michael@0: 
michael@0: /*
michael@0:  * Copyright 2006 The Android Open Source Project
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: 
michael@0: #ifndef SkEventSink_DEFINED
michael@0: #define SkEventSink_DEFINED
michael@0: 
michael@0: #include "SkRefCnt.h"
michael@0: #include "SkEvent.h"
michael@0: 
michael@0: struct SkTagList;
michael@0: 
michael@0: /** \class SkEventSink
michael@0: 
michael@0:     SkEventSink is the base class for all objects that receive SkEvents.
michael@0: */
michael@0: class SkEventSink : public SkRefCnt {
michael@0: public:
michael@0:     SK_DECLARE_INST_COUNT(SkEventSink)
michael@0: 
michael@0:              SkEventSink();
michael@0:     virtual ~SkEventSink();
michael@0: 
michael@0:     /**
michael@0:      *  Returns this eventsink's unique ID. Use this to post SkEvents to
michael@0:      *  this eventsink.
michael@0:      */
michael@0:     SkEventSinkID getSinkID() const { return fID; }
michael@0: 
michael@0:     /**
michael@0:      *  Call this to pass an event to this object for processing. Returns true if the
michael@0:      *  event was handled.
michael@0:      */
michael@0:     bool doEvent(const SkEvent&);
michael@0: 
michael@0:     /** Returns true if the sink (or one of its subclasses) understands the event as a query.
michael@0:         If so, the sink may modify the event to communicate its "answer".
michael@0:     */
michael@0:     bool doQuery(SkEvent* query);
michael@0: 
michael@0:     /**
michael@0:      *  Add sinkID to the list of listeners, to receive events from calls to sendToListeners()
michael@0:      *  and postToListeners(). If sinkID already exists in the listener list, no change is made.
michael@0:      */
michael@0:     void addListenerID(SkEventSinkID sinkID);
michael@0: 
michael@0:     /**
michael@0:      *  Copy listeners from one event sink to another, typically from parent to child.
michael@0:      *  @param from the event sink to copy the listeners from
michael@0:      */
michael@0:     void copyListeners(const SkEventSink& from);
michael@0: 
michael@0:     /**
michael@0:      *  Remove sinkID from the list of listeners. If sinkID does not appear in the list,
michael@0:      *  no change is made.
michael@0:      */
michael@0:     void removeListenerID(SkEventSinkID);
michael@0: 
michael@0:     /**
michael@0:      *  Returns true if there are 1 or more listeners attached to this eventsink
michael@0:      */
michael@0:     bool hasListeners() const;
michael@0: 
michael@0:     /**
michael@0:      *  Posts a copy of evt to each of the eventsinks in the lisener list.
michael@0:      *  This ignores the targetID and target proc in evt.
michael@0:      */
michael@0:     void postToListeners(const SkEvent& evt, SkMSec delay = 0);
michael@0: 
michael@0:     enum EventResult {
michael@0:         kHandled_EventResult,       //!< the eventsink returned true from its doEvent method
michael@0:         kNotHandled_EventResult,    //!< the eventsink returned false from its doEvent method
michael@0:         kSinkNotFound_EventResult   //!< no matching eventsink was found for the event's getSink().
michael@0:     };
michael@0: 
michael@0:     /**
michael@0:      *  DoEvent handles dispatching the event to its target ID or proc.
michael@0:      */
michael@0:     static EventResult DoEvent(const SkEvent&);
michael@0: 
michael@0:     /**
michael@0:      *  Returns the matching eventsink, or null if not found
michael@0:      */
michael@0:     static SkEventSink* FindSink(SkEventSinkID);
michael@0: 
michael@0: protected:
michael@0:     /** Override this to handle events in your subclass. Be sure to call the inherited version
michael@0:         for events that you don't handle.
michael@0:     */
michael@0:     virtual bool onEvent(const SkEvent&);
michael@0:     virtual bool onQuery(SkEvent*);
michael@0: 
michael@0:     SkTagList*  findTagList(U8CPU tag) const;
michael@0:     void        addTagList(SkTagList*);
michael@0:     void        removeTagList(U8CPU tag);
michael@0: 
michael@0: private:
michael@0:     SkEventSinkID   fID;
michael@0:     SkTagList*      fTagHead;
michael@0: 
michael@0:     // for our private link-list
michael@0:     SkEventSink*    fNextSink;
michael@0: 
michael@0:     typedef SkRefCnt INHERITED;
michael@0: };
michael@0: 
michael@0: #endif