1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/include/views/SkEventSink.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,112 @@
1.4 +
1.5 +/*
1.6 + * Copyright 2006 The Android Open Source Project
1.7 + *
1.8 + * Use of this source code is governed by a BSD-style license that can be
1.9 + * found in the LICENSE file.
1.10 + */
1.11 +
1.12 +
1.13 +#ifndef SkEventSink_DEFINED
1.14 +#define SkEventSink_DEFINED
1.15 +
1.16 +#include "SkRefCnt.h"
1.17 +#include "SkEvent.h"
1.18 +
1.19 +struct SkTagList;
1.20 +
1.21 +/** \class SkEventSink
1.22 +
1.23 + SkEventSink is the base class for all objects that receive SkEvents.
1.24 +*/
1.25 +class SkEventSink : public SkRefCnt {
1.26 +public:
1.27 + SK_DECLARE_INST_COUNT(SkEventSink)
1.28 +
1.29 + SkEventSink();
1.30 + virtual ~SkEventSink();
1.31 +
1.32 + /**
1.33 + * Returns this eventsink's unique ID. Use this to post SkEvents to
1.34 + * this eventsink.
1.35 + */
1.36 + SkEventSinkID getSinkID() const { return fID; }
1.37 +
1.38 + /**
1.39 + * Call this to pass an event to this object for processing. Returns true if the
1.40 + * event was handled.
1.41 + */
1.42 + bool doEvent(const SkEvent&);
1.43 +
1.44 + /** Returns true if the sink (or one of its subclasses) understands the event as a query.
1.45 + If so, the sink may modify the event to communicate its "answer".
1.46 + */
1.47 + bool doQuery(SkEvent* query);
1.48 +
1.49 + /**
1.50 + * Add sinkID to the list of listeners, to receive events from calls to sendToListeners()
1.51 + * and postToListeners(). If sinkID already exists in the listener list, no change is made.
1.52 + */
1.53 + void addListenerID(SkEventSinkID sinkID);
1.54 +
1.55 + /**
1.56 + * Copy listeners from one event sink to another, typically from parent to child.
1.57 + * @param from the event sink to copy the listeners from
1.58 + */
1.59 + void copyListeners(const SkEventSink& from);
1.60 +
1.61 + /**
1.62 + * Remove sinkID from the list of listeners. If sinkID does not appear in the list,
1.63 + * no change is made.
1.64 + */
1.65 + void removeListenerID(SkEventSinkID);
1.66 +
1.67 + /**
1.68 + * Returns true if there are 1 or more listeners attached to this eventsink
1.69 + */
1.70 + bool hasListeners() const;
1.71 +
1.72 + /**
1.73 + * Posts a copy of evt to each of the eventsinks in the lisener list.
1.74 + * This ignores the targetID and target proc in evt.
1.75 + */
1.76 + void postToListeners(const SkEvent& evt, SkMSec delay = 0);
1.77 +
1.78 + enum EventResult {
1.79 + kHandled_EventResult, //!< the eventsink returned true from its doEvent method
1.80 + kNotHandled_EventResult, //!< the eventsink returned false from its doEvent method
1.81 + kSinkNotFound_EventResult //!< no matching eventsink was found for the event's getSink().
1.82 + };
1.83 +
1.84 + /**
1.85 + * DoEvent handles dispatching the event to its target ID or proc.
1.86 + */
1.87 + static EventResult DoEvent(const SkEvent&);
1.88 +
1.89 + /**
1.90 + * Returns the matching eventsink, or null if not found
1.91 + */
1.92 + static SkEventSink* FindSink(SkEventSinkID);
1.93 +
1.94 +protected:
1.95 + /** Override this to handle events in your subclass. Be sure to call the inherited version
1.96 + for events that you don't handle.
1.97 + */
1.98 + virtual bool onEvent(const SkEvent&);
1.99 + virtual bool onQuery(SkEvent*);
1.100 +
1.101 + SkTagList* findTagList(U8CPU tag) const;
1.102 + void addTagList(SkTagList*);
1.103 + void removeTagList(U8CPU tag);
1.104 +
1.105 +private:
1.106 + SkEventSinkID fID;
1.107 + SkTagList* fTagHead;
1.108 +
1.109 + // for our private link-list
1.110 + SkEventSink* fNextSink;
1.111 +
1.112 + typedef SkRefCnt INHERITED;
1.113 +};
1.114 +
1.115 +#endif
