1 // Copyright 2013 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_PROCESSOR_H_ 6 #define UI_EVENTS_EVENT_PROCESSOR_H_ 7 8 #include "ui/events/event_dispatcher.h" 9 #include "ui/events/event_source.h" 10 11 namespace ui { 12 13 // EventProcessor receives an event from an EventSource and dispatches it to a 14 // tree of EventTargets. 15 class EVENTS_EXPORT EventProcessor : public EventDispatcherDelegate { 16 public: 17 virtual ~EventProcessor() {} 18 19 // Returns the root of the tree this event processor owns. 20 virtual EventTarget* GetRootTarget() = 0; 21 22 // Dispatches an event received from the EventSource to the tree of 23 // EventTargets (whose root is returned by GetRootTarget()). The co-ordinate 24 // space of the source must be the same as the root target, except that the 25 // target may have a high-dpi scale applied. 26 virtual EventDispatchDetails OnEventFromSource(Event* event) 27 WARN_UNUSED_RESULT; 28 29 protected: 30 // Prepares the event so that it can be dispatched. This is invoked before 31 // an EventTargeter is used to find the target of the event. So this can be 32 // used to update the event so that the targeter can operate correctly (e.g. 33 // it can be used to updated the location of the event when disptaching from 34 // an EventSource in high-DPI). 35 virtual void PrepareEventForDispatch(Event* event); 36 37 // Invoked when the processing of |event| has finished (i.e., when no further 38 // dispatching of |event| will be performed by this EventProcessor). Note 39 // that the last target to which |event| was dispatched may have been 40 // destroyed. 41 virtual void OnEventProcessingFinished(Event* event); 42 }; 43 44 } // namespace ui 45 46 #endif // UI_EVENTS_EVENT_PROCESSOR_H_ 47
