窗口居中

Question

本人初学Delphi 请问高手如何使窗口居中，及定义全局变量

Answer 1

form.position := poMainFormCenter;全局变量
public
  i : Integer;   // 公有的
private 
  iLen : Integer; //私有的

Answer 2

设置Form的Position属性可以单独建立一个公用单元然后再定一些你需要的变量……

Answer 3

下面是一个小程序：自己看吧;
  private
    databasename: string;
    procedure DoEnterAsTab(var Msg: TMsg; var Handled: Boolean); //enter代替tab
    procedure addnewdata;//插入备份记录
    { Private declarations }
  public//全局变量的定义
    databasename1, databasename2, databasename3, databasename4, databasename5：string;
procedure getdatabasename; //获取数据库名   
    { Public declarations }
  end;var
  backupdata: Tbackupdata;implementationuses U_location, U_backuprecord;{$R *.dfm}procedure Tbackupdata.BitBtn2Click(Sender: TObject);
begin
  self.Close;
end;procedure Tbackupdata.DoEnterAsTab(var Msg: TMsg; var Handled: Boolean); //enter代替tab
begin
  if Msg.Message = WM_KEYDOWN then
    begin
      if (Msg.wParam = VK_RETURN) then
        Keybd_event(VK_TAB, 0, 0, 0);
    end; //if
end;procedure Tbackupdata.FormCreate(Sender: TObject);
var
  serverid, databaseusername, databasepassword, servername: string;
begin
  self.ValueListEditor1.Visible := false;
  panel3.Visible := false;
  self.ValueListEditor1.Strings.LoadFromFile((extractfilepath(application.ExeName) + 'setup.txt'));
  serverid := trim(self.ValueListEditor1.Values['serverid']); //服务器ID
  databasepassword := trim(self.ValueListEditor1.Values['databasepassword']); //数据库密码
  databaseusername := trim(self.ValueListEditor1.Values['databaseusername']); //数据库用户名
  servername := trim(self.ValueListEditor1.Values['servername']);
  ADOConnection1.Connected := false;
  ADOConnection2.Connected := false;
  ADOConnection1.ConnectionString := 'Provider=SQLOLEDB.1;Password=' + trim(databasepassword) + ';Persist Security Info=True;User ID=' + trim(databaseusername) + ';Data Source=' + trim(serverid);
  ADOConnection2.ConnectionString:='Provider=Microsoft.Jet.OLEDB.4.0;Data Source='+(extractfilepath(application.ExeName) + '备份记录.mdb')+';Persist Security Info=False';
self.dxPickEdit2.Items.Clear;
  if trim(self.ValueListEditor1.Values['databasenamez1']) <> '' then //添加数据库名
    self.dxPickEdit2.Items.Add(trim(self.ValueListEditor1.Values['databasenamez1']));
  if trim(self.ValueListEditor1.Values['databasenamez2']) <> '' then //添加数据库名
    self.dxPickEdit2.Items.Add(trim(self.ValueListEditor1.Values['databasenamez2']));
  if trim(self.ValueListEditor1.Values['databasenamez3']) <> '' then //添加数据库名
    self.dxPickEdit2.Items.Add(trim(self.ValueListEditor1.Values['databasenamez3']));
  if trim(self.ValueListEditor1.Values['databasenamez4']) <> '' then //添加数据库名
    self.dxPickEdit2.Items.Add(trim(self.ValueListEditor1.Values['databasenamez4']));
  if trim(self.ValueListEditor1.Values['databasenamez5']) <> '' then //添加数据库名
    self.dxPickEdit2.Items.Add(trim(self.ValueListEditor1.Values['databasenamez5']));
  self.dxPickEdit1.Items.Add(trim(self.ValueListEditor1.Values['servername']));
  self.dxPickEdit1.ItemIndex := 0;
  databasename1 := trim(self.ValueListEditor1.Values['databasename1']); //数据库名
  databasename2 := trim(self.ValueListEditor1.Values['databasename2']); //数据库名
  databasename3 := trim(self.ValueListEditor1.Values['databasename3']); //数据库名
  databasename4 := trim(self.ValueListEditor1.Values['databasename4']); //数据库名
  databasename5 := trim(self.ValueListEditor1.Values['databasename5']); //数据库名
end;procedure Tbackupdata.dxEdit1KeyPress(Sender: TObject; var Key: Char);
begin
  Application.OnMessage := DoEnterAsTab;
end;

Answer 4

procedure Tbackupdata.dxButtonEdit1ButtonClick(Sender: TObject;
  AbsoluteIndex: Integer);
begin
  if location = nil then
    location := tlocation.Create(self);
  location.ShowModal;
end;procedure Tbackupdata.dxPickEdit2Change(Sender: TObject);
begin
  self.dxButtonEdit1.Text := trim(self.dxPickEdit2.Text) + datetostr(date())+'-'+inttostr(hourof(now))+'-'+inttostr(minuteof(now)) + '.bak';
  location.dxEdit1.Text := trim(backupdata.dxPickEdit2.Text) + datetostr(date())+'-'+inttostr(hourof(now))+'-'+inttostr(minuteof(now)) + '.bak';
  self.Label7.Caption := trim(valuelisteditor1.Values['location']) + '\' + trim(self.dxPickEdit2.Text) + datetostr(date())+'-'+inttostr(hourof(now))+'-'+inttostr(minuteof(now))+ '.bak';
end;
procedure Tbackupdata.BitBtn1Click(Sender: TObject);
var str: string;
  flag: integer;
  NetSource: TNetResource;
  F: TShFileOpStruct;
  ErrInfo: longint;
  m:integer;
  driver:pchar;
  drivername,str1,str2:string;
  i,lenth:integer;
begin
  lenth:=length(trim(label7.Caption));
   str1:='';str2:='';
   for i:=1 to lenth do begin
     str1:=midstr(trim(label7.Caption),i,1);
     str2:=str2+str1;
     if trim(str1)='\' then
       break;
   end;
   driver:=pchar(str2);//pchar(label7.Caption);
   m:= GetDriveType(driver);
   {case x of
    DRIVE_REMOVABLE: drivername := '可移动驱动器';
    DRIVE_FIXED: drivername := '固定驱动器';
    4: drivername := '网络驱动器';
    5: drivername := 'CD-ROM驱动器';
    6: drivername := '虚拟驱动器';
    Else drivername:= '该驱动器无效';
   end; }
  flag := 0;
  //panel3.Caption:='正在备份数据,请稍候......';
  self.getdatabasename; //获取数据库名
  if ((trim(dxedit1.Text) = trim(ValueListEditor1.Values['username1'])) and (trim(dxedit2.Text) = trim(valuelisteditor1.Values['password1']))) or
    ((trim(dxedit1.Text) = trim(ValueListEditor1.Values['username2'])) and (trim(dxedit2.Text) = trim(valuelisteditor1.Values['password2']))) or
    ((trim(dxedit1.Text) = trim(ValueListEditor1.Values['username3'])) and (trim(dxedit2.Text) = trim(valuelisteditor1.Values['password3']))) then begin //判断密码的正确
      str := 'BACKUP DATABASE ' + databasename + ' TO disk=' + '''' + trim(valuelisteditor1.Values['serverlocation1']) + '\' + trim(self.dxButtonEdit1.Text) + '''' + ' WITH init'; //备份
      with adoquery1 do begin //备份数据库
          // panel3.Caption:='正在备份数据,请稍候......';
          close; sql.Clear;
          sql.Add(str);
          prepared;
          try
            panel3.Visible := true;
            //panel3.Height:=40;
            adoquery1.ExecSQL;
            flag := 1;
            // panel3.Visible := false;
          except
            panel3.Visible := false;
            application.MessageBox('数据库备份失败!', '提示', mb_ok);
          end; //try
        end; //with
      if flag = 1 then begin
          with NetSource do begin
              dwType := RESOURCETYPE_ANY;
              lpLocalName := 'x:';
              // 将远程资源映射到此驱动器
              lpRemoteName := pchar(trim(self.ValueListEditor1.Values['serverlocation']));
              // 远程网络资源
              lpProvider := ''; // 必须赋值,如为空则使用lpRemoteName的值。
            end;
          WnetAddConnection2(NetSource, pchar(trim(valuelisteditor1.Values['sharepassword'])), pchar(trim(valuelisteditor1.Values['shareusername'])),
            //用户名为Guest，口令为Password
            CONNECT_UPDATE_PROFILE);
          panel3.Visible := false;
         if m=3 then begin  //本地磁盘
          F.wnd := Handle;
          F.wFunc := FO_COPY; {操作方式}
          F.pFrom := PCHAR(trim(self.ValueListEditor1.Values['serverlocation']) + '\' + trim(self.dxButtonEdit1.Text)+#0#0);
          F.pTo := PCHAR(trim(self.ValueListEditor1.Values['location'])+'\'+ trim(self.dxButtonEdit1.Text)+#0#0);
          F.fFlags := FOF_NOCONFIRMATION; {操作选项}
          if ShFileOperation(F) <> 0 then
            application.MessageBox('文件拷贝失败！', '提示', mb_ok)
          else begin    //插入备份记录
            self.addnewdata;
          end;
         end// if m=3 then begin
         {else if m=4 then begin  //网络驱动器
          if application.MessageBox('确实要把文件复制到网络磁盘上吗?','提示',mb_okcancel)=1 then begin
          F.wnd := Handle;
          F.wFunc := FO_COPY; {操作方式}
         { F.pFrom := PCHAR(trim(self.ValueListEditor1.Values['serverlocation']) + '\' + trim(self.dxButtonEdit1.Text)+#0#0);
          F.pTo := PCHAR(trim(self.ValueListEditor1.Values['location'])+'\'+ trim(self.dxButtonEdit1.Text)+#0#0);
          F.fFlags := FOF_NOCONFIRMATION; {操作选项}
          {if ShFileOperation(F) <> 0 then
            application.MessageBox('文件拷贝失败！', '提示', mb_ok)
          else begin    //插入备份记录
            self.addnewdata;
          end;
          end;
         end//else if m=4 then begin  //网络驱动器  }
         else
           application.MessageBox(pchar('     当前所指路径不存在!'+#13+#10+'请检查移动硬盘是否已插上或插好!'),'提示');
          WNetCancelConnection2('x:', CONNECT_UPDATE_PROFILE, True);
        end; //if flag=1 then begin
    end
  else begin
      application.MessageBox('用户名或密码不正确,请重新输入!', '提示', mb_ok);
    end;
end;procedure Tbackupdata.getdatabasename; //获取数据库名
begin
  if trim(dxpickedit2.Text) = trim(valuelisteditor1.Values['databasenamez1']) then
    databasename := trim(valuelisteditor1.Values['databasename1']);
  if trim(dxpickedit2.Text) = trim(valuelisteditor1.Values['databasenamez2']) then
    databasename := trim(valuelisteditor1.Values['databasename2']);
  if trim(dxpickedit2.Text) = trim(valuelisteditor1.Values['databasenamez3']) then
    databasename := trim(valuelisteditor1.Values['databasename3']);
  if trim(dxpickedit2.Text) = trim(valuelisteditor1.Values['databasenamez4']) then
    databasename := trim(valuelisteditor1.Values['databasename4']);
  if trim(dxpickedit2.Text) = trim(valuelisteditor1.Values['databasenamez5']) then
    databasename := trim(valuelisteditor1.Values['databasename5']);
end;procedure Tbackupdata.N1Click(Sender: TObject);
begin
 if frm_backuprecord=nil then
    frm_backuprecord:=tfrm_backuprecord.Create(self);
    frm_backuprecord.Show;
  if trim(self.ValueListEditor1.Values['databasenamez1']) <> '' then //添加数据库名
    frm_backuprecord.dxPickEdit1.Items.Add(trim(self.ValueListEditor1.Values['databasenamez1']));
  if trim(self.ValueListEditor1.Values['databasenamez2']) <> '' then //添加数据库名
    frm_backuprecord.dxPickEdit1.Items.Add(trim(self.ValueListEditor1.Values['databasenamez2']));
  if trim(self.ValueListEditor1.Values['databasenamez3']) <> '' then //添加数据库名
    frm_backuprecord.dxPickEdit1.Items.Add(trim(self.ValueListEditor1.Values['databasenamez3']));
  if trim(self.ValueListEditor1.Values['databasenamez4']) <> '' then //添加数据库名
    frm_backuprecord.dxPickEdit1.Items.Add(trim(self.ValueListEditor1.Values['databasenamez4']));
  if trim(self.ValueListEditor1.Values['databasenamez5']) <> '' then //添加数据库名
    frm_backuprecord.dxPickEdit1.Items.Add(trim(self.ValueListEditor1.Values['databasenamez5']));
end;procedure Tbackupdata.addnewdata; //插入备份记录
begin
   with add_query do begin
     close; sql.Clear;
     sql.Add('insert into 数据库备份记录(备份人,数据库名,备份时间,备份路径)values(:a,:b,:c,:d)');
     parameters.ParamByName('a').Value:=trim(backupdata.dxedit1.Text);
     parameters.ParamByName('b').Value:=trim(backupdata.dxpickedit2.Text);
     parameters.ParamByName('c').Value:=now();
     parameters.ParamByName('d').Value:=trim(backupdata.label7.Caption);
     //parameters.ParamByName('e').Value:=trim(drivername);
     prepared;
     execsql;
   end;
end;end.

Answer 5

设置position属性poScreenCenter
public
  i : Integer;   // 公有的
private 
  iLen : Integer; //私有的

Answer 6

form.position := poScreenCenter;