如何得到滚动条的指针？

[swalo]

[背景]为了在对话框中显示不变形的图片,从CWnd派生出类"CImageBox"。在创建"CImageBox"时使用"...|WS_HSCROLL|WS_VSCROLL"风格。
[问题]如何得到滚动条的指针？
[尝试]失败经验有：
<1>CWnd::GetScrollBarCtrl() 总返回 NULL;
<2>CView::GetScrollBarCtrl()似乎不适用;
<3>在"CImageBox"中处理WM_VSCROLL消息:
void CImageBox::OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar) ;
参数"pScrollBar"一定是NULL因而不能使用SetScrollPos()成员函数.
[感想]然而"CEdit"(MFC)却做到了,可以得到CEdit::GetScrollBarCtrl()的原代码吗？


请各位大虾不吝赐教。

[lengnuan]

This member function does not operate on scroll bars created when the WS_HSCROLL or WS_VSCROLL bits are set during the creation of a window. The CWnd implementation of this function simply returns NULL. Derived classes, such as CView, implement the described functionality.

CWnd没有实现,是CView实现的.

看MFC代码很容易.
把你的Search设为MFC的目录即可,


CScrollBar* CView::GetScrollBarCtrl(int nBar) const
{
ASSERT(nBar == SB_HORZ || nBar == SB_VERT);
if (GetStyle() & ((nBar == SB_HORZ) ? WS_HSCROLL : WS_VSCROLL))
{
// it has a regular windows style scrollbar (no control)
return NULL;
}

CWnd* pParent = GetParentSplitter(this, TRUE);
if (pParent == NULL)
return NULL; // no splitter

UINT nID = _AfxGetDlgCtrlID(m_hWnd);
if (nID < AFX_IDW_PANE_FIRST || nID > AFX_IDW_PANE_LAST)
return NULL; // not a standard pane ID

// appropriate PANE id - look for sibling (splitter, or just frame)
UINT nIDScroll;
if (nBar == SB_HORZ)
nIDScroll = AFX_IDW_HSCROLL_FIRST + (nID - AFX_IDW_PANE_FIRST) % 16;
else
nIDScroll = AFX_IDW_VSCROLL_FIRST + (nID - AFX_IDW_PANE_FIRST) / 16;

// return shared scroll bars that are immediate children of splitter
return (CScrollBar*)pParent->GetDlgItem(nIDScroll);
}

[xianglusong]

Please Use GetScrollInfo(..),GetScrollPos(..),GetScrollRange(..) and other API function, You should not necessary get the scrollbar pointer.