Delphi 滚动条的使用介绍

Delphi 滚动条的使用介绍

1、DELPHI的滚动条默认发送消息格式：

function TControl.Perform(
  Msg: Cardinal;
  WParam: WPARAM;
  LParam: LPARAM
): LRESULT;
//如：Memo1.Perform(WM_HSCROLL, SB_LEFT, 0);

2、水平/垂直滚动条：

2.1 水平滚动条 消息 WM_HSCROLL

SendMessage(Memo1.Handle, WM_HSCROLL, MAKEWPARAM(SB_THUMBPOSITION, 50), 0); //滚动至此 
SendMessage(Memo1.Handle, WM_HSCROLL, SB_LEFT, 0); //左边缘 
SendMessage(Memo1.Handle, WM_HSCROLL, SB_RIGHT, 0); //右边缘 
SendMessage(Memo1.Handle, WM_HSCROLL, SB_PAGELEFT, 0); //向左翻页 
SendMessage(Memo1.Handle, WM_HSCROLL, SB_PAGERIGHT, 0); //向右翻页 
SendMessage(Memo1.Handle, WM_HSCROLL, SB_LINELEFT, 0); //向左滚动 
SendMessage(Memo1.Handle, WM_HSCROLL, SB_LINERIGHT, 0); //向右滚动

2.2 垂直滚动条 消息 WM_VSCROLL

SendMessage(Memo1.Handle, WM_VSCROLL, MAKEWPARAM(SB_THUMBPOSITION, 50), 0); //滚动至此 50为位置 滚动到指定行号 
SendMessage(Memo1.Handle, WM_VSCROLL, SB_TOP, 0); //顶部 
SendMessage(Memo1.Handle, WM_VSCROLL, SB_BOTTOM, 0); //底部 
SendMessage(Memo1.Handle, WM_VSCROLL, SB_PAGEUP, 0); //向上翻页 
SendMessage(Memo1.Handle, WM_VSCROLL, SB_PAGEDOWN, 0); //向下翻页 
SendMessage(Memo1.Handle, WM_VSCROLL, SB_LINEUP, 0); //向上滚动 
SendMessage(Memo1.Handle, WM_VSCROLL, SB_LINEDOWN, 0); //向下滚动

3、获得滚动条的位置（GetScrollPos函数）

GetScrollPos函数检索指定滚动条中滚动框（拇指）的当前位置。当前位置是一个相对值，取决于当前滚动范围。

例如，如果滚动范围为0到100，并且滚动框位于条的中间，则当前位置为50。

int GetScrollPos( 
  HWND hWnd,
  int nBar
);

示例：

var
  h, v: Integer;
begin
  h := GetScrollPos(Memo1.Handle, SB_HORZ);
  v := GetScrollPos(Memo1.Handle, SB_VERT);
  Caption := Format('水平数值=%d 垂直数值=%d', [h, v]);
end;

4、显示和隐藏滚动条

ShowScrollBar(Memo1.Handle,SB_HORZ,false); //隐藏MEMO水平滚动条
ShowScrollBar(Memo1.Handle,SB_VERT,false); //隐藏MEMO垂直滚动条

5、判断 滚动条是否出现

procedure TForm1.Button1Click(Sender: TObject); 
begin 
  if (GetWindowlong(Memo1.Handle, GWL_STYLE) and WS_VSCROLL) > 0 then ShowMessage('垂直滚动条显示'); 
  if (GetWindowlong(Memo1.Handle, GWL_STYLE) and WS_HSCROLL) > 0 then ShowMessage('水平滚动条显示'); 
end;

创建时间：2019.11.18　　更新时间：2020.05.18