clientfrm.pas

《Delphi 7经典问题解析》源代码 第一到七章 基础篇源程序 应用篇源程序

unit clientFrm;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ScktComp, ExtCtrls, ToolWin, ComCtrls, Menus, Buttons, shellapi,
  jpeg, ImgList;

type
  TfrmClient = class(TForm)
    Image: TImage;
    ClientSocket: TClientSocket;
    ImageList1: TImageList;
    ToolBar1: TToolBar;
    btnConnect: TToolButton;
    btnSnap: TToolButton;
    btnDisConnect: TToolButton;
    btnClose: TToolButton;
    procedure bu_snapClick(Sender: TObject);
    procedure ClientSocketRead(Sender: TObject; Socket: TCustomWinSocket);
    procedure FormCreate(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure btnConnectClick(Sender: TObject);
    procedure btnSnapClick(Sender: TObject);
    procedure btnDisConnectClick(Sender: TObject);
    procedure ClientSocketConnect(Sender: TObject;
      Socket: TCustomWinSocket);
    procedure ClientSocketError(Sender: TObject; Socket: TCustomWinSocket;
      ErrorEvent: TErrorEvent; var ErrorCode: Integer);
    procedure BtnCloseClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  frmClient: TfrmClient;

implementation


const bufsize = 2048;//接收数据缓冲区的最大值

var
  stream: Tmemorystream; //存储接收到jpeg内存流
  jpegscreen: Tjpegimage; //存储jpeg图象
{$R *.DFM}

//当窗体创建时，创建Stream，jpegStream对象
procedure TfrmClient.FormCreate(Sender: TObject);
begin
  stream := Tmemorystream.Create;
  jpegscreen := Tjpegimage.Create;
end;

//当窗体关闭时，关闭套接字的连接，并释放stream,jpegStream对象
procedure TfrmClient.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  clientsocket.Active := false;
  stream.Free;
  jpegscreen.Free;
end;

//连接服务器
procedure TfrmClient.BtnConnectClick(Sender: TObject);
var
  remotehost: string;
begin
  //输入远程服务器的IP地址
  remotehost := inputbox('建立连接', '请输入被察看的机器的IP地址或名称：', '');
  if trim(remotehost) <> '' then
  begin
    if clientsocket.Active then clientsocket.Active := true;
    clientsocket.Port := 1234;
    clientsocket.Host := remotehost;
    //连接
    try
      clientsocket.Active := true;
    except
      raise Exception.Create('连接失败！');
    end;
  end;
end;

//断开连接
procedure TfrmClient.btnDisConnectClick(Sender: TObject);
begin
  clientsocket.Active := false;
  stream.Clear;
end;

//向服务器端发出'show'指令，要求获取它的屏幕
procedure TfrmClient.btnSnapClick(Sender: TObject);
begin
  stream.Clear;
  if not ClientSocket.Active then
  Raise Exception.Create('请先连接');
  clientsocket.Socket.SendText('show');
end;

//关闭窗口
procedure TfrmClient.BtnCloseClick(Sender: TObject);
begin
  clientsocket.Active := false;
  close;
end;


//客户端接收远程屏幕图象
procedure TfrmClient.ClientSocketRead(Sender: TObject;
  Socket: TCustomWinSocket);
var
  buf: array[0..bufsize - 1] of char;
  numberbytes: integer;
begin
  numberbytes := socket.ReceiveLength;
  //接收数据
  socket.receiveBuf(buf, numberbytes);
  //累加读到stream内存流中
  stream.Write(buf, numberbytes);
  //当接收到的数据不等于bufSize，代表接收的屏幕图象的最后一个数据,
  //否则，代表还没有接收完，继续相服务器端发送'show'指令，继续获取数据
  if NumberBytes = bufSize then
    Socket.SendText('show')
  else
    begin
      try
        //此句代码，非常重要，千万不要忘写，它将内存流指针移到头，
        //否则读取内存流时，会从当前位置开始读
        Stream.Position := 0;
        //将内存流读到JpegScreen图象中
        jpegscreen.LoadFromStream(stream);
        //显示在image组件中
        image.Picture.Bitmap.Assign(jpegscreen);
      except
        stream.Clear;
      end;
    end;
end;

procedure TfrmClient.ClientSocketConnect(Sender: TObject;
  Socket: TCustomWinSocket);
begin
  showmessage('连接成功！');
end;

//当客户端Socket出错时，清空stream数据
procedure TfrmClient.ClientSocketError(Sender: TObject;
  Socket: TCustomWinSocket; ErrorEvent: TErrorEvent;
  var ErrorCode: Integer);
begin
  stream.Clear;
end;

end.