Support IMM32 reconversion on Windows

views/ime/input_method_win.cc

 // Copyright (c) 2011 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 "views/ime/input_method_win.h"
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/string_util.h"
 #include "ui/base/keycodes/keyboard_codes.h"
 #include "views/events/event.h"
 
+static const size_t kExtraNumberOfChars = 100;

[James Su, 2011/10/28 04:20:45]

I think 10~20 should be enough.
And how about to add a comment to describe the purpose of this constant?

[Peng, 2011/10/28 15:42:19]

Done.

+
 namespace views {
 
 InputMethodWin::InputMethodWin(internal::InputMethodDelegate* delegate)
     : active_(false),
       direction_(base::i18n::UNKNOWN_DIRECTION),
       pending_requested_direction_(base::i18n::UNKNOWN_DIRECTION) {
   set_delegate(delegate);
 }
 
 InputMethodWin::~InputMethodWin() {
@@ skipping 85 matching lines @@
       break;
     case WM_IME_STARTCOMPOSITION:
       result = OnImeStartComposition(message, w_param, l_param, handled);
       break;
     case WM_IME_COMPOSITION:
       result = OnImeComposition(message, w_param, l_param, handled);
       break;
     case WM_IME_ENDCOMPOSITION:
       result = OnImeEndComposition(message, w_param, l_param, handled);
       break;
+    case WM_IME_REQUEST:
+      result = OnImeRequest(message, w_param, l_param, handled);
+      break;
     case WM_CHAR:
     case WM_SYSCHAR:
       result = OnChar(message, w_param, l_param, handled);
       break;
     case WM_DEADCHAR:
     case WM_SYSDEADCHAR:
       result = OnDeadChar(message, w_param, l_param, handled);
       break;
     default:
       NOTREACHED() << "Unknown IME message:" << message;
@@ skipping 84 matching lines @@
     return 0;
 
   if (GetTextInputClient()->HasCompositionText())
     GetTextInputClient()->ClearCompositionText();
 
   ime_input_.ResetComposition(hwnd());
   ime_input_.DestroyImeWindow(hwnd());
   return 0;
 }
 
+LRESULT InputMethodWin::OnImeRequest(
+    UINT message, WPARAM wparam, LPARAM lparam, BOOL* handled) {
+  *handled = FALSE;
+
+  // Should not receive WM_IME_REQUEST message, if IME is disabled.
+  const ui::TextInputType type = GetTextInputType();
+  if (type == ui::TEXT_INPUT_TYPE_NONE ||
+      type == ui::TEXT_INPUT_TYPE_PASSWORD) {
+    return 0;
+  }
+
+  switch (wparam) {
+    case IMR_RECONVERTSTRING:
+      *handled = TRUE;
+      return OnReconvertString(reinterpret_cast<RECONVERTSTRING*>(lparam));
+    case IMR_DOCUMENTFEED:
+      *handled = TRUE;
+      return OnDocumentFeed(reinterpret_cast<RECONVERTSTRING*>(lparam));
+    default:
+      return 0;
+  }
+}
+
 LRESULT InputMethodWin::OnChar(
     UINT message, WPARAM wparam, LPARAM lparam, BOOL* handled) {
   *handled = TRUE;
 
   // We need to send character events to the focused text input client event if
   // its text input type is ui::TEXT_INPUT_TYPE_NONE.
   if (!GetTextInputClient())
     return 0;
 
   int flags = 0;
@@ skipping 15 matching lines @@
   // what dead key was pressed.
   ui::CompositionText composition;
   composition.text.assign(1, static_cast<char16>(wparam));
   composition.selection = ui::Range(0, 1);
   composition.underlines.push_back(
       ui::CompositionUnderline(0, 1, SK_ColorBLACK, false));
   GetTextInputClient()->SetCompositionText(composition);
   return 0;
 }
 
+LRESULT InputMethodWin::OnDocumentFeed(RECONVERTSTRING *reconv) {

[James Su, 2011/10/28 04:20:45]

Per our discussion, feel free to remove this method if you think it's not
important at all. But it'll be best if you can add some comment to explain the
reason. And maybe we can add a TODO for it, in case we want it in the future.

+  TextInputClient* client = GetTextInputClient();
+  if (!client)
+    return 0;
+
+  ui::Range text_range;
+  if (!client->GetTextRange(&text_range) || text_range.is_empty())
+    return 0;
+
+  bool result = false;
+  ui::Range target_range;
+  if (client->HasCompositionText())
+    result = client->GetCompositionTextRange(&target_range);
+
+  if (!result || target_range.is_empty()) {
+    if (!client->GetSelectionRange(&target_range) ||
+        !target_range.IsValid()) {
+      return 0;
+    }
+  }
+
+  if (!text_range.Contains(target_range))
+    return 0;
+
+  if (target_range.GetMin() - text_range.start() > kExtraNumberOfChars)
+    text_range.set_start(target_range.GetMin() - kExtraNumberOfChars);
+
+  if (text_range.end() - target_range.GetMax() > kExtraNumberOfChars)
+    text_range.set_end(target_range.GetMax() + kExtraNumberOfChars);
+
+  size_t len = text_range.length();
+  size_t need_size = sizeof(RECONVERTSTRING) + len * sizeof(WCHAR);
+
+  if (!reconv)
+    return need_size;
+
+  if (reconv->dwSize < need_size)
+    return 0;
+
+  string16 text;
+  if (!GetTextInputClient()->GetTextFromRange(text_range, &text))
+    return 0;
+
+  reconv->dwVersion = 0;
+  reconv->dwStrLen = len;
+  reconv->dwStrOffset = sizeof(RECONVERTSTRING);
+  reconv->dwCompStrLen =
+      client->HasCompositionText() ? target_range.length() : 0;
+  reconv->dwCompStrOffset =
+      (target_range.GetMin() - text_range.start()) * sizeof(WCHAR);
+  reconv->dwTargetStrLen = target_range.length();
+  reconv->dwTargetStrOffset = reconv->dwCompStrOffset;
+
+  memcpy((char*)reconv + sizeof(RECONVERTSTRING),
+      text.c_str(), len * sizeof(WCHAR));
+
+  return reinterpret_cast<LRESULT>(reconv);
+}
+
+LRESULT InputMethodWin::OnReconvertString(RECONVERTSTRING *reconv) {
+  TextInputClient* client = GetTextInputClient();
+  if (!client)
+    return 0;
+
+  // If there is a composition string already, we don't allow reconversion.
+  if (client->HasCompositionText())
+    return 0;
+
+  ui::Range text_range;
+  if (!client->GetTextRange(&text_range) || text_range.is_empty())
+    return 0;
+
+  ui::Range selection_range;
+  if (!client->GetSelectionRange(&selection_range) ||
+      selection_range.is_empty()) {
+    return 0;
+  }
+
+  DCHECK(text_range.Contains(selection_range));
+
+  size_t len = selection_range.length();

[James Su, 2011/10/28 04:20:45]

If you really don't want to return extra surrounding context, please add a
comment to explain the reason and add a TODO, in case we want to support it in
the future to help improve IMEs' reconversion accuracy.

[Peng, 2011/10/28 15:42:19]

Done.

+  size_t need_size = sizeof(RECONVERTSTRING) + len * sizeof(WCHAR);
+
+  if (!reconv)
+    return need_size;
+
+  if (reconv->dwSize < need_size)
+    return 0;
+
+  string16 text;
+  if (!GetTextInputClient()->GetTextFromRange(selection_range, &text))

[James Su, 2011/10/28 04:20:45]

nit: check the text length in case it's shorter than len?

[Peng, 2011/10/28 15:42:19]

The API guarantee the text has right size with given range. So checking it is
not necessary.

+    return 0;
+
+  reconv->dwVersion = 0;
+  reconv->dwStrLen = len;
+  reconv->dwStrOffset = sizeof(RECONVERTSTRING);
+  reconv->dwCompStrLen = len;
+  reconv->dwCompStrOffset = 0;
+  reconv->dwTargetStrLen = len;
+  reconv->dwTargetStrOffset = 0;
+
+  memcpy(reinterpret_cast<char*>(reconv) + sizeof(RECONVERTSTRING),
+      text.c_str(), len * sizeof(WCHAR));
+
+  return reinterpret_cast<LRESULT>(reconv);

[James Su, 2011/10/28 04:20:45]

Though msdn says that this method should return the structure on success, but
I'd rather believe it's a mistake of the document, because any implementations I
can find on the internet return the structure size instead, even the sample
provided by Microsoft.

[Peng, 2011/10/28 15:42:19]

I am not sure. Most IME just tests the return value is not zero. So both are OK.
But if some IMEs test the return value with the structure pointer, it may has
problem. So I guess following API document is safer.

+}
+
 void InputMethodWin::ConfirmCompositionText() {
   if (!IsTextInputTypeNone()) {
     ime_input_.CleanupComposition(hwnd());
     // Though above line should confirm the client's composition text by sending
     // a result text to us, in case the input method and the client are in
     // inconsistent states, we check the client's composition state again.
     if (GetTextInputClient()->HasCompositionText())
       GetTextInputClient()->ConfirmCompositionText();
   }
 }
 
 void InputMethodWin::UpdateIMEState() {
   // Use switch here in case we are going to add more text input types.
   // We disable input method in password field.
   switch (GetTextInputType()) {
     case ui::TEXT_INPUT_TYPE_NONE:
     case ui::TEXT_INPUT_TYPE_PASSWORD:
       ime_input_.DisableIME(hwnd());
       break;
     default:
       ime_input_.EnableIME(hwnd());
       break;
   }
 }
 
 }  // namespace views