grab from latest android

git-svn-id: http://skia.googlecode.com/svn/trunk@27 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 103 insertions, 0 deletions

diff --git a/include/views/SkEventSink.h b/include/views/SkEventSink.h
new file mode 100644
index 0000000000..27a67437c3
--- /dev/null
+++ b/include/views/SkEventSink.h
@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2006 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SkEventSink_DEFINED
+#define SkEventSink_DEFINED
+
+#include "SkRefCnt.h"
+#include "SkEvent.h"
+
+struct SkTagList;
+
+/** \class SkEventSink
+
+    SkEventSink is the base class for all objects that receive SkEvents.
+*/
+class SkEventSink : public SkRefCnt {
+public:
+            SkEventSink();
+    virtual ~SkEventSink();
+
+    /** Returns this eventsink's unique ID. Use this to post SkEvents to
+        this eventsink.
+    */
+    SkEventSinkID getSinkID() const { return fID; }
+
+    /** Call this to pass an event to this object for processing. Returns true if the
+        event was handled.
+    */
+    bool doEvent(const SkEvent&);
+    /** Returns true if the sink (or one of its subclasses) understands the event as a query.
+        If so, the sink may modify the event to communicate its "answer".
+    */
+    bool doQuery(SkEvent* query);
+
+    /** Add sinkID to the list of listeners, to receive events from calls to sendToListeners()
+        and postToListeners(). If sinkID already exists in the listener list, no change is made.
+    */
+    void    addListenerID(SkEventSinkID sinkID);
+    /** Copy listeners from one event sink to another, typically from parent to child.
+        @param from the event sink to copy the listeners from
+    */
+    void copyListeners(const SkEventSink& from);
+    /** Remove sinkID from the list of listeners. If sinkID does not appear in the list,
+        no change is made.
+    */
+    void    removeListenerID(SkEventSinkID);
+    /** Returns true if there are 1 or more listeners attached to this eventsink
+    */
+    bool    hasListeners() const;
+    /** Posts a copy of evt to each of the eventsinks in the lisener list.
+    */
+    void    postToListeners(const SkEvent& evt, SkMSec delay = 0);
+
+    enum EventResult {
+        kHandled_EventResult,       //!< the eventsink returned true from its doEvent method
+        kNotHandled_EventResult,    //!< the eventsink returned false from its doEvent method
+        kSinkNotFound_EventResult   //!< no matching eventsink was found for the event's getSink().
+    };
+    /** DoEvent handles searching for an eventsink object that matches the targetID.
+        If one is found, it calls the sink's doEvent method, returning
+        either kHandled_EventResult or kNotHandled_EventResult. If no matching
+        eventsink is found, kSinkNotFound_EventResult is returned.
+    */
+    static EventResult DoEvent(const SkEvent&, SkEventSinkID targetID);
+
+    /** Returns the matching eventsink, or null if not found
+    */
+    static SkEventSink* FindSink(SkEventSinkID);
+
+protected:
+    /** Override this to handle events in your subclass. Be sure to call the inherited version
+        for events that you don't handle.
+    */
+    virtual bool onEvent(const SkEvent&);
+    virtual bool onQuery(SkEvent*);
+
+    SkTagList*  findTagList(U8CPU tag) const;
+    void        addTagList(SkTagList*);
+    void        removeTagList(U8CPU tag);
+
+private:
+    SkEventSinkID   fID;
+    SkTagList*      fTagHead;
+
+    // for our private link-list
+    SkEventSink*    fNextSink;
+};
+
+#endif
+