要注意是誰響應WM_VSCROLL ，WM_HSCROLL，在對話框上添加scrollbar ，對話框要響應此消息。
void CMyView::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)
{
// Get the minimum and maximum scroll-bar positions.
int minpos;
int maxpos;
pScrollBar->GetScrollRange(&minpos, &maxpos);
maxpos = pScrollBar->GetScrollLimit();
// Get the current position of scroll box.
int curpos = pScrollBar->GetScrollPos();
// Determine the new position of scroll box.
switch (nSBCode)
{
case SB_LEFT: // Scroll to far left.
curpos = minpos;
break;
case SB_RIGHT: // Scroll to far right.
curpos = maxpos;
break;
case SB_ENDSCROLL: // End scroll.
break;
case SB_LINELEFT: // Scroll left.
if (curpos > minpos)
curpos--;
break;
case SB_LINERIGHT: // Scroll right.
if (curpos < maxpos)
curpos++;
break;
case SB_PAGELEFT: // Scroll one page left.
{
// Get the page size.
SCROLLINFO info;
pScrollBar->GetScrollInfo(&info, SIF_ALL);
if (curpos > minpos)
curpos = max(minpos, curpos - (int) info.nPage);
}
break;
case SB_PAGERIGHT: // Scroll one page right.
{
// Get the page size.
SCROLLINFO info;
pScrollBar->GetScrollInfo(&info, SIF_ALL);
if (curpos < maxpos)
curpos = min(maxpos, curpos + (int) info.nPage);
}
break;
case SB_THUMBPOSITION: // Scroll to absolute position. nPos is the position
curpos = nPos; // of the scroll box at the end of the drag operation.
break;
case SB_THUMBTRACK: // Drag scroll box to specified position. nPos is the
curpos = nPos; // position that the scroll box has been dragged to.
break;
}
// Set the new position of the thumb (scroll box).
pScrollBar->SetScrollPos(curpos);
CView::OnHScroll(nSBCode, nPos, pScrollBar);
}
