VC++中图像处理类CBitmap的用法

class CBitmap : public CGdiObject
{
  DECLARE_DYNAMIC(CBitmap)

public:
  static CBitmap* PASCAL FromHandle(HBITMAP hBitmap);

// Constructors
  CBitmap();

  BOOL LoadBitmap(LPCTSTR lpszResourceName);
  BOOL LoadBitmap(UINT nIDResource);
  BOOL LoadOEMBitmap(UINT nIDBitmap); // for OBM_/OCR_/OIC_
#ifndef _AFX_NO_AFXCMN_SUPPORT
  BOOL LoadMappedBitmap(UINT nIDBitmap, UINT nFlags = 0,
    LPCOLORMAP lpColorMap = NULL, int nMapSize = 0);
#endif
  BOOL CreateBitmap(int nWidth, int nHeight, UINT nPlanes, UINT nBitcount,
      const void* lpBits);
  BOOL CreateBitmapIndirect(LPBITMAP lpBitmap);
  BOOL CreateCompatibleBitmap(CDC* pDC, int nWidth, int nHeight);
  BOOL CreateDiscardableBitmap(CDC* pDC, int nWidth, int nHeight);

// Attributes
  operator HBITMAP() const;
  int GetBitmap(BITMAP* pBitMap);

// Operations
  DWORD SetBitmapBits(DWORD dwCount, const void* lpBits);
  DWORD GetBitmapBits(DWORD dwCount, LPVOID lpBits) const;
  CSize SetBitmapDimension(int nWidth, int nHeight);
  CSize GetBitmapDimension() const;

// Implementation
public:
  virtual ~CBitmap();
#ifdef _DEBUG
  virtual void Dump(CDumpContext& dc) const;
#endif
};

class CGdiObject : public CObject
{
  DECLARE_DYNCREATE(CGdiObject)
public:

// Attributes
  HGDIOBJ m_hObject;         // must be first data member
  operator HGDIOBJ() const;
  HGDIOBJ GetSafeHandle() const;

  static CGdiObject* PASCAL FromHandle(HGDIOBJ hObject);
  static void PASCAL DeleteTempMap();
  BOOL Attach(HGDIOBJ hObject);
  HGDIOBJ Detach();

// Constructors
  CGdiObject(); // must Create a derived class object
  BOOL DeleteObject();

// Operations
#pragma push_macro("GetObject")
#undef GetObject
  int _AFX_FUNCNAME(GetObject)(int nCount, LPVOID lpObject) const;
  int GetObject(int nCount, LPVOID lpObject) const;
#pragma pop_macro("GetObject")
  UINT GetObjectType() const;
  BOOL CreateStockObject(int nIndex);
  BOOL UnrealizeObject();
  BOOL operator==(const CGdiObject& obj) const;
  BOOL operator!=(const CGdiObject& obj) const;

// Implementation
public:
  virtual ~CGdiObject();
#ifdef _DEBUG
  virtual void Dump(CDumpContext& dc) const;
  virtual void AssertValid() const;
#endif
};

// 装载位图

  CBitmap bmp;
  bmp.LoadBitmap(IDB_BITMAP);

HANDLE LoadImage(
 HINSTANCE hinst,  // handle of the instance containing the image
 LPCTSTR lpszName, // name or identifier of image
 UINT uType,    // type of image
 int cxDesired,   // desired width
 int cyDesired,   // desired height
 UINT fuLoad    // load flags
);

HBITMAP hBmp = (HBITMAP)LoadImage(NULL,
    m_fileName,
    IMAGE_BITMAP, 
    0, 0, 
    LR_LOADFROMFILE | LR_DEFAULTCOLOR | LR_DEFAULTSIZE);

HBITMAP  hBmp = (HBITMAP)::LoadImage(AfxGetInstanceHandle(),
    "BG.bmp",
    IMAGE_BITMAP,
    0,0,
    LR_LOADFROMFILE);

if (hBmp != NULL) {
    CBitmap *pBmp = CBitmap::FromHandle(hBmp);
  }

CBitmap bmp;
  if (hBmp != NULL) {
    bmp.DeleteObject();
    bmp.Attach(hBmp);  
  }

CBitmap bmp;
  bmp.LoadBitmap(IDB_BITMAP1);
  
  BITMAP bm;
  bmp.GetBitmap(&bm);

  CDC dc;
  dc.CreateCompatibleDC(pDC);
  CBitmap*pOldBmp=(CBitmap *)dc.SelectObject(&bmp);

  pDC->BitBlt(0,0,bm.bmWidth,bm.bmHeight,&dc,0,0,SRCCOPY);
  pDC->SelectObject(pOldBmp);

  bmp.DeleteObject();
  bmp.LoadBitmap(IDB_BITMAP2);

CBitmap bmp;
  bmp.LoadBitmap(IDB_BITMAP);

  CBitmap *pOld=pDC->SelectObject(&bmp);

  // 此时位图对象还在pDC中，因此不能马上删除
  // 而是先将位图从DC中选出 然后再删除
  pDC->SelectObject(pOld);
  bmp.DeleteObject();

//-------------------在内存中建立区域以存放所得位图-------------------
// hBitmapSrc 为 CBitmap中保存的矩形原图资源句柄
// hDC 句柄  
// 在内存中开辟位图资源，用以保存原图
HBITMAP CopyHBitmap(HBITMAP hBitmapSrc,HDC hDC)
{
  
  BITMAP bm;
  HBITMAP hBitmapDst;
  HDC hdcSrc,hdcDst;

  GetObject(hBitmapSrc,sizeof(BITMAP),&bm);
  hBitmapDst=CreateCompatibleBitmap(hDC,bm.bmWidth,bm.bmHeight);

  hdcSrc=CreateCompatibleDC(hDC);
  hdcDst=CreateCompatibleDC(hDC);

  SelectObject(hdcSrc,hBitmapSrc); 
  SelectObject(hdcDst,hBitmapDst);

  BitBlt(hdcDst,0,0,bm.bmWidth,bm.bmHeight,hdcSrc,0,0,SRCCOPY);
  
  DeleteDC(hdcSrc);
  DeleteDC(hdcDst);  
  return hBitmapDst;

}

// 使用下面的代码，可以把CBitmap类中的图像保存到图像文件中。支持格式：BMP、JPG、GIF和PNG。 
 
void SaveBitmap(CString strFilePath, CBitmap Bitmap)
{
   if ( Bitmap.m_hObject )
   {
      CImage imgTemp;   // CImage是MFC中的类。
      imgTemp.Attach(Bitmap.operator HBITMAP());
      imgTemp.Save(strFilePath);
   }
} 
 
// 注意文件路径名strFilePath必须包含后缀，即BMP、JPG、GIF或PNG中的一种。