你的电脑有没有摄像头？看到别人用QQ玩视屏你会不会去想怎么实现的？
这里介绍使用DELPHI使用MS的AVICAP32.DLL就可轻松的实现对摄像头编程，
如果再加上你的网络编程水平，实现一个视屏聊天就不成什么问题了。
看看下面代码的代码：

const WM_CAP_START = WM_USER;
const WM_CAP_STOP = WM_CAP_START + 68;
const WM_CAP_DRIVER_CONNECT = WM_CAP_START + 10;
const WM_CAP_DRIVER_DISCONNECT = WM_CAP_START + 11;
const WM_CAP_SAVEDIB = WM_CAP_START + 25;
const WM_CAP_GRAB_FRAME = WM_CAP_START + 60;
const WM_CAP_SEQUENCE = WM_CAP_START + 62;
const WM_CAP_FILE_SET_CAPTURE_FILEA = WM_CAP_START + 20;
const WM_CAP_SEQUENCE_NOFILE =WM_CAP_START+ 63
const WM_CAP_SET_OVERLAY =WM_CAP_START+ 51
const WM_CAP_SET_PREVIEW =WM_CAP_START+ 50
const WM_CAP_SET_CALLBACK_VIDEOSTREAM = WM_CAP_START +6;
const WM_CAP_SET_CALLBACK_ERROR=WM_CAP_START +2;
const WM_CAP_SET_CALLBACK_STATUSA= WM_CAP_START +3;
const WM_CAP_SET_CALLBACK_FRAME= WM_CAP_START +5;
const WM_CAP_SET_SCALE=WM_CAP_START+ 53
const WM_CAP_SET_PREVIEWRATE=WM_CAP_START+ 52

function capCreateCaptureWindowA(lpszWindowName : PCHAR; dwStyle : longint; x : integer;
y : integer;nWidth : integer;nHeight : integer;ParentWin : HWND;
nId : integer): HWND;STDCALL EXTERNAL ‘AVICAP32.DLL‘;

上面的代码就是我们主要用到的一个函数和常量的定义。

好了，打开你的Delphi，新建一个工程，将上面的定义加上吧。

新建一个窗口，放个Panel上去，添加一个按钮，Caption设置为"开始"
这里需要定义一个全局变量，var hWndC : THandle;

开始按钮代码如下：

begin
hWndC := capCreateCaptureWindowA(‘My Own Capture Window‘,WS_CHILD or WS_VISIBLE ,Panel1.Left,Panel1.Top,Panel1.Width,Panel1.Height,Form1.Handle,0);

hWndC := capCreateCaptureWindowA(‘My Own Capture Window‘,WS_CHILD or WS_VISIBLE ,Panel1.Left,Panel1.Top,Panel1.Width,Panel1.Height,Form1.Handle,0);
if hWndC <> 0 then
begin
SendMessage(hWndC, WM_CAP_SET_CALLBACK_VIDEOSTREAM, 0, 0);
SendMessage(hWndC, WM_CAP_SET_CALLBACK_ERROR, 0, 0);
SendMessage(hWndC, WM_CAP_SET_CALLBACK_STATUSA, 0, 0);
SendMessage(hWndC, WM_CAP_DRIVER_CONNECT, 0, 0);
SendMessage(hWndC, WM_CAP_SET_SCALE, 1, 0);
SendMessage(hWndC, WM_CAP_SET_PREVIEWRATE, 66, 0);
SendMessage(hWndC, WM_CAP_SET_OVERLAY, 1, 0);
SendMessage(hWndC, WM_CAP_SET_PREVIEW, 1, 0);
end;
按F9运行一下，怎么样，是不是可以看到摄像头的视屏了？

那怎么停下来？再加个按钮caption设置成"停止"
代码如下：
if hWndC <> 0 then begin
SendMessage(hWndC, WM_CAP_DRIVER_DISCONNECT, 0, 0);
hWndC := 0;
end;

视屏截到了，怎么把它给保存下来呢？

下面按两种方式保存，一个是BMP静态图，一个是AVI动画。

再放三个按钮到窗体上去，caption分别设置成"保存BMP"、"开始录像"、"停止录像"
三个按钮的代码分别如下：

//保存BMP
if hWndC <> 0 then begin
SendMessage(hWndC,WM_CAP_SAVEDIB,0,longint(pchar(‘c:\\test.bmp‘)));
end;

//开始录像
if hWndC <> 0 then
begin
SendMessage(hWndC,WM_CAP_FILE_SET_CAPTURE_FILEA,0, Longint(pchar(‘c:\\test.avi‘)));
SendMessage(hWndC, WM_CAP_SEQUENCE, 0, 0);
end;

//停止录像
if hWndC <> 0 then begin
SendMessage(hWndC, WM_CAP_STOP, 0, 0);
end;

再运行看看吧。。可以保存几张图看看，也可以录成AVI以后慢慢欣赏。

程序运行效果： [ 相关贴图 ]
http://yousoft.hi.com.cn/upload/forum/2004715161959.jpg

完整的程序代码如下：

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ExtCtrls;

type
TForm1 = class(TForm)
Panel1: TPanel;
Button1: TButton;
Button2: TButton;
Button3: TButton;
Button4: TButton;
Button5: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
procedure Button4Click(Sender: TObject);
procedure Button5Click(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
private
hWndC : THandle;
public
{ Public declarations }
end;

var
Form1: TForm1;


const WM_CAP_START = WM_USER;
const WM_CAP_STOP = WM_CAP_START + 68;
const WM_CAP_DRIVER_CONNECT = WM_CAP_START + 10;
const WM_CAP_DRIVER_DISCONNECT = WM_CAP_START + 11;
const WM_CAP_SAVEDIB = WM_CAP_START + 25;
const WM_CAP_GRAB_FRAME = WM_CAP_START + 60;
const WM_CAP_SEQUENCE = WM_CAP_START + 62;
const WM_CAP_FILE_SET_CAPTURE_FILEA = WM_CAP_START + 20;
const WM_CAP_SEQUENCE_NOFILE =WM_CAP_START+ 63
const WM_CAP_SET_OVERLAY =WM_CAP_START+ 51
const WM_CAP_SET_PREVIEW =WM_CAP_START+ 50
const WM_CAP_SET_CALLBACK_VIDEOSTREAM = WM_CAP_START +6;
const WM_CAP_SET_CALLBACK_ERROR=WM_CAP_START +2;
const WM_CAP_SET_CALLBACK_STATUSA= WM_CAP_START +3;
const WM_CAP_SET_CALLBACK_FRAME= WM_CAP_START +5;
const WM_CAP_SET_SCALE=WM_CAP_START+ 53
const WM_CAP_SET_PREVIEWRATE=WM_CAP_START+ 52

function capCreateCaptureWindowA(lpszWindowName : PCHAR;
dwStyle : longint;x : integer;y : integer;nWidth : integer;
nHeight : integer;ParentWin : HWND;nId : integer): HWND;
STDCALL EXTERNAL ‘AVICAP32.DLL‘;


implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
hWndC := capCreateCaptureWindowA(‘My Own Capture Window‘,WS_CHILD or WS_VISIBLE ,Panel1.Left,Panel1.Top,Panel1.Width,Panel1.Height,Form1.Handle,0);

hWndC := capCreateCaptureWindowA(‘My Own Capture Window‘,WS_CHILD or WS_VISIBLE ,Panel1.Left,Panel1.Top,Panel1.Width,Panel1.Height,Form1.Handle,0);
if hWndC <> 0 then
begin
SendMessage(hWndC, WM_CAP_SET_CALLBACK_VIDEOSTREAM, 0, 0);
SendMessage(hWndC, WM_CAP_SET_CALLBACK_ERROR, 0, 0);
SendMessage(hWndC, WM_CAP_SET_CALLBACK_STATUSA, 0, 0);
SendMessage(hWndC, WM_CAP_DRIVER_CONNECT, 0, 0);
SendMessage(hWndC, WM_CAP_SET_SCALE, 1, 0);
SendMessage(hWndC, WM_CAP_SET_PREVIEWRATE, 66, 0);
SendMessage(hWndC, WM_CAP_SET_OVERLAY, 1, 0);
SendMessage(hWndC, WM_CAP_SET_PREVIEW, 1, 0);
end;

end;

procedure TForm1.Button2Click(Sender: TObject);
begin
if hWndC <> 0 then begin
SendMessage(hWndC, WM_CAP_DRIVER_DISCONNECT, 0, 0);
hWndC := 0;
end;
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
if hWndC <> 0 then begin
SendMessage(hWndC,WM_CAP_SAVEDIB,0,longint(pchar(‘c:\\test.bmp‘)));
end;
end;

procedure TForm1.Button4Click(Sender: TObject);
begin
if hWndC <> 0 then
begin
SendMessage(hWndC,WM_CAP_FILE_SET_CAPTURE_FILEA,0, Longint(pchar(‘c:\\test.avi‘)));
SendMessage(hWndC, WM_CAP_SEQUENCE, 0, 0);
end;
end;

procedure TForm1.Button5Click(Sender: TObject);
begin
if hWndC <> 0 then begin
SendMessage(hWndC, WM_CAP_STOP, 0, 0);
end;
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
if hWndC <> 0 then begin
SendMessage(hWndC, WM_CAP_DRIVER_DISCONNECT, 0, 0);
end;
end;

end.



如果电脑没有摄像头，但又想看看程序的效果，可以么？
呵呵，当然可以，找个虚拟摄像头不就搞定，大家可以试试SoftCam这个软件，它是一个名副其实的软件摄像机，
能模拟成为“真实的”摄像机，提醒一下各位，大家可不要用这个东东用在QQ，MSN等聊天软件上欺骗MM或GG啊。


关于摄像头编程，大家也可以看看这组VCL组件：DSPack，DSPack是一套使用微软Direct Show和DirectX技术的类和组件，设计工作于DirectX 9，支持系统Win9X, ME, 2000和Windows XP。
好了，就介绍这些了，至于视屏聊天怎么实现，就看你的了，无非是按数据压缩传输给对方，显示出来，不过话又说回来，看似简单，实现起来还有些难度的。