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..a8c0fcabcb8e5b1b43b1fbd94865571d1dac1431 100644
--- a/views/ime/input_method_win.cc
+++ b/views/ime/input_method_win.cc
@@ -10,6 +10,10 @@
 #include "ui/base/keycodes/keyboard_codes.h"
 #include "views/events/event.h"
 
+// Extra number of chars before and after selection (or composition) range which
+// is returned to IME for improving conversion accuracy.
+static const size_t kExtraNumberOfChars = 20;
+
 namespace views {
 
 InputMethodWin::InputMethodWin(internal::InputMethodDelegate* delegate)
@@ -115,6 +119,9 @@ 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 +226,29 @@ 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 +284,117 @@ LRESULT InputMethodWin::OnDeadChar(
   return 0;
 }
 
+LRESULT InputMethodWin::OnDocumentFeed(RECONVERTSTRING* reconv) {
+  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;

[James Su, 2011/10/28 18:16:04]

nit: DCHECK_EQ(text_range.length(), text.length());

[Peng, 2011/10/28 19:13:06]

Done.

+
+  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));

[James Su, 2011/10/28 18:16:04]

nit: alignment.

[Peng, 2011/10/28 19:13:06]

Done.

+
+  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();
+  size_t need_size = sizeof(RECONVERTSTRING) + len * sizeof(WCHAR);
+
+  if (!reconv)
+    return need_size;
+
+  if (reconv->dwSize < need_size)
+    return 0;
+
+  // Because we don't not support IME adjusts the reconvert range right now and
+  // returning extra content may have privacy issue. So in the first step, we
+  // don't return exrat content.

[James Su, 2011/10/28 18:16:04]

I'd suggest to remove this paragraph. As I said returning extra context has
nothing to do with adjusting the reconvert range. And I don't think there is a
privacy issue.

[Peng, 2011/10/28 19:13:06]

Done.

+  // TODO(penghuang): support IME adjusts the reconvert range.

[James Su, 2011/10/28 18:16:04]

Just: // TODO(penghuang): Return some extra context to help improve IME's
reconversion accuracy.

It's better to put the TODO of adjusting the reconvert range elsewhere. This
place has nothing to do with this feature.

[Peng, 2011/10/28 19:13:06]

Done.

+  string16 text;
+  if (!GetTextInputClient()->GetTextFromRange(selection_range, &text))
+    return 0;

[James Su, 2011/10/28 18:16:04]

nit: DCHECK_EQ(selection_range.length(), text.length());

[Peng, 2011/10/28 19:13:06]

Done.

+
+  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));

[James Su, 2011/10/28 18:16:04]

nit: alignment.

[Peng, 2011/10/28 19:13:06]

Done.

+
+  return reinterpret_cast<LRESULT>(reconv);

[James Su, 2011/10/28 18:16:04]

If you insistent on returning the pointer here, I'd suggest to add a comment in
case somebody else wants to change it back to size in the future.

[Peng, 2011/10/28 19:13:06]

Done.

+}
+
 void InputMethodWin::ConfirmCompositionText() {
   if (!IsTextInputTypeNone()) {
     ime_input_.CleanupComposition(hwnd());