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
};
父
CGdiObject
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
};
1 装载已导入工程的位图资源
// 装载位图
CBitmap bmp;
bmp.LoadBitmap(IDB_BITMAP);
2 装载位图文件
为了能让CBitmap能够装载位图文件，必须调用API函数LoadImage
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
);
装载： Example 1:
HBITMAP hBmp = (HBITMAP)LoadImage(NULL,
m_fileName,
IMAGE_BITMAP,
0, 0,
LR_LOADFROMFILE | LR_DEFAULTCOLOR | LR_DEFAULTSIZE);
Example 2:
HBITMAP hBmp = (HBITMAP)::LoadImage(AfxGetInstanceHandle(),
"BG.bmp",
IMAGE_BITMAP,
0,0,
LR_LOADFROMFILE);
将装载后得到的HBITMAP资源句柄 与 CBitmap 对象 相连
if (hBmp != NULL) {
CBitmap *pBmp = CBitmap::FromHandle(hBmp);
}
或
CBitmap bmp;
if (hBmp != NULL) {
bmp.DeleteObject();
bmp.Attach(hBmp);
}
3 显示位图
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);
4 删除资源
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();
5 CBitmap 析构
当CBitmap作为局部变量 在其退出作用范围后，会发生析构，这时候CBitmap会将其对应的位图资源（hBitmap ）释放掉。
若想继续使用该位图资源hBitmap，则在退出作用范围前，应将位图资源hBitmap和CBitmap对象通过Detach()函数进行分离
HBITMAP CMyClass::Load()
{
CBitmap bmp;
bmp.LoadBitmap(IDB_BITMAP); // 通过Detach 将资源与对象分离，这样bmp析构后，资源仍存在
// 否则 ，bmp析构时，会将位图资源一起析构掉，这样出了局部范围外，就不可再使用这个位图资源了
return bmp.Detach();
}
6 在仅获得HBITMAP资源句柄情况下，如何获得这个资源的BITMAP信息
BITMAP bm;
GetObject(hBitmap,sizeof(BITMAP),&bm);
7 在内存中开辟资源空间 将原图保存到内存中
//-------------------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; }