图片格式转换

void Bmp2Png(LPCWSTR szBmpFile, LPCWSTR szPngFile)
{
    Image* image = nullptr;
    CLSID clsid;

    image = Image::FromFile(szBmpFile, TRUE);

    if (!image)
    {
        printf("failed to call FromFile\n");
    }

    if (!GetEncodeCLSID(L"image/png", &clsid))
    {
        printf("failed to call GetEncodeCLSID\n");
    }
    
    if (image->Save(szPngFile, &clsid))
    {
        printf("failed to call Save\n");
    }

    delete image;
}

void Pgn2Bmp(LPCWSTR szPngFile, LPCWSTR szImgFile)
{
    Image* image = nullptr;
    CLSID clsid;

    image = Image::FromFile(szPngFile, TRUE);

    if (!image)
    {
        printf("failed to call FromFile\n");
    }

    if (!GetEncodeCLSID(L"image/bmp", &clsid))
    {
        printf("failed to call GetEncodeCLSID\n");
    }

    if (image->Save(szImgFile, &clsid))
    {
        printf("failed to call Save\n");
    }

    delete image;
}

bool GetEncodeCLSID(LPCWSTR szMimeType, CLSID* clsid)
{
    UINT num = 0, size = 0;
    ImageCodecInfo* pImageCodecInfo = NULL;
    GetImageEncodersSize(&num, &size);
    if (size == 0)
    {
        return FALSE;
    }

    pImageCodecInfo = (ImageCodecInfo*)(malloc(size));
    if (pImageCodecInfo == NULL)
    {
        return FALSE;
    }

    GetImageEncoders(num, size, pImageCodecInfo);

    BOOL bfound = FALSE;
    for (UINT i = 0; !bfound && i < num; i++)
    {
        if (_wcsicmp(pImageCodecInfo[i].MimeType, szMimeType) == 0)
        {
            *clsid = pImageCodecInfo[i].Clsid;
            bfound = TRUE;
        }
    }

    free(pImageCodecInfo);
    return bfound;
}