父子窗体滚动条支持鼠标滚轮移动

//作者： 415799952   追寻
//       513187410   疯狂→delphi 
//       1746539685 dnyy  
        

//1.设置哪个方向移动
procedure TForm1.BitBtn2Click(Sender: TObject);
begin
  if bitbtn2.Caption='纵向滚动' then
  begin
    bitbtn2.Caption:='横向滚动';
    bitbtn2.Tag:=0;
  end
  else
  begin
    bitbtn2.Caption:='纵向滚动';
    bitbtn2.Tag:=1;
  end;
end; 

//2.移动一
procedure TForm1.FormMouseWheelDown(Sender: TObject; Shift: TShiftState;
  MousePos: TPoint; var Handled: Boolean);
begin
  if bitbtn2.Tag=1 then
    postmessage(Form1.ClientHandle,WM_VSCROLL,SB_LINEDOWN,0)
  else
    postmessage(Form1.ClientHandle,WM_HSCROLL,SB_LINERIGHT,0);
end;

//3.移动二
procedure TForm1.FormMouseWheelUp(Sender: TObject; Shift: TShiftState;
  MousePos: TPoint; var Handled: Boolean);
begin
  if bitbtn2.Tag=1 then
    postmessage(Form1.ClientHandle,WM_VSCROLL,SB_LINEUP,0)
  else
    postmessage(Form1.ClientHandle,WM_HSCROLL,SB_LINELEFT,0);
end;