在MFC中显示Jpg格式图片的简单实现方法

在做的时候在网上找了很多这方面的资料,但实现方法都很烦，最近发现了一个很简单的实现方法,，与大家分享一下……思路主要还是利用MS的IPicture类完成。

1. 在窗口类中添加IPicture指针……

private :
   LPPICTURE m_pPct;
public :
   int LoadPct(CString pcFile); // 将pcFile路径所指向的文件装载到m_pPct上
   int DrawPct();

private : LPPICTURE m_pPct; public : int LoadPct(CString pcFile); // 将pcFile路径所指向的文件装载到m_pPct上 int DrawPct();
2. LoadPct(CString pcFile)图片的实现方法：（其中加了断言）

HANDLE hFile = CreateFile(pcFile, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
cmn_assert(INVALID_HANDLE_VALUE != hFile);

// 获得文件大小
DWORD dwFileSize = GetFileSize(hFile, NULL);
cmn_assert(-1 != dwFileSize);
LPVOID pvData = NULL;

// 分配全局内存，获得内存句柄
HGLOBAL hGlobal = GlobalAlloc(GMEM_MOVEABLE, dwFileSize);
cmn_assert(NULL != hGlobal);

// 锁定内存，获得内存指针
pvData = GlobalLock(hGlobal);
cmn_assert(NULL != pvData);
DWORD dwBytesRead = 0;

// 读取文件
BOOL bRead = ReadFile(hFile, pvData, dwFileSize, &dwBytesRead, NULL);
cmn_assert(FALSE != bRead);
GlobalUnlock(hGlobal);
CloseHandle(hFile);
LPSTREAM pstm = NULL;

//从内存数据创建IStream*
HRESULT hr = CreateStreamOnHGlobal(hGlobal, TRUE, &pstm);
cmn_assert(SUCCEEDED(hr) && pstm);

// 创建IPicture
if (m_pPct)
  m_pPct->Release();

// 从IStream接口中载入图片到IPicture中
hr = ::OleLoadPicture(pstm, dwFileSize, FALSE, IID_IPicture, (LPVOID *)&m_pPct);
cmn_assert(SUCCEEDED(hr) && m_pPct);
// 释放IStream接口
pstm->Release();
HANDLE hFile = CreateFile(pcFile, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
cmn_assert(INVALID_HANDLE_VALUE != hFile);

// 获得文件大小
DWORD dwFileSize = GetFileSize(hFile, NULL);
cmn_assert(-1 != dwFileSize);
LPVOID pvData = NULL;

// 分配全局内存，获得内存句柄
HGLOBAL hGlobal = GlobalAlloc(GMEM_MOVEABLE, dwFileSize);
cmn_assert(NULL != hGlobal);

// 锁定内存，获得内存指针
pvData = GlobalLock(hGlobal);
cmn_assert(NULL != pvData);
DWORD dwBytesRead = 0;

// 读取文件
BOOL bRead = ReadFile(hFile, pvData, dwFileSize, &dwBytesRead, NULL);
cmn_assert(FALSE != bRead);
GlobalUnlock(hGlobal);
CloseHandle(hFile);
LPSTREAM pstm = NULL;

//从内存数据创建IStream*
HRESULT hr = CreateStreamOnHGlobal(hGlobal, TRUE, &pstm);
cmn_assert(SUCCEEDED(hr) && pstm);

// 创建IPicture
if (m_pPct)
  m_pPct->Release();

// 从IStream接口中载入图片到IPicture中
hr = ::OleLoadPicture(pstm, dwFileSize, FALSE, IID_IPicture, (LPVOID *)&m_pPct);
cmn_assert(SUCCEEDED(hr) && m_pPct);
// 释放IStream接口
pstm->Release();

HANDLE hFile = CreateFile(pcFile, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL); cmn_assert(INVALID_HANDLE_VALUE != hFile); // 获得文件大小 DWORD dwFileSize = GetFileSize(hFile, NULL); cmn_assert(-1 != dwFileSize); LPVOID pvData = NULL; // 分配全局内存，获得内存句柄 HGLOBAL hGlobal = GlobalAlloc(GMEM_MOVEABLE, dwFileSize); cmn_assert(NULL != hGlobal); // 锁定内存，获得内存指针 pvData = GlobalLock(hGlobal); cmn_assert(NULL != pvData); DWORD dwBytesRead = 0; // 读取文件 BOOL bRead = ReadFile(hFile, pvData, dwFileSize, &dwBytesRead, NULL); cmn_assert(FALSE != bRead); GlobalUnlock(hGlobal); CloseHandle(hFile); LPSTREAM pstm = NULL; //从内存数据创建IStream* HRESULT hr = CreateStreamOnHGlobal(hGlobal, TRUE, &pstm); cmn_assert(SUCCEEDED(hr) && pstm); // 创建IPicture if (m_pPct) m_pPct->Release(); // 从IStream接口中载入图片到IPicture中 hr = ::OleLoadPicture(pstm, dwFileSize, FALSE, IID_IPicture, (LPVOID *)&m_pPct); cmn_assert(SUCCEEDED(hr) && m_pPct); // 释放IStream接口 pstm->Release(); HANDLE hFile = CreateFile(pcFile, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL); cmn_assert(INVALID_HANDLE_VALUE != hFile); // 获得文件大小 DWORD dwFileSize = GetFileSize(hFile, NULL); cmn_assert(-1 != dwFileSize); LPVOID pvData = NULL; // 分配全局内存，获得内存句柄 HGLOBAL hGlobal = GlobalAlloc(GMEM_MOVEABLE, dwFileSize); cmn_assert(NULL != hGlobal); // 锁定内存，获得内存指针 pvData = GlobalLock(hGlobal); cmn_assert(NULL != pvData); DWORD dwBytesRead = 0; // 读取文件 BOOL bRead = ReadFile(hFile, pvData, dwFileSize, &dwBytesRead, NULL); cmn_assert(FALSE != bRead); GlobalUnlock(hGlobal); CloseHandle(hFile); LPSTREAM pstm = NULL; //从内存数据创建IStream* HRESULT hr = CreateStreamOnHGlobal(hGlobal, TRUE, &pstm); cmn_assert(SUCCEEDED(hr) && pstm); // 创建IPicture if (m_pPct) m_pPct->Release(); // 从IStream接口中载入图片到IPicture中 hr = ::OleLoadPicture(pstm, dwFileSize, FALSE, IID_IPicture, (LPVOID *)&m_pPct); cmn_assert(SUCCEEDED(hr) && m_pPct); // 释放IStream接口 pstm->Release();
3. DrawPct()函数的实现

if(m_pPct)
{
  CWnd   *pWnd;
  CDC   *pDvc;
  CRect rc;
  long hmWidth;
  long hmHeight;

  pWnd = GetDlgItem(IDC_STATIC_IMG); /* 获取句柄 ，IDC_STATIC_IMG是建立的STATIC类型窗体的ID号*/
  pDvc = pWnd->GetDC(); /* 获取设备上下文 */
  m_pPct->get_Width(&hmWidth); /* 图片宽 高度 */
  m_pPct->get_Height(&hmHeight);
  pWnd -> GetClientRect(&rc);  /* 获取相关的Rect类 */

  // 拉伸显示
  m_pPct->Render(pDvc->GetSafeHdc(), 0, 0,
   rc.Width(), rc.Height(), 0, hmHeight, hmWidth, -hmHeight, &rc);
  UpdateData(FALSE);
  return EXCU_SUCCESS;
}
return EXCU_FAILURE;
if(m_pPct)
{
  CWnd   *pWnd;
  CDC   *pDvc;
  CRect rc;
  long hmWidth;
  long hmHeight;

  pWnd = GetDlgItem(IDC_STATIC_IMG); /* 获取句柄 ，IDC_STATIC_IMG是建立的STATIC类型窗体的ID号*/
  pDvc = pWnd->GetDC(); /* 获取设备上下文 */
  m_pPct->get_Width(&hmWidth); /* 图片宽 高度 */
  m_pPct->get_Height(&hmHeight);
  pWnd -> GetClientRect(&rc);  /* 获取相关的Rect类 */

  // 拉伸显示
  m_pPct->Render(pDvc->GetSafeHdc(), 0, 0,
   rc.Width(), rc.Height(), 0, hmHeight, hmWidth, -hmHeight, &rc);
  UpdateData(FALSE);
  return EXCU_SUCCESS;
}
return EXCU_FAILURE;


[总结]：只要能读到数据，然后通过的ID获取窗体句柄，就能在其中进行显示……当然在调用Render时，只要修改其中相应的参数，就能进行缩放。

OK，打完收工。

PS: 最近刚刚开始整MFC什么的，水平有限，多多包涵