1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef UI_EVENTS_EVENT_REWRITER_H_ 6 #define UI_EVENTS_EVENT_REWRITER_H_ 7 8 #include "base/memory/scoped_ptr.h" 9 #include "ui/events/events_export.h" 10 11 namespace ui { 12 13 class Event; 14 15 // Return status of EventRewriter operations; see that class below. 16 enum EventRewriteStatus { 17 // Nothing was done; no rewritten event returned. Pass the original 18 // event to later rewriters, or send it to the EventProcessor if this 19 // was the final rewriter. 20 EVENT_REWRITE_CONTINUE, 21 22 // The event has been rewritten. Send the rewritten event to the 23 // EventProcessor instead of the original event (without sending 24 // either to any later rewriters). 25 EVENT_REWRITE_REWRITTEN, 26 27 // The event should be discarded, neither passing it to any later 28 // rewriters nor sending it to the EventProcessor. 29 EVENT_REWRITE_DISCARD, 30 31 // The event has been rewritten. As for EVENT_REWRITE_REWRITTEN, 32 // send the rewritten event to the EventProcessor instead of the 33 // original event (without sending either to any later rewriters). 34 // In addition the rewriter has one or more additional new events 35 // to be retrieved using |NextDispatchEvent()| and sent to the 36 // EventProcessor. 37 EVENT_REWRITE_DISPATCH_ANOTHER, 38 }; 39 40 // EventRewriter provides a mechanism for Events to be rewritten 41 // before being dispatched from EventSource to EventProcessor. 42 class EVENTS_EXPORT EventRewriter { 43 public: 44 virtual ~EventRewriter() {} 45 46 // Potentially rewrites (replaces) an event, or requests it be discarded. 47 // or discards an event. If the rewriter wants to rewrite an event, and 48 // dispatch another event once the rewritten event is dispatched, it should 49 // return EVENT_REWRITE_DISPATCH_ANOTHER, and return the next event to 50 // dispatch from |NextDispatchEvent()|. 51 virtual EventRewriteStatus RewriteEvent( 52 const Event& event, 53 scoped_ptr<Event>* rewritten_event) = 0; 54 55 // Supplies an additional event to be dispatched. It is only valid to 56 // call this after the immediately previous call to |RewriteEvent()| 57 // or |NextDispatchEvent()| has returned EVENT_REWRITE_DISPATCH_ANOTHER. 58 // Should only return either EVENT_REWRITE_REWRITTEN or 59 // EVENT_REWRITE_DISPATCH_ANOTHER; otherwise the previous call should not 60 // have returned EVENT_REWRITE_DISPATCH_ANOTHER. 61 virtual EventRewriteStatus NextDispatchEvent( 62 const Event& last_event, 63 scoped_ptr<Event>* new_event) = 0; 64 }; 65 66 } // namespace ui 67 68 #endif // UI_EVENTS_EVENT_REWRITER_H_ 69
