Windows API学习之滚动条系列函数

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作者：朱金灿
来源：http://blog.csdn.net/clever101

      Windows API中滚动条相关函数有两个：
int SetScrollInfo(
  HWND hwnd,
  int fnBar,
  LPSCROLLINFO lpsi,
  BOOL fRedraw
);       

BOOL GetScrollInfo(
  HWND hwnd,
  int fnBar,
  LPSCROLLINFO lpsi
);

见名知意，SetScrollInfo就是用来设置窗口的滚动信息，GetScrollInfo就是用来获取窗口的滚动信息。SetScrollInfo的参数含义如下：
参数 意义
hwnd
 滚动条控件的句柄或带有标准滚动栏的窗口的句柄
fnBar
 用于指定哪一种滚动条，只能是下面的值之一：
SB_CTL ：滚动条控件
SB_HORZ：水平滚动条
SB_VERT：垂直滚动条
lpsi
 滚动条信息结构体指针。下面作进一步详细介绍。
fRedraw 值为TRUE表示要Windows重新绘制计算了新信息后的滚动条，FALSE表示不绘制。

GetScrollInfo的参数含义如下：

参数 意义
hwnd
 滚动条控件的句柄或带有标准滚动栏的窗口的句柄
fnBar
 用于指定哪一种滚动条，只能是下面的值之一：
SB_CTL ：滚动条控件
SB_HORZ：水平滚动条
SB_VERT：垂直滚动条
lpsi
 滚动条信息结构体指针。下面作进一步详细介绍。

值得注意的是在调用GetScrollInfo函数时要获取相关滚动信息，需要指定SCROLLINFO结构体中的fMask成员的值。fMask取下面的值的组合值：
值 意义
SIF_PAGE 获取SCROLLINFO中的nPage成员的值（即一页的大小）。
SIF_POS 获取SCROLLINFO中的nPos成员的值。
SIF_RANGE
 获取SCROLLINFO中的nPos成员的nMin 和 nMax的值。
SIF_TRACKPOS
 获取SCROLLINFO中的nTrackPos成员的值。
nTrackPos
 SIF_RANGE、SIF_POS、SIF_PAGE和SIF_TRACKPOS的组合。

使用例程（据petzod的《windows程序设计》第四章，仅列出主要代码片段，具体请下载源码）：

case WM_SIZE:
    {
        // save the width and height of window when changed the size of window
        cxClient = LOWORD(lp); // the width
        cyClient = HIWORD(lp); // the height
           // set vertical scroll bar range and page size
        si.cbSize = sizeof(SCROLLBARINFO);
        si.fMask = SIF_RANGE|SIF_PAGE;
           si.nMin = 0;
           si.nMax = NUMLINES - 1;
        si.nPage = cyClient/cyChar;
           SetScrollInfo(hWnd,SB_VERT,&si,TRUE);
           // set horizontal scroll bar and page size
        si.cbSize = sizeof(SCROLLBARINFO);
        si.fMask = SIF_RANGE|SIF_PAGE;
        si.nMin = 0;
        si.nMax = 2 + nMaxWidth/cxChar;
        si.nPage = cxClient/cxChar;
        SetScrollInfo(hWnd,SB_HORZ,&si,TRUE);
        return 0;
    }
case WM_VSCROLL:
    {
// get all vertical scroll bar information
si.cbSize = sizeof(SCROLLINFO);
si.fMask = SIF_ALL;
::GetScrollInfo(hWnd,SB_VERT,&si);
   // save the position for comparison later on
nVertPos = si.nPos;
    switch (LOWORD(wp))
           {
        case SB_LINEUP:
            {
                si.nPos -=1;// the height decrease 1 unit
                break;
            }
        case SB_LINEDOWN:
            {
                si.nPos +=1;// the height increase 1 unit
                break;
            }
        case SB_PAGEUP:
            {
                   // back to prev page, the cyClient/cyChar is the number of row in one page
                si.nPos -= cyClient/cyChar;
                break;
            }
        case SB_PAGEDOWN:
            {
                // back to next page
                si.nPos += cyClient/cyChar;
                break;
            }
        case SB_THUMBPOSITION:
            {
                si.nPos = HIWORD(wp);
                break;
            }
        default:
            break;
           }
           // set the position and then retrieve it.Due to adjustments
        // by Windows it may not be the same as the value set.
        si.fMask = SIF_POS;
        SetScrollInfo(hWnd,SB_VERT,&si,TRUE);
        GetScrollInfo(hWnd,SB_VERT,&si);
        //if the position has changed,scroll the window update it
        if (si.nPos!=nVertPos)
        {
            ::ScrollWindow(hWnd,0,cyChar*(nVertPos-si.nPos),NULL,NULL);
            ::UpdateWindow(hWnd);
        }
        return 0;
    }
case WM_HSCROLL:
    {
        // get all the vertical scroll bar information
        si.cbSize = sizeof(si);
        si.fMask = SIF_ALL;
        // save the position for comparison later on
        ::GetScrollInfo(hWnd,SB_HORZ,&si);
        nHorzPos = si.nPos;
        switch (LOWORD(wp))
        {
        case SB_LINELEFT:
            {
                si.nPos -=1;
                break;
            }
        case SB_LINERIGHT:
            {
                si.nPos +=1;
                break;
            }
        case SB_PAGELEFT:
            {
                si.nPos -= si.nPage;
                break;
            }
        case SB_PAGERIGHT:
            {
                si.nPos += si.nPage;
                break;
            }
        case SB_THUMBPOSITION:
            {
                si.nPos = si.nTrackPos;
                break;
            }
        default:
               break;
        }
        // set the position and then retrieve it.due to adjustments
        // by windows it may not be the same as the value set
        si.fMask = SIF_POS;
        ::SetScrollInfo(hWnd,SB_HORZ,&si,TRUE);
        ::GetScrollInfo(hWnd,SB_HORZ,&si);
        // if the postion has changed ,scroll the window
        if (si.nPos!=nHorzPos)
        {
            ::ScrollWindow(hWnd,cxChar*(nHorzPos-si.nPos),0,NULL,NULL);
        }
        return 0;
    }
case WM_PAINT:
    {
        hdc = ::BeginPaint(hWnd,&ps);
           // get vertical scroll bar position
        si.cbSize = sizeof(si);
           si.fMask = SIF_POS;
        ::GetScrollInfo(hWnd,SB_VERT,&si);
        nVertPos = si.nPos;
        // get horizontal scroll bar position
           GetScrollInfo(hWnd,SB_HORZ,&si);
           nHorzPos = si.nPos;
        // find painting limits
           int nPaintBeg = max(0,nVertPos+ps.rcPaint.top/cyChar); // the begin row
           int nPaintEnd = min(NUMLINES-1,nVertPos+ps.rcPaint.bottom/cyChar); // the end row
        for (int i =nPaintBeg;i<=nPaintEnd;i++)
        {
               // calculate the y position of draw region, when y position less 0,skip
            int x = cxChar*(1-nHorzPos);
            int y = cyChar*(i-nVertPos);
            ::TextOut(hdc,x,y,sysmetrics[i].szLabel,lstrlen(sysmetrics[i].szLabel));
            ::TextOut(hdc,x+22*cxCaps,y,sysmetrics[i].szDesc,lstrlen(sysmetrics[i].szDesc));
            ::SetTextAlign(hdc,TA_RIGHT|TA_TOP);
            ::TextOut(hdc,x+22*cxCaps+40*cxChar,y,szBuffer,wsprintf(szBuffer,_T("%5d"),::GetSystemMetrics(sysmetrics[i].Index)));
            ::SetTextAlign(hdc,TA_LEFT|TA_TOP);
        }
        ::EndPaint(hWnd,&ps);
        return 0;
    }

 case WM_SIZE:  {   // save the width and height of window when changed the size of window   cxClient = LOWORD(lp); // the width   cyClient = HIWORD(lp); // the height            // set vertical scroll bar range and page size   si.cbSize = sizeof(SCROLLBARINFO);   si.fMask = SIF_RANGE|SIF_PAGE;            si.nMin = 0;            si.nMax = NUMLINES - 1;   si.nPage = cyClient/cyChar;            SetScrollInfo(hWnd,SB_VERT,&si,TRUE);            // set horizontal scroll bar and page size   si.cbSize = sizeof(SCROLLBARINFO);   si.fMask = SIF_RANGE|SIF_PAGE;   si.nMin = 0;   si.nMax = 2 + nMaxWidth/cxChar;   si.nPage = cxClient/cxChar;   SetScrollInfo(hWnd,SB_HORZ,&si,TRUE);   return 0;  } case WM_VSCROLL:  { // get all vertical scroll bar information si.cbSize = sizeof(SCROLLINFO); si.fMask = SIF_ALL; ::GetScrollInfo(hWnd,SB_VERT,&si);    // save the position for comparison later on nVertPos = si.nPos;     switch (LOWORD(wp))            {   case SB_LINEUP:    {     si.nPos -=1;// the height decrease 1 unit     break;    }   case SB_LINEDOWN:    {     si.nPos +=1;// the height increase 1 unit     break;    }   case SB_PAGEUP:    {                    // back to prev page, the cyClient/cyChar is the number of row in one page     si.nPos -= cyClient/cyChar;      break;    }   case SB_PAGEDOWN:    {     // back to next page     si.nPos += cyClient/cyChar;     break;    }   case SB_THUMBPOSITION:    {     si.nPos = HIWORD(wp);     break;    }   default:    break;            }            // set the position and then retrieve it.Due to adjustments         // by Windows it may not be the same as the value set.         si.fMask = SIF_POS;   SetScrollInfo(hWnd,SB_VERT,&si,TRUE);   GetScrollInfo(hWnd,SB_VERT,&si);   //if the position has changed,scroll the window update it   if (si.nPos!=nVertPos)   {    ::ScrollWindow(hWnd,0,cyChar*(nVertPos-si.nPos),NULL,NULL);    ::UpdateWindow(hWnd);   }   return 0;  } case WM_HSCROLL:  {   // get all the vertical scroll bar information   si.cbSize = sizeof(si);   si.fMask = SIF_ALL;   // save the position for comparison later on   ::GetScrollInfo(hWnd,SB_HORZ,&si);   nHorzPos = si.nPos;   switch (LOWORD(wp))   {   case SB_LINELEFT:    {     si.nPos -=1;     break;    }   case SB_LINERIGHT:    {     si.nPos +=1;     break;    }   case SB_PAGELEFT:    {     si.nPos -= si.nPage;     break;    }   case SB_PAGERIGHT:    {     si.nPos += si.nPage;     break;    }   case SB_THUMBPOSITION:    {     si.nPos = si.nTrackPos;     break;    }   default:                break;   }   // set the position and then retrieve it.due to adjustments   // by windows it may not be the same as the value set   si.fMask = SIF_POS;   ::SetScrollInfo(hWnd,SB_HORZ,&si,TRUE);   ::GetScrollInfo(hWnd,SB_HORZ,&si);   // if the postion has changed ,scroll the window   if (si.nPos!=nHorzPos)   {    ::ScrollWindow(hWnd,cxChar*(nHorzPos-si.nPos),0,NULL,NULL);   }   return 0;  } case WM_PAINT:  {   hdc = ::BeginPaint(hWnd,&ps);            // get vertical scroll bar position   si.cbSize = sizeof(si);            si.fMask = SIF_POS;   ::GetScrollInfo(hWnd,SB_VERT,&si);   nVertPos = si.nPos;   // get horizontal scroll bar position            GetScrollInfo(hWnd,SB_HORZ,&si);            nHorzPos = si.nPos;   // find painting limits             int nPaintBeg = max(0,nVertPos+ps.rcPaint.top/cyChar); // the begin row            int nPaintEnd = min(NUMLINES-1,nVertPos+ps.rcPaint.bottom/cyChar); // the end row   for (int i =nPaintBeg;i<=nPaintEnd;i++)   {                // calculate the y position of draw region, when y position less 0,skip    int x = cxChar*(1-nHorzPos);     int y = cyChar*(i-nVertPos);    ::TextOut(hdc,x,y,sysmetrics[i].szLabel,lstrlen(sysmetrics[i].szLabel));    ::TextOut(hdc,x+22*cxCaps,y,sysmetrics[i].szDesc,lstrlen(sysmetrics[i].szDesc));    ::SetTextAlign(hdc,TA_RIGHT|TA_TOP);    ::TextOut(hdc,x+22*cxCaps+40*cxChar,y,szBuffer,wsprintf(szBuffer,_T("%5d"),::GetSystemMetrics(sysmetrics[i].Index)));    ::SetTextAlign(hdc,TA_LEFT|TA_TOP);   }   ::EndPaint(hWnd,&ps);   return 0;  } 

    相关源码下载：

Windows API学习之滚动条系列函数演示程序

           

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