最近在使用Usb摄像头做了个项目,其中写了一个操作usb摄像头类分享给大家

{*******************************************************}
{                                                       }
{       操作USB摄像头类                                 }
{                                                       }
{       作者：lqen                                      }
{       日期：2015.05.18                                }
{                                                       }
{*******************************************************}

unit untUsbCamera;

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

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;

const WM_CAP_DLG_VIDEODISPLAY = WM_CAP_START + 41; //打开视频格式设置对话框，选择数字视频的框架大小和视频图像的色深，以及捕获视频图像的压缩格式。

type
  TUsbCamera = class
  private
    FPanel: TPanel;
    hWndC: THandle; //定义捕捉窗句柄
    FIsOpen: boolean;

    function BmpToJpg(BmpPath: string): string;
    function Image_FitBitmap(const Source, Dest: string; const x, y: integer): Boolean;
  protected

  public
    constructor Create();
    destructor Destroy; override;
    function Play(Panel: TPanel): boolean;
    function Stop: boolean;
    function StartRecord(FileName: string): Boolean;
    function StopRecord: Boolean;
    function Capture(FileName: string): Boolean;
  published
    property IsOpen: boolean read FIsOpen write FIsOpen;
  end;
function capCreateCaptureWindowA(lpszWindowName: PCHAR; dwStyle: longint; x: integer; y: integer; nWidth: integer; nHeight: integer; ParentWin: HWND; nId: integer): HWND; STDCALL EXTERNAL 'AVICAP32.DLL';
implementation

{ TUsbCamera }

function TUsbCamera.BmpToJpg(BmpPath: string): string;
var
  Jpg: TJpegImage;
  BMP: TBitMap;
begin
  Result := '';
  BmpPath := Trim(BmpPath);
  Jpg := TJpegImage.Create;
  BMP := TBitmap.Create;
  try
    BMP.LoadFromFile(BmpPath);
    Jpg.Assign(BMP);
    Jpg.SaveToFile(Copy(BmpPath, 1, Length(BmpPath) - 3) + 'jpg');
    Result := Copy(BmpPath, 1, Length(BmpPath) - 3) + 'jpg';
  finally
    BMP.Free;
    Jpg.Free;
    BMP := nil;
    Jpg := nil;
  end;
end;

function TUsbCamera.Image_FitBitmap(const Source, Dest: string; const x, y: integer): Boolean;
var
  abmp, bbmp: tbitmap; //定义变量  abmp为源对象变量  bbmp为目的对象变量
begin
  abmp := tbitmap.Create; //创建位图资源
  bbmp := tbitmap.Create; //创建位图资源
  try
    abmp.LoadFromFile(Source); //载入源位图资源
    bbmp.Width := x; //设置目的位图的宽
    bbmp.Height := y; //设置目的位图的高
    bbmp.PixelFormat := pfDevice; //设置位图格式为当前设备默认格式
    SetStretchBltMode(bbmp.Canvas.Handle, COLORONCOLOR); //设置指位图拉伸模式
    StretchBlt(bbmp.Canvas.Handle, 0, 0, bbmp.Width, bbmp.Height, abmp.Canvas.Handle, 0, 0, abmp.Width, abmp.Height, srccopy); //从源矩形中复制一个位图到目标矩形并适当压缩
    bbmp.SaveToFile(Dest); //保存转换后的目的图片
  finally
    abmp.Free; //释放资源
    bbmp.Free; //释放资源
  end;
end;


function TUsbCamera.Capture(FileName: string): boolean;
begin
  Result := False;
  if hWndC <> 0 then
  begin
    ForceDirectories(ExtractFilePath(FileName));
    if SendMessage(hWndC, WM_CAP_SAVEDIB, 0, longint(pchar(FileName))) <> 1 then exit; //截图
    if FileExists(FileName) then
    begin
      Image_FitBitmap(FileName, FileName, 400, 400);
      FileName := BmpToJpg(FileName);
      Result := True;
    end;
  end;
end;

constructor TUsbCamera.Create();
begin
end;

destructor TUsbCamera.Destroy;
begin
  Stop;

  inherited;
end;

function TUsbCamera.Play(Panel: TPanel): boolean;
begin
  Result := False;
  FPanel := Panel;
  //使用Tpanel控件来创建捕捉窗口
  hWndC := CapCreateCaptureWindowA('My Own Capture Window',
    WS_CHILD or WS_VISIBLE, //窗口样式
    0, //X坐标
    0, //Y坐标
    FPanel.Width, //窗口宽
    FPanel.Height, //窗口高
    FPanel.Handle, //窗口句柄
    0); //一般为0
  if hWndC <> 0 then
  begin
    if SendMessage(hWndC, WM_CAP_SET_CALLBACK_VIDEOSTREAM, 0, 0) <> 1 then exit;
    //捕捉一个视频流
    if SendMessage(hWndC, WM_CAP_SET_CALLBACK_ERROR, 0, 0) <> 1 then exit; //得到一个设备错误
    if SendMessage(hWndC, WM_CAP_SET_CALLBACK_STATUSA, 0, 0) <> 1 then exit; //得到一个设备状态
    if SendMessage(hWndC, WM_CAP_DRIVER_CONNECT, 0, 0) <> 1 then exit;
    //将一个捕捉窗口与一个设备驱动相关联
    if SendMessage(hWndC, WM_CAP_SET_SCALE, 1, 0) <> 1 then exit;
    if SendMessage(hWndC, WM_CAP_SET_PREVIEWRATE, 66, 0) <> 1 then exit;
    SendMessage(hWndC, WM_CAP_SET_OVERLAY, 1, 0);
    if SendMessage(hWndC, WM_CAP_SET_PREVIEW, 1, 0) <> 1 then exit;
    Result := True;
    FIsOpen := True;
  end;
end;

function TUsbCamera.StartRecord(FileName: string): Boolean;
begin
  Result := False;
  if hWndC <> 0 then
  begin
    SendMessage(hWndC, WM_CAP_FILE_SET_CAPTURE_FILEA, 0, Longint(pchar(FileName))); // 录成AVI
    Result := SendMessage(hWndC, WM_CAP_SEQUENCE, 0, 0) = 1;
  end;
end;

function TUsbCamera.StopRecord: Boolean;
begin
  Result := False;
  if hWndC <> 0 then Result := SendMessage(hWndC, WM_CAP_STOP, 0, 0) = 1;
end;

function TUsbCamera.Stop: boolean;
begin
  Result := False;
  if hWndC <> 0 then
  begin
    Result := SendMessage(hWndC, WM_CAP_DRIVER_DISCONNECT, 0, 0) = 1; //将捕捉窗同驱动器断开
    FIsOpen := False;
  end;
end;

end.