ui/events/platform/platform_event_dispatcher.h

   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_PLATFORM_PLATFORM_EVENT_DISPATCHER_H_
   6 #define UI_EVENTS_PLATFORM_PLATFORM_EVENT_DISPATCHER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "ui/events/events_export.h"
  10 #include "ui/events/platform/platform_event_types.h"
  11
  12 namespace ui {
  13
  14 // See documentation for |PlatformEventDispatcher::DispatchEvent()| for
  15 // explanation of the meaning of the flags.
  16 enum PostDispatchAction {
  17   POST_DISPATCH_NONE = 0x0,
  18   POST_DISPATCH_PERFORM_DEFAULT = 0x1,
  19   POST_DISPATCH_STOP_PROPAGATION = 0x2,
  20 };
  21
  22 // PlatformEventDispatcher receives events from a PlatformEventSource and
  23 // dispatches them.
  24 class EVENTS_EXPORT PlatformEventDispatcher {
  25  public:
  26   // Returns whether this dispatcher wants to dispatch |event|.
  27   virtual bool CanDispatchEvent(const PlatformEvent& event) = 0;
  28
  29   // Dispatches |event|. If this is not the default dispatcher, then the
  30   // dispatcher can request that the default dispatcher gets a chance to
  31   // dispatch the event by setting POST_DISPATCH_PERFORM_DEFAULT to the return
  32   // value. If the dispatcher has processed the event, and no other dispatcher
  33   // should be allowed to dispatch the event, then the dispatcher should set
  34   // POST_DISPATCH_STOP_PROPAGATION flag on the return value.
  35   virtual uint32_t DispatchEvent(const PlatformEvent& event) = 0;
  36
  37  protected:
  38   virtual ~PlatformEventDispatcher() {}
  39 };
  40
  41 }  // namespace ui
  42
  43 #endif  // UI_EVENTS_PLATFORM_PLATFORM_EVENT_DISPATCHER_H_