请问一个关于句柄的问题.

[dodont]

在一个函数中用以下语句
HBITMAP bitmap;
bitmap=(HBITMAP)LoadImage(AfxGetInstanceHandle(),"plane.BMP",IMAGE_BITMAP,300,300,LR_LOADFROMFILE|LR_LOADMAP3DCOLORS);
ASSERT(bitmap);
HBITMAP OldBitmap;
CDC MemDC;
CRect rect;
MemDC.CreateCompatibleDC(pdc);
GetClientRect(rect);
OldBitmap=(HBITMAP)MemDC.SelectObject(bitmap);
///显示它
TransparentBlt(bitmap,50,50,rect.Width()-20,rect.Height()-20,&MemDC,0,0,100,100,50);

编译时显示：E:\loppp\program\bmp1\bmp1Dlg.cpp(208) : error C2664: 'TransparentBlt' : cannot convert parameter 6 from 'class CDC *' to 'struct HDC__ *'
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

请问是为什么？？

[dodont]

改成这样之后，
TransparentBlt(bitmap,50,50,rect.Width()-20,rect.Height()-20,MemDC.m_hDC,0,0,100,100,50);
它又说
E:\loppp\program\bmp1\bmp1Dlg.cpp(208) : error C2664: 'TransparentBlt' : cannot convert parameter 1 from 'struct HBITMAP__ *' to 'struct HDC__ *'
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
Error executing cl.exe.

[kimryo]

HDC hdc=CreateCompatibleDC(NULL);

SelectObject(bitmap);

.........

TransparentBlt(hdc,50,50,rect.Width()-20,rect.Height()-20,MemDC.m_hDC,0,0,100,100,50);

[plusplus]

changed &memDC to memDC.GetSafeHdc();
then it will ok.

[kimryo]

MemDC.m_hdc