GetWindowRect,GetClientRect,ScreenToClient的区别

GetWindowRect()   得到的是在屏幕坐标系下的RECT；（即以屏幕左上角为原点）   
GetClientRect()   得到的是在客户区坐标系下的RECT；   （即以所在窗口左上角为原点）   
ScreenToClient()   就是把屏幕坐标系下的RECT坐标转换为客户区坐标系下的RECT坐标。

GetWindowRect()取的是整个窗口的矩形。。。   
GetClientRect()取的仅是客户区的矩形，也就是说不包括标题栏，外框等。。。  

第一个函数获得的是窗口在屏幕上的位置，得到的结果可能是这样CRect(10,10,240,240);   
第二个函数和它不同，它只获得了客户区的大小，因此得到的结果总是这样CRect(0,0,width,height);   

用法：：
// get dialog's and control's rect（这时指ListBox）
 CRect wndrc, objrc;

 GetClientRect(&wndrc);
 ::GetWindowRect(wnd, &objrc);
 ScreenToClient(&objrc);

//Demo.rc(96):    LISTBOX   IDC_LB,7,47,247,146,LBS_SORT | LBS_NOINTEGRALHEIGHT
//AddAnchor( IDC_LB, TOP_LEFT, BOTTOM_RIGHT );

void CResizableDialog::AddAnchor(HWND wnd, CSize tl_type, CSize br_type)
{
 ASSERT(wnd != NULL && ::IsWindow(wnd));
 ASSERT(::IsChild(*this, wnd));
 ASSERT(tl_type != NOANCHOR);

 // get control's window class
 
 CString st;
 GetClassName(wnd, st.GetBufferSetLength(MAX_PATH), MAX_PATH);
 st.ReleaseBuffer();
 st.MakeUpper();

 // add the style 'clipsiblings' to a GroupBox
 // to avoid unnecessary repainting of controls inside
 if (st == "BUTTON")
 {
  DWORD style = GetWindowLong(wnd, GWL_STYLE);
  if (style & BS_GROUPBOX)
   SetWindowLong(wnd, GWL_STYLE, style | WS_CLIPSIBLINGS);
 }

 // wnd classes that don't redraw client area correctly
 // when the hor scroll pos changes due to a resizing
 BOOL hscroll = FALSE;
 if (st == "LISTBOX")
  hscroll = TRUE;

 // wnd classes that need refresh when resized
 BOOL refresh = FALSE;
 if (st == "STATIC")
 {
  DWORD style = GetWindowLong(wnd, GWL_STYLE);

  switch (style & SS_TYPEMASK)
  {
  case SS_LEFT:
  case SS_CENTER:
  case SS_RIGHT:
   // word-wrapped text needs refresh
   refresh = TRUE;
  }

  // centered images or text need refresh
  if (style & SS_CENTERIMAGE)
   refresh = TRUE;

  // simple text never needs refresh
  if (style & SS_TYPEMASK == SS_SIMPLE)
   refresh = FALSE;
 }

 // get dialog's and control's rect
 CRect wndrc, objrc;

 GetClientRect(&wndrc);
 ::GetWindowRect(wnd, &objrc);
 ScreenToClient(&objrc);
 
 CSize tl_margin, br_margin;

 if (br_type == NOANCHOR)
  br_type = tl_type;
 
 // calculate margin for the top-left corner

 tl_margin.cx = objrc.left - wndrc.Width() * tl_type.cx / 100;
 tl_margin.cy = objrc.top - wndrc.Height() * tl_type.cy / 100;
 
 // calculate margin for the bottom-right corner

 br_margin.cx = objrc.right - wndrc.Width() * br_type.cx / 100;
 br_margin.cy = objrc.bottom - wndrc.Height() * br_type.cy / 100;

 // add to the list
 Layout obj(wnd, tl_type, tl_margin, br_type, br_margin, hscroll, refresh);
 m_arrLayout.Add(obj);
}