blob: 2bdc8fb13f4a0424907877b455c548749c3b48d0 [file] [log] [blame]
// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Copyright 2013 The Flutter 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 "flutter/shell/platform/windows/text_input_manager.h"
#include <imm.h>
#include <cassert>
#include <memory>
namespace flutter {
// RAII wrapper for the Win32 Input Method Manager context.
class ImmContext {
public:
ImmContext(HWND window_handle)
: context_(::ImmGetContext(window_handle)),
window_handle_(window_handle) {
assert(window_handle);
}
~ImmContext() {
if (context_ != nullptr) {
::ImmReleaseContext(window_handle_, context_);
}
}
// Prevent copying.
ImmContext(const ImmContext& other) = delete;
ImmContext& operator=(const ImmContext& other) = delete;
// Returns true if a valid IMM context has been obtained.
bool IsValid() const { return context_ != nullptr; }
// Returns the IMM context.
HIMC get() {
assert(context_);
return context_;
}
private:
HWND window_handle_;
HIMC context_;
};
void TextInputManager::SetWindowHandle(HWND window_handle) {
window_handle_ = window_handle;
}
void TextInputManager::CreateImeWindow() {
if (window_handle_ == nullptr) {
return;
}
// Some IMEs ignore calls to ::ImmSetCandidateWindow() and use the position of
// the current system caret instead via ::GetCaretPos(). In order to behave
// as expected with these IMEs, we create a temporary system caret.
if (!ime_active_) {
::CreateCaret(window_handle_, nullptr, 1, 1);
}
ime_active_ = true;
// Set the position of the IME windows.
UpdateImeWindow();
}
void TextInputManager::DestroyImeWindow() {
if (window_handle_ == nullptr) {
return;
}
// Destroy the system caret created in CreateImeWindow().
if (ime_active_) {
::DestroyCaret();
}
ime_active_ = false;
}
void TextInputManager::UpdateImeWindow() {
if (window_handle_ == nullptr) {
return;
}
ImmContext imm_context(window_handle_);
if (imm_context.IsValid()) {
MoveImeWindow(imm_context.get());
}
}
void TextInputManager::UpdateCaretRect(const Rect& rect) {
caret_rect_ = rect;
if (window_handle_ == nullptr) {
return;
}
ImmContext imm_context(window_handle_);
if (imm_context.IsValid()) {
MoveImeWindow(imm_context.get());
}
}
long TextInputManager::GetComposingCursorPosition() const {
if (window_handle_ == nullptr) {
return false;
}
ImmContext imm_context(window_handle_);
if (imm_context.IsValid()) {
// Read the cursor position within the composing string.
return ImmGetCompositionString(imm_context.get(), GCS_CURSORPOS, nullptr,
0);
}
return -1;
}
std::optional<std::u16string> TextInputManager::GetComposingString() const {
return GetString(GCS_COMPSTR);
}
std::optional<std::u16string> TextInputManager::GetResultString() const {
return GetString(GCS_RESULTSTR);
}
void TextInputManager::AbortComposing() {
if (window_handle_ == nullptr || !ime_active_) {
return;
}
ImmContext imm_context(window_handle_);
if (imm_context.IsValid()) {
// Cancel composing and close the candidates window.
::ImmNotifyIME(imm_context.get(), NI_COMPOSITIONSTR, CPS_CANCEL, 0);
::ImmNotifyIME(imm_context.get(), NI_CLOSECANDIDATE, 0, 0);
// Clear the composing string.
wchar_t composition_str[] = L"";
wchar_t reading_str[] = L"";
::ImmSetCompositionStringW(imm_context.get(), SCS_SETSTR, composition_str,
sizeof(wchar_t), reading_str, sizeof(wchar_t));
}
}
std::optional<std::u16string> TextInputManager::GetString(int type) const {
if (window_handle_ == nullptr || !ime_active_) {
return std::nullopt;
}
ImmContext imm_context(window_handle_);
if (imm_context.IsValid()) {
// Read the composing string length.
const long compose_bytes =
::ImmGetCompositionString(imm_context.get(), type, nullptr, 0);
const long compose_length = compose_bytes / sizeof(wchar_t);
if (compose_length < 0) {
return std::nullopt;
}
std::u16string text(compose_length, '\0');
::ImmGetCompositionString(imm_context.get(), type, &text[0], compose_bytes);
return text;
}
return std::nullopt;
}
void TextInputManager::MoveImeWindow(HIMC imm_context) {
if (GetFocus() != window_handle_ || !ime_active_) {
return;
}
LONG left = caret_rect_.left();
LONG top = caret_rect_.top();
LONG right = caret_rect_.right();
LONG bottom = caret_rect_.bottom();
::SetCaretPos(left, bottom);
// Set the position of composition text.
COMPOSITIONFORM composition_form = {CFS_POINT, {left, top}};
::ImmSetCompositionWindow(imm_context, &composition_form);
// Set the position of candidate window.
CANDIDATEFORM candidate_form = {
0, CFS_EXCLUDE, {left, bottom}, {left, top, right, bottom}};
::ImmSetCandidateWindow(imm_context, &candidate_form);
}
} // namespace flutter