能不能提供一个GDI+画图的双缓冲Demo?该如何处理

能不能提供一个GDI+画图的双缓冲Demo?
拖动时会闪烁啊！！求个Demo!!

------解决方案--------------------
双缓冲就是先把复杂的绘图先画到内存DC上，然后再一起bitblt到真正显示的DC上嘛。

看DELPHI里面的控件是怎么使用双缓冲防止闪烁的：
procedure TWinControl.WMPaint(var Message: TWMPaint);
var
DC, MemDC: HDC;
MemBitmap, OldBitmap: HBITMAP;
PS: TPaintStruct;
begin
if not FDoubleBuffered or (Message.DC <> 0) then
begin
if not (csCustomPaint in ControlState) and (ControlCount = 0) then
inherited
else
PaintHandler(Message);
end
else
begin
DC := GetDC(0);
MemBitmap := CreateCompatibleBitmap(DC, ClientRect.Right, ClientRect.Bottom);
ReleaseDC(0, DC);
MemDC := CreateCompatibleDC(0);
OldBitmap := SelectObject(MemDC, MemBitmap);
try
DC := BeginPaint(Handle, PS);
Perform(WM_ERASEBKGND, MemDC, MemDC);
Message.DC := MemDC;
WMPaint(Message);
Message.DC := 0;
BitBlt(DC, 0, 0, ClientRect.Right, ClientRect.Bottom, MemDC, 0, 0, SRCCOPY);
EndPaint(Handle, PS);
finally
SelectObject(MemDC, OldBitmap);
DeleteDC(MemDC);
DeleteObject(MemBitmap);
end;
end;
end;