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