pjs/dom/public/nsIJSEventListener.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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* The Original Code is mozilla.org code.
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#ifndef nsIJSEventListener_h__
#define nsIJSEventListener_h__
#include "nsIScriptContext.h"
class nsIScriptObjectOwner;
class nsIDOMEventListener;
class nsIAtom;
#define NS_IJSEVENTLISTENER_IID \
{ 0xa6cf9118, 0x15b3, 0x11d2, \
{0x93, 0x2e, 0x00, 0x80, 0x5f, 0x8a, 0xdd, 0x32} }
// Implemented by script event listeners. Used to retrieve the
// script object corresponding to the event target.
// (Note this interface is now used to store script objects for all
// script languages, so is no longer JS specific)
class nsIJSEventListener : public nsISupports
{
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IJSEVENTLISTENER_IID)
nsIJSEventListener(nsIScriptContext *aContext, void *aScopeObject,
nsISupports *aTarget)
: mContext(aContext), mScopeObject(aScopeObject), mTarget(nsnull)
{
// We keep a weak-ref to the event target to prevent cycles that prevent
// GC from cleaning up our global in all cases. However, as this is a
// weak-ref, we must ensure it is the identity of the event target and
// not a "tear-off" or similar that may not live as long as we expect.
aTarget->QueryInterface(NS_GET_IID(nsISupports),
NS_REINTERPRET_CAST(void **, &mTarget));
if (mTarget)
// We keep a weak-ref, so remove the reference the QI added.
mTarget->Release();
else {
NS_ERROR("Failed to get identity pointer");
}
// To help debug such leaks, we keep a counter of the event listeners
// currently alive. If you change |mTarget| to a strong-ref, this never
// hits zero (running seamonkey.)
#ifdef NS_DEBUG
PR_AtomicIncrement(&sNumJSEventListeners);
#endif
}
nsIScriptContext *GetEventContext()
{
return mContext;
}
nsISupports *GetEventTarget()
{
return mTarget;
}
void *GetEventScope()
{
return mScopeObject;
}
virtual void SetEventName(nsIAtom* aName) = 0;
#ifdef NS_DEBUG
static PRInt32 sNumJSEventListeners;
#endif
protected:
virtual ~nsIJSEventListener()
{
#ifdef NS_DEBUG
PR_AtomicDecrement(&sNumJSEventListeners);
#endif
}
nsCOMPtr<nsIScriptContext> mContext;
void *mScopeObject;
nsISupports *mTarget; // weak ref.
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIJSEventListener, NS_IJSEVENTLISTENER_IID)
/* factory function */
nsresult NS_NewJSEventListener(nsIScriptContext *aContext,
void *aScopeObject, nsISupports *aObject,
nsIDOMEventListener **aReturn);
#endif // nsIJSEventListener_h__