Question

请教在mfc中怎么将IPictureDisp中的图像通过DC显示出来

Answer 1

jpg显示的步骤：
1。打开图片控件的绘图DC。
2。使用OleLoadPicture函数读取jpg图像到内存中。（导入olepro32.dll）
3。向DC上绘制图像

示例如下：
CDC *pDC = GetDlgItem(IDC_STATIC_IMG)->GetDC(); //获取控件DC
HDC hDC = (HDC)pDC;
HANDLE hFile=CreateFile(szImagePath, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);//从指定的路径szImagePath中读取文件句柄
DWORD dwFileSize=GetFileSize(hFile, NULL); //获得图片文件的大小，用来分配全局内存
HGLOBAL hImageMemory=GlobalAlloc(GMEM_MOVEABLE, dwFileSize); //给图片分配全局内存
void *pImageMemory=GlobalLock(hImageMemory); //锁定内存
DWORD dwReadedSize; //保存实际读取的文件大小
ReadFile(hFile, pImageMemory, dwFileSize, &dwReadedSize, NULL); //读取图片到全局内存当中
GlobalUnlock(hImageMemory); //解锁内存
CloseHandle(hFile); //关闭文件句柄
IStream *pIStream;//创建一个IStream接口指针，用来保存图片流
IPicture *pIPicture;//创建一个IPicture接口指针，表示图片对象
CreateStreamOnHGlobal(hImageMemory, false, &pIStream); //用全局内存初使化IStream接口指针
OleLoadPicture(pIStream, 0, false, IID_IPicture, (LPVOID*)&(pIPicture));//用OleLoadPicture获得IPicture接口指针
//得到IPicture COM接口对象后，你就可以进行获得图片信息、显示图片等操作
OLE_XSIZE_HIMETRIC hmWidth;
OLE_YSIZE_HIMETRIC hmHeight;
pIPicture->get_Width(&hmWidth); //用接口方法获得图片的宽和高
pIPicture->get_Height(&hmHeight);
pIPicture->Render(hDC,0,0,100,100,0,hmHeight,hmWidth,-hmHeight,NULL); //在指定的DC上绘出图片
GlobalFree(hImageMemory); //释放全局内存
pIStream->Release(); //释放pIStream
pIPicture->Release(); //释放pIPicture
ReleaseDC(pDC);