API proposal for chrome.app.window to intercept all keys.

ui/views/widget/desktop_aura/desktop_keyboard_capture_win.h

Index: ui/views/widget/desktop_aura/desktop_keyboard_capture_win.h
diff --git a/ui/views/widget/desktop_aura/desktop_keyboard_capture_win.h b/ui/views/widget/desktop_aura/desktop_keyboard_capture_win.h
new file mode 100644
index 0000000000000000000000000000000000000000..8ccef2c2502676a59cfb80cee9f6a815ce072dec
--- /dev/null
+++ b/ui/views/widget/desktop_aura/desktop_keyboard_capture_win.h
@@ -0,0 +1,51 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.

[sky, 2014/07/29 23:07:26]

2014.

[Sriram, 2014/07/31 00:21:14]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_VIEWS_WIDGET_DESKTOP_KEYBOARD_CAPTURE_WIN_H_
+#define UI_VIEWS_WIDGET_DESKTOP_KEYBOARD_CAPTURE_WIN_H_
+
+#include <map>
+
+#include "base/containers/scoped_ptr_hash_map.h"
+#include "ui/gfx/native_widget_types.h"
+#include "ui/views/views_export.h"
+
+namespace base {
+class Lock;
+class TaskRunner;
+}
+
+namespace views {
+
+class VIEWS_EXPORT DesktopKeyboardCaptureWin {

[sky, 2014/07/29 23:07:26]

Please add class level descriptions and in general more comments.

[sky, 2014/07/29 23:07:26]

I think this code would be less error prone if it was effectively a one shot. In
the constructor/Init() it installs the hook and in its destructor it releases
it.

[Sriram, 2014/07/31 00:21:14]

Done.

[Sriram, 2014/07/31 00:21:14]

The registration should be done on a thread that would live for the lifetime of
the hook and so we would either have to create a dedicated thread (or I am using
UI thread here for this). That is the reason for it not done inline.

On 2014/07/29 23:07:26, sky wrote:

[sky, 2014/07/31 15:21:22]

I don't understand. I'm suggesting the following:
{
  DesktopKeyboardCaptureWin capturer(hwnd);   // sets capture.
}  // capturer is deleted and releases capture.

[Sriram, 2014/07/31 19:40:05]

Done.

+ public:
+  static void Capture(HWND window_handle, base::TaskRunner* task_runner);

[sky, 2014/07/29 23:07:26]

Why does this take a task_runner?

[Sriram, 2014/07/31 00:21:14]

See above.

On 2014/07/29 23:07:26, sky wrote:

[sky, 2014/07/31 15:21:22]

And see my other comments about thread usage.

[Sriram, 2014/07/31 19:40:05]

Done.

+  static void Release(HWND window_handle);
+
+ private:
+  // Low level keyboard hook processing related functions.
+  // Hook callback called from the OS.
+  static LRESULT CALLBACK
+      KeyboardHook(int code, WPARAM w_param, LPARAM l_param);
+
+  static bool IsKeyUp(WPARAM w_param);
+  static bool IsBitSet(ULONG value, ULONG mask);
+  static DWORD RemoveLocationOnKeycode(DWORD vk_code);
+  static bool UpdateThreadKeyboardState();
+  static LPARAM GetLParamFromHookStruct(WPARAM w_param,
+                                        KBDLLHOOKSTRUCT hook_struct);
+
+  // Registration list related functions.
+  static bool AddToRegistrationList(HWND handle);
+  static void RegisterExistingHandle(HWND handle);
+  static bool IsRegistered(HWND handle);
+
+  class KeyboardInterceptRegistration;
+  static base::Lock registration_lock_;

[sky, 2014/07/29 23:07:26]

statics should only be POD (see style guide).

[Sriram, 2014/07/31 00:21:14]

Done.

+  static base::ScopedPtrHashMap<HWND, KeyboardInterceptRegistration>
+      registrations_;
+};
+}
+
+#endif  // UI_VIEWS_WIDGET_DESKTOP_KEYBOARD_CAPTURE_WIN_H_