WIP: Ash IME support

win8/metro_driver/ime/keyevent_filter.cc

Index: win8/metro_driver/ime/keyevent_filter.cc
diff --git a/win8/metro_driver/ime/keyevent_filter.cc b/win8/metro_driver/ime/keyevent_filter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7b974800ba689139073690c773cea9c69aee44a3
--- /dev/null
+++ b/win8/metro_driver/ime/keyevent_filter.cc
@@ -0,0 +1,80 @@
+// Copyright (c) 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.
+
+#include "win8/metro_driver/ime/keyevent_filter.h"
+
+#include <Windows.h>
+#include <msctf.h>
+
+#include "base/win/scoped_comptr.h"
+
+namespace metro_driver {
+namespace {
+
+ITfKeystrokeMgr* g_keystroke_manager = NULL;
+HHOOK g_hook = NULL;
+
+LRESULT CALLBACK GetMsgProc(int code, WPARAM wparam, LPARAM lparam) {
+  MSG* msg = reinterpret_cast<MSG*>(lparam);
+  if (code >= 0 && (wparam & PM_REMOVE) == PM_REMOVE &&
+      (msg->message == WM_KEYDOWN || msg->message == WM_KEYUP)) {
+    HRESULT hr = S_OK;
+    BOOL eaten = FALSE;
+    if (msg->message == WM_KEYDOWN)
+      hr = g_keystroke_manager->KeyDown(msg->wParam, msg->lParam, &eaten);
+    else
+      hr = g_keystroke_manager->KeyUp(msg->wParam, msg->lParam, &eaten);
+
+    // Emulate IMM32. Any key event that is eaten by an IME will be replaced
+    // with a key event whose virtual key code is VK_PROCESSKEY.
+    if (SUCCEEDED(hr) && !!eaten)
+      msg->wParam = VK_PROCESSKEY;
+  }
+  return CallNextHookEx(g_hook, code, wparam, lparam);
+}
+
+}  // namespace
+
+bool InstallKeyEventFilter() {
+  base::win::ScopedComPtr<ITfThreadMgr2> thread_manager;
+  if (FAILED(thread_manager.CreateInstance(CLSID_TF_ThreadMgr)))
+    return false;
+  base::win::ScopedComPtr<ITfKeystrokeMgr> keystroke_manager;
+  if (FAILED(keystroke_manager.QueryFrom(thread_manager)))
+    return false;
+  base::win::ScopedComPtr<ITfConfigureSystemKeystrokeFeed> feed;
+  if (FAILED(feed.QueryFrom(thread_manager)))
+    return false;
+
+  // Here we replace CUAS's message hook with our own message hook so that
+  // ITfKeystrokeMgr::KeyDown/KeyUp can be called only once per key event.
+
+  // Disables CUAS's own message hook.
+  if (FAILED(feed->DisableSystemKeystrokeFeed()))
+    return false;
+  g_keystroke_manager = keystroke_manager.Detach();
+
+  // Installs our own message hook.
+  g_hook = ::SetWindowsHookExW(
+      WH_GETMESSAGE, GetMsgProc, NULL, GetCurrentThreadId());
+  if (g_hook == NULL) {
+    g_keystroke_manager->Release();
+    g_keystroke_manager = NULL;
+    return false;
+  }
+  return true;
+}
+
+void UninstallKeyEventFilter() {
+  if (g_hook) {
+    UnhookWindowsHookEx(g_hook);
+    g_hook = NULL;
+  }
+  if (g_keystroke_manager) {
+    g_keystroke_manager->Release();
+    g_keystroke_manager = NULL;
+  }
+}
+
+}  // namespace metro_driver