Support IMM32 reconversion on Windows

views/ime/input_method_win.cc

Index: views/ime/input_method_win.cc
diff --git a/views/ime/input_method_win.cc b/views/ime/input_method_win.cc
index 4ab1a187378d389ba70bf8dc6d3131b107afa847..e9eeb070d4cb41665e0a5eb60c356bdce0ac8219 100644
--- a/views/ime/input_method_win.cc
+++ b/views/ime/input_method_win.cc
@@ -10,6 +10,8 @@
 #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)
@@ -115,6 +117,9 @@ LRESULT InputMethodWin::OnImeMessages(
     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);
@@ -219,6 +224,29 @@ LRESULT InputMethodWin::OnImeEndComposition(
   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;
@@ -254,6 +282,113 @@ LRESULT InputMethodWin::OnDeadChar(
   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());