
 182   }
 183   void SetHandler(dom::OnBeforeUnloadEventHandlerNonNull* aHandler) {
 184     mTypedHandler.SetHandler(aHandler);
 185   }
 186   void SetHandler(dom::OnErrorEventHandlerNonNull* aHandler) {
 187     mTypedHandler.SetHandler(aHandler);
 188   }
 189
 190   size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
 191     return 0;
 192
 193     // Measurement of the following members may be added later if DMD finds it
 194     // is worthwhile:
 195     // - mTarget
 196     //
 197     // The following members are not measured:
 198     // - mTypedHandler: may be shared with others
 199     // - mEventName: shared with others
 200   }
 201
 202   size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) {
 203     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
 204   }
 205
 206   NS_DECL_CYCLE_COLLECTION_SKIPPABLE_CLASS(JSEventHandler)
 207
 208   bool IsBlackForCC();
 209
 210  protected:
 211   virtual ~JSEventHandler();
 212
 213   nsISupports* mTarget;
 214   RefPtr<nsAtom> mEventName;
 215   TypedEventHandler mTypedHandler;
 216 };
 217
 218 NS_DEFINE_STATIC_IID_ACCESSOR(JSEventHandler, NS_JSEVENTHANDLER_IID)
 219
 220 }  // namespace mozilla
 221
 222 /**
 223  * Factory function.  aHandler must already be bound to aTarget.
 224  * aContext is allowed to be null if aHandler is already set up.
 225  */
 226 nsresult NS_NewJSEventHandler(nsISupports* aTarget, nsAtom* aType,
 227                               const mozilla::TypedEventHandler& aTypedHandler,
 228                               mozilla::JSEventHandler** aReturn);
 229
 230 #endif  // mozilla_JSEventHandler_h_