void Update()

{

    CDC dc = GetDC(m_hWnd);

    CDC dcMemory;

    dcMemory.CreateCompatibleDC(dc);

    CRect rect;

    GetClientRect(m_hWnd, &rect);

    CBitmap bmp = CreateCompatibleBitmap(dc, rect.Width(), rect.Height());

    dcMemory.SelectBitmap(bmp);

    {

        Graphics g(dcMemory);

        g.SetInterpolationMode(InterpolationModeNearestNeighbor);

        g.SetPixelOffsetMode(PixelOffsetModeHalf);

        // Rendering...

    }

    POINT pt = { 0, 0};

    BLENDFUNCTION stBlend = { AC_SRC_OVER, 0, 255, AC_SRC_ALPHA };

    SIZE szWindow = { rect.Width(), rect.Height() };

    UpdateLayeredWindow(m_hWnd, dc, NULL, &szWindow, dcMemory, &pt, 0, &stBlend, ULW_ALPHA);

}

void Update()

{

    CDC dc = GetDC(m_hWnd);

    CDC dcMemory;

    dcMemory.CreateCompatibleDC(dc);

    CRect rect;

    GetClientRect(m_hWnd, &rect);

    //

    // 注意：一定要自己創建一個 32 位位圖，不要 CreateCompatibleBitmap，否則遠程協助下可能無法正常顯示

    //

    BITMAPINFOHEADER bmih = { sizeof(BITMAPINFOHEADER) };

    bmih.biWidth          = rect.Width();

    bmih.biHeight         = rect.Height();

    bmih.biPlanes         = 1;

    bmih.biBitCount       = 32; // !注意：要 32 位

    bmih.biCompression    = BI_RGB;

    BYTE *pBits = NULL;

    HBITMAP hBitmap = CreateDIBSection(NULL, (BITMAPINFO *)&bmih, 0, (LPVOID *)&pBits, NULL, 0);

    if (hBitmap == NULL)

    {

        return;

    }

    CBitmap bmp(hBitmap);

    dcMemory.SelectBitmap(bmp);

    {

        Graphics g(dcMemory);

        g.SetInterpolationMode(InterpolationModeNearestNeighbor);

        g.SetPixelOffsetMode(PixelOffsetModeHalf);

        // Rendering...

    }

    POINT pt = { 0, 0};

    BLENDFUNCTION stBlend = { AC_SRC_OVER, 0, 255, AC_SRC_ALPHA };

    SIZE szWindow = { rect.Width(), rect.Height() };

    UpdateLayeredWindow(m_hWnd, dc, NULL, &szWindow, dcMemory, &pt, 0, &stBlend, ULW_ALPHA);

}