104 lines
3.6 KiB
C
104 lines
3.6 KiB
C
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/*
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* Copyright (C) 2006 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef SkEventSink_DEFINED
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#define SkEventSink_DEFINED
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#include "SkRefCnt.h"
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#include "SkEvent.h"
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struct SkTagList;
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/** \class SkEventSink
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SkEventSink is the base class for all objects that receive SkEvents.
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*/
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class SkEventSink : public SkRefCnt {
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public:
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SkEventSink();
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virtual ~SkEventSink();
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/** Returns this eventsink's unique ID. Use this to post SkEvents to
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this eventsink.
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*/
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SkEventSinkID getSinkID() const { return fID; }
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/** Call this to pass an event to this object for processing. Returns true if the
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event was handled.
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*/
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bool doEvent(const SkEvent&);
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/** Returns true if the sink (or one of its subclasses) understands the event as a query.
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If so, the sink may modify the event to communicate its "answer".
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*/
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bool doQuery(SkEvent* query);
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/** Add sinkID to the list of listeners, to receive events from calls to sendToListeners()
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and postToListeners(). If sinkID already exists in the listener list, no change is made.
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*/
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void addListenerID(SkEventSinkID sinkID);
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/** Copy listeners from one event sink to another, typically from parent to child.
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@param from the event sink to copy the listeners from
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*/
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void copyListeners(const SkEventSink& from);
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/** Remove sinkID from the list of listeners. If sinkID does not appear in the list,
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no change is made.
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*/
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void removeListenerID(SkEventSinkID);
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/** Returns true if there are 1 or more listeners attached to this eventsink
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*/
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bool hasListeners() const;
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/** Posts a copy of evt to each of the eventsinks in the lisener list.
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*/
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void postToListeners(const SkEvent& evt, SkMSec delay = 0);
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enum EventResult {
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kHandled_EventResult, //!< the eventsink returned true from its doEvent method
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kNotHandled_EventResult, //!< the eventsink returned false from its doEvent method
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kSinkNotFound_EventResult //!< no matching eventsink was found for the event's getSink().
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};
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/** DoEvent handles searching for an eventsink object that matches the targetID.
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If one is found, it calls the sink's doEvent method, returning
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either kHandled_EventResult or kNotHandled_EventResult. If no matching
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eventsink is found, kSinkNotFound_EventResult is returned.
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*/
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static EventResult DoEvent(const SkEvent&, SkEventSinkID targetID);
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/** Returns the matching eventsink, or null if not found
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*/
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static SkEventSink* FindSink(SkEventSinkID);
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protected:
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/** Override this to handle events in your subclass. Be sure to call the inherited version
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for events that you don't handle.
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*/
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virtual bool onEvent(const SkEvent&);
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virtual bool onQuery(SkEvent*);
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SkTagList* findTagList(U8CPU tag) const;
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void addTagList(SkTagList*);
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void removeTagList(U8CPU tag);
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private:
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SkEventSinkID fID;
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SkTagList* fTagHead;
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// for our private link-list
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SkEventSink* fNextSink;
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};
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#endif
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