Automatically remap Command key on an Apple keyboard to Control [part 1 of 2 - Ash part]

Add key_rewriter_event_filter.h which allows its delegate to rewrite or delete an aura::KeyEvent. The new interface will be used for implementing the following three features:

* crosbug.com/25097: Remap keys on external keyboards (R19)
* crosbug.com/27167: Consider adding a way to send function keys to web pages (R20)
* crbug.com/115112: Move modifier remapping code from X to Chrome (M20)

Part 2 of 2: http://codereview.chromium.org/9854025/

BUG=chromium-os:25097
BUG=chromium-os:27167
BUG=115112
TEST=try

Review URL: https://chromiumcodereview.appspot.com/9838010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@129076 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 165 insertions, 5 deletions

diff --git a/ash/ash.gyp b/ash/ash.gyp
index 615ddd2..f3ee74b 100644
--- a/ash/ash.gyp
+++ b/ash/ash.gyp
@@ -83,6 +83,7 @@
         'ime/event.h',
         'ime/input_method_event_filter.cc',
         'ime/input_method_event_filter.h',
+        'key_rewriter_delegate.h',
         'launcher/background_animator.cc',
         'launcher/background_animator.h',
         'launcher/launcher.cc',
@@ -192,6 +193,8 @@
         'wm/frame_painter.h',
         'wm/image_grid.cc',
         'wm/image_grid.h',
+        'wm/key_rewriter_event_filter.cc',
+        'wm/key_rewriter_event_filter.h',
         'wm/panel_frame_view.cc',
         'wm/panel_frame_view.h',
         'wm/panel_layout_manager.cc',
diff --git a/ash/key_rewriter_delegate.h b/ash/key_rewriter_delegate.h
new file mode 100644
index 0000000..16fcad9
--- /dev/null
+++ b/ash/key_rewriter_delegate.h
@@ -0,0 +1,33 @@
+// Copyright (c) 2012 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_KEY_REWRITER_DELEGATE_H_
+#define ASH_KEY_REWRITER_DELEGATE_H_
+#pragma once
+
+namespace aura {
+class KeyEvent;
+}  // namespace aura
+
+namespace ash {
+
+// Delegate for rewriting or filtering a key event.
+class KeyRewriterDelegate {
+ public:
+  enum Action {
+    ACTION_REWRITE_EVENT,
+    ACTION_DROP_EVENT,
+  };
+
+  virtual ~KeyRewriterDelegate() {}
+
+  // A derived class can do either of the following:
+  // 1) Just return ACTION_DROP_EVENT to drop the |event|.
+  // 2) Rewrite the |event| and return ACTION_REWRITE_EVENT.
+  virtual Action RewriteOrFilterKeyEvent(aura::KeyEvent* event) = 0;
+};
+
+}  // namespace ash
+
+#endif  // ASH_KEY_REWRITER_DELEGATE_H_
diff --git a/ash/shell.cc b/ash/shell.cc
index 87021be..fb24006 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -43,6 +43,7 @@
 #include "ash/wm/custom_frame_view_ash.h"
 #include "ash/wm/dialog_frame_view.h"
 #include "ash/wm/event_client_impl.h"
+#include "ash/wm/key_rewriter_event_filter.h"
 #include "ash/wm/panel_window_event_filter.h"
 #include "ash/wm/panel_layout_manager.h"
 #include "ash/wm/partial_screenshot_event_filter.h"
@@ -523,6 +524,7 @@ Shell::Shell(ShellDelegate* delegate)
 }
 
 Shell::~Shell() {
+  RemoveRootWindowEventFilter(key_rewriter_filter_.get());
   RemoveRootWindowEventFilter(partial_screenshot_filter_.get());
   RemoveRootWindowEventFilter(input_method_filter_.get());
   RemoveRootWindowEventFilter(window_modality_controller_.get());
@@ -620,20 +622,24 @@ void Shell::Init() {
   // Pass ownership of the filter to the root window.
   GetRootWindow()->SetEventFilter(root_filter_);
 
+  // KeyRewriterEventFilter must be the first one.
   DCHECK(!GetRootWindowEventFilterCount());
+  key_rewriter_filter_.reset(new internal::KeyRewriterEventFilter);
+  AddRootWindowEventFilter(key_rewriter_filter_.get());
 
-  // PartialScreenshotEventFilter must be the first one to capture key
+  // PartialScreenshotEventFilter must be the second one to capture key
   // events when the taking partial screenshot UI is there.
+  DCHECK_EQ(1U, GetRootWindowEventFilterCount());
   partial_screenshot_filter_.reset(new internal::PartialScreenshotEventFilter);
   AddRootWindowEventFilter(partial_screenshot_filter_.get());
 
   // Then AcceleratorFilter and InputMethodEventFilter must be added (in this
   // order) since they have the second highest priority.
-  DCHECK_EQ(1U, GetRootWindowEventFilterCount());
+  DCHECK_EQ(2U, GetRootWindowEventFilterCount());
 #if !defined(OS_MACOSX)
   accelerator_filter_.reset(new internal::AcceleratorFilter);
   AddRootWindowEventFilter(accelerator_filter_.get());
-  DCHECK_EQ(2U, GetRootWindowEventFilterCount());
+  DCHECK_EQ(3U, GetRootWindowEventFilterCount());
 #endif
   input_method_filter_.reset(new internal::InputMethodEventFilter);
   AddRootWindowEventFilter(input_method_filter_.get());
diff --git a/ash/shell.h b/ash/shell.h
index 10f972a..2c864ad 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -64,6 +64,7 @@ class DragDropController;
 class EventClientImpl;
 class FocusCycler;
 class InputMethodEventFilter;
+class KeyRewriterEventFilter;
 class MonitorController;
 class PartialScreenshotEventFilter;
 class ResizeShadowController;
@@ -178,6 +179,9 @@ class ASH_EXPORT Shell {
   internal::TooltipController* tooltip_controller() {
     return tooltip_controller_.get();
   }
+  internal::KeyRewriterEventFilter* key_rewriter_filter() {
+    return key_rewriter_filter_.get();
+  }
   internal::PartialScreenshotEventFilter* partial_screenshot_filter() {
     return partial_screenshot_filter_.get();
   }
@@ -296,8 +300,8 @@ class ASH_EXPORT Shell {
   scoped_ptr<internal::EventClientImpl> event_client_;
   scoped_ptr<internal::MonitorController> monitor_controller_;
 
-  // An event filter that pre-handles all key events to send them to an IME.
-  scoped_ptr<internal::InputMethodEventFilter> input_method_filter_;
+  // An event filter that rewrites or drops a key event.
+  scoped_ptr<internal::KeyRewriterEventFilter> key_rewriter_filter_;
 
   // An event filter that pre-handles key events while the partial
   // screenshot UI is active.
@@ -308,6 +312,9 @@ class ASH_EXPORT Shell {
   scoped_ptr<internal::AcceleratorFilter> accelerator_filter_;
 #endif
 
+  // An event filter that pre-handles all key events to send them to an IME.
+  scoped_ptr<internal::InputMethodEventFilter> input_method_filter_;
+
   // The shelf for managing the launcher and the status widget in non-compact
   // mode. Shell does not own the shelf. Instead, it is owned by container of
   // the status area.
diff --git a/ash/wm/key_rewriter_event_filter.cc b/ash/wm/key_rewriter_event_filter.cc
new file mode 100644
index 0000000..30ba84d
--- /dev/null
+++ b/ash/wm/key_rewriter_event_filter.cc
@@ -0,0 +1,61 @@
+// Copyright (c) 2012 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.
+
+#include "ash/wm/key_rewriter_event_filter.h"
+
+#include "base/logging.h"
+#include "ash/key_rewriter_delegate.h"
+#include "ui/aura/event.h"
+
+namespace ash {
+namespace internal {
+
+KeyRewriterEventFilter::KeyRewriterEventFilter() {}
+
+KeyRewriterEventFilter::~KeyRewriterEventFilter() {}
+
+void KeyRewriterEventFilter::SetKeyRewriterDelegate(
+    scoped_ptr<KeyRewriterDelegate> delegate) {
+  delegate_.swap(delegate);
+}
+
+bool KeyRewriterEventFilter::PreHandleKeyEvent(
+    aura::Window* target, aura::KeyEvent* event) {
+  if (!delegate_.get())
+    return false;
+
+  // Do not consume a translated key event which is generated by an IME.
+  if (event->type() == ui::ET_TRANSLATED_KEY_PRESS ||
+      event->type() == ui::ET_TRANSLATED_KEY_RELEASE) {
+    return false;
+  }
+
+  switch (delegate_->RewriteOrFilterKeyEvent(event)) {
+    case KeyRewriterDelegate::ACTION_REWRITE_EVENT:
+      return false;
+    case KeyRewriterDelegate::ACTION_DROP_EVENT:
+      return true;
+  }
+
+  NOTREACHED();
+  return false;
+}
+
+bool KeyRewriterEventFilter::PreHandleMouseEvent(
+    aura::Window* target, aura::MouseEvent* event) {
+  return false;  // Not handled.
+}
+
+ui::TouchStatus KeyRewriterEventFilter::PreHandleTouchEvent(
+    aura::Window* target, aura::TouchEvent* event) {
+  return ui::TOUCH_STATUS_UNKNOWN;  // Not handled.
+}
+
+ui::GestureStatus KeyRewriterEventFilter::PreHandleGestureEvent(
+    aura::Window* target, aura::GestureEvent* event) {
+  return ui::GESTURE_STATUS_UNKNOWN;  // Not handled.
+}
+
+}  // namespace internal
+}  // namespace ash
diff --git a/ash/wm/key_rewriter_event_filter.h b/ash/wm/key_rewriter_event_filter.h
new file mode 100644
index 0000000..55aeeb3
--- /dev/null
+++ b/ash/wm/key_rewriter_event_filter.h
@@ -0,0 +1,50 @@
+// Copyright (c) 2012 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_WM_KEY_REWRITER_EVENT_FILTER_
+#define ASH_WM_KEY_REWRITER_EVENT_FILTER_
+#pragma once
+
+#include "ash/ash_export.h"
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/aura/event_filter.h"
+
+namespace ash {
+
+class KeyRewriterDelegate;
+
+namespace internal {
+
+// An event filter that rewrites or drops a key event.
+class ASH_EXPORT KeyRewriterEventFilter : public aura::EventFilter {
+ public:
+  KeyRewriterEventFilter();
+  virtual ~KeyRewriterEventFilter();
+
+  void SetKeyRewriterDelegate(scoped_ptr<KeyRewriterDelegate> delegate);
+
+ private:
+  // Overridden from aura::EventFilter:
+  virtual bool PreHandleKeyEvent(aura::Window* target,
+                                 aura::KeyEvent* event) OVERRIDE;
+  virtual bool PreHandleMouseEvent(aura::Window* target,
+                                   aura::MouseEvent* event) OVERRIDE;
+  virtual ui::TouchStatus PreHandleTouchEvent(
+      aura::Window* target,
+      aura::TouchEvent* event) OVERRIDE;
+  virtual ui::GestureStatus PreHandleGestureEvent(
+      aura::Window* target,
+      aura::GestureEvent* event) OVERRIDE;
+
+  scoped_ptr<KeyRewriterDelegate> delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(KeyRewriterEventFilter);
+};
+
+}  // namespace internal
+}  // namespace ash
+
+#endif  // ASH_WM_KEY_REWRITER_EVENT_FILTER_