viewmain.~pas

本光盘是《Delphi 7应用教程》一书的配套光盘

unit VIEWMAIN;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  Menus;

type
  TMDIfileVIEWER = class(TForm)
    MainMenu1: TMainMenu;
    File1: TMenuItem;
    Open1: TMenuItem;
    N1: TMenuItem;
    Exit1: TMenuItem;
    Help1: TMenuItem;
    About1: TMenuItem;
    fileOpenDialog: TOpenDialog;
    procedure Exit1Click(Sender: TObject);
    procedure Open1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    procedure closeallchildren;
  end;

var
  MDIfileVIEWER: TMDIfileVIEWER;

implementation
  uses pictureview,textview;  //引用子窗口所在的单元文件
{$R *.DFM}

procedure tmdifileviewer.closeallchildren;//该过程用来关闭所有子窗体
var
  i:integer;
  begin
    for i:=0  to mdichildcount-1  do // 循环遍历所有的子窗体
      mdichildren[i].close;   //关闭子窗体
  end;
//"退出"菜单项
procedure TMDIfileVIEWER.Exit1Click(Sender: TObject);
begin
     close;  //关闭主窗体
end;

//“打开”菜单项
procedure TMDIfileVIEWER.Open1Click(Sender: TObject);
var
  PicViewer:tpictureviewer;  //该变量用来保存程序执行时生成的子窗体
  TextView:TtextViewer;
  fileext:string[4];
begin
  If  Fileopendialog.execute  then
    begin
      fileext:=extractfileext(fileopendialog.filename); //获得扩展名
      if (fileext='.BMP') OR (fileext='.JPG')  then //如果是图片文件
        begin
          PicViewer:=tpictureviewer.create(self);//创建一个子窗口
          PicViewer.open(fileopendialog.filename);//打开文件
          Picviewer.visible:=true; //使创建的窗体可见
          PicViewer.setfocus;  //把焦点设置在新创建的窗体上
        end
      else  if  (fileext='.txt') then  //如果是文件文件
                 begin
                   TextViewer:=TtextViewer.create(self);  //创建一个浏览文本文件的子窗口
                   TextViewer.open(fileopendialog.FileName ); //打开文本文件
                   Textviewer.Visible :=True; //使浏览文本文件的子窗口可见
                   TextViewer.SetFocus ; //把焦点设置在新创建的窗体上
                 end
                   else
                      ShowMessage('不合法的文件扩展名');
    end;
end;

end.