Win32APIでIMEを使用（１）

#include <windows.h>
#include <imm.h>
#pragma comment(lib, "imm32.lib")



LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) {

    HIMC hIMC;

    int inx = 100;
    int iny = 100;
    switch (message) {
    case WM_CREATE:

        // IMEを使用可能にする
        ImmAssociateContext(hWnd, ImmCreateContext());

        break;

    case WM_IME_STARTCOMPOSITION:

        // IMEでの入力が開始される
        OutputDebugString(L"IME 入力開始\n");

        hIMC = ImmGetContext(hWnd);  // IMEコンテキストを取得
        if (hIMC)
        {
            //　IMEのウィンドウ位置を設定
            COMPOSITIONFORM cf2;
            cf2.dwStyle = CFS_POINT;
            cf2.ptCurrentPos.x = inx;
            cf2.ptCurrentPos.y = iny;
            ImmSetCompositionWindow(hIMC, &cf2); // IMEのウィンドウ位置を設定
            ImmReleaseContext(hWnd, hIMC);
        }
        break;

    case WM_IME_COMPOSITION:

        // IMEの入力中の処理

        hIMC = ImmGetContext(hWnd);
        if (hIMC) {
            if (lParam & GCS_RESULTSTR) {
                // GCS_RESULTSTR ... IMEの入力が確定されたフラグ

                // 確定した文字列のバイト数を取得(NULLは含まない)
                DWORD inputBytes = ImmGetCompositionStringW(hIMC, GCS_RESULTSTR, NULL, 0);
                if (inputBytes) {

                    size_t U16Count = inputBytes / sizeof(wchar_t) + 1;// wchar_tでの、NULLを含んだ文字数
                    wchar_t* buffer = new wchar_t[U16Count];

                    // 確定した文字列を取得
                    ImmGetCompositionStringW(hIMC, GCS_RESULTSTR, buffer, inputBytes);
                    buffer[U16Count - 1] = L'\0';

                    // 確定した文字列を描画
                    HDC hdc = GetDC(hWnd);
                    TextOutW(hdc, inx, iny, buffer, wcslen(buffer));
                    ReleaseDC(hWnd, hdc);

                    delete[] buffer;
                }
            }
            ImmReleaseContext(hWnd, hIMC);
        }
        break;

    case WM_IME_ENDCOMPOSITION:

        OutputDebugString(L"IME 入力終了\n");
        break;

    case WM_DESTROY:
        PostQuitMessage(0);
        break;

    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return DefWindowProc(hWnd, message, wParam, lParam);;
}

int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PWSTR pCmdLine, int nCmdShow) {

    WNDCLASS wc;
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = WndProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wc.lpszMenuName = NULL;
    wc.lpszClassName = L"SZL-IME-TEST";

    RegisterClass(&wc);

    HWND hWnd = CreateWindowW(L"SZL-IME-TEST", L"title", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 640, 480, NULL, NULL, hInstance, NULL);


    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);

    MSG msg = {};
    while (GetMessage(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return (int)msg.wParam;
}