Convert sticky keys to a chromeos::EventRewriter phase.

ash/sticky_keys/sticky_keys_controller.h

 // Copyright 2013 The Chromium 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 ASH_STICKY_KEYS_STICKY_KEYS_CONTROLLER_H_
 #define ASH_STICKY_KEYS_STICKY_KEYS_CONTROLLER_H_
 
 #include "ash/ash_export.h"
 #include "ash/sticky_keys/sticky_keys_state.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/events/event_constants.h"
 #include "ui/events/event_handler.h"
+#include "ui/events/event_rewriter.h"
+#include "ui/events/keycodes/keyboard_codes.h"
 
 namespace ui {
 class Event;
 class KeyEvent;
 class MouseEvent;
 }  // namespace ui
 
 namespace aura {
 class Window;
 }  // namespace aura
@@ skipping 29 matching lines @@
 // 6. Release 1 key    : 1 Keyup event with Ctrl modifier.
 // 7. Press 2 key      : 2 Keydown event with Ctrl modifier.
 // 8. Release 2 key    : 2 Keyup event with Ctrl modifier.
 // 9. Press Ctrl key   : No event
 // 10. Release Ctrl key: Ctrl Keyup
 //
 // In the case of Chrome OS, StickyKeysController supports Shift,Alt,Ctrl
 // modifiers. Each handling or state is performed independently.
 //
 // StickyKeysController is disabled by default.
-class ASH_EXPORT StickyKeysController : public ui::EventHandler {
+class ASH_EXPORT StickyKeysController {
  public:
   StickyKeysController();
   virtual ~StickyKeysController();
 
   // Activate sticky keys to intercept and modify incoming events.
   void Enable(bool enabled);
 
   void SetModifiersEnabled(bool mod3_enabled, bool altgr_enabled);
 
-  // Overridden from ui::EventHandler:
-  virtual void OnKeyEvent(ui::KeyEvent* event) OVERRIDE;
-  virtual void OnMouseEvent(ui::MouseEvent* event) OVERRIDE;
-  virtual void OnScrollEvent(ui::ScrollEvent* event) OVERRIDE;
-
   // Returns the StickyKeyOverlay used by the controller. Ownership is not
   // passed.
   StickyKeysOverlay* GetOverlayForTest();
 
+  // Handles keyboard event. Returns an |EventRewriteStatus|:
+  // - ui::EVENT_REWRITE_DISCARD if the event is consumed (i.e. a sticky
+  //   modifier press or release);
+  // - ui::EVENT_REWRITE_REWRITTEN if the event needs to be modified
+  //   according to the changes to |state|;

[Tim Song, 2014/06/16 18:32:24]

What does |state| refer to here? The StickyKeyState of the modifier key
handlers? 

Also, please mention in the comments here that the rewritten modifier flags will
be written to the |flags| argument, which will remain unchanged except if
ui::EVENT_REWRITE_REWRITTEN or ui::EVENT_REWRITE_DISPATCH_ANOTHER is returned.

[kpschoedel, 2014/06/16 21:09:08]

Should read |flags|; fixed.
Done.

+  // - ui::EVENT_REWRITE_DISPATCH_ANOTHER if there are delayed modifier-up
+  //   events now to be retrieved using |NextDispatchEvent()|;
+  // - ui::EVENT_REWRITE_CONTINUE otherwise (no external action necessary).
+  ui::EventRewriteStatus RewriteKeyEvent(const ui::KeyEvent& event,
+                                         ui::KeyboardCode key_code,
+                                         int* flags);
+
+  // Handles mouse event.
+  ui::EventRewriteStatus RewriteMouseEvent(const ui::MouseEvent& event,
+                                           int* flags);
+
+  // Handles scroll event.
+  ui::EventRewriteStatus RewriteScrollEvent(const ui::ScrollEvent& event,
+                                            int* flags);
+
+  // Obtains a pending modifier-up event. Returns:
+  // - ui::EVENT_REWRITE_DISPATCH_ANOTHER if there is at least one more
+  //   pending modifier-up event;
+  // - ui::EVENT_REWRITE_REWRITE if this is the last or only modifier-up event;
+  // - ui::EVENT_REWRITE_CONTINUE if there are no pending modifier-up events.

[Tim Song, 2014/06/16 18:32:23]

Mention that |new_event| will be null in this case.

[kpschoedel, 2014/06/16 21:09:08]

Done (borrowing from the corresponding comment in ui/events/event_rewriter.h).

+  ui::EventRewriteStatus NextDispatchEvent(scoped_ptr<ui::Event>* new_event);
+
  private:
   // Handles keyboard event. Returns true if Sticky key consumes keyboard event.
-  bool HandleKeyEvent(ui::KeyEvent* event);
+  // Adds to |mod_down_flags| any flag to be added to the key event.
+  // Adds to |mod_up_flags| any flag to be released after the key event.
+  bool HandleKeyEvent(const ui::KeyEvent& event,
+                      ui::KeyboardCode key_code,
+                      int* mod_down_flags,
+                      int* mod_up_flags);
 
-  // Handles mouse event. Returns true if sticky key consumes mouse event.
-  bool HandleMouseEvent(ui::MouseEvent* event);
+  // Handles mouse event. Returns true if Sticky key consumes keyboard event.
+  // Adds to |mod_up_flags| any flag to be released after the key event.
+  bool HandleMouseEvent(const ui::MouseEvent& event,
+                        int* mod_down_flags,
+                        int* mod_up_flags);
 
-  // Handles scroll event. Returns true if sticky key consumes scroll event.
-  bool HandleScrollEvent(ui::ScrollEvent* event);
+  // Handles scroll event. Returns true if Sticky key consumes keyboard event.
+  // Adds to |mod_up_flags| any flag to be released after the key event.
+  bool HandleScrollEvent(const ui::ScrollEvent& event,
+                         int* mod_down_flags,
+                         int* mod_up_flags);
 
   // Updates the overlay UI with the current state of the sticky keys.
   void UpdateOverlay();
 
   // Whether sticky keys is activated and modifying events.
   bool enabled_;
 
   // Whether the current layout has a mod3 key.
   bool mod3_enabled_;
 
@@ skipping 36 matching lines @@
 // Other KeyUp/Down |   noop        |    noop        |    noop     |
 // Mouse Press      |   noop        |    noop(#)     |    noop(#)  |
 // Mouse Release    |   noop        | To DISABLED(#) |    noop(#)  |
 // Mouse Wheel      |   noop        | To DISABLED(#) |    noop(#)  |
 // Other Mouse Event|   noop        |    noop        |    noop     |
 //
 // Here, (*) means key event will be consumed by StickyKeys, and (#) means event
 // is modified.
 class ASH_EXPORT StickyKeysHandler {
  public:
-  class StickyKeysHandlerDelegate {
-   public:
-    StickyKeysHandlerDelegate();
-    virtual ~StickyKeysHandlerDelegate();
-
-    // Dispatches keyboard event synchronously. |event| is an event that has
-    // been previously dispatched.
-    virtual void DispatchKeyEvent(ui::KeyEvent* event,
-                                  aura::Window* target) = 0;
-
-    // Dispatches mouse event synchronously. |event| is an event that has
-    // been previously dispatched.
-    virtual void DispatchMouseEvent(ui::MouseEvent* event,
-                                    aura::Window* target) = 0;
-
-    // Dispatches scroll event synchronously. |event| is an event that has
-    // been previously dispatched.
-    virtual void DispatchScrollEvent(ui::ScrollEvent* event,
-                                     aura::Window* target) = 0;
-  };
-
-  // This class takes an ownership of |delegate|.
-  StickyKeysHandler(ui::EventFlags modifier_flag,
-                    StickyKeysHandlerDelegate* delegate);
+  explicit StickyKeysHandler(ui::EventFlags modifier_flag);
   ~StickyKeysHandler();
 
-  // Handles key event. Returns true if key is consumed.
-  bool HandleKeyEvent(ui::KeyEvent* event);
+  // Handles keyboard event. Returns true if Sticky key consumes keyboard event.
+  // Sets its own modifier flag in |mod_down_flags| if it is active and needs
+  // to be added to the event; sets its own modifier flag in |mod_up_flags| if
+  // releasing it.
+  bool HandleKeyEvent(const ui::KeyEvent& event,
+                      ui::KeyboardCode key_code,
+                      int* mod_down_flags,
+                      int* mod_up_flags);
 
-  // Handles a mouse event. Returns true if mouse event is consumed.
-  bool HandleMouseEvent(ui::MouseEvent* event);
+  // Handles mouse event. Returns true if sticky key consumes mouse event.
+  // Sets its own modifier flag in |mod_down_flags| if it is active and needs
+  // to be added to the event; sets its own modifier flag in |mod_up_flags| if
+  // releasing it.
+  bool HandleMouseEvent(const ui::MouseEvent& event,
+                        int* mod_down_flags,
+                        int* mod_up_flags);
 
-  // Handles a scroll event. Returns true if scroll event is consumed.
-  bool HandleScrollEvent(ui::ScrollEvent* event);
+  // Handles scroll event. Returns true if sticky key consumes scroll event.
+  // Sets its own modifier flag in |mod_down_flags| if it is active and needs
+  // to be added to the event; sets its own modifier flag in |mod_up_flags| if
+  // releasing it.
+  bool HandleScrollEvent(const ui::ScrollEvent& event,
+                         int* mod_down_flags,
+                         int* mod_up_flags);
+
+  // Fetches a pending modifier-up event if one exists and the return
+  // parameter |new_event| is available (i.e. not set). Returns the number
+  // of pending events still remaining to be returned.
+  int GetModifierUpEvent(scoped_ptr<ui::Event>* new_event);
 
   // Returns current internal state.
   StickyKeyState current_state() const { return current_state_; }
 
  private:
   // Represents event type in Sticky Key context.
   enum KeyEventType {
     TARGET_MODIFIER_DOWN,  // The monitoring modifier key is down.
     TARGET_MODIFIER_UP,  // The monitoring modifier key is up.
     NORMAL_KEY_DOWN,  // The non modifier key is down.
     NORMAL_KEY_UP,  // The non modifier key is up.
     OTHER_MODIFIER_DOWN,  // The modifier key but not monitored key is down.
     OTHER_MODIFIER_UP,  // The modifier key but not monitored key is up.
   };
 
-  // Translates |event| to sticky keys event type.
-  KeyEventType TranslateKeyEvent(ui::KeyEvent* event);
+  // Translates event type and key code to sticky keys event type.
+  KeyEventType TranslateKeyEvent(ui::EventType type, ui::KeyboardCode key_code);
 
-  // Handles key event in DISABLED state.
-  bool HandleDisabledState(ui::KeyEvent* event);
+  // Handles key event in DISABLED state. Returns true if sticky keys
+  // consumes the keyboard event.
+  bool HandleDisabledState(const ui::KeyEvent& event,
+                           ui::KeyboardCode key_code);
 
-  // Handles key event in ENABLED state.
-  bool HandleEnabledState(ui::KeyEvent* event);
+  // Handles key event in ENABLED state. Returns true if sticky keys
+  // consumes the keyboard event.
+  bool HandleEnabledState(const ui::KeyEvent& event,
+                          ui::KeyboardCode key_code,
+                          int* mod_down_flags,
+                          int* mod_up_flags);
 
-  // Handles key event in LOCKED state.
-  bool HandleLockedState(ui::KeyEvent* event);
-
-  // Dispatches |event| to its target and then dispatch a key released event
-  // for the modifier key. This function is required to ensure that the events
-  // are sent in the correct order when disabling sticky key after a key/mouse
-  // button press.
-  void DispatchEventAndReleaseModifier(ui::Event* event);
-
-  // Adds |modifier_flags_| to a native X11 event state mask.
-  void AppendNativeEventMask(unsigned int* state);
-
-  // Adds |modifier_flags_| into |event|.
-  void AppendModifier(ui::KeyEvent* event);
-  void AppendModifier(ui::MouseEvent* event);
-  void AppendModifier(ui::ScrollEvent* event);
+  // Handles key event in LOCKED state. Returns true if sticky keys
+  // consumes the keyboard event.
+  bool HandleLockedState(const ui::KeyEvent& event,
+                         ui::KeyboardCode key_code,
+                         int* mod_down_flags,
+                         int* mod_up_flags);
 
   // The modifier flag to be monitored and appended to events.
   const ui::EventFlags modifier_flag_;
 
   // The current sticky key status.
   StickyKeyState current_state_;
 
-  // True if the received key event is sent by StickyKeyHandler.
-  bool event_from_myself_;
-
   // True if we received the TARGET_MODIFIER_DOWN event while in the DISABLED
   // state but before we receive the TARGET_MODIFIER_UP event. Normal
   // shortcuts (eg. ctrl + t) during this time will prevent a transition to
   // the ENABLED state.
   bool preparing_to_enable_;
 
   // Tracks the scroll direction of the current scroll sequence. Sticky keys
   // stops modifying the scroll events of the sequence when the direction
   // changes. If no sequence is tracked, the value is 0.
   int scroll_delta_;
 
   // The modifier up key event to be sent on non modifier key on ENABLED state.
   scoped_ptr<ui::KeyEvent> modifier_up_event_;
 
-  scoped_ptr<StickyKeysHandlerDelegate> delegate_;
-
   DISALLOW_COPY_AND_ASSIGN(StickyKeysHandler);
 };
 
 }  // namespace ash
 
 #endif  // ASH_STICKY_KEYS_STICKY_KEYS_CONTROLLER_H_