Enable basic IME functionality under Ash on Windows

win8/metro_driver/ime/text_service.cc

+// 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/text_service.h"
+
+#include <msctf.h>
+
+#include "base/win/scoped_variant.h"
+#include "ui/metro_viewer/ime_types.h"
+#include "win8/metro_driver/ime/text_service_delegate.h"
+#include "win8/metro_driver/ime/text_store.h"
+#include "win8/metro_driver/ime/text_store_delegate.h"
+
+// Architecture overview of input method support on Ash mode:
+//
+// Overview:

[ananta, 2013/11/27 20:02:47]

Thanks for the detailed overview here. Very helpful.

[yukawa, 2013/11/28 06:06:20]

Yey!

+// On Ash mode, the system keyboard focus is owned by the metro_driver process
+// while most of event handling are still implemented in the browser process.
+// Thus the metro_driver basically works as a proxy that simply forwards
+// keyevents to the metro_driver process. IME support must be involved somewhere
+// in this flow.
+//
+// In short, we need to interact with an IME in the metro_driver process since
+// TSF (Text Services Framework) runtime wants to processes keyevents while
+// (and only while) the attached UI thread owns keyboard focus.
+//
+// Due to this limitation, we need to split IME handling into two parts, one
+// is in the metro_driver process and the other is in the browser process.
+// The metro_driver process is responsible for implementing the primary data
+// store for the composition text and tying it up with an IME via TSF APIs.
+// On the other hand, the browser process is responsible for calculating
+// character position in the composition text whenever the composition text
+// is updated.
+//
+// IPC overview:
+// Fortunately, we don't need so many IPC messages to support IMEs. In fact,
+// only 4 messages are required to enable basic functionality for IMEs.
+//
+//   metro_driver process -> browser process
+//     Message Type:
+//       - MetroViewerHostMsg_ImeCompositionChanged
+//       - MetroViewerHostMsg_ImeTextCommitted
+//     Message Routing:
+//       TextServiceImpl
+//         -> ChromeAppViewAsh
+//         -- (process boundary) --
+//         -> RemoteRootWindowHostWin
+//         -> RemoteInputMethodWin
+//
+//   browser process -> metro_driver process
+//     Message Type:
+//       - MetroViewerHostMsg_ImeCancelComposition
+//       - MetroViewerHostMsg_ImeTextInputClientUpdated
+//     Message Routing:
+//       RemoteInputMethodWin
+//         -> RemoteRootWindowHostWin
+//         -- (process boundary) --
+//         -> ChromeAppViewAsh
+//         -> TextServiceImpl
+//
+// Note that a keyevent may be forwarded through a different path. When a
+// keyevent is not handled by an IME, such keyevent and subsequent character
+// events will be sent from the metro_driver process to the browser process as
+// following IPC messages.
+//  - MetroViewerHostMsg_KeyDown
+//  - MetroViewerHostMsg_KeyUp
+//  - MetroViewerHostMsg_Character
+//
+// How TextServiceImpl works:
+// Here is list of the major tasks that are handled in TextServiceImpl.
+//  - Manages a session object obtained from the TSF runtime. We need them
+//    to call most of TSF APIs.
+//  - Handles OnDocumentChanged event. Whenever the document context is changed,
+//    TextServiceImpl destroyes the current document and initializes new one
+//    according to the given |input_scopes|.
+//  - Stores the |composition_character_bounds_| passed from OnDocumentChanged
+//    event so that an IME or on-screen keyboard can query the character
+//    position synchronously.
+// The most complicated part is the OnDocumentChanged handler. Since some IMEs
+// such as Japanese IMEs dramatically change their behavior depending on
+// properties exposed from the virtual document, we need to set up a lot
+// attributes carefully and correctly. See DocumentBinding class in this file
+// about what will be involved in this multi-phase construction. See also
+// text_store.cc and input_scope.cc for mroe underlying details.
+
+namespace metro_driver {
+namespace {
+typedef TSFTextStore TextStore;
+
+// Japanese IME expects the default value of this compartment is
+// TF_SENTENCEMODE_PHRASEPREDICT like IMM32 implementation. This value is
+// managed per thread, thus setting this value at once is enough. This
+// value never affects other IMEs except for Japanese.
+bool InitializeSentenceMode(ITfThreadMgr2* thread_manager,
+                            TfClientId client_id) {
+  base::win::ScopedComPtr<ITfCompartmentMgr> thread_compartment_manager;
+  if (FAILED(thread_compartment_manager.QueryFrom(thread_manager)))
+    return false;
+  base::win::ScopedComPtr<ITfCompartment> sentence_compartment;
+  if (FAILED(thread_compartment_manager->GetCompartment(
+      GUID_COMPARTMENT_KEYBOARD_INPUTMODE_SENTENCE,
+      sentence_compartment.Receive()))) {
+    return false;
+  }
+
+  base::win::ScopedVariant sentence_variant;
+  sentence_variant.Set(TF_SENTENCEMODE_PHRASEPREDICT);
+  if (FAILED(sentence_compartment->SetValue(client_id, &sentence_variant)))
+    return false;
+  return true;
+}
+
+// Initializes |context| as disabled context where IMEs will be disabled.
+bool InitializeDisabledContext(ITfContext* context, TfClientId client_id) {
+  base::win::ScopedComPtr<ITfCompartmentMgr> compartment_mgr;
+  if (FAILED(compartment_mgr.QueryFrom(context)))
+    return false;
+
+  base::win::ScopedComPtr<ITfCompartment> disabled_compartment;
+  if (FAILED(compartment_mgr->GetCompartment(GUID_COMPARTMENT_KEYBOARD_DISABLED,
+                                             disabled_compartment.Receive()))) {
+    return false;
+  }
+
+  base::win::ScopedVariant variant;
+  variant.Set(1);
+  if (FAILED(disabled_compartment->SetValue(client_id, &variant)))
+    return false;
+
+  base::win::ScopedComPtr<ITfCompartment> empty_context;
+  if (FAILED(compartment_mgr->GetCompartment(GUID_COMPARTMENT_EMPTYCONTEXT,
+                                             empty_context.Receive()))) {
+    return false;
+  }
+
+  base::win::ScopedVariant empty_context_variant;
+  empty_context_variant.Set(static_cast<int32>(1));
+  if (FAILED(empty_context->SetValue(client_id, &empty_context_variant)))
+    return false;
+
+  return true;
+}
+
+scoped_refptr<TextStore> CreateTextStore(const std::vector<int32>& input_scopes,
+                                         HWND window_handle,
+                                         TextStoreDelegate* delegate) {
+  // Note: An empty |input_scopes| is not an error but means that an IME must be
+  // disabled in this context. We can safely omit its instantiation.
+  if (input_scopes.empty())
+    return NULL;
+  std::vector<InputScope> buffer(input_scopes.size());
+  for (size_t i = 0; i < input_scopes.size(); ++i)
+    buffer[i] = static_cast<InputScope>(input_scopes[i]);
+  return new TextStore(window_handle, buffer, delegate);
+}
+
+// A class that manages the lifetime of the event callback registration. When
+// this object is destroyed, corresponding event callback will be unregistered.
+class EventSink {
+ public:
+  EventSink(DWORD cookie, base::win::ScopedComPtr<ITfSource> source)
+      : cookie_(cookie),
+        source_(source) {}
+  ~EventSink() {
+    if (!source_ || cookie_ != TF_INVALID_COOKIE)
+      return;
+    source_->UnadviseSink(cookie_);
+    cookie_ = TF_INVALID_COOKIE;
+    source_.Release();
+  }
+
+ private:
+  DWORD cookie_;
+  base::win::ScopedComPtr<ITfSource> source_;
+  DISALLOW_COPY_AND_ASSIGN(EventSink);
+};
+
+scoped_ptr<EventSink> CreateTextEditSink(ITfContext* context,
+                                         ITfTextEditSink* text_store) {
+  if (!text_store)
+    return scoped_ptr<EventSink>();
+  base::win::ScopedComPtr<ITfSource> source;
+  DWORD cookie = TF_INVALID_EDIT_COOKIE;
+  if (FAILED(source.QueryFrom(context)))
+    return scoped_ptr<EventSink>();
+  if (FAILED(source->AdviseSink(IID_ITfTextEditSink, text_store, &cookie)))
+    return scoped_ptr<EventSink>();
+  return scoped_ptr<EventSink>(new EventSink(cookie, source));
+}
+
+// A set of objects that should have the same lifetime. Following things
+// are maingained.

[ananta, 2013/11/27 20:02:47]

maintained.

[yukawa, 2013/11/28 06:06:20]

Done.

+//  - TextStore: a COM object that abstracts text buffer. This object is
+//      actually implemented by us in text_store.cc
+//  - ITfDocumentMgr: a focusable unit in TSF. This object is implemented by
+//      TSF runtime and works as a container of TextStore.
+//  - EventSink: an object that ensures that the event callback between
+//      TSF runtime and TextStore is unregistered when this object is destroyed.
+class DocumentBinding {
+ public:
+  ~DocumentBinding() {
+    if (!document_manager_)
+      return;
+    document_manager_->Pop(TF_POPF_ALL);
+  }
+
+  static scoped_ptr<DocumentBinding> Create(
+      ITfThreadMgr2* thread_manager,
+      TfClientId client_id,
+      const std::vector<int32>& input_scopes,
+      HWND window_handle,
+      TextStoreDelegate* delegate) {
+    base::win::ScopedComPtr<ITfDocumentMgr> document_manager;
+    if (!thread_manager)
+      return scoped_ptr<DocumentBinding>();

[ananta, 2013/11/27 20:02:47]

These failures here and below warrant DCHECKs and traces at least.

[yukawa, 2013/11/28 06:06:20]

OK. For this particular case, |thread_manager| must not be NULL and I just
removed the check. (It should crash here). For other cases, I generally put
LOG(INFO) and VLOG(0, ...) so that we can ask QA persons to send us logs with
canary build.

+    if (FAILED(thread_manager->CreateDocumentMgr(document_manager.Receive())))
+      return scoped_ptr<DocumentBinding>();
+
+    // Note: |text_store| can be NULL and it's not an error. It means that the
+    // document expects an IME to be disabled while the document is focused.
+    scoped_refptr<TextStore> text_store = CreateTextStore(input_scopes,
+                                                          window_handle,

[ananta, 2013/11/27 20:02:47]

CreateTextStore can return NULL if input scopes are empty. Is there a NULL check
needed here on return?

[yukawa, 2013/11/28 06:06:20]

Yeah, this is a bit complicated point. I updated the code around here to clarify
when |text_store| is allowed to be NULL.
PTAL?

+                                                          delegate);
+
+    base::win::ScopedComPtr<ITfContext> context;
+    DWORD edit_cookie = TF_INVALID_EDIT_COOKIE;
+    if (FAILED(document_manager->CreateContext(
+        client_id,
+        0,
+        static_cast<ITextStoreACP*>(text_store.get()),
+        context.Receive(),
+        &edit_cookie))) {
+      return scoped_ptr<DocumentBinding>();

[ananta, 2013/11/27 20:02:47]

DCHECK and trace here

[yukawa, 2013/11/28 06:06:20]

I put LOG(ERROR) here for debugging.

+    }
+    const bool is_password_field =
+        std::find(input_scopes.begin(), input_scopes.end(), IS_PASSWORD) !=
+        input_scopes.end();
+    const bool use_disabled_context = input_scopes.empty() || is_password_field;
+    if (use_disabled_context && !InitializeDisabledContext(context, client_id))
+      return scoped_ptr<DocumentBinding>();
+    scoped_ptr<EventSink> text_edit_sink = CreateTextEditSink(context,
+                                                              text_store);
+    if (!text_edit_sink)
+      return scoped_ptr<DocumentBinding>();

[ananta, 2013/11/27 20:02:47]

This needs a DCHECK here?

[yukawa, 2013/11/28 06:06:20]

I put LOG(ERROR) here for debugging.

+    if (FAILED(document_manager->Push(context)))
+      return scoped_ptr<DocumentBinding>();

[ananta, 2013/11/27 20:02:47]

Ditto

[yukawa, 2013/11/28 06:06:20]

Ditto.

+    return scoped_ptr<DocumentBinding>(
+        new DocumentBinding(text_store,
+                            document_manager,
+                            text_edit_sink.Pass()));
+  }
+
+  ITfDocumentMgr* document_manager() const {
+    return document_manager_;
+  }
+
+  scoped_refptr<TextStore> text_store() {
+    return text_store_;
+  }
+
+ private:
+  DocumentBinding(scoped_refptr<TextStore> text_store,
+                  base::win::ScopedComPtr<ITfDocumentMgr> document_manager,
+                  scoped_ptr<EventSink> text_edit_sink)
+      : text_store_(text_store),
+        document_manager_(document_manager),
+        text_edit_sink_(text_edit_sink.Pass()) {}
+
+  scoped_refptr<TextStore> text_store_;
+  base::win::ScopedComPtr<ITfDocumentMgr> document_manager_;
+  scoped_ptr<EventSink> text_edit_sink_;
+
+  DISALLOW_COPY_AND_ASSIGN(DocumentBinding);
+};
+
+class TextServiceImpl : public TextService,
+                        public TextStoreDelegate {
+ public:
+  TextServiceImpl(base::win::ScopedComPtr<ITfThreadMgr2> thread_manager,

[ananta, 2013/11/27 20:02:47]

No need to pass ScopedComPtr here. Please change to ITfThreadMgr2*

[yukawa, 2013/11/28 06:06:20]

Right. Done.

+                  TfClientId client_id,
+                  HWND window_handle,
+                  TextServiceDelegate* delegate)
+      : client_id_(client_id),
+        window_handle_(window_handle),
+        delegate_(delegate),
+        thread_manager_(thread_manager) {
+    DCHECK_NE(TF_CLIENTID_NULL, client_id);
+    DCHECK(window_handle != NULL);
+    DCHECK(thread_manager_);
+  }
+  virtual ~TextServiceImpl() {
+    thread_manager_->Deactivate();
+  }
+
+ private:
+  // TextService overrides:
+  virtual void TextService::CancelComposition() OVERRIDE {
+    DocumentBinding* document = current_document_.get();
+    if (!document)
+      return;
+    TextStore* text_store = document->text_store();
+    if (!text_store)
+      return;
+    text_store->CancelComposition();
+  }
+
+  virtual void OnDocumentChanged(
+      const std::vector<int32>& input_scopes,
+      const std::vector<metro_viewer::CharacterBounds>& character_bounds)
+      OVERRIDE {
+    bool document_type_changed = input_scopes_ != input_scopes;
+    input_scopes_ = input_scopes;
+    composition_character_bounds_ = character_bounds;
+    if (document_type_changed)
+      OnDocumentTypeChanged(input_scopes);
+  }
+
+  virtual void OnWindowActivated() OVERRIDE {
+    if (!current_document_)

[ananta, 2013/11/27 20:02:47]

It does not seem like this will be NULL when this function is called. Please
remove this check.

[yukawa, 2013/11/28 06:06:20]

As commented in OnDocumentTypeChanged, now this can be NULL if
DocumentBinding::Create failed. I added VLOG for debugging.

+      return;
+    ITfDocumentMgr* document_manager = current_document_->document_manager();
+    if (!document_manager)

[ananta, 2013/11/27 20:02:47]

Having no ITfDocumentMgr instance here seems like an error condition. If yes
then please DCHECK and trace here.

[yukawa, 2013/11/28 06:06:20]

OK. I added VLOG for debugging.

+      return;
+    if (FAILED(thread_manager_->SetFocus(document_manager)))

[ananta, 2013/11/27 20:02:47]

Ditto

+      return;
+  }
+
+  virtual void OnCompositionChanged(
+      const string16& text,
+      int32 selection_start,
+      int32 selection_end,
+      const std::vector<metro_viewer::UnderlineInfo>& underlines) OVERRIDE {
+    if (!delegate_)
+      return;
+    delegate_->OnCompositionChanged(text,
+                                    selection_start,
+                                    selection_end,
+                                    underlines);
+  }
+
+  virtual void OnTextCommitted(const string16& text) OVERRIDE {
+    if (!delegate_)
+      return;
+    delegate_->OnTextCommitted(text);
+  }
+
+  virtual RECT GetCaretBounds() {
+    if (composition_character_bounds_.empty()) {
+      const RECT rect = {};
+      return rect;
+    }
+    const metro_viewer::CharacterBounds& bounds =
+        composition_character_bounds_[0];
+    POINT left_top = { bounds.left, bounds.top };
+    POINT right_bottom = { bounds.right, bounds.bottom };
+    ClientToScreen(window_handle_, &left_top);
+    ClientToScreen(window_handle_, &right_bottom);
+    const RECT rect = {
+      left_top.x,
+      left_top.y,
+      right_bottom.x,
+      right_bottom.y,
+    };
+    return rect;
+  }
+
+  virtual bool GetCompositionCharacterBounds(uint32 index,
+                                             RECT* rect) OVERRIDE {
+    if (index >= composition_character_bounds_.size()) {
+      return false;
+    }
+    const metro_viewer::CharacterBounds& bounds =
+        composition_character_bounds_[index];
+    POINT left_top = { bounds.left, bounds.top };
+    POINT right_bottom = { bounds.right, bounds.bottom };
+    ClientToScreen(window_handle_, &left_top);
+    ClientToScreen(window_handle_, &right_bottom);
+    SetRect(rect, left_top.x, left_top.y, right_bottom.x, right_bottom.y);
+    return true;
+  }
+
+  void OnDocumentTypeChanged(const std::vector<int32>& input_scopes) {
+    scoped_ptr<DocumentBinding> new_document =
+        DocumentBinding::Create(thread_manager_.get(),
+                                client_id_,
+                                input_scopes,
+                                window_handle_,
+                                this);
+    if (!new_document)

[ananta, 2013/11/27 20:02:47]

If we are unable to create a DocumentBinding here, then should we scream?.
Having a silent failure does not seem right. DCHECK maybe and also a log
statement for debugging.

[yukawa, 2013/11/28 06:06:20]

Agree. Put LOG_IF for debugging.

I also removed "return;" rather than keeping the previous document in
|current_document_|. This might be better in the following case in particular.
1. A normal textarea is focused. |current_document_| is valid so far.
2. Moved to any password field.
3. OnDocumentTypeChanged is fired but DocumentBinding::Create fails.
If |current_document_| still points something for a normal textarea, a user can
turn on an IME after step 3. This is bad.

With this modification, a failure of DocumentBinding::Create() can be observed
by a user like "Hey, I'm not able to turn on IME here! But still able to type
alphabet."  This sounds not so bad. If a user heavily depends on an IME, he
himself screams anyway.

+      return;
+    current_document_.swap(new_document);
+    OnWindowActivated();
+  }
+
+  TfClientId client_id_;
+  HWND window_handle_;
+  TextServiceDelegate* delegate_;
+  scoped_ptr<DocumentBinding> current_document_;
+  base::win::ScopedComPtr<ITfThreadMgr2> thread_manager_;
+
+  // An vector of InputScope enumeration, which represent the context type of
+  // the focused text field. If this vector is empty, it means that IMEs must
+  // be disabled there.
+  std::vector<int32> input_scopes_;
+  // Character bounds of the composition. When there is no composition but this
+  // vector is not empty, the first element contains the caret bounds.
+  std::vector<metro_viewer::CharacterBounds> composition_character_bounds_;
+
+  DISALLOW_COPY_AND_ASSIGN(TextServiceImpl);
+};
+
+}  // namespace
+
+scoped_ptr<TextService>
+CreateTextService(TextServiceDelegate* delegate, HWND window_handle) {
+  if (!delegate)
+    return scoped_ptr<TextService>();
+  base::win::ScopedComPtr<ITfThreadMgr2> thread_manager;
+  if (FAILED(thread_manager.CreateInstance(CLSID_TF_ThreadMgr)))
+    return scoped_ptr<TextService>();
+  TfClientId client_id = TF_CLIENTID_NULL;
+  if (FAILED(thread_manager->ActivateEx(&client_id, 0)))
+    return scoped_ptr<TextService>();
+  if (!InitializeSentenceMode(thread_manager, client_id)) {
+    thread_manager->Deactivate();
+    return scoped_ptr<TextService>();
+  }
+  return scoped_ptr<TextService>(new TextServiceImpl(thread_manager,
+                                                     client_id,
+                                                     window_handle,
+                                                     delegate));
+}
+
+}  // namespace metro_driver