| // Copyright 2013 The Flutter Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_KEYBOARD_KEY_HANDLER_H_ |
| #define FLUTTER_SHELL_PLATFORM_WINDOWS_KEYBOARD_KEY_HANDLER_H_ |
| |
| #include <windows.h> |
| #include <deque> |
| #include <memory> |
| #include <string> |
| |
| #include "flutter/shell/platform/common/client_wrapper/include/flutter/basic_message_channel.h" |
| #include "flutter/shell/platform/windows/keyboard_handler_base.h" |
| #include "rapidjson/document.h" |
| |
| namespace flutter { |
| |
| // Handles key events. |
| // |
| // This class detects whether an incoming event is a redispatched one, |
| // dispatches native events to delegates and collect their responses, |
| // and redispatches events unhandled by Flutter back to the system. |
| // See |KeyboardHook| for more information about dispatching. |
| // |
| // This class owns multiple |KeyboardKeyHandlerDelegate|s, which |
| // implements the exact behavior to asynchronously handle events. In |
| // reality, this design is only to support sending events through |
| // "channel" (RawKeyEvent) and "embedder" (KeyEvent) simultaneously, |
| // the former of which shall be removed after the deprecation window |
| // of the RawKeyEvent system. |
| class KeyboardKeyHandler : public KeyboardHandlerBase { |
| public: |
| // An interface for concrete definition of how to asynchronously handle key |
| // events. |
| class KeyboardKeyHandlerDelegate { |
| public: |
| // Defines how to how to asynchronously handle key events. |
| // |
| // |KeyboardHook| should invoke |callback| with the response (whether the |
| // event is handled) later for exactly once. |
| virtual void KeyboardHook(int key, |
| int scancode, |
| int action, |
| char32_t character, |
| bool extended, |
| bool was_down, |
| KeyEventCallback callback) = 0; |
| |
| virtual ~KeyboardKeyHandlerDelegate(); |
| }; |
| |
| // Create a KeyboardKeyHandler. |
| explicit KeyboardKeyHandler(); |
| |
| ~KeyboardKeyHandler(); |
| |
| // Add a delegate that handles events received by |KeyboardHook|. |
| void AddDelegate(std::unique_ptr<KeyboardKeyHandlerDelegate> delegate); |
| |
| // Handles a key event. |
| // |
| // Returns whether this handler claims to handle the event, which is true if |
| // and only if the event is a non-synthesized event. |
| // |
| // Windows requires a synchronous response of whether a key event should be |
| // handled, while the query to Flutter is always asynchronous. This is |
| // resolved by the "redispatching" algorithm: by default, the response to a |
| // fresh event is always always true. The event is then sent to the framework. |
| // If the framework later decides not to handle the event, this class will |
| // create an identical event and dispatch it to the system, and remember all |
| // synthesized events. The fist time an exact event (by |ComputeEventHash|) is |
| // received in the future, the new event is considered a synthesized one, |
| // causing |KeyboardHook| to return false to fall back to other keyboard |
| // handlers. |
| // |
| // Whether a non-synthesized event is considered handled by the framework is |
| // decided by dispatching the event to all delegates, simultaneously, |
| // unconditionally, in insertion order, and collecting their responses later. |
| // It's not supported to prevent any delegates to process the events, because |
| // in reality this will only support 2 hardcoded delegates, and only to |
| // continue supporting the legacy API (channel) during the deprecation window, |
| // after which the channel delegate should be removed. |
| // |
| // Inherited from |KeyboardHandlerBase|. |
| void KeyboardHook(int key, |
| int scancode, |
| int action, |
| char32_t character, |
| bool extended, |
| bool was_down, |
| KeyEventCallback callback) override; |
| |
| private: |
| struct PendingEvent { |
| // Self-incrementing ID attached to an event sent to the framework. |
| uint64_t sequence_id; |
| // The number of delegates that haven't replied. |
| size_t unreplied; |
| // Whether any replied delegates reported true (handled). |
| bool any_handled; |
| |
| // Where to report the delegates' result to. |
| // |
| // Typically a callback provided by KeyboardManager32. |
| KeyEventCallback callback; |
| }; |
| |
| void ResolvePendingEvent(uint64_t sequence_id, bool handled); |
| |
| std::vector<std::unique_ptr<KeyboardKeyHandlerDelegate>> delegates_; |
| |
| // The queue of key events that have been sent to the framework but have not |
| // yet received a response. |
| std::deque<std::unique_ptr<PendingEvent>> pending_responds_; |
| |
| // The sequence_id attached to the last event sent to the framework. |
| uint64_t last_sequence_id_; |
| }; |
| |
| } // namespace flutter |
| |
| #endif // FLUTTER_SHELL_PLATFORM_WINDOWS_KEYBOARD_KEY_HANDLER_H_ |