1 files changed, 278 insertions, 0 deletions
diff --git a/src/win/gui/InputMethod.cpp b/src/win/gui/InputMethod.cpp
new file mode 100644
index 00000000..d6f2146d
--- /dev/null
+++ b/src/win/gui/InputMethod.cpp
@@ -0,0 +1,278 @@
+#include "cru/win/gui/InputMethod.hpp"
+
+#include "cru/common/Logger.hpp"
+#include "cru/common/StringUtil.hpp"
+#include "cru/platform/Check.hpp"
+#include "cru/win/Exception.hpp"
+#include "cru/win/gui/Window.hpp"
+
+#include <vector>
+
+namespace cru::platform::gui::win {
+AutoHIMC::AutoHIMC(HWND hwnd) : hwnd_(hwnd) {
+  Expects(hwnd);
+  handle_ = ::ImmGetContext(hwnd);
+}
+
+AutoHIMC::AutoHIMC(AutoHIMC&& other)
+    : hwnd_(other.hwnd_), handle_(other.handle_) {
+  other.hwnd_ = nullptr;
+  other.handle_ = nullptr;
+}
+
+AutoHIMC& AutoHIMC::operator=(AutoHIMC&& other) {
+  if (this != &other) {
+    Object::operator=(std::move(other));
+    this->hwnd_ = other.hwnd_;
+    this->handle_ = other.handle_;
+    other.hwnd_ = nullptr;
+    other.handle_ = nullptr;
+  }
+  return *this;
+}
+
+AutoHIMC::~AutoHIMC() {
+  if (handle_) {
+    if (!::ImmReleaseContext(hwnd_, handle_))
+      log::TagWarn(log_tag, u"Failed to release HIMC.");
+  }
+}
+
+// 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);
+  if (clause_length) {
+    result.reserve(clause_length - 1);
+    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::u16string GetString(HIMC imm_context) {
+  LONG string_size =
+      ::ImmGetCompositionString(imm_context, GCS_COMPSTR, NULL, 0);
+  std::u16string result((string_size / sizeof(char16_t)), 0);
+  ::ImmGetCompositionString(imm_context, GCS_COMPSTR, result.data(),
+                            string_size);
+  return result;
+}
+
+std::u16string GetResultString(HIMC imm_context) {
+  LONG string_size =
+      ::ImmGetCompositionString(imm_context, GCS_RESULTSTR, NULL, 0);
+  std::u16string result((string_size / sizeof(char16_t)), 0);
+  ::ImmGetCompositionString(imm_context, GCS_RESULTSTR, 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 text = GetString(imm_context);
+
+  int length = static_cast<int>(text.length());
+  // Find out the range selected by the user.
+  int target_start = length;
+  int target_end = length;
+  GetCompositionTargetRange(imm_context, &target_start, &target_end);
+
+  auto clauses = GetCompositionClauses(imm_context, target_start, target_end);
+
+  int cursor = ::ImmGetCompositionString(imm_context, GCS_CURSORPOS, NULL, 0);
+
+  return CompositionText{std::move(text), std::move(clauses),
+                         TextRange{cursor}};
+}
+
+}  // namespace
+
+WinInputMethodContext::WinInputMethodContext(
+    gsl::not_null<WinNativeWindow*> window)
+    : native_window_(window) {
+  event_guard_ += window->NativeMessageEvent()->AddHandler(
+      std::bind(&WinInputMethodContext::OnWindowNativeMessage, this,
+                std::placeholders::_1));
+}
+
+WinInputMethodContext::~WinInputMethodContext() {}
+
+void WinInputMethodContext::EnableIME() {
+  const auto hwnd = native_window_->GetWindowHandle();
+  if (::ImmAssociateContextEx(hwnd, nullptr, IACE_DEFAULT) == FALSE) {
+    log::TagWarn(log_tag, u"Failed to enable ime.");
+  }
+}
+
+void WinInputMethodContext::DisableIME() {
+  const auto hwnd = native_window_->GetWindowHandle();
+  AutoHIMC himc{hwnd};
+
+  if (!::ImmNotifyIME(himc.Get(), NI_COMPOSITIONSTR, CPS_COMPLETE, 0)) {
+    log::TagWarn(log_tag,
+                 u"Failed to complete composition before disable ime.");
+  }
+
+  if (::ImmAssociateContextEx(hwnd, nullptr, 0) == FALSE) {
+    log::TagWarn(log_tag, u"Failed to disable ime.");
+  }
+}
+
+void WinInputMethodContext::CompleteComposition() {
+  auto himc = GetHIMC();
+  if (!::ImmNotifyIME(himc.Get(), NI_COMPOSITIONSTR, CPS_COMPLETE, 0)) {
+    log::TagWarn(log_tag, u"Failed to complete composition.");
+  }
+}
+
+void WinInputMethodContext::CancelComposition() {
+  auto himc = GetHIMC();
+  if (!::ImmNotifyIME(himc.Get(), NI_COMPOSITIONSTR, CPS_CANCEL, 0)) {
+    log::TagWarn(log_tag, u"Failed to complete composition.");
+  }
+}
+
+CompositionText WinInputMethodContext::GetCompositionText() {
+  auto himc = GetHIMC();
+  return GetCompositionInfo(himc.Get());
+}
+
+void WinInputMethodContext::SetCandidateWindowPosition(const Point& point) {
+  auto himc = GetHIMC();
+
+  ::CANDIDATEFORM form;
+  form.dwIndex = 1;
+  form.dwStyle = CFS_CANDIDATEPOS;
+
+  form.ptCurrentPos = native_window_->DipToPixel(point);
+
+  if (!::ImmSetCandidateWindow(himc.Get(), &form))
+    log::TagDebug(log_tag,
+                  u"Failed to set input method candidate window position.");
+}
+
+IEvent<std::nullptr_t>* WinInputMethodContext::CompositionStartEvent() {
+  return &composition_start_event_;
+}
+
+IEvent<std::nullptr_t>* WinInputMethodContext::CompositionEndEvent() {
+  return &composition_end_event_;
+};
+
+IEvent<std::nullptr_t>* WinInputMethodContext::CompositionEvent() {
+  return &composition_event_;
+}
+
+IEvent<std::u16string_view>* WinInputMethodContext::TextEvent() {
+  return &text_event_;
+}
+
+void WinInputMethodContext::OnWindowNativeMessage(
+    WindowNativeMessageEventArgs& args) {
+  const auto& message = args.GetWindowMessage();
+  switch (message.msg) {
+    case WM_CHAR: {
+      const auto c = static_cast<char16_t>(message.w_param);
+      if (IsUtf16SurrogatePairCodeUnit(c)) {
+        // I don't think this will happen because normal key strike without ime
+        // should only trigger ascci character. If it is a charater from
+        // supplementary planes, it should be handled with ime messages.
+        log::TagWarn(log_tag,
+                     u"A WM_CHAR message for character from supplementary "
+                     u"planes is ignored.");
+      } else {
+        char16_t s[1] = {c};
+        text_event_.Raise({s, 1});
+      }
+      args.HandleWithResult(0);
+      break;
+    }
+    case WM_IME_COMPOSITION: {
+      composition_event_.Raise(nullptr);
+      auto composition_text = GetCompositionText();
+      log::TagDebug(log_tag, u"WM_IME_COMPOSITION composition text:\n{}",
+                    composition_text);
+      if (message.l_param & GCS_RESULTSTR) {
+        auto result_string = GetResultString();
+        text_event_.Raise(result_string);
+      }
+      break;
+    }
+    case WM_IME_STARTCOMPOSITION: {
+      composition_start_event_.Raise(nullptr);
+      break;
+    }
+    case WM_IME_ENDCOMPOSITION: {
+      composition_end_event_.Raise(nullptr);
+      break;
+    }
+  }
+}
+
+std::u16string WinInputMethodContext::GetResultString() {
+  auto himc = GetHIMC();
+  auto result = win::GetResultString(himc.Get());
+  return result;
+}
+
+AutoHIMC WinInputMethodContext::GetHIMC() {
+  const auto hwnd = native_window_->GetWindowHandle();
+  return AutoHIMC{hwnd};
+}
+}  // namespace cru::platform::gui::win