/*
 函数介绍：将文件加载到内存流中
 入口参数：wzFilename：表示要打开的文件
 出口参数：ppStream : 表示内存流，将文件中的内容输出到此内存流中
 返回值：S_OK :表示成功，否则失败
*/
HRESULT CreateStreamOnFile(const TCHAR * wzFilename, IStream ** ppStream)
{
 HRESULT hrRet = S_FALSE;
 HGLOBAL hg = NULL;
    HANDLE hFile = NULL;
    DWORD dwSize, dwRead;
    BYTE* pbLocked = NULL;
 
    //打开文件
    hFile = CreateFile(wzFilename, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
    if (INVALID_HANDLE_VALUE == hFile)
    {
        goto error;
    }
 
    //得到文件大小
    dwSize = GetFileSize(hFile, NULL);
    if (0xffffffff == dwSize)
    {
        goto error;
    }
 
    //分配内存
    hg = GlobalAlloc(GMEM_MOVEABLE, dwSize);
    if (NULL == hg)
    {
        goto error;
    }
 
    //得到已经分配的内存指针
    pbLocked = (BYTE*) GlobalLock(hg);
    if (NULL == pbLocked)
    {
        goto error;
    }
 
    //读取文件内容到内存中
    if (!ReadFile(hFile, pbLocked, dwSize, &dwRead, NULL))
    {
        goto error;
    }
 
    //解锁已经分配全局内存，对应GlobalLock(hg)
    GlobalUnlock(hg);

    //创建Stream对象
    hrRet = CreateStreamOnHGlobal(hg, TRUE, ppStream);
 
    //关闭文件流
    CloseHandle(hFile);
    return hrRet;
 
error: //错误处理,并释放内存
    if (pbLocked) GlobalUnlock(hg);
    if (hg) GlobalFree(hg);
    if (hFile) CloseHandle(hFile);
    return hrRet;
}

/*
 函数介绍：根据编码器类型名称，得到指定的编码器CLSID
 入口参数：pImagingFactory: Image工厂接口对象
   wzMimeType : Image编码格式名称
 出口参数：pclsid :编码器的CLSID
 返回值：TRUE : 成功; FALSE: 失败
*/
BOOL GetEnCodecCLSID(IImagingFactory* pImagingFactory, WCHAR * wzMimeType, CLSID * pclsid)
{
 UINT uiCount;
    ImageCodecInfo * codecs;
    HRESULT hr;
    BOOL fRet = FALSE;

    //枚举系统已经安装的编码器
    hr = pImagingFactory->GetInstalledEncoders(&uiCount, &codecs);

 //查找制定编码器的CLSID
    for (UINT i = 0; i < uiCount; i++)
    {
        if (wzMimeType && !wcscmp(wzMimeType, codecs[i].MimeType))
        {
            *pclsid = codecs[i].Clsid;
            fRet = TRUE;
            break;
        }
    }

    //释放内存
    CoTaskMemFree(codecs);
    return fRet;
}

/*
 函数介绍：BMP,JPG,GIF,PNG图片格式互相转换，通过IStream
 入口参数：wzInFileName: 指定待转换的图象文件
    wzOutFileName: 指定转换后的图象文件
    wzMimeType: 指定转换后，图象文件的格式
       L"image/bmp", L"image/jpeg", L"image/gif", L"image/png"
 返回值：TRUE : 成功; FALSE: 失败
*/
BOOL ImageConvert(TCHAR *wzInFileName, TCHAR *wzOutFileName, TCHAR *wzMimeType)
{
 HRESULT hr;
 IImagingFactory * pImagingFactory = NULL; //Image工厂接口对象
 IStream *pStream = NULL; // 流接口对象
 IImageSink *pImageSink = NULL; //Image Sink接口对象
 IImageDecoder *pImageDecoder = NULL;   //解码器接口对象
 IImageEncoder *pImageEncoder = NULL;   //编码器接口对象
 CLSID clsidEncoder;  //编码器CLSID
 
 BOOL fRet = FALSE;
 //初始化COM环境
 if (FAILED(hr = CoInitializeEx(NULL, COINIT_MULTITHREADED)))
 {
  TRACE(L"COINIT_MULTITHREADED ERROR");
  return fRet;
 }
 
 //得到Image工厂接口对象
 hr = CoCreateInstance(CLSID_ImagingFactory, NULL, CLSCTX_INPROC_SERVER, IID_IImagingFactory, (void**) &pImagingFactory);
 if (FAILED(hr))
 {
  TRACE(L"IMAGE FACTORY CREATED ERROR");
  goto finish;
 }
 
 //将文件内容加载到流中
 if (FAILED(hr = CreateStreamOnFile(wzInFileName, &pStream)))
 {
  goto finish;
 }
 
 //根据编码器类型名称得到编码器CLSID
 if (!GetEnCodecCLSID(pImagingFactory,wzMimeType, &clsidEncoder ))
 {
  goto finish;
 }
 
 //创建编码器接口，并关联到输出文件中
 if (FAILED(hr = pImagingFactory->CreateImageEncoderToFile(&clsidEncoder, wzOutFileName, &pImageEncoder)))
 {
  goto finish;
 }
 
 //创建解码器接口
 if (FAILED(hr = pImagingFactory->CreateImageDecoder(pStream, DecoderInitFlagBuiltIn1st, &pImageDecoder)))
 {
  goto finish;
 }
 
 //得到编码器接口的sink对象。此ImageSink接口作为一个槽或者管道来理解；
 //是用于负责pImageEncoder和pImageDecoder之间的传输
 if (FAILED(hr = pImageEncoder->GetEncodeSink(&pImageSink)))
 {
  goto finish;
 }
 
 //开始解码
 if (FAILED(hr = pImageDecoder->BeginDecode(pImageSink, NULL)))
 {
  goto finish;
 }
 
 //循环解码，直到结束
 for(;;)
 {
  //解码
  hr = pImageDecoder->Decode();
  
  //继续解码后面的部分
  if (E_PENDING == hr)
  {
   Sleep(500);
  }
  //失败
  else if (FAILED(hr))
  {
   //终止解码
   pImageDecoder->EndDecode(hr);
   goto finish;
  }
  else
  {
   //解码成功
   fRet = TRUE;
   break;
  }
 }
 
 //结束解码
 pImageDecoder->EndDecode(hr);
 
 //释放pImageSink对象
 pImageSink->Release();
 pImageSink = NULL;
 
 //结束编码，此时就已经完成了文件格式的转换
 pImageEncoder->TerminateEncoder();

finish:
 //释放pStream对象
 if (pStream) pStream->Release();
 
 //释放pImageSink对象
 if (pImageSink) pImageSink->Release();
 
 //释放pImageDecoder对象
 if (pImageDecoder) pImageDecoder->Release();
 
 //释放pImageEncoder对象
 if (pImageEncoder) pImageEncoder->Release();
 
 //释放IImagingFactory接口对象
 if (pImagingFactory) pImagingFactory->Release();
 
 //释放程序占用的COM资源
 CoUninitialize();
 return fRet;
}

/*
 函数介绍：BMP,JPG,GIF,PNG图片格式互相转换，通过IImage
 入口参数：wzInFileName: 指定待转换的图象文件
    wzOutFileName: 指定转换后的图象文件
    wzMimeType: 指定转换后，图象文件的格式
       L"image/bmp", L"image/jpeg", L"image/gif", L"image/png"
 返回值：TRUE : 成功; FALSE: 失败
*/
BOOL ImageConvert(TCHAR *wzInFileName, TCHAR *wzOutFileName, TCHAR *wzMimeType)
{
 HRESULT hr;
 IImage *pImage = NULL;
 IImagingFactory * pImagingFactory = NULL; //Image工厂接口对象
 IImageSink *pImageSink = NULL; //Image Sink接口对象
 IImageEncoder *pImageEncoder = NULL;   //编码器接口对象
 CLSID clsidEncoder;  //编码器CLSID

 BOOL fRet = FALSE;
 //初始化COM环境
 if (FAILED(hr = CoInitializeEx(NULL, COINIT_MULTITHREADED)))
 {
  TRACE(L"COINIT_MULTITHREADED ERROR");
  return fRet;
 }
 
 //得到Image工厂接口对象
 hr = CoCreateInstance(CLSID_ImagingFactory, NULL, CLSCTX_INPROC_SERVER, IID_IImagingFactory, (void**) &pImagingFactory);
 if (FAILED(hr))
 {
  TRACE(L"IMAGE FACTORY CREATED ERROR");
  goto finish;
 }

 if(FAILED(hr = pImagingFactory->CreateImageFromFile(wzInFileName,&pImage)))
 {
  goto finish;
 }

 //根据编码器类型名称得到编码器CLSID
 if (!GetEnCodecCLSID(pImagingFactory,wzMimeType, &clsidEncoder ))
 {
  goto finish;
 }
 
 //创建编码器接口，并关联到输出文件中
 if (FAILED(hr = pImagingFactory->CreateImageEncoderToFile(&clsidEncoder, wzOutFileName, &pImageEncoder)))
 {
  goto finish;
 }

 //得到编码器接口的sink对象。此ImageSink接口作为一个槽或者管道来理解
 if (FAILED(hr = pImageEncoder->GetEncodeSink(&pImageSink)))
 {
  goto finish;
 }

  if(FAILED(hr = pImage->PushIntoSink(pImageSink)))
  {
   goto finish;
  }

 //释放pImageSink对象
 pImageSink->Release();
 pImageSink = NULL;
 
 //结束编码，此时就已经完成了文件格式的转换
 pImageEncoder->TerminateEncoder();

finish:
 if (pImage) pImage->Release();

 //释放pImageSink对象
 if (pImageSink) pImageSink->Release();
 
 //释放pImageEncoder对象
 if (pImageEncoder) pImageEncoder->Release();
 
 //释放IImagingFactory接口对象
 if (pImagingFactory) pImagingFactory->Release();
 
 //释放程序占用的COM资源
 CoUninitialize();
 return fRet;
}