ScrollBar的消息处理

ScrollBar的消息处理ScrollBar分成窗口的ScrollBar，和单独的ScrollBar两种，处理方式有所不同，但差别不大。如果是窗口的ScrollBar，OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)中的pScrollBar为NULL，要用GetScrollLimit(SB_VERT);如果是控件的就用SB_CTL与之对应。下面是CMySVView（从CView继承）的消息处理（参考MSDN）框架void CMySVView::OnVScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar){// Get the minimum and maximum scroll-bar positions.int minpos;int maxpos;GetScrollRange(SB_VERT, &minpos, &maxpos); maxpos = GetScrollLimit(SB_VERT);// Get the current position of scroll box.int curpos = GetScrollPos(SB_VERT);// Determine the new position of scroll box.switch (nSBCode){case SB_TOP: // Scroll to far TOP.curpos = minpos;break;case SB_BOTTOM: // Scroll to far BOTTOM.curpos = maxpos;break;case SB_ENDSCROLL: // End scroll.break;case SB_LINEUP: // Scroll UP.if (curpos > minpos)curpos--;break;case SB_LINEDOWN: // Scroll DOWN.if (curpos < maxpos)curpos++;break;case SB_PAGEUP: // Scroll one page UP.{// Get the page size. SCROLLINFO info;GetScrollInfo(SB_VERT, &info, SIF_ALL);if (curpos > minpos)curpos = max(minpos, curpos - (int) info.nPage);}break;case SB_PAGEDOWN: // Scroll one page DOWN.{// Get the page size. SCROLLINFO info;GetScrollInfo(SB_VERT, &info, SIF_ALL);if (curpos < maxpos)curpos = min(maxpos, curpos + (int) info.nPage);}break;case SB_THUMBPOSITION: // Scroll to absolute position. nPos is the positioncurpos = nPos; // of the scroll box at the end of the drag operation.break;case SB_THUMBTRACK: // Drag scroll box to specified position. nPos is thecurpos = nPos; // position that the scroll box has been dragged to.break;}// Set the new position of the thumb (scroll box).SetScrollPos(SB_VERT, curpos);CView::OnVScroll(nSBCode, nPos, pScrollBar);}void CMySVView::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar){// Get the minimum and maximum scroll-bar positions.int minpos;int maxpos;GetScrollRange(SB_HORZ, &minpos, &maxpos); maxpos = GetScrollLimit(SB_HORZ);// Get the current position of scroll box.int curpos = GetScrollPos(SB_HORZ);// 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;GetScrollInfo(SB_HORZ, &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;GetScrollInfo(SB_HORZ, &info, SIF_ALL);if (curpos < maxpos)curpos = min(maxpos, curpos + (int) info.nPage);}break;case SB_THUMBPOSITION: // Scroll to absolute position. nPos is the positioncurpos = nPos; // of the scroll box at the end of the drag operation.break;case SB_THUMBTRACK: // Drag scroll box to specified position. nPos is thecurpos = nPos; // position that the scroll box has been dragged to.break;}// Set the new position of the thumb (scroll box).SetScrollPos(SB_HORZ, curpos);CView::OnHScroll(nSBCode, nPos, pScrollBar);}