关于HBITMAP句柄的一个问题..高手请进,有分的-->
设置了一个全局变量: HBITMAP hbmp ...想利用它来画图
用一个函数来设置hbmp.
CTest::SetPic()
{ CBitmap bitmap;
bitmap.LoadBitmap(IDB_BITMAP1);
hbmp = (HBITMAP) bitmap.GetSafeHandle();
Draw();
}
CTest::Draw()
{ BITMAP bm;
GetObject(hbmp,sizeof(bm),bm);
CDC memDC;
CClientDC dc(this);
memDC.CreateCompatiableDC(&dc);
HBITMAP old = (HBITMAP)memDC.SelectObject(&hbmp);
dc.BitBlt(0,0,bm.bmWidth,bm.bmHeight,&memDC,0,0,SRCCOPY);
memDC.SelectObject(old);
}
但程序并不能把图形正确的画出来,原来以为SetPic()里没有得到正确的htmp但发现
在Draw()里的bm.bmWidth和bm.bmHeight能够得到正确的图形的宽和高...
另外,如果我把程序改写成下列的方式却可以正确的显示:
CTest::SetPic()
{ Draw();
}
CTest::Draw()
{ CBitmap bitmap;
bitmap.LoadBitmap(IDB_BITMAP1);
hbmp = (HBITMAP) bitmap.GetSafeHandle();
BITMAP bm;
GetObject(hbmp,sizeof(bm),bm);
CDC memDC;
CClientDC dc(this);
memDC.CreateCompatiableDC(&dc);
HBITMAP old = (HBITMAP)memDC.SelectObject(&hbmp);
dc.BitBlt(0,0,bm.bmWidth,bm.bmHeight,&memDC,0,0,SRCCOPY);
memDC.SelectObject(old);
}
或是改写成下面的形式也可以:
SetPic()
{ hbmp = (HBITMAP)LoadImage(NULL,"d:\\pic.bmp",IMAGE_BITMAP,0,0,LR_CREATEDIBSECTION|LR_ LOADFROMFILE|LR_DEFAULTSIZE);
Draw();
}
Draw()
{ BITMAP bm;
GetObject(hbmp,sizeof(bm),bm);
CDC memDC;
CClientDC dc(this);
memDC.CreateCompatiableDC(&dc);
HBITMAP old = (HBITMAP)memDC.SelectObject(&hbmp);
dc.BitBlt(0,0,bm.bmWidth,bm.bmHeight,&memDC,0,0,SRCCOPY);
memDC.SelectObject(old);
}
请问这是为何??? 请高手回答.......谢谢.