Proposed alternative for supporting ChromeVox keyboard commands.

chrome/browser/chromeos/accessibility/spoken_feedback_event_rewriter.h

+// Copyright 2015 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 CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_SPOKEN_FEEDBACK_EVENT_REWRITER_H_
+#define CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_SPOKEN_FEEDBACK_EVENT_REWRITER_H_
+
+#include <vector>
+
+#include "ui/events/event_rewriter.h"
+
+namespace ui {
+class KeyEvent;
+}
+
+// Receives requests for spoken feedback enabled state and command dispatch.
+class SpokenFeedbackEventRewriterDelegate {
+ public:
+  // Returns true when ChromeVox is enabled.
+  virtual bool IsSpokenFeedbackEnabled() const = 0;
+
+  // Returns true when |key_event| is dispatched to ChromeVox.
+  virtual bool DispatchKeyToChromeVox(const ui::KeyEvent key_event) = 0;
+};
+
+// SpokenFeedbackEventRewriter discards all keyboard events mapped by the spoken
+// feedback manifest commands block. It dispatches the associated command name
+// directly to spoken feedback. This only occurs whenever spoken feedback is
+// enabled.
+class SpokenFeedbackEventRewriter : public ui::EventRewriter,
+                                    public SpokenFeedbackEventRewriterDelegate {
+ public:
+  explicit SpokenFeedbackEventRewriter(
+      SpokenFeedbackEventRewriterDelegate* delegate);
+  ~SpokenFeedbackEventRewriter() override;
+
+  // EventRewriter:
+  ui::EventRewriteStatus RewriteEvent(
+      const ui::Event& event,
+      scoped_ptr<ui::Event>* new_event) override;
+  ui::EventRewriteStatus NextDispatchEvent(
+      const ui::Event& last_event,
+      scoped_ptr<ui::Event>* new_event) override;
+
+  // SpokenFeedbackEventRewriterDelegate:
+  bool IsSpokenFeedbackEnabled() const override;
+  bool DispatchKeyToChromeVox(const ui::KeyEvent key_event) override;
+
+ private:
+  // Modifier keys held down as a result of a ChromeVox command.
+  int modifiers_down_;
+
+  // Provides dispatch and state services.
+  SpokenFeedbackEventRewriterDelegate* delegate_;
+
+  // Stores all key codes we've cpatured.
+  std::vector<int> captured_key_codes_;
+
+  DISALLOW_COPY_AND_ASSIGN(SpokenFeedbackEventRewriter);
+};
+
+#endif  // CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_SPOKEN_FEEDBACK_EVENT_REWRITER_H_