DELPHI开发摄像头

DELPHI可以通过调用Windows API来实现摄像头的开发。以下是一个简单的例子，可以在DELPHI中调用Windows API来打开和关闭摄像头，并显示摄像头捕获的图像：

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    btnStart: TButton;
    btnStop: TButton;
    imgVideo: TImage;
    tmrVideo: TTimer;
    procedure btnStartClick(Sender: TObject);
    procedure btnStopClick(Sender: TObject);
    procedure tmrVideoTimer(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
  private
    { Private declarations }
    hCapWnd: HWND;
    hCapDC: HDC;
    hBitMap: HBITMAP;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

const
  WM_CAP_START = WM_USER;
  WM_CAP_STOP = WM_USER + 1;
  WM_CAP_DRIVER_CONNECT = WM_USER + 10;
  WM_CAP_DRIVER_DISCONNECT = WM_USER + 11;
  WM_CAP_SET_PREVIEWRATE = WM_USER + 52;
  WM_CAP_SET_PREVIEW = WM_USER + 50;
  WM_CAP_GET_FRAME = WM_USER + 60;
  WM_CAP_COPY = WM_USER + 105;

function capCreateCaptureWindowA(lpszWindowName: LPCSTR; dwStyle: DWORD;
  x, y, nWidth, nHeight: Integer; hWndParent: HWND; nID: Integer): HWND;
  stdcall; external 'avicap32.dll' name 'capCreateCaptureWindowA';

function capGetDriverDescriptionA(wDriverIndex: UINT; lpszName: LPSTR;
  cbName: Integer; lpszVer: LPSTR; cbVer: Integer): Boolean; stdcall;
  external 'avicap32.dll' name 'capGetDriverDescriptionA';

procedure TForm1.FormCreate(Sender: TObject);
var
  drvName, drvVer: array[0..255] of Char;
  i: Integer;
begin
  for i := 0 to 9 do
  begin
    if capGetDriverDescriptionA(i, @drvName, SizeOf(drvName), @drvVer,
      SizeOf(drvVer)) then
      ShowMessage(IntToStr(i) + ': ' + string(drvName) + ' ' + string(drvVer));
  end;
end;

procedure TForm1.btnStartClick(Sender: TObject);
begin
  hCapWnd := capCreateCaptureWindowA('Webcam', WS_VISIBLE, 0, 0, 640, 480,
    imgVideo.Handle, 0);
  if hCapWnd <> 0 then
  begin
    SendMessage(hCapWnd, WM_CAP_DRIVER_CONNECT, 0, 0);
    SendMessage(hCapWnd, WM_CAP_SET_PREVIEWRATE, 30, 0);
    SendMessage(hCapWnd, WM_CAP_SET_PREVIEW, 1, 0);
    tmrVideo.Enabled := True;
  end;
end;

procedure TForm1.btnStopClick(Sender: TObject);
begin
  tmrVideo.Enabled := False;
  SendMessage(hCapWnd, WM_CAP_DRIVER_DISCONNECT, 0, 0);
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  if tmrVideo.Enabled then
    btnStopClick(nil);
end;

procedure TForm1.tmrVideoTimer(Sender: TObject);
begin
  SendMessage(hCapWnd, WM_CAP_GET_FRAME, 0, 0);
  hCapDC := GetDC(hCapWnd);
  hBitMap := GetCurrentObject(hCapDC, OBJ_BITMAP);
  imgVideo.Picture.Bitmap.Handle := hBitMap;
end;

end.

这个例子中，我们调用了Windows API中的`capCreateCaptureWindowA`函数创建了一个名为“Webcam”的摄像头窗口，并将该窗口的句柄传递给`imgVideo`控件。然后，我们通过发送各种消息来控制摄像头的行为，例如打开和关闭摄像头、设置预览速率以及捕获帧等。最后，我们使用`imgVideo.Picture.Bitmap.Handle`来获取摄像头捕获的图像，并将其显示在`imgVideo`控件上。