1 files changed, 114 insertions, 6 deletions

diff --git a/src/win/native/input_method.cpp b/src/win/native/input_method.cpp
index 7153b50d..dace5827 100644
--- a/src/win/native/input_method.cpp
+++ b/src/win/native/input_method.cpp
@@ -39,6 +39,102 @@ AutoHIMC::~AutoHIMC() {
   }
 }
 
+// copied from chromium
+namespace {
+// Determines whether or not the given attribute represents a target
+// (a.k.a. a selection).
+bool IsTargetAttribute(char attribute) {
+  return (attribute == ATTR_TARGET_CONVERTED ||
+          attribute == ATTR_TARGET_NOTCONVERTED);
+}
+// Helper function for ImeInput::GetCompositionInfo() method, to get the target
+// range that's selected by the user in the current composition string.
+void GetCompositionTargetRange(HIMC imm_context, int* target_start,
+                               int* target_end) {
+  int attribute_size =
+      ::ImmGetCompositionString(imm_context, GCS_COMPATTR, NULL, 0);
+  if (attribute_size > 0) {
+    int start = 0;
+    int end = 0;
+    std::vector<char> attribute_data(attribute_size);
+    ::ImmGetCompositionString(imm_context, GCS_COMPATTR, attribute_data.data(),
+                              attribute_size);
+    for (start = 0; start < attribute_size; ++start) {
+      if (IsTargetAttribute(attribute_data[start])) break;
+    }
+    for (end = start; end < attribute_size; ++end) {
+      if (!IsTargetAttribute(attribute_data[end])) break;
+    }
+    if (start == attribute_size) {
+      // This composition clause does not contain any target clauses,
+      // i.e. this clauses is an input clause.
+      // We treat the whole composition as a target clause.
+      start = 0;
+      end = attribute_size;
+    }
+    *target_start = start;
+    *target_end = end;
+  }
+}
+// Helper function for ImeInput::GetCompositionInfo() method, to get underlines
+// information of the current composition string.
+CompositionClauses GetCompositionClauses(HIMC imm_context, int target_start,
+                                         int target_end) {
+  CompositionClauses result;
+  int clause_size =
+      ::ImmGetCompositionString(imm_context, GCS_COMPCLAUSE, NULL, 0);
+  int clause_length = clause_size / sizeof(std::uint32_t);
+  result.reserve(clause_length - 1);
+  if (clause_length) {
+    std::vector<std::uint32_t> clause_data(clause_length);
+    ::ImmGetCompositionString(imm_context, GCS_COMPCLAUSE, clause_data.data(),
+                              clause_size);
+    for (int i = 0; i < clause_length - 1; ++i) {
+      CompositionClause clause;
+      clause.start = clause_data[i];
+      clause.end = clause_data[i + 1];
+      clause.target = false;
+      // Use thick underline for the target clause.
+      if (clause.start >= target_start && clause.end <= target_end) {
+        clause.target = true;
+      }
+      result.push_back(clause);
+    }
+  }
+  return result;
+}
+
+std::wstring GetString(HIMC imm_context) {
+  LONG string_size =
+      ::ImmGetCompositionString(imm_context, GCS_COMPSTR, NULL, 0);
+  std::wstring result((string_size / sizeof(wchar_t)) + 1, 0);
+  ::ImmGetCompositionString(imm_context, GCS_COMPSTR, result.data(),
+                            string_size);
+  return result;
+}
+
+CompositionText GetCompositionInfo(HIMC imm_context) {
+  // We only care about GCS_COMPATTR, GCS_COMPCLAUSE and GCS_CURSORPOS, and
+  // convert them into underlines and selection range respectively.
+
+  auto w_text = GetString(imm_context);
+
+  int w_length = static_cast<int>(w_text.length());
+  // Find out the range selected by the user.
+  int w_target_start = w_length;
+  int w_target_end = w_length;
+  GetCompositionTargetRange(imm_context, &w_target_start, &w_target_end);
+
+  auto clauses =
+      GetCompositionClauses(imm_context, w_target_start, w_target_end);
+
+  int cursor = ::ImmGetCompositionString(imm_context, GCS_CURSORPOS, NULL, 0);
+
+  // TODO: Finish this.
+}
+
+}  // namespace
+
 WinInputMethodContext::WinInputMethodContext(
     gsl::not_null<WinNativeWindow*> window)
     : native_window_resolver_(window->GetResolver()) {
@@ -51,29 +147,41 @@ WinInputMethodContext::WinInputMethodContext(
 WinInputMethodContext::~WinInputMethodContext() {}
 
 void WinInputMethodContext::EnableIME() {
-  // TODO!
+  const auto native_window = Resolve(native_window_resolver_.get());
+  if (native_window == nullptr) return;
+  const auto hwnd = native_window->GetWindowHandle();
+
+  if (::ImmAssociateContextEx(hwnd, nullptr, IACE_DEFAULT) == FALSE) {
+    log::Warn("WinInputMethodContext: Failed to enable ime.");
+  }
 }
 
 void WinInputMethodContext::DisableIME() {
-  // TODO!
+  const auto native_window = Resolve(native_window_resolver_.get());
+  if (native_window == nullptr) return;
+  const auto hwnd = native_window->GetWindowHandle();
+
+  if (::ImmAssociateContextEx(hwnd, nullptr, 0) == FALSE) {
+    log::Warn("WinInputMethodContext: Failed to disable ime.");
+  }
 }
 
 void WinInputMethodContext::CompleteComposition() {
-  // TODO!
+  // TODO: Not implemented.
 }
 
 void WinInputMethodContext::CancelComposition() {
-  // TODO!
+  // TODO: Not implemented.
 }
 
 const CompositionText& WinInputMethodContext::GetCompositionText() {
-  // TODO!
+  // TODO: Not implemented.
 }
 
 void WinInputMethodContext::SetCandidateWindowPosition(const Point& point) {
   auto optional_himc = TryGetHIMC();
   if (!optional_himc.has_value()) return;
-  auto himc = std::move(optional_himc).value();
+  auto himc = *std::move(optional_himc);
 
   ::CANDIDATEFORM form;
   form.dwIndex = 1;